Inorganic Chemistry

CSIR NET Chemical Science — Organometallic Compounds previous year questions

112 questions · 2011–2021 · all with verified answer · last checked 2026-11-06

Make a PDF of this topic

Q1 · June 2021 · 2 marks

Consider following statement(s) in the context of NO and CO ligands

(a) In the bent mode, NO donates three electrons to the metal center. A only
(b) In IR spectrum, the v_{\mathrm{NO}} for the bent nitrosyl ligand typically lies between 1525 and 1690 \mathrm{~cm}^{-1} B and C
(c) The HOMO of NO and CO are \pi^{*} and \sigma orbitals, respectively A and C
(d) A and B

Show answer

Answer: (b)

Report an error in ABC26IN1504

Q2 · June 2021 · 2 marks

The correct geometries for the metal carbonyl clusters, A-C

(a) \left[\mathrm{Ru}_{6}(\mathrm{CO})_{17} \mathrm{~B}\right]^{-} A: pentagonal bipyramidal, B: trigonal prismatic, and C:tetrahedral
(b) \left[\mathrm{Os}_{6}(\mathrm{CO})_{18} \mathrm{P}\right]^{-} A: pentagonal bipyramidal, B: octahedral, and C: square
(c) \left[\mathrm{Os}_{4}(\mathrm{CO})_{16}\right] are A: octahedral, B: trigonal prismatic, and C: tetrahedral
(d) A: octahedral, B: trigonal prismatic, and C: square

Show answer

Answer: (d)

Report an error in ABC26IN1506

Q3 · 2020 · 2 marks

Among the following complexes, the one showing the highest rate of substitution of a CO ligand on heating with one equivalent of \mathrm{PPh_3} in decalin, is

(a) (\eta^5\text{-}\mathrm{C_5H_5})\mathrm{Mn(CO)_3}
(b) (\eta^5\text{-}\mathrm{C_5Ph_5})\mathrm{Mn(CO)_3}
(c) (\eta^5\text{-}\mathrm{C_5Me_5})\mathrm{Mn(CO)_3}
(d) (\eta^5\text{-indenyl})\mathrm{Mn(CO)_3}

Show answer

Answer: (d)

Report an error in ABC26IN0286

Q4 · 2020 · 2 marks

The geometry/shape of the Fe4 core of the cluster \left[\mathrm{Fe}{ }_{4} \mathrm{C}(\mathrm{CO})_{12}\right]^{-2} is

(a) tetrahedron
(b) square pyramid
(c) butterfly
(d) trigonal bipyramid

Show answer

Answer: (c)

Report an error in ABC26IN1500

Q5 · 2020 · 2 marks

The number of peaks with relative intensities observed in the { }^{1} \mathrm{H} \mathrm{NMR} spectra of [ \left(\mathbf{C p})_{2} \mathbf{F e}(\mathbf{C O})_{2}\right] at +30^{\circ} \mathrm{C} and -80^{\circ} \mathrm{C} in diethyl ether are, respectively

(a) Two peaks (1:1) and four peaks (5:2:2:1)
(b) One peak and two peaks (1:1)
(c) Two peaks (1:1) at both the temperatures
(d) One peak and four peaks (5: 2: 2: 1)

Show answer

Answer: (a)

Report an error in ABC26IN1502

Q6 · 2019 · 2 marks

The rate-determining step in the catalytic synthesis of acetic acid by Monsanto process is

(a) oxidative addition of \mathrm{CH_3I} to \mathrm{[RhI_2(CO)_2]^-}
(b) migration of \mathrm{CH_3} group to CO of \mathrm{[RhI_3(CO)_2(CH_3)]^-}
(c) loss of \mathrm{CH_3COI} from \mathrm{[RhI_3(CO)_2(COCH_3)]^-}
(d) coordination of CO to \mathrm{[RhI_3CO(COCH_3)]^-}

Show answer

Answer: (a)

Report an error in ABC26IN0283

Q7 · June 2019 · 2 marks

The number of \mathrm{Ni}-\mathrm{Ni} bonds in \left[\mathrm{CpNi}\left(\mu-\mathrm{PPh}_{2}\right)\right]_{2} complex obeying the 18 electron rule is

(a) 0
(b) 1
(c) 2
(d) 3

Show answer

Answer: (a)

Report an error in ABC26IN1483

Q8 · 2018 · 2 marks

For the reaction of trans- [\operatorname{Ir} \mathrm{X}(\mathrm{CO})(\mathrm{PPh} 3) 2](\mathrm{X}=\mathrm{F}, \mathrm{Cl}, \mathrm{Br}, \mathrm{I}) with O 2 , correct order of variation of rate with X is

(a) \mathrm{Br}>\mathrm{I}>\mathrm{F}>\mathrm{Cl}
(b) \mathrm{F}>\mathrm{Cl}>\mathrm{Br}>\mathrm{I}
(c) \mathrm{F} \approx \mathrm{Cl} \approx \mathrm{Br} \approx 1
(d) I > Br > Cl > F

Show answer

Answer: (d)

Report an error in ABC26IN1484

Q9 · June 2019 · 2 marks

The organic species isolobal to \left[\mathrm{Fe}(\mathrm{CO})_{2}\left(\mathrm{PPh}_{3}\right)\right]^{-}is

(a) \mathrm{CH}_{2}{ }^{+}
(b) \mathrm{CH}^{-}
(c) \mathrm{CH}_{3}
(d) CH

Show answer

Answer: (d)

Report an error in ABC26IN1485

Q10 · 2018 · 2 marks

The correct statements about \left[\mathrm{Ru}_{6} \mathrm{C}(\mathrm{CO})_{17}\right] cluster from the following (1) it is an 86 electron cluster (2) it is a closo structure type (3) its shape is capped square pyramid (4) carbon interacts with all the Ru centres in the cluster are

(a) 1, 2, 3 and 4
(b) 1 and 2 only
(c) 1, 2 and 3
(d) 1, 2 and 4

Show answer

Answer: (d)

Report an error in ABC26IN1486

Q11 · 2018 · 2 marks

Considering \sigma-bonding only, in the MO diagram of a metal complex with trigonal bipyramidal (TBP) geometry, the d-orbitals which remain non-bonding are

(a) \mathrm{dz}^{2} and \mathrm{d}_{\mathrm{xz}}
(b) \mathrm{d}_{\mathrm{xz}} and \mathrm{d}_{\mathrm{yz}}
(c) \mathrm{d}_{\mathrm{x}^{2}-\mathrm{v}^{2}} and \mathrm{d}_{\mathrm{xy}}
(d) \mathrm{dz}^{2} and \mathrm{d}_{\mathrm{yz}}

Show answer

Answer: (b)

Report an error in ABC26IN1489

Q12 · Dec 2019 · 2 marks

The most stable vanadium species in aqueous medium is

(a) \left[\mathrm{V}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}(\mathrm{OH})\right]^{+2}
(b) \left[\mathrm{VO}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}\right]^{+2}
(c) \left[\mathrm{VO}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}\right]^{+}
(d) \left[\mathrm{V}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}(\mathrm{OH})_{2}\right]^{+2}

Show answer

Answer: (b)

Report an error in ABC26IN1491

Q13 · Dec 2019 · 2 marks

The correct order of metal-carbon distance is

(a) \mathrm{Fe}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Co}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Ni}\left(\eta^{5}-\mathrm{Cp}\right)_{2}
(b) \mathrm{Fe}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Ni}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Co}\left(\eta^{5}-\mathrm{Cp}\right)_{2}
(c) \mathrm{Ni}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Fe}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Co}\left(\eta^{5}-\mathrm{Cp}\right)_{2}
(d) \mathrm{Ni}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Co}\left(\eta^{5}-\mathrm{Cp}\right)_{2}>\mathrm{Fe}\left(\eta^{5}-\mathrm{Cp}\right)_{2}

Show answer

Answer: (d)

Report an error in ABC26IN1492

Q14 · Dec 2019 · 2 marks

The rate-determining step in the catalytic synthesis of acetic acid by Monsanto process is

(a) oxidative addition of \mathrm{CH}_{3} \mathrm{I} to \left[\mathrm{RhI}_{2}(\mathrm{CO})_{2}\right]^{-}
(b) migration of \mathrm{CH}_{3} group to CO of \left[\mathrm{RhI}_{3}(\mathrm{CO})_{2}\left(\mathrm{CH}_{3}\right)\right]^{-}
(c) loss of \mathrm{CH}_{3} \mathrm{COI} from \left[\mathrm{RhI}_{3}(\mathrm{CO})_{2}\left(\mathrm{COCH}_{3}\right)\right]^{-}
(d) coordination of CO to \left[\mathrm{RhI}_{3} \mathrm{CO}\left(\mathrm{COCH}_{3}\right)\right]^{-}

Show answer

Answer: (a)

Report an error in ABC26IN1493

Q15 · Dec 2019 · 2 marks

The cluster types of \left[\mathrm{Fe}_{5}(\mathrm{CO})_{14} \mathrm{~N}\right]^{-}and \left[\mathrm{Co}_{6}(\mathrm{CO})_{13} \mathrm{~N}\right]^{-}are, respectively,

(a) nido-, nido
(b) nido-, closo
(c) closo-, nido
(d) closo-, closo

Show answer

Answer: (b)

Report an error in ABC26IN1494

Q16 · Dec 2019 · 2 marks

Among the following complexes, the one showing the highest rate of substitution of a CO ligand on heating with one equivalent of PPh3 in decalin, is

(a) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Mn}(\mathrm{CO})_{3}
(b) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{Ph}_{5}\right) \mathrm{Mn}(\mathrm{CO})_{3}
(c) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{Me}_{5}\right) \mathrm{Mn}(\mathrm{CO})_{3}
(d) ( \eta^{5}-indenyl) \mathrm{Mn}(\mathrm{CO})_{3}

Show answer

Answer: (d)

Report an error in ABC26IN1497

Q17 · 2018 · 2 marks

The correct order of acceptor ability of the phosphorus ligands is

(a) \mathrm{PMe_3 > PPh_3 > P(OPh)_3 > PF_3}
(b) \mathrm{PF_3 > P(OPh)_3 > PPh_3 > PMe_3}
(c) \mathrm{PF_3 > PMe_3 > PPh_3 > P(OPh)_3}
(d) \mathrm{P(OPh)_3 > PF_3 > PMe_3 > PPh_3}

Show answer

Answer: (b)

Report an error in ABC26IN0273

Q18 · 2018 · 2 marks

The number of Ni-Ni bonds in [\mathrm{CpNi}(\mu\text{-}\mathrm{PPh_2})]_2 complex obeying the 18 electron rule is

(a) 0
(b) 1
(c) 2
(d) 3

Show answer

Answer: (a)

Report an error in ABC26IN0277

Q19 · 2018 · 2 marks

The organic species isolobal to \mathrm{[Fe(CO)_2(PPh_3)]^-} is

(a) \mathrm{CH_2^+}
(b) \mathrm{CH^-}
(c) \mathrm{CH_3}
(d) CH

Show answer

Answer: (d)

Report an error in ABC26IN0278

Q20 · June 2018 · 2 marks

The correct of \mathrm{C}-\mathrm{O} bond length is

(a) \mathrm{H}_{3} \mathrm{~B} . \mathrm{CO}>\left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}>\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]>\left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}
(b) \left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}>\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]>\left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}>\mathrm{H}_{3} \mathrm{~B} . \mathrm{CO}
(c) \left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}>\mathrm{H}_{3} \mathrm{~B} . \mathrm{CO}>\left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}<\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]
(d) \left[\mathrm{Cr}(\mathrm{CO})_{6}\right]>\left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}>\mathrm{H}_{3} \mathrm{~B} . \mathrm{CO}>\left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}

Show answer

Answer: (b)

Report an error in ABC26IN1466

Q21 · 2018 · 2 marks

Which of the following are NOT closo clusters?

\left[\left\{\mathrm{Co}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\right\} 2\left(\mathrm{C}_{2} \mathrm{~B}_{6} \mathrm{H}_{8}\right)\right](\mathrm{A})\left[\mathrm{B}_{4} \mathrm{C}_{2} \mathrm{H}_{8}\right](\mathrm{B})\left[\mathrm{B}_{10} \mathrm{H}_{13}\left\{\left(\mathrm{Au}\left(\mathrm{PPh}_{3}\right)\right\}\right](\mathrm{C})\left[\mathrm{C}_{2} \mathrm{~B}_{8} \mathrm{H}_{10}\right](\mathrm{D})\right.

(a) (C) and (D)
(b) (A) and (B)
(c) (A) and (C)
(d) (B) and (C)

Show answer

Answer: (d)

Report an error in ABC26IN1469

Q22 · 2018 · 2 marks

The structures of \left[\mathrm{Re}_{2} \mathrm{C}_{18}\right]^{-2}(\mathrm{~A}) and \left[\mathrm{Os}_{2} \mathrm{Cl}_{8}\right]^{-2}(\mathrm{~B}) are made up of two \mathrm{MCl}_{4} units. For these structure which statement is correct?

(a) (A) and (B) both have \mathrm{MCl}_{4} units eclipsed.
(b) (A) and (B) both have \mathrm{MCl}_{4} units staggered.
(c) (A) has both \mathrm{MCl}_{4} units staggered and (B) has both \mathrm{MCl}_{4} units eclipsed.
(d) (A) has both \mathrm{MCl}_{4} units eclipsed and (B) has both \mathrm{MCl}_{4} units staggered.

Show answer

Answer: (d)

Report an error in ABC26IN1473

Q23 · Dec 2018 · 2 marks

The correct order of acceptor ability of the phosphorus ligands is

(a) \mathrm{PMe}_{3}>\mathrm{PPh}_{3}>\mathrm{P}(\mathrm{OPh})_{3}>\mathrm{PF}_{3}
(b) \mathrm{PF}_{3}>\mathrm{P}(\mathrm{OPh})_{3}>\mathrm{PPh}_{3}>\mathrm{PMe}_{3}
(c) \mathrm{PF}_{3}>\mathrm{PMe}_{3}>\mathrm{PPh}_{3}>\mathrm{P}(\mathrm{OPh})_{3}
(d) \mathrm{P}(\mathrm{OPh})_{3}>\mathrm{PF}_{3}>\mathrm{PMe}_{3}>\mathrm{PPh}_{3}

Show answer

Answer: (b)

Report an error in ABC26IN1475

Q24 · 2018 · 2 marks

Identify the correct statement(s) for \mathrm{H}_{3} \mathrm{~B} . \mathrm{CO}

(a) \mathbf{s p}^{\mathbf{2}} hybridized orbital of \mathbf{B} accepts the lone pair of \mathbf{C O}.
(b) Its \overline{\mathbf{v}}_{\mathrm{CO}} value is more than that for free CO
(c) Formal oxidation state of C is +4 in the compound

Show answer

Answer: (b)

Report an error in ABC26IN1476

Q25 · 2018 · 2 marks

The VCN in \left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{-3}(\mathrm{~A}) and \left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{-4}(\mathrm{~B}) and \mathrm{V}_{\mathrm{co}} in \left[\mathrm{Cr}(\mathrm{CO})_{3}\left(\mathrm{NH}_{3}\right)_{3}\right](\mathrm{C}) and \left[\mathrm{Cr}(\mathrm{CO})_{6}\right](\mathrm{D}) are compared below. The pair with correct order is

(a) A > B ; C > D
(b) A > B ; C < D
(c) A < B ; C > D
(d) A < B ; C < D

Show answer

Answer: (b)

Report an error in ABC26IN1479

Q26 · 2018 · 2 marks

The cluster type and geometry of the species \left[\mathrm{R} \mathrm{h}_{9} \mathrm{P}(\mathrm{CO})_{21}\right]^{-2} are

(a) closo, tricapped trigonal prism
(b) arachno, trigonal prism
(c) nido, capped square antiprism
(d) nido, bicapped trigonal prism

Show answer

Answer: (c)

Report an error in ABC26IN1480

Q27 · 2017 · 2 marks

Choose the isoelectronic pair among the following: A. \mathrm{[V(CO)_6]} B. [\mathrm{Cu}(\eta^5\text{-}\mathrm{C_5H_5})(\mathrm{CO})] C. \mathrm{[Co(CO)_4]^-} D. \mathrm{[IrCl(CO)(PPh_3)]}

(a) A and B
(b) B and C
(c) C and D
(d) A and D

Show answer

Answer: (b)

Report an error in ABC26IN0263

Q28 · June 2017 · 2 marks

Choose the isoelectronic pair among the following:

(a) \left[\mathrm{V}(\mathrm{CO})_{6}\right] A and B
(b) \left[\mathrm{Cu}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)(\mathrm{CO})\right] B and C
(c) \left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-} C and D
(d) \left[\operatorname{IrCl}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)\right] A and D

Show answer

Answer: (b)

Report an error in ABC26IN1455

Q29 · 2017 · 2 marks

An organometallic fragment that is isolobal to \mathrm{CH}_{3}{ }^{+}is

(a) \left[\mathrm{Fe}(\mathrm{CO})_{5}\right]
(b) \left[\mathrm{Mn}(\mathrm{CO})_{5}\right]
(c) \left[\mathrm{Cr}(\mathrm{CO})_{5}\right]
(d) \left[\mathrm{Ni}(\mathrm{CO})_{3}\right]^{+}

Show answer

Answer: (c)

Report an error in ABC26IN1456

Q30 · 2017 · 2 marks

The number of bonding molecular orbitals and the number of available skeletal electrons in \left[\mathrm{B}_{6} \mathrm{H}_{6}\right]^{-2}, respectively, are:

(a) 7 and 14
(b) 6 and 12
(c) 18 and 12
(d) 11 and 14

Show answer

Answer: (a)

Report an error in ABC26IN1458

Q31 · June 2017 · 2 marks

Addition of \mathrm{NaBH}_{4} to \left[\left(\eta^{5}-\mathrm{C}_{\mathrm{p}}\right) \mathrm{Fe}\left(\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{6}\right)\right]^{+}will give

(a) \left[\left(\eta^{5}-\mathrm{Cp}\right) \mathrm{Fe}(\mathrm{H})_{2}\right]
(b) \left[\left(\eta^{5}-\mathrm{Cp}\right) \mathrm{Fe}(\mathrm{H})\left(\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{6}\right)\right]
(c) \left[\left(\eta^{5}-\mathrm{Cp}\right) \mathrm{Fe}\left(\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{6}\right)\right]
(d) \left[\left(\eta^{5}-\mathrm{Cp}\right) \mathrm{Fe}\left(\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{7}\right)\right]

Show answer

Answer: (d)

Report an error in ABC26IN1459

Q32 · 2017 · 2 marks

Among the following species isolobal to \mathbf{C H}_{\mathbf{2}} are

(a) \mathrm{CpCr}(\mathrm{CO})_{2} A, C and E
(b) CpCu B, C and D
(c) \mathrm{Ni}(\mathrm{CO})_{2} B, C and E
(d) \mathrm{Cr}(\mathrm{CO})_{4} E. \mathrm{Fe}(\mathrm{CO})_{4} A, B and D

Show answer

Answer: (c)

Report an error in ABC26IN1463

Q33 · 2017 · 2 marks

According to Wade's rules, the cluster type and geometry of \left[\mathrm{Sn}_{9}\right]^{-4}, respectively, are

(a) closo and tricapped trigonal prismatic
(b) nido and monocapped square-antiprismatic
(c) arachno and heptagonal bipyramidal
(d) closo and monocapped square antiprismatic

Show answer

Answer: (b)

Report an error in ABC26IN1465

Q34 · 2016 · 2 marks

\mathrm{CpM}\left[\mathrm{Cp}\right. is \left.\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\right] fragment isolobal with a BH fragment is

(a) CpGe
(b) CpMn
(c) CpRu
(d) CpCo

Show answer

Answer: (d)

Report an error in ABC26IN1435

Q35 · 2016 · 2 marks

The number of metal-metal bonds in \left[\mathrm{Co}_{2} \mathrm{Fe}_{2}(\mathrm{CO})_{11}\left(\eta_{4}-\mathrm{PPh}\right)_{2}\right] is

(a) 3
(b) 4
(c) 5
(d) 6

Show answer

Answer: (b)

Report an error in ABC26IN1436

Q36 · 2016 · 2 marks

Choose the correct option for carbonyl fluoride with respect to bond angle and bond length

(a) \angle \mathrm{F}-\mathrm{C}-\mathrm{F}>\angle \mathrm{F}-\mathrm{C}-\mathrm{O} and \mathrm{C}-\mathrm{F}>\mathrm{C}-\mathrm{O}
(b) \angle \mathrm{F}-\mathrm{C}-\mathrm{F}>\angle \mathrm{F}-\mathrm{C}-\mathrm{O} and \mathrm{C}-\mathrm{F}<\mathrm{C}-\mathrm{O}
(c) \angle \mathrm{F}-\mathrm{C}-\mathrm{F}<\angle \mathrm{F}-\mathrm{C}-\mathrm{O} and \mathrm{C}-\mathrm{F}>\mathrm{C}-\mathrm{O}
(d) \angle \mathrm{F}-\mathrm{C}-\mathrm{F}<\angle \mathrm{F}-\mathrm{C}-\mathrm{O} and \mathrm{C}-\mathrm{F}<\mathrm{C}-\mathrm{O}

Show answer

Answer: (c)

Report an error in ABC26IN1437

Q37 · 2016 · 2 marks

The { }^{1} \mathrm{H} NMR spectrum of \left[\mathrm{Ru}\left(\eta^{4}-\mathrm{C}_{8} \mathrm{H}_{8}\right)(\mathrm{CO})_{3}\right] at 23^{\circ} \mathrm{C} consists of a sharp single line. The number of signals observed at low temperature (-140 °C) in its spectrum is

(a) 8
(b) 6
(c) 4
(d) 2

Show answer

Answer: (c)

Report an error in ABC26IN1439

Q38 · 2016 · 2 marks

The numbers of skeletal electrons present in the compounds \mathrm{C}_{2} \mathrm{~B}_{3} \mathrm{H}_{5}, \mathrm{C}_{2} \mathrm{~B}_{4} \mathrm{H}_{6}, and \mathrm{B}_{5} \mathrm{H}_{9} are, respectively

(a) 10, 12 and 12
(b) 12, 14 and 14
(c) 10, 12 and 14
(d) 12, 14 and 12

Show answer

Answer: (b)

Report an error in ABC26IN1440

Q39 · 2016 · 2 marks

The rate of alkene coordination to \left[\mathrm{PtCl}_{4}\right]^{-2} is highest for

(a) norbornene
(b) ethylene
(c) cyclohexene
(d) 1-butene

Show answer

Answer: (a)

Report an error in ABC26IN1447

Q40 · 2016 · 2 marks

Consider the following statements, I and II: \mathrm{I}:\left[\mathrm{Rh}(\mathrm{CO})_{2} \mathrm{I}_{2}\right]^{-}catalytically converts \mathrm{CH}_{3} \mathrm{I} and CO to \mathrm{CH}_{3} \mathrm{COI} II : \left[\mathrm{Rh}(\mathrm{CO})_{2} \mathrm{I}_{2}\right]^{-}is diamagnetic in nature The correct from the following is

(a) I and II are correct and II is an explanation of I
(b) I and II are correct and II is not an explanation of I
(c) I is correct and II is incorrect
(d) I and II are incorrect

Show answer

Answer: (b)

Report an error in ABC26IN1448

Q41 · 2016 · 2 marks

According to Wade's rules, the correct structural types of \left[\mathrm{Co}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{B}_{4} \mathrm{H}_{8}\right] and \left[\mathrm{Mn}\left(\eta^{2}-\mathrm{B}_{3} \mathrm{H}_{8}\right)(\mathrm{CO})_{4}\right] are

(a) closo and nido
(b) nido and arachno
(c) closo and arachno
(d) nido and nido

Show answer

Answer: (b)

Report an error in ABC26IN1451

Q42 · 2016 · 2 marks

The correct geometry of \left[\mathrm{Rh}_{6} \mathrm{C}(\mathrm{CO})_{15}\right]^{-2} is

(a) octahedron
(b) pentagonal pyramid
(c) trigonal prism
(d) monocapped square pyramid

Show answer

Answer: (c)

Report an error in ABC26IN1452

Q43 · 2015 · 2 marks

According to Wade's theory the anion \mathrm{[B_{12}H_{12}]^{2-}} adopts

(a) closo-structure
(b) arachno-structure
(c) hypo-structure
(d) nido-structure

Show answer

Answer: (a)

Report an error in ABC26IN0251

Q44 · 2015 · 2 marks

The reaction of \mathrm{SbCl_3}, with 3 equivalents of EtMgBr yields compound X. Two equivalents of \mathrm{SbI_3} react with one equivalent of X to give Y. In the solid state, Y has a 1D-polymeric structure in which each Sb is in a square pyramidal environment. Compounds X and Y respectively, are

(a) \mathrm{SbEt_3}, and [\mathrm{Sb(Et)I_2}]_n
(c) \mathrm{SbEt_3}, and [\mathrm{SbEt_2Br_2}]_n
(b) \mathrm{Sb(Et_2)Cl} and [\mathrm{Sb(Et)Cl}]_n
(d) \mathrm{Sb(Et)Br_2} and [\mathrm{SbEt(I)(Br)}]_n

Show answer

Answer: (a)

Report an error in ABC26IN0252

Q45 · 2015 · 2 marks

Amongst the following (A) [\mathrm{Mn}(\eta^5\text{-Cp})(\mathrm{CO})_3] (B) [\mathrm{Os}(\eta^5\text{-Cp})_2] (C) [\mathrm{Ru}(\eta^5\text{-Cp})_2] and (D) [\mathrm{Fe}(\eta^5\text{-Cp})_2] the compounds with most shielded and deshielded Cp protons respectively, are

(a) D and A
(b) D and B
(c) C and A
(d) C and B

Show answer

Answer: (a)

Report an error in ABC26IN0254

Q46 · 2015 · 2 marks

The approximate positions of \nu_{\mathrm{co}} bands (\mathrm{cm^{-1}}) in the solid-state infrared spectrum and the Fe-Fe bond order in \mathrm{[Fe(\eta^5\text{-}C_5H_5)(\mu\text{-}CO)(CO)]_2} (non-centrosymmetric) respectively, are

(a) (2020, 1980, 1800) and one
(b) (2020, 1980, 1800) and two
(c) (2020, 1980) and one
(d) (2143) and one

Show answer

Answer: (a)

Report an error in ABC26IN0258

Q47 · 2015 · 2 marks

The binding modes of NO in 18 electron compounds [\mathrm{Co}(\mathrm{CO}) 3(\mathrm{NO})] and [\mathrm{Ni}(\eta 5-\mathrm{Cp})(\mathrm{NO})], respectively, are

(a) linear and bent
(b) bent and linear
(c) linear and linear
(d) bent and bent

Show answer

Answer: (c)

Report an error in ABC26IN1408

Q48 · 2015 · 2 marks

The role of copper salt as co-catalyst in Wacker process is

(a) oxidation of \operatorname{Pd}(0) by Cu (II)
(b) oxidation of \operatorname{Pd}(\mathbf{0}) by \mathbf{C u}(\mathbf{I})
(c) oxidation of Pd(II) by Cu(I)
(d) oxidation of Pd(II) by Cu(II)

Show answer

Answer: (a)

Report an error in ABC26IN1409

Q49 · June 2015 · 2 marks

According to Wade's theory the anion \left[\mathrm{B}_{12} \mathrm{H}_{12}\right]^{2-} adopts

(a) closo-structure
(b) arachno-structure
(c) hypo-structure
(d) nido-structure

Show answer

Answer: (a)

Report an error in ABC26IN1414

Q50 · June 2015 · 2 marks

The reaction of \mathrm{SbCl}_{3}, with 3 equivalents of EtMgBr yields compound X . Two equivalents of \mathrm{SbI}_{3} react with one equivalent of X to give Y . In the solid state, Y has a 1 D -polymeric structure in which each Sb is in a square pyramidal environment. Compounds X and Y respectively, are

(a) \mathrm{SbEt}_{3}, and \left[\mathrm{Sb}(\mathrm{Et}) \mathrm{I}_{2}\right]_{\mathrm{n}}
(c) \mathrm{SbEt}_{3}, and \left[\mathrm{SbEt}_{2} \mathrm{Br}_{2}\right]_{\mathrm{n}}
(b) \mathrm{Sb}\left(\mathrm{Et}_{2}\right) \mathrm{Cl} and [\mathrm{Sb}(\mathrm{Et}) \mathrm{Cl}]_{\mathrm{n}}
(d) \mathrm{Sb}(\mathrm{Et}) \mathrm{Br}_{2} and [\mathrm{SbEt}(\mathrm{I})(\mathrm{Br})]_{\mathrm{n}}

Show answer

Answer: (a)

Report an error in ABC26IN1415

Q51 · 2015 · 2 marks

The following statements are given regarding the agostic interaction C-H----Ir observed in \left[\operatorname{Ir}\left(\mathrm{Ph}_{3} \mathrm{P}\right)_{3} \mathrm{Cl}\right].

(a) Upfield shift of C-H proton in 1H NMR spectrum
(b) Increased acid character of C-H
(c) \bar{v} co- in IR spectrum shifts to higher wavenumber

Show answer

Answer: (c)

Report an error in ABC26IN1416

Q52 · June 2015 · 2 marks

Amongst the following

(a) \left[\mathrm{Mn}\left(\eta^{5}-\mathrm{Cp}\right)(\mathrm{CO})_{3}\right] D and A
(b) \left[\mathrm{Os}\left(\eta^{5}-\mathrm{Cp}\right)_{2}\right] D and B
(c) \left[\mathrm{Ru}\left(\eta^{5}-\mathrm{Cp}\right)_{2}\right] and C and A
(d) \left[\mathrm{Fe}\left(\eta^{5}-\mathrm{Cp}\right)_{2}\right] the compounds with most shielded and deshielded \mathrm{C}_{\mathrm{p}} protons respectively, are C and B

Show answer

Answer: (a)

Report an error in ABC26IN1418

Q53 · 2015 · 2 marks

Total number of vertices in metal clusters \left[\mathrm{Ru}_{6}(\mathrm{C})(\mathrm{CO})_{17}\right]\left[\mathrm{Os}_{5}(\mathrm{C})(\mathrm{CO})_{15}\right] and \left[\mathbf{R u}_{\mathbf{5}}(\mathbf{C})(\mathbf{C O})_{\mathbf{1 6}}\right] are 6, 5 and 5, respectively. The predicted structures of these complexes, respectively are

(a) closo, nido and nido
(b) closo, nido and arachno
(c) arachno, closo and nido
(d) arachno, nido and closo

Show answer

Answer: (b)

Report an error in ABC26IN1419

Q54 · 2015 · 2 marks

The W-W bond order in \left[\mathrm{W}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)(\mu-\mathrm{Cl})(\mathrm{CO})_{2}\right]_{2} is

(a) three
(b) two
(c) one
(d) zero

Show answer

Answer: (d)

Report an error in ABC26IN1423

Q55 · 2015 · 2 marks

For the reaction of \left[\mathrm{Fe}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\mathrm{CH}_{3}\right)(\mathrm{CO})_{2}\right] with \mathrm{PMe}_{3}, the main intermediate is

(a) \left[\mathrm{Fe}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\mathrm{CH}_{3}\right)(\mathrm{CO})_{2}\left(\mathrm{PMe}_{3}\right)\right]
(b) \left[\mathrm{Fe}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\mathrm{COCH}_{3}\right)(\mathrm{CO})\right]
(c) \left[\mathrm{Fe}\left(\eta^{3}-\mathrm{C}_{5} \mathrm{H}_{5}\right)(\mathrm{CH} 3)(\mathrm{CO})_{2}\right]
(d) ) \left[\mathrm{Fe}\left(\eta^{3}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\mathrm{COCH}_{3}\right)(\mathrm{CO})\left(\mathrm{PMe}_{3}\right)\right]

Show answer

Answer: (b)

Report an error in ABC26IN1424

Q56 · 2015 · 2 marks

For uranocene, the correct statement(s) is/are

(a) oxidation state of uranium is '+4'
(b) it has cyclooctatetraenide ligands
(c) it is bent sandwich compound
(d) it has '-2' charge.

Show answer

Answer: (a)

Report an error in ABC26IN1427

Q57 · Dec 2015 · 2 marks

The final products of the reaction of carbonyl metalates \left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}and \left[\mathrm{Co}(\mathrm{CO})_{4}\right]- with \mathrm{H}_{3} \mathrm{PO}_{4} respectively, are

(a) \mathrm{V}(\mathrm{CO})_{6} and \mathrm{HCo}(\mathrm{CO})_{4}
(b) \mathrm{HV}(\mathrm{CO})_{6} and \mathrm{Co}_{2}(\mathrm{CO})_{8}
(c) \left[\mathrm{H}_{2} \mathrm{~V}(\mathrm{CO})_{6}\right]^{+}and \mathrm{HCo}(\mathrm{CO})_{4}
(d) \mathrm{V}(\mathrm{CO})_{6} and \mathrm{Co}_{2}(\mathrm{CO})_{8}

Show answer

Answer: (a)

Report an error in ABC26IN1428

Q58 · 2015 · 2 marks

The number of valence electrons provided by \left[\mathrm{Ru}(\mathrm{CO})_{3}\right] fragment towards cluster bonding is

(a) 1
(b) 14
(c) 6
(d) 2

Show answer

Answer: (d)

Report an error in ABC26IN1429

Q59 · Dec 2015 · 2 marks

Heating a sample of \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Mo}(\mathrm{CO})_{3}\right]_{2} results in the formation of \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Mo}(\mathrm{CO})_{2}\right] with elimination of 2 equivalents of CO. The Mo-Mo bond order in this reaction changes from

(a) 2 to 3
(b) 1 to 2
(c) 1 to 3
(d) 2 to 4

Show answer

Answer: (c)

Report an error in ABC26IN1444

Q60 · 2014 · 2 marks

Amongst the following which is not isolobal pairs

(a) \mathrm{Mn(CO)_5}, \mathrm{CH_3}
(b) \mathrm{Fe(CO)_4}, O
(c) \mathrm{Co(CO)_3}, \mathrm{R_2Si}
(d) \mathrm{Mn(CO)_5}, RS

Show answer

Answer: (c)

Report an error in ABC26IN0244

Q61 · 2014 · 2 marks

Complexes \mathrm{HM(CO)_5} and \mathrm{[((\eta^5\text{-}C_5H_5)M'(CO)_3]_2} obey the 18-electron rule. Identify M and M' and their {}^{1}\mathrm{H} NMR chemical shifts relative to TMS.

(a) M = Mn, -7.5; M' = Cr, 4.10
(b) M = Cr, -4.10; M' = Mn, -7.5
(c) M = V, -7.5; M' = Cr, 4.10
(d) M = Mn, -10.22; M' = Fe, 2.80

Show answer

Answer: (a)

Report an error in ABC26IN0247

Q62 · 2014 · 2 marks

The ligand(s) that is (are) fluxional in [(\eta^{5}-\mathrm{C}_{5}\mathrm{H}_{5})(\eta-\mathrm{C}_{5}\mathrm{H}_{5})\mathrm{Fe}(\mathrm{CO})_{2}] in the temperature range 221-298\mathrm{K}, is (are)

(a) \eta^{5}-\mathrm{C}_{5}\mathrm{H}_{5}
(b) \eta^{1}-\mathrm{C}_{5}\mathrm{H}_{5}
(c) \eta^{5}-\mathrm{C}_{5}\mathrm{H}_{5} and \mathrm{CO}
(d) \eta^{1}-\mathrm{C}_{5}\mathrm{H}_{5} and \mathrm{CO}

Show answer

Answer: (b)

Report an error in ABC26IN1389

Q63 · 2014 · 2 marks

The typical electronic configurations of the transition metal centre for oxidative addition

(a) \mathrm{d}^{0} and \mathrm{d}^{8}
(b) \mathrm{d}^{6} and \mathrm{d}^{8}
(c) \mathrm{d}^{8} and \mathrm{d}^{10}
(d) \mathrm{d}^{5} and \mathrm{d}^{10}

Show answer

Answer: (c)

Report an error in ABC26IN1390

Q64 · 2014 · 2 marks

The oxidation state of Ni and the number of metal-metal bonds in \left[\mathrm{Ni}_{2}(\mathrm{CO})_{6}\right]^{2-} that are consistent with the 18 electron rule are Ni (-II), I bond (b) Ni(IV), 2 bonds (c) Ni(-I), 1 bond (d) Ni(IV), 3 bonds

Show answer

Answer: (c)

Report an error in ABC26IN1391

Q65 · 2014 · 2 marks

{ }^{1} \mathrm{H} NMR spectrum of \left.\left[\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{Rh}\right)\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)_{2}\right] at -20^{\circ} \mathrm{C} shows a typical \mathrm{AA}^{\prime} \mathrm{XX}^{\prime} pattern in the olefinic region. On increasing the temperature to -70^{\circ} \mathrm{C}, the separate lines collapse into a single line which is due to

(a) free rotation of the ethylene ligand about the metal-olefin bond
(b) interamolecular exchange between the ethylene ligands
(c) intermolecular exchange between the ethylene ligands
(d) change in hapticity of the cyclopentadienyl ligand

Show answer

Answer: (a)

Report an error in ABC26IN1394

Q66 · June 2014 · 2 marks

Amongst the following which is not isolobal pairs

(a) \mathrm{Mn}(\mathrm{CO})_{5}, \mathrm{CH}_{3}
(b) \mathrm{Fe}(\mathrm{CO})_{4}, O
(c) \mathrm{Co}(\mathrm{CO})_{3}, \mathrm{R}_{2} \mathrm{Si}
(d) \mathrm{Mn}(\mathrm{CO})_{5}, RS

Show answer

Answer: (c)

Report an error in ABC26IN1395

Q67 · 2014 · 2 marks

The hepticities 'x' and 'y' of the arene moieties in the diamagnetic complex \left[\left(\eta^{\mathrm{x}}-\mathrm{C}_{6} \mathrm{H}_{6}\right) \mathrm{Ru}\left(\eta^{\mathrm{y}}-\mathrm{C}_{6} \mathrm{H}_{6}\right)\right] respectively are

(a) 6 and 6
(b) 4 and 4
(c) 4 and 6
(d) 6 and 2

Show answer

Answer: (c)

Report an error in ABC26IN1396

Q68 · 2014 · 2 marks

The rate of the reaction \mathrm{Ni}(\mathrm{CO})_{4}+\mathrm{PPh}_{3} \xrightarrow{\Delta}\left[\mathrm{Ni}(\mathrm{CO})_{3}\left(\mathrm{PPh}_{3}\right)\right]+\mathrm{CO} depends on

(a) Concentration of both the reactants Butanoic acid
(b) Concentration of \mathrm{Ni}(\mathrm{CO})_{4} only Butanal
(c) Concentration of \mathrm{PPh}_{3} only 2-butanone
(d) The steric bulk of \mathrm{PPh}_{3} 8 Methylpropanoate

Show answer

Answer: (b)

Report an error in ABC26IN1397

Q69 · Dec 2014 · 2 marks

The product of the reaction of propene, \mathrm{CO} and \mathrm{H}_{2} in the presence of \mathrm{Co}_{2}(\mathrm{CO})_{8} as a catalyst is

(a) Butanoic acid
(b) Butanal
(c) 2-butanone
(d) Methylpropanoate

Show answer

Answer: (b)

Report an error in ABC26IN1398

Q70 · 2014 · 2 marks

Reductive elimination step in hydrogenation of alkenes by Wilkinson catalyst results in (neglecting solvent in coordination sphere of Rh)

(a) T-shaped \left[\mathrm{Rh}\left(\mathrm{PPh}_{3}\right)_{2} \mathrm{Cl}\right]
(b) Trigonal-planar \left[\mathrm{Rh}\left(\mathrm{PPh}_{3}\right)_{2} \mathrm{Cl}\right]^{2+}
(c) T-shaped \left[\mathrm{Rh}(\mathrm{H})\left(\mathrm{PPh}_{3}\right) \mathrm{Cl}\right]^{+}
(d) Trigonal-planar \left[\mathrm{Rh}(\mathrm{H})\left(\mathrm{PPh}_{3}\right)_{2}\right]

Show answer

Answer: (a)

Report an error in ABC26IN1401

Q71 · 2014 · 2 marks

\mathrm{NaI}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} ] reacts with \mathrm{Br}_{2} to give A. Reaction of A with \mathrm{LiAlH}_{4} results in B. The proton NMR spectrum of B consists of two singlets of relative intensity 5: 1. Compounds A and B respectively, are

(a) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{Br}, and \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{H}
(b) \left(\eta^{4}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO}){ }_{2} \mathrm{Br}_{2} and \left(\eta^{4}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{HBr}
(c) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{Br} and \left(\eta^{4}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2}(\mathrm{H})_{2}
(d) \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{Br} and \left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2} \mathrm{HBr}

Show answer

Answer: (a)

Report an error in ABC26IN1402

Q72 · 2014 · 2 marks

The compound that undergoes oxidative addition reaction in presence of \mathrm{H}_{2}, is

(a) \left[\mathrm{Mn}(\mathrm{CO})_{5}\right]^{-1}
(b) \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{MCO}_{3}\right]^{-1}
(c) \left[\operatorname{IrCl}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)_{2}\right]
(d) \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2} \mathrm{ReH}\right]

Show answer

Answer: (c)

Report an error in ABC26IN1403

Q73 · 2014 · 2 marks

{ }^{1} \mathrm{H} NMR spectrum of free benzene shows a peak at -7.2 ppm . The expected chemical shift (in ppm) of

(c) _{6} \mathrm{H}_{6} ligand in { }^{1} \mathrm{H} \mathrm{NMR} spectrum of \left[\left(\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{6}\right) \mathrm{Cr}(\mathrm{CO})_{3}\right] and the reason for it, if an, is/are 7.2
(a) 4.5; disruption of ring current
(b) 9.0 ; inductive effect
(d) 2.5 combination of inductive effect and disruption of ring current.

Show answer

Answer: (a)

Report an error in ABC26IN1404

Q74 · Dec 2014 · 2 marks

Complexes \mathrm{HM}(\mathrm{CO})_{5} and \left[\left(\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{M}^{\prime}(\mathrm{CO})_{3}\right]_{2}\right. obey the 18 -electron rule. Identify M and \mathrm{M}^{\prime} and their { }^{1} H NMR chemical shifts relative to TMS.

(a) \mathrm{M}=\mathrm{Mn},-7.5 ; \mathrm{M}^{\prime}=\mathrm{Cr}, 4.10
(b) \mathrm{M}=\mathrm{Cr},-4.10 ; \mathrm{M}^{\prime}=\mathrm{Mn},-7.5
(c) \mathrm{M}=\mathrm{V},-7.5 ; \mathrm{M}^{\prime}=\mathrm{Cr}, 4.10
(d) \mathrm{M}=\mathrm{Mn},-10.22 \mathrm{M}^{\prime}=\mathrm{Fe}, 2.80

Show answer

Answer: (a)

Report an error in ABC26IN1407

Q75 · 2013 · 2 marks

The ligand in uranocene is:

(a) \mathrm{C_8H_8^{2-}}
(b) \mathrm{C_5H_5^{2-}}
(c) \mathrm{C_6H_6}
(d) \mathrm{C_4H_4^{2-}}

Show answer

Answer: (a)

Report an error in ABC26IN0237

Q76 · 2013 · 2 marks

The number of metal-metal bonds in \mathrm{Ir_4(CO)_{12}} is

(a) 4
(b) 6
(c) 10
(d) 12

Show answer

Answer: (b)

Report an error in ABC26IN0239

Q77 · 2013 · 2 marks

In a cluster, \mathrm{H_3CoRu_3(CO)_{12}} total number of electrons considered to be involved in its formation is

(a) 57
(b) 60
(c) 63
(d) 72

Show answer

Answer: (b)

Report an error in ABC26IN0240

Q78 · 2013 · 2 marks

The correct statement regarding terminal/bridging CO groups in solid \mathrm{Co_4(CO)_{12}} and \mathrm{Ir_4(CO)_{12}} is

(a) both have equal number of bridging CO groups
(b) number of bridging CO groups in \mathrm{Co_4(CO)_{12}} is 4
(c) the number of terminal CO groups in \mathrm{Co_4(CO)_{12}} is 8
(d) the number of bridging CO groups in \mathrm{Ir_4(CO)_{12}} is zero.

Show answer

Answer: (d)

Report an error in ABC26IN0241

Q79 · 2013 · 2 marks

The oxidation state of molybdenum in \left[\left(\eta^{7} \text {-tropylium }\right) \mathrm{Mo}(\mathrm{CO})_{3}\right]^{+}is:

(a) +2
(b) +1
(c) 0
(d) -1

Show answer

Answer: (c)

Report an error in ABC26IN1374

Q80 · 2013 · 2 marks

The reaction, \left[(\mathrm{CO})_{5} \mathrm{Mn}(\mathrm{Me})\right]+\mathrm{CO} \rightarrow\left[(\mathrm{CO})_{5} \mathrm{Mn}\{\mathrm{C}(\mathrm{O}) \mathrm{Me}\}\right] is an example for

(a) oxidative addition
(b) electrophilic substitution
(c) nucleophilic substitution
(d) migratory insertion

Show answer

Answer: (d)

Report an error in ABC26IN1375

Q81 · June 2013 · 2 marks

The orders of reactivity of ligands, NMe3 PMe3, and CO with complexes MeTiCl, and (\mathrm{CO})_{5} \mathrm{Mo} (thf) are

(a) \mathrm{CO}>\mathrm{PMe}_{3}>\mathrm{NMe}_{3} and \mathrm{CO}>\mathrm{NMe}_{3}>\mathrm{PMe}_{3}
(b) \mathrm{PMe}_{3}>\mathrm{CO}>\mathrm{NMe}_{3} and \mathrm{NMe}_{3}>\mathrm{CO}>\mathrm{PMe}_{3}
(c) \mathrm{NMe}_{3}>\mathrm{PMe}_{3}>\mathrm{CO} and \mathrm{CO}>\mathrm{PMe}_{3}>\mathrm{NMe}_{3}
(d) \mathrm{NMe}_{3}>\mathrm{CO}>\mathrm{PMe}_{3} and \mathrm{PMe}_{3}>\mathrm{NMe}_{3}>\mathrm{CO}

Show answer

Answer: (c)

Report an error in ABC26IN1376

Q82 · 2013 · 2 marks

The number of metal-metal bonds in \left[\mathrm{W} 2(\mathrm{OPh})_{6}\right] is:

(a) 1
(b) 2
(c) 3
(d) 4

Show answer

Answer: (c)

Report an error in ABC26IN1377

Q83 · June 2013 · 2 marks

The number of metal-metal bonds in \operatorname{Ir}_{4}(\mathrm{CO})_{12} is

(a) 4
(b) 6
(c) 10
(d) 12

Show answer

Answer: (b)

Report an error in ABC26IN1378

Q84 · 2013 · 2 marks

The bond order of the metal-metal bond in the dimeric complex \left[\mathrm{Re}_{2} \mathrm{Cl}_{4}\left(\mathrm{PMe}_{2} \mathrm{Ph}\right)_{4}\right] is

(a) 4.0
(b) 3.5
(c) 3.0
(d) 2.5

Show answer

Answer: (b)

Report an error in ABC26IN1379

Q85 · 2013 · 2 marks

Which of the following in NOT suitable as catalyst for hydroformylation?

(a) \mathrm{HCo}(\mathrm{CO})_{4}
(b) \mathrm{HCo}(\mathrm{CO})_{3} \mathrm{PBu}_{3}
(c) \mathrm{HRh}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)_{3}
(d) \mathrm{H}_{2} \mathrm{Rh}\left(\mathrm{PPh}_{3}\right)_{2} \mathrm{Cl}

Show answer

Answer: (d)

Report an error in ABC26IN1380

Q86 · Dec 2013 · 2 marks

In a cluster, \mathrm{H}_{3} \mathrm{CoRu}_{3}(\mathrm{CO}) 12 total number of electrons considered to be involved in its formation is

(a) 57
(b) 60
(c) 63
(d) 72

Show answer

Answer: (b)

Report an error in ABC26IN1381

Q87 · 2013 · 2 marks

Among the following clusters,

\mathrm{A}=\left[(\mathrm{H}) \mathrm{Co}_{6}(\mathrm{CO})_{15}\right] \mathrm{B}=\left[(\mathrm{H})_{2} \mathrm{Os}_{6}(\mathrm{CO})_{18}\right] \mathrm{C}=\left[(\mathrm{H})_{2} \mathrm{Os}_{5}(\mathrm{CO})_{16}\right]

H is encapsulated in

(a) A only
(b) B only
(c) B and C only
(d) A and B only

Show answer

Answer: (a)

Report an error in ABC26IN1382

Q88 · Dec 2013 · 2 marks

The electrophile \mathrm{Ph}_{3} \mathrm{C} reacts with \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2}\left(\mathrm{CDMe}_{2}\right)\right]^{+}to give a product A . The product A is formed because

(a) Fe is oxidized
(b) alkyl is substituted with \mathrm{Ph}_{3} \mathrm{C}
(c) Fe-Ph bond is formed
(d) Alkyl is converted to alkene

Show answer

Answer: (d)

Report an error in ABC26IN1384

Q89 · 2013 · 2 marks

On reducing \mathbf{F e}_{3}(\mathbf{C O})_{12} with an excess of sodium, a carbonylate ion is formed. The iron is isoelectronic with

(a) \left[\mathrm{Mn}(\mathrm{CO})_{5}\right]^{-}
(b) \left[\mathrm{Ni}(\mathrm{CO})_{4}\right]
(c) \left[\mathrm{Mn}(\mathrm{CO})_{5}\right]^{+}
(d) \left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}

Show answer

Answer: (b)

Report an error in ABC26IN1388

Q90 · 2012 · 2 marks

The complex that DOES NOT obey 18- electron rule is:

(a) [(\eta^5\text{-}\mathrm{C_5H_5})\mathrm{RuCl(CO)(PPh_3)}]
(b) [\mathrm{W(CO)_3(SiMe_3)(Cl)(NCMe)_2}]
(c) [\mathrm{IrCl_3(PPh_3)_2(AsPh)_2}]^{-}
(d) [\mathrm{Os(N)Br_2(PMe_3)(NMe_2)}]^{-}

Show answer

Answer: (d)

Report an error in ABC26IN0233

Q91 · Dec 2012 · 2 marks

In hydrofomylation reaction using \mathrm{[Rh(PPh_3)_2(CO)(H)]} as the catalyst, addition of excess \mathrm{PPh_3}, would

(a) increase the rate of reaction
(b) decrease the rate of reaction.
(c) not influence of the rate of reaction
(d) stop the reaction.

Show answer

Answer: (b)

Report an error in ABC26IN0235

Q92 · 2012 · 2 marks

The reactions of \mathrm{Ni}(\mathrm{CO})_{4} with the ligand \left(\mathrm{L}=\mathrm{PMe}_{3}\right. or \left.\mathrm{P}(\mathrm{OMe})_{3}\right) \mathrm{L} yields \mathrm{Ni}(\mathrm{CO})_{3} \mathrm{~L}. The reaction is

(a) Associative
(b) Dissociative
(c) Interchange \left(\mathrm{I}_{\mathrm{a}}\right)
(d) Interchange \left(\mathrm{I}_{\mathrm{d}}\right)

Show answer

Answer: (b)

Report an error in ABC26IN1357

Q93 · 2012 · 2 marks

Among the following the strongest oxidizing agent is:

(a) \left[\mathrm{WO}_{4}\right]^{-2}
(b) \left[\mathrm{CrO}_{4}\right]^{-2}
(c) \left[\mathrm{MoO}_{4}\right]^{-2}
(d) \left[\mathrm{ReO}_{4}\right]^{-2}

Show answer

Answer: (b)

Report an error in ABC26IN1358

Q94 · 2012 · 2 marks

For the reaction, trans- \left[\mathrm{IrCl}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)_{2}\right]+\mathrm{Cl}_{2} \rightarrow trans -\left[\mathrm{IrCl}_{3}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)_{2}\right] the correct observation

(a) \bar{v} \operatorname{co} (product) >\bar{v} \operatorname{co} (reactant)
(b) \bar{v} \operatorname{co} (product) <\bar{v} \operatorname{co} (reactant)
(c) \bar{v} \operatorname{co} (product) =\bar{v} \operatorname{co} (reactant)
(d) \bar{v} \operatorname{co}( product )=\bar{v} \operatorname{co}( free CO)

Show answer

Answer: (a)

Report an error in ABC26IN1359

Q95 · June 2012 · 2 marks

The cluster having arachno type structure is:

(a) \left[\mathrm{Os}_{5}(\mathrm{CO})_{16}\right]
(b) \left[\mathrm{Os}_{3}(\mathrm{CO})_{12}\right]
(c) \left[\operatorname{Ir}_{4}(\mathrm{CO})_{12}\right]
(d) \left[\mathrm{Rh}_{6}(\mathrm{CO})_{16}\right]

Show answer

Answer: (b)

Report an error in ABC26IN1361

Q96 · 2012 · 2 marks

The final product of the reaction \left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}+\mathrm{MeLi} \rightarrow is:

(a) \left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+} \mathrm{Me}^{-}
(b) \left[\mathrm{Mn}(\mathrm{CO})_{5} \mathrm{Me}\right]
(c) \left[\mathrm{Mn}(\mathrm{CO})_{6}\right]
(d) \left[(\mathrm{MeCO}) \mathrm{Mn}(\mathrm{CO})_{5}\right]

Show answer

Answer: (d)

Report an error in ABC26IN1362

Q97 · Dec 2012 · 2 marks

The substitution of \eta^{5}-\mathrm{Cp} group with nitric oxide is the easiest for

(a) \left(\eta^{5}-\mathrm{Cp}_{2}\right) \mathrm{Fe}
(b) \left(\eta^{5}-\mathrm{Cp}_{2}\right) \mathrm{CoCl}
(c) \left(\eta^{5}-\mathrm{Cp}_{2}\right) \mathrm{Ni}
(d) \left(\eta^{5}-\mathrm{Cp}_{2}\right) \mathrm{Co}

Show answer

Answer: (c)

Report an error in ABC26IN1365

Q98 · Dec 2012 · 2 marks

In the cluster \left[\mathrm{Co}_{3}(\mathrm{CH})(\mathrm{CO})_{9}\right] obeying 18e rule, the number of metal-metal bonds and the bridging ligands respectively, are

(a) 3 and 1 CH
(b) 0 and 3 CO
(c) 3 and 1 CO
(d) 6 and 1 CH

Show answer

Answer: (a)

Report an error in ABC26IN1368

Q99 · Dec 2012 · 2 marks

Which one of the following will NOT undergo oxidative addition by methyl iodide?

(a) \left[\mathrm{Rh}(\mathrm{CO})_{2} \mathrm{I}_{2}\right]^{-}
(b) \left[\operatorname{Ir}\left(\mathrm{PPh}_{3}\right)_{2}(\mathrm{CO}) \mathrm{Cl}\right]
(c) \left[\left(\eta^{2}-\mathrm{CpRu}(\mathrm{CO})_{2}\right]\right.
(d) \left[\left(\eta^{5}-\mathrm{C} \mathrm{p}_{2} \mathrm{Ti}(\mathrm{Me}) \mathrm{Cl}\right]\right.

Show answer

Answer: (d)

Report an error in ABC26IN1371

Q100 · Dec 2012 · 2 marks

In hydrofomylation reaction using \left[\mathrm{Rh}\left(\mathrm{PPh}_{3}\right)_{2}(\mathrm{CO})(\mathrm{H})\right] as the catalyst, addition of excess \mathrm{PPh}_{3}, would

(a) increase the rate of reaction
(b) decrease the rate of reaction.
(c) not influence of the rate of reaction
(d) stop the reaction.

Show answer

Answer: (b)

Report an error in ABC26IN1372

Q101 · June 2011 · 2 marks

The oxidative addition and reductive elimination steps are favoured by

(a) Electron rich metal centres.
(b) Electron deficient metal centers
(c) Electron deficient and electron rich metal centers respectively.
(d) Electron rich and electron deficient metal centers respectively

Show answer

Answer: (d)

Report an error in ABC26IN0225

Q102 · June 2011 · 2 marks

Oxidation occurs very easily in case of

(a) \mathrm{(\eta^5\text{-}C_5H_5)_2Fe}
(b) \mathrm{(\eta^5\text{-}C_5H_5)_2Co}
(c) \mathrm{(\eta^5\text{-}C_5H_5)_2Ru}
(d) \mathrm{(\eta^5\text{-}C_5H_5)_2Co^+}

Show answer

Answer: (b)

Report an error in ABC26IN0227

Q103 · 2011 · 2 marks

In the trans-\mathrm{PtCl_2L(CO)} complex, the CO stretching frequency for L = \mathrm{NH_3}, pyridine, \mathrm{NMe_3} decreases in the order.

(a) pyridine > \mathrm{NH_3} > \mathrm{NMe_3}
(b) \mathrm{NH_3} > pyridine > \mathrm{NMe_3}
(c) \mathrm{NMe_3} > \mathrm{NH_3} > pyridine
(d) pyridine > \mathrm{NMe_3} > \mathrm{NH_3}

Show answer

Answer: (a)

Report an error in ABC26IN0229

Q104 · June 2011 · 2 marks

Identify the order according to increasing stability of the following organometallic \mathrm{TiMe}_{4}, \mathrm{Ti}\left(\mathrm{CH}_{2} \mathrm{Ph}\right)_{4}, \mathrm{Ti}(\mathrm{i}-\mathrm{Pr})_{4}, and \mathrm{TiEt}_{4}(\mathrm{Me}= methyl, \mathrm{Ph}= phenyl, i-Pr = isopropyl, \mathrm{Et}= ethyl )

(a) \mathrm{Ti}\left(\mathrm{CH}_{2} \mathrm{Ph}\right)_{4}<\mathrm{Ti}(\mathrm{i}-\mathrm{pr})_{4}<\mathrm{TiEt}_{4}<\mathrm{TiMe}_{4}
(b) \mathrm{TiEt}_{4}<\mathrm{TiMe}_{4}<\mathrm{Ti}(\mathrm{i}-\mathrm{Pr})_{4}<\mathrm{Ti}\left(\mathrm{CH}_{2} \mathrm{Ph}\right)_{4}
(c) \mathrm{Ti}(\mathrm{i}-\mathrm{Pr})_{4}<\mathrm{TiEt}_{4}<\mathrm{TiMe}_{4}<\mathrm{Ti}\left(\mathrm{CH}_{2} \mathrm{Ph}\right)_{4}
(d) \mathrm{TiMe}_{4}<\mathrm{TiEt}_{4}<\mathrm{Ti}(\mathrm{i}-\mathrm{Pr})_{4}<\mathrm{Ti}\left(\mathrm{CH}_{2} \mathrm{Ph}\right)_{4}

Show answer

Answer: (c)

Report an error in ABC26IN1343

Q105 · Dec 2011 · 2 marks

Among the metals \mathrm{Mn}, \mathrm{Fe}, \mathrm{Co} and Ni , the ones those would react in its native form directly with CO giving metal carbonyl compounds are:

(a) Co and Mn
(b) Mn and Fe
(c) Fe and Ni
(d) Ni and Co

Show answer

Answer: (c)

Report an error in ABC26IN1345

Q106 · June 2011 · 2 marks

In the \mathrm{H}_{2} \mathrm{Ru}_{6}(\mathrm{CO})_{18} cluster, containing 8-coordinated Ru centers, the hydrogen atoms are

(a) Both terminal
(b) One terminal and the other bridging
(c) Both bridging between two Ru centers
(d) Both bridging between three Ru centers.

Show answer

Answer: (d)

Report an error in ABC26IN1346

Q107 · 2011 · 2 marks

The correct combination of metal, number of carbonyl ligands and the charge for a metal carbonyl complex [\mathrm{M}(\mathrm{CO}) \mathrm{x}] \mathrm{z} - that satisfies the 18 electron rule is

(a) M=T i, x=6, z=1
(b) M=V, x=6, z=1
(c) M=C o, x=4, z=2
(d) M=M o, x=5, z=1

Show answer

Answer: (b)

Report an error in ABC26IN1349

Q108 · 2011 · 2 marks

The stable cyclopentadienyl complex of beryllium is

(a) \left[\mathrm{Be}\left(\eta^{2}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}\right]
(b) \left[\mathrm{Be}\left(\eta^{2}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\eta^{3}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\right]
(c) \left[\mathrm{Be}\left(\eta^{1}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\eta^{3}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\right]
(d) \left[\mathrm{Be}\left(\eta^{1}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\right]

Show answer

Answer: (d)

Report an error in ABC26IN1350

Q109 · 2011 · 2 marks

Reaction of \mathrm{Fe}(\mathrm{CO})_{5} with \mathrm{OH} leads to complex A which on oxidation with \mathrm{MnO}_{2} gives B. Compounds A and B respectively are

(a) [\mathrm{HFe}(\mathrm{CO})_{4}]^{-} and \mathrm{Fe}_{3}(\mathrm{CO})_{12}
(b) [\mathrm{Fe}(\mathrm{CO})_{5}(\mathrm{OH})]^{-} and \mathrm{Fe}_{2}(\mathrm{CO})_{10}
(c) [\mathrm{Fe}(\mathrm{CO})_{4}]^{-2} and \mathrm{Mn}_{2}(\mathrm{CO})_{10}
(d) [\mathrm{HFe}(\mathrm{CO})_{4}]^{-}, and \mathrm{Fe}_{2}\mathrm{O}_{3}

Show answer

Answer: (a)

Report an error in ABC26IN1351

Q110 · 2011 · 2 marks

The number of metal-metal bonds in the dimers, [\mathrm{CpFe}(\mathrm{CO})(\mathrm{NO})]_{2} and [\mathrm{CpMo}(\mathrm{CO})_{3}]_{2} respectively, are

(a) two and two
(b) two and three
(c) one and two
(d) zero and one

Show answer

Answer: (d)

Report an error in ABC26IN1352

Q111 · Dec 2011 · 2 marks

In the trans- \mathrm{PtCl}_{2} \mathrm{~L}(\mathrm{CO}) complex, the CO stretching frequency for \mathrm{L}=\mathrm{NH}_{3}, pyridine, \mathrm{NMe}_{3} decreases in the order.

(a) pyridine >\mathrm{NH}_{3}>\mathrm{NMe}_{3}
(b) \mathrm{NH}_{3}> pyridine >\mathrm{NMe}_{3}
(c) \mathrm{NMe}_{3}>\mathrm{NH}_{3}> pyridine
(d) pyridine >\mathrm{NMe}_{3}>\mathrm{NH}_{3}

Show answer

Answer: (a)

Report an error in ABC26IN1353

Q112 · 2011 · 2 marks

The greater stability of \left(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{CH}_{2}{ }^{-}\right)_{4} \mathrm{Ti}(\mathrm{A}) compared to that of \left(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{CH}_{2}{ }^{-}\right)_{4} \mathrm{Ti}(\mathrm{B}) is due to

(a) Hyperconjugation present in complex (A)
(b) \beta-hydride elimination is not possible in complex (A)
(c) Steric protection of titanium from reactive species in complex (A)
(d) The stronger nature of Ti-C bond in complex (A).

Show answer

Answer: (b)

Report an error in ABC26IN1355

Prepare with the CSIR NET batch

Every PYQ is discussed live in the batch. See the course or call +91 92121 42427.

Questions from the ABC Question Bank, typed from the official papers. A question whose answer is still under review is not shown.