Inorganic Chemistry

IIT-JAM Chemistry — Organometallic Compounds previous year questions

18 questions · 2005 · all with verified answer · last checked 2026-11-10

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Q1 · 2005-2022 · 2 marks

Metal-carbon multiple bonds in metal carbonyl are preferably identified from the stretching frequency of

(a) Carbon-oxygen bond
(b) Metal-carbon bond
(c) Metal-oxygen bond
(d) Carbon-carbon bond IIT JAM 2009

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Answer: (a)

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Q2 · 2005-2022 · 2 marks

\mathrm{B}_{2} \mathrm{H}_{6} and \mathrm{B}_{4} \mathrm{H}_{10}, respectively, are examples of

(a) Nido and arachno boranes
(b) Nido and closo boranes
(c) Closo and arachno boranes
(d) Nido boranes IIT JAM 2012

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Answer: (a)

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Q3 · 2005-2022 · 2 marks

The Correct order of CO vibrational stretching frequency in the following complexes is (I) \left(\mathrm{PF}_{3}\right)_{3} \mathrm{Mo}(\mathrm{CO})_{3} (II) \left(\mathrm{PCl}_{3}\right)_{3} \mathrm{Mo}(\mathrm{CO})_{3} (III) \left\{\mathrm{P}(\mathrm{OMe})_{3}\right\}_{3} \mathrm{Mo}(\mathrm{CO})_{3}

(a) I < II < III
(b) III < II < I
(c) II < I < III
(d) III < I < II IIT JAM 2014

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Answer: (b)

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Q4 · 2005-2022 · 2 marks

The carbonyl stretching frequency \left(v_{\mathrm{C}=\mathrm{O}}\right) is highest for:

(a)
(b)
(c)
(d)

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Answer: (c)

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Q5 · 2005-2022 · 2 marks

For the following reactions, the metal complexes X and Y are (i) \mathrm{Ni}(\mathrm{s}) \xrightarrow[1 \mathrm{~atm} / 25^{\circ} \mathrm{C}]{\mathrm{CO}(\mathrm{g})} \mathrm{X} (ii) \mathrm{FeCl}_{2} \xrightarrow{2 \mathrm{NaC}_{5} \mathrm{H}_{5}} \mathrm{Y}

(a) \mathrm{X}=\mathrm{Ni}(\mathrm{CO})_{4} ; \mathrm{Y}=\mathrm{Fe}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}
(b) \mathrm{X}=\mathrm{Ni}(\mathrm{CO})_{4} ; \mathrm{Y}=\mathrm{Fe}\left(\eta^{1}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}
(c) \mathrm{X}=\mathrm{Ni}(\mathrm{CO})_{5} ; \mathrm{Y}=\mathrm{Fe}\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}
(d) \mathrm{X}=\mathrm{Ni}(\mathrm{CO})_{6} ; \mathrm{Y}=\mathrm{Fe}\left(\eta^{1}-\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2} IIT JAM 2015

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Answer: (a)

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Q6 · 2005-2022 · 2 marks

The value of 'x' in \left[\mathrm{Cu}(\mathrm{CO})_{\mathrm{x}}\right]^{+}such that it obeys the 18 electron rule is

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

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Answer: (c)

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Q7 · 2005-2022 · 2 marks

The homogeneous catalyst used in water-gas shift reaction is

(a) \mathrm{PdCl}_{2}
(b) \mathrm{Cr}_{2} \mathrm{O}_{3}
(c) \left[\mathrm{RhCl}\left(\mathrm{PPh}_{3}\right)_{3}\right]
(d) \left[\mathrm{RuCl}_{2}(\text { bipyridyl })_{2}\right]

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Answer: (d)

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Q8 · 2005-2022 · 2 marks

Among the following metal carbonyl species, the one with the highest metal-carbon back bonding is

(a) \left[\mathrm{Ti}(\mathrm{CO})_{6}\right]^{2-}
(b) \left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}
(c) \mathrm{Cr}(\mathrm{CO})_{6}
(d) \left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}

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Answer: (a)

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Q9 · 2005-2022 · 2 marks

The correct option having one complex from each of the following pairs which is more reactive towards the oxidative addition reaction by hydrogen molecule is Pair 1: \mathrm{IrCl}\left(\mathrm{PMe}_{3}\right)_{3}(\mathrm{I}) and \mathrm{IrCl}(\mathrm{CO})\left(\mathrm{PMe}_{3}\right)_{2}(\mathrm{II}) Pair 2: \mathrm{IrCl}(\mathrm{CO})\left(\mathrm{PPh}_{3}\right)_{2} (III) and \mathrm{IrCl}_{3}\left(\mathrm{PPh}_{3}\right) (IV)

(a) (I) and (III)
(b) (I) and (IV)
(c) (II) and (III)
(d) (II) and (IV)

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Answer: (a)

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Q10 · 2005-2022 · 2 marks

Number of vertices in an icosahedral closo-borane is ____ . IIT JAM 2020

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Answer: 12

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Q11 · 2005-2022 · 2 marks

The order of the \mathrm{M}-\mathrm{C} bond strength in the following species is (Atomic number for \mathrm{Cr}=24, \mathrm{Mn}=25, \mathrm{Ti}=22, \mathrm{Co}=27 )

\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]	\left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}	\left[\mathrm{Ti}(\mathrm{CO})_{6}\right]^{2-}	\left[\mathrm{Co}(\mathrm{CO})_{4}\right]
I	II	III	IV

(a) II > I > IV > III
(b) I > III > II > IV
(c) III > IV > I > II
(d) III > I > II > IV

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Answer: (c)

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Q12 · 2005-2022 · 2 marks

The complex which does NOT obey 18 - electron rule is (atomic number for \mathrm{Mn}=25, \mathrm{Fe}=26, \mathrm{Co}=27, \mathrm{Ru}=44 )

(a) \left[\mathrm{Co}_{2}(\mathrm{CO})_{8}\right]
(b) \left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-}
(c) \left[\mathrm{HMn}(\mathrm{CO})_{5}\right]
(d) \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{RuCl}(\mathrm{CO})\left(\mathrm{PPh}_{2}\right)\right]

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Answer: (d)

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Q13 · 2005-2022 · 2 marks

The CORRECT order of \mathrm{pK}_{\mathrm{a}} for the compounds I to IV in water at 298 K is

\underset{\mathbf{I}}{\mathrm{HCo}}(\mathrm{CO})_{4} \underset{\text { II }}{\mathrm{HCo}(\mathrm{CO})_{3}\left(\mathrm{PPh}_{3}\right)} \underset{\text { III }}{\mathrm{HCo}(\mathrm{CO})_{3}\left(\mathrm{P}(\mathrm{OPh})_{3}\right)} \underset{\text { IV }}{\mathrm{HCo}(\mathrm{CO})_{2}\left(\mathrm{PPh}_{3}\right)_{2}}

(a) I > III > II > IV
(b) IV > II > III > I
(c) IV > III > II > I
(d) I > II > III > IV

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Answer: (d)

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Q14 · 2005-2022 · 2 marks

The complex that does NOT obey the 18-electron rule is (Given: Atomic numbers of Ti, Mn, Ta and Ir are 22, 25, 73 and 77, respectively)

(a) \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Ti}(\mathrm{CO})_{4}\right]^{-}
(b) \left[\mathrm{TaCl}_{3}\left(\mathrm{PEt}_{3}\right)_{2}\left(\mathrm{CHCMe}_{3}\right)\right]
(c) \left[\mathrm{Mn}\left(\mathrm{SnPh}_{3}\right)_{2}(\mathrm{CO})_{4}\right]^{-}
(d) \left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \operatorname{Ir}\left(\mathrm{CH}_{2}\right)\left(\mathrm{PMe}_{3}\right)\right]

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Answer: (b)

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Q15 · 2005-2022 · 2 marks

The decreasing order of \mathrm{C}=\mathrm{C} bond length in the following complexes is

\left[\mathrm{Cl}_{3} \mathrm{Pt}\left(\mathrm{CH}_{2}=\mathrm{CH}_{2}\right)\right]^{-}	\left[\mathrm{Cl}_{3} \mathrm{Pt}\left(\mathrm{C}(\mathrm{CN})_{2}=\mathrm{C}(\mathrm{CN})_{2}\right)\right]^{-}	\left[\mathrm{Cl}_{3} \mathrm{Pt}\left(\mathrm{CF}_{2}=\mathrm{CH}_{2}\right)\right]^{-}	\left[\mathrm{Cl}_{3} \mathrm{Pt}\left(\mathrm{CF}_{2}=\mathrm{CF}_{2}\right)\right]^{-}
I	II	III	IV

(a) \mathrm{II}>\mathrm{III}>\mathrm{IV}>\mathrm{I} \mathrm{CpMo}(\mathrm{CO})_{3} and \mathrm{CpW}(\mathrm{CO})_{3} are isoelectronic (where Cp is cyclopentadienyl)
(b) \mathrm{IV}>\mathrm{II}>\mathrm{III}>\mathrm{I} \mathrm{BH} and \mathrm{CH} are isolobal and isoelectronic
(c) \mathrm{II}>\mathrm{IV}>\mathrm{III}>\mathrm{I} \mathrm{CH}_{3} and \mathrm{Mn}(\mathrm{CO})_{5} are isolobal
(d) \mathrm{IV}>\mathrm{II}>\mathrm{I}>\mathrm{III} \mathrm{CH}_{2}^{-} and \mathrm{NH}_{2} are isolobal and isoelectronic IIT JAM 2022

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Answer: (c)

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Q16 · 2005-2022 · 2 marks

The structure types of \mathrm{B}_{10} \mathrm{H}_{10}{ }^{2-} and \mathrm{B}_{10} \mathrm{H}_{14}, respectively, are

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

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Answer: (a)

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Q17 · 2005-2022 · 2 marks

The order of increasing CO stretching frequencies in \left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-},\left[\mathrm{Cu}(\mathrm{CO})_{4}\right]^{+},\left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-} and \left[\mathrm{Ni}(\mathrm{CO})_{4}\right] is

(a) \left[\mathrm{Cu}(\mathrm{CO})_{4}\right]^{+}<\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]<\left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-}<\left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-}
(b) \left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-}<\left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-}<\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]<\left[\mathrm{Cu}(\mathrm{CO})_{4}\right]^{+}
(c) \left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-}<\left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-}<\left[\mathrm{Cu}(\mathrm{CO})_{4}\right]^{+}<\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]
(d) \left[\mathrm{Ni}(\mathrm{CO})_{4}\right]<\left[\mathrm{Cu}(\mathrm{CO})_{4}\right]^{+}<\left[\mathrm{Co}(\mathrm{CO})_{4}\right]^{-}<\left[\mathrm{Fe}(\mathrm{CO})_{4}\right]^{2-}

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Answer: (b)

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Q18 · 2005-2022 · 2 marks

The number of CO stretching bands in the infrared spectrum of \mathrm{Fe}(\mathrm{CO})_{5} is

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

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Answer: (b)

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