Reactions of Organometallic Compounds | MCQs for CSIR NET & GATE - Download PDF

Vijay Ishwar
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Reactions of OGMCs
MCQs for CSIR NET & GATE

Organometallic Compounds
Topic wise Assignment-4

QUIZ              PDF

Q1. Oxidation occurs very easily in case of

[NET June 2011]
(a) (n5-C5H5)2Fe
(b) (n5-C5H5)2Co
(c) (n5-C5H5)2Ru
(d) (n5-C5H5)2Co+

Q2. The oxidative addition and reductive elimination steps are favored by

[NET June 2011]
(a) Electron rich metal centres.
(b) Electron deficient metal centres.
(c) Electron deficient & electron rich metal centres respectively.
(d) Electron rich & electron deficient metal centres respectively.

Q3. Identify the order according to increasing stability of the following organometallic compounds, TiMe4, Ti(CH2Ph)4, Ti(i-Pr)4 and TiEt4.

[NET June 2011]
(Me= methyl, Ph= Phenyl, i-Pr= iso-Propyl, Et= Ethyl)
(a) Ti(CH2Ph)4 < Ti(i-Pr)4 < TiEt4 < TiMe4
(b) TiEt4 < TiMe4 < Ti(i-Pr)4 < Ti(CH2Ph)4
(c) Ti(i-Pr)4 < TiEt4 < TiMe4 < Ti(CH2Ph)4
(d) TiMe4 < TiEt4 < Ti(i-Pr)4 < Ti(CH2Ph)4

Q4. Reaction of Fe(CO)5 with OH- leads to complex A which on oxidation with MnO2 gives B. Compounds A and B respectively are

[NET Dec 2011]
(a) [HFe(CO)4]- and Fe3(CO)12
(b) [Fe(CO)5(OH)]- and Fe2(CO)9
(c) [Fe(CO)4]2- and Mn2(CO)10
(d) [HFe(CO)4]- and Fe2O3

Q5. The greater stability of ((CH3)3C-CH2-)4Ti (A) compared to ((CH3)2CH-CH2-)4Ti (B) is due to

[NET Dec 2011]
(a) Hyperconjugation present in complex A.
(b) β-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.

Q6. A compound A having the composition FeC9H8O3 shows one signal at 2.5 ppm and another one around 5.0 ppm in it’s 1H NMR spectrum. The IR spectrum of this compound shows two bands around 1900 cm-1 and 1680 cm-1. The compound follows the 18 electrons rule of the following statements for A, the correct one is/are

[NET Dec 2011]
(A) it has n5Cp group.
(B) it has a terminal CO ligand.
(C) it has a CH3 ligand.
(D) it has Fe-H bond.
(a) A and B only
(b) C only
(c) A and C only
(d) B and D only

Q7. The reactions of Ni(CO)4 with the ligand L (L= PMe3 or P(OMe)3)L yields Ni(CO)3 L. The reaction is

[NET June 2012]
(a) Associative
(b) Dissociative
(c) Interchange (Ia)
(d) Interchange (Id)

Q8. The final product of the reaction [Mn(CO)6]+ + MeLi → is

[NET June 2012]
(a) [Mn(CO)6]+ Me-
(b) [Mn(CO)5Me]
(c) [Mn(CO)6]
(d) [(MeCO)Mn(CO)5]

Q9. The reaction 3[Rh4(CO)12] → 2[Rh6(CO)16] + 4CO [25 oC, 500 atm CO] is:

[NET June 2012]
(a) exothermic as more metal metal-metal bonds are formed.
(b) endothermic as stronger metal-carbonyl bonds are cleaved while weaker metal-metal bonds are formed.
(c) is entropically favorable but enthalpically unfavorable such that ΔG=0
(d) thermodynamically unfavorable (ΔG > 0)

Q10. In [Mo2(S2)6]2- cluster the number of bridging S22- and coordination number of Mo respectively, are

[NET Dec 2012]
(a) 2 and 8
(b) 2 and 6
(c) 1 and 8
(d) 1 and 6

Q11. The substitution of n5Cp group with nitric oxide is the easiest for

[NET Dec 2012]
(a) n5Cp2Fe
(b) n5Cp2CoCl
(c) n5Cp2Ni
(d) n5Cp2Co

Q12. Which one of the following will NOT undergo oxidative addition by methyl chloride?

[NET Dec 2012]
(a) [Rh(CO)2I2]-
(b) [Ir(PPh3)2(CO)Cl]
(c) [n5CpRh(CO)2]
(d) [n5Cp2Ti(Me)Cl]

Q13. The reaction, [(CO)5MnMe] + CO → [(CO)5Mn{C(O)Me}] is an example of

[NET June 2013]
(a) oxidative addition
(b) electrophilic substitution
(c) nucleophilic substitution
(d) migratory insertion

Q14. The bond order of the metal-metal bond in the dimeric complex [Re2Cl4(PMe2Ph)4]+ is

[NET Dec 2013]
(a) 4.0
(b) 3.5
(c) 3.0
(d) 2.5

Q15. The electrophilic Ph3C+ reacts with [(n5C5H5)Fe(CO)2(CDMe2)]+ to give a product A. The product A is formed because

[NET Dec 2013]
(a) Fe is oxidized
(b) alkyl is substituted with Ph3C
(c) Fe-Ph bond is formed
(d) Alkyl is converted to alkene

Q16. Substitution of L with other ligands will be easiest for the species

[NET Dec 2013]

Q17. The compound [Re2(Me2PPh)4Cl4] (M) having a configuration of σ2 π2 δ2 δ*2 can be oxidized to M+ and M2+. The formal metal-metal order in M, M+ and M2+ respectively, are

[NET June 2014]
(a) 3.0, 3.5 and 4.0
(b) 3.0, 4.0 and 3.0
(c) 4.0, 3.5 and 3.0
(d) 3.0, 4.0 and 3.5

Q18. 1H NMR spectrum of [(n5 C5H5Rh(C2H4)2)] at -20oC shows a typical AA ‘XX’ pattern in the olefinic region. On increasing the temperature to ~70 oC, the separate lines collapse into a single line which is due to

[NET June 2014]
(a) free rotation of the ethylene ligand about the metal olefin bond.
(b) intramolecular exchange between the ethylene ligands.
(c) intermolecular exchange between the ethylene ligands.
(d) change in hapticity of the cyclopentadienyl ligand.

Q19. The typical electronic configurations of the transition metal centre for oxidative addition
(a) d0 and d8
(b) d6 and d8
(c) d8 and d10
(d) d5 and d10

Q20. The rate of the reaction Ni(CO)4 + PPh3 → [Ni(CO)3(PPh3)] + CO depends on
(a) Concentration of both the reactants
(b) Concentration of Ni(CO)4 only
(c) Concentration of PPh3 only
(d) The steric bulk of PPh3

Answer Key:

Q1.b Q2.d Q3.c Q4.a Q5.b Q6.a Q7.b Q8.d Q9.b Q10.a Q11.c Q12.d Q13.d Q14.b Q15.d Q16.c Q17.a Q18.a Q19.c Q20.b

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