Reactions of OGMCs
MCQs for CSIR NET & GATE
Organometallic Compounds
Topic wise Assignment-4
Q1. Oxidation occurs very easily in case of
(b) (n5-C5H5)2Co
(c) (n5-C5H5)2Ru
(d) (n5-C5H5)2Co+
Q2. The oxidative addition and reductive elimination steps are favored by
(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.
(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
(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
(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
(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
(b) Dissociative
(c) Interchange (Ia)
(d) Interchange (Id)
Q8. The final product of the reaction [Mn(CO)6]+ + MeLi → is
(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:
(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
(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
(b) n5Cp2CoCl
(c) n5Cp2Ni
(d) n5Cp2Co
Q12. Which one of the following will NOT undergo oxidative addition by methyl chloride?
(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
(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
(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
(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
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
(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
(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
Where is detailed explanation
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