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Topic Question Set

Q 1 :    

[Mn2(CO)10] and [Co2(CO)8] structures have

A. metal–metal linkage
B. terminal CO groups
C. bridging CO groups
D. metal in zero oxidation state.

Choose the correct answer from the options given below.             [2024]

  • Only A, B, C

     

  • Only B, C, D

     

  • Only A, C, D

     

  • Only A, B, D

     

(4)

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Q 2 :    

Iron carbonyl, Fe(CO)5 is           [2018]

  • tetranuclear

     

  • mononuclear

     

  • trinuclear

     

  • dinuclear

     

(2)

Based on the number of metal atoms present in a complex, they are classified as:

e.g., Fe(CO)5 : mononuclear; Co2(CO)8 : dinuclear; Fe3(CO)12 : trinuclear

Q 3 :    

An example of a sigma bonded organometallic compound is              [2017]

  • Grignard’s reagent

     

  • ferrocene

     

  • cobaltocene

     

  • ruthenocene

     

(1)

In sigma bonded organometallic complexes, the metal atom and carbon atom of the ligand are joined together with a sigma bond, i.e., ligand contributes one electron and is therefore, called one electron donor, e.g., Grignard’s reagent R–Mg–X.

Q 4 :    

Which of the following has longest C-O bond length? (Free C-O bond length in CO is 1.128 Å.)            [2016]

  • [Fe(CO)4]2-

     

  • [Mn(CO)6]+

     

  • Ni(CO)4

     

  • [Co(CO)4]-

     

(1)

The greater the negative charge on the carbonyl complex, the more easy it would be for the metal to permit its electrons to participate in the back bonding, the higher would be the M–C bond order and simultaneously there would be larger reduction in the C–O bond order. Thus, [Fe(CO)4]2- has the lowest C–O bond order means the longest bond length.