More practice questions

  1. Q3. For the structures drawn by NCERT, including the bridged cobalt form, count the metal–carbon and metal–metal connections in [Mn2(CO)10] and [Co2(CO)8].

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    [Mn2(CO)10]: 10 Mn–C and 1 Mn–Mn. The bridged [Co2(CO)8] form: 6 terminal Co–C plus 2 × 2 = 4 bridging Co–C, 10 in all, and 1 Co–Co (NCERT page 135, with its Fig. 5.13 on page 136; reasoned).

  2. Q4. Is the C–O bond in [Ni(CO)4] longer or shorter than in free CO?

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    Longer: back donation puts metal d electrons into the antibonding π* orbital of CO (NCERT page 136), which lowers the C–O bond order, ½(Nb − Na), and a bond gets longer as its bond order falls (reasoned from NCERT Class 11 Chemistry, Unit 4, page 129).