JEE Advanced2007ChemistryCoordination CompoundsActual
Among the following metal carbonyls, the C - O bond order is lowest in
Options
- A[ MO ( CO )₆ ]⁺
- B[ Fe ( CO )₅ ]
- C[ Cr ( CO )₆ ]
- D[ V ( CO )₆ ]⁻
Correct answer
B. [ Fe ( CO )₅ ]
Step-by-step solution
(a) Mn ⁺=3 d^5 4 s^1 In presence of CO effective configuration =3 d^6 4 s^0, 3 lone pair for back bonding with vacant orbital of C in CO . (b) Fe ^ =3 d^6 4 s^2 in presence of CO effective configuration =3 d^8, 4 lone pair for back bonding with CO . (c) Cr ^ =3 d^5 4 s^1 , effective configuration =3 d^6 3 lone pair for back bonding with CO . (d) V ⁻=3 d^4 s^2 , effective configuration =3 d^6, 3 lone pair for back bonding with CO . Maximum back bonding in Fe ( CO )₅ , therefore CO bond order is lowest here.