Order of C – O bond strength ;

[Mn(CO) 6 ] + > [Cr(CO) 6 ] > [V(CO) 6 ] – > [Ti(CO) 6 ] 2– and [Ni(CO) 4 ] > [Co(CO) 4 ] – > [Fe(CO) 4 ] 2– .

True statement.

As + ve charge on the central metal atom increases, the less readily the metal can donate electron density into the π * orbitals of CO ligand to weaken the C – O bond.

In the carbonylate anions, the metal has a greater electron density to be dispersed, with the result that M – C π bonding is enhanced and the C – O bond is diminished in strength.