Two important physical evidences supporting the synergic bonding in non-classical complexes are bond lengths and vibrational spectra. Vibrational spectra is based on the fact that the compression and extension of a bond may be analogous to the behaviour of a spring and obeys Hook's law. overline(v)=(1)/(2pic)sqrt((k)/(mu))cm^(-1) where, k=force force constant of the bond which is directly proportional to bonnd strength of CO mu=reduced mass of ligand overline(v)=stretching frequency of the CO bond c=velocity of light Q. In which of the following complex stretching frequecy for CO ligand is least as well as bond energy of M-C bond is higher.

Two important physical evidences supporting the synergic bonding in no

1.	Two important physical evidences supporting the synergic bonding in non-classical complexes are bond lengths and vibrational spectra. Vibrational spectra is based on the fact that the compression and extension of a bond may be analogous to the behaviour of a spring and obeys Hook's law. overline(v)=(1)/(2pic)sqrt((k)/(mu))cm^(-1) where, k=force force constant of the bond which is directly proportional to bonnd strength of CO mu=reduced mass of ligand overline(v)=stretching frequency of the CO bond c=velocity of light Q. In which of the following complex stretching frequecy for CO ligand is least as well as bond energy of M-C bond is higher.
Answer» (dien) `Mo(CO)_(3)` `(Et_(3)P)_(3)Mo(CO)_(3)` `(F_(3)P)_(3)Mo(CO)_(3)` `(Cl_(3)P)_(3)Mo(CO)_(3)` Solution :Dienn is not `pi`-ACID ligannd while `PF_(3),PC l_(3),PE t_(3)` are `pi`-acid ligands, THEREFORE extent of `Mo overset(pi) to CO` back BONDING in (dien) `Mo(CO)_(3)` is maximum in order of DISPERSE incrased electron density at Mo: while in other complexes al ligands participate in `M overset(pi) to I`. back bonding. Extent of back bonding `alphaMo-CO` bond order `prop(1)/("STRETCHING frequency of CO")`