Solid‐state infrared and Raman spectra of carbonyl‐tert‐butyl isocyanide complexes of chromium(0), molybdenum(0) and tungsten(0), M(CO)6−n(CNBu‐t)n (n = 1–3)

Vibrational assignments are reported for the room‐temperature IR and Raman spectra of three series of solid group 6B metal(0) carbonyl‐tert‐butyl isocyanide complexes of the general formula M(CO)6‐n(CNBu‐t)n, where M = Cr, Mo, W and n = 1–3. Sequential replacement of the CO groups by CNBu‐t leads to gradual shifts of the ν(CN) bands to higher energies, while the ν(CO) bands shift to lower energies. These results provide good evidence for the stronger σ‐donor and weaker π‐acceptor capacities of the CNBu‐t ligand compared with those of CO.