Characterization of metal-to-ligand charge-transfer and intraligand transitions of fac-[Re(CO)3L(X)] complexes [L = di-imine; X = halide or Mn(CO)5] and explanation of the photochemistry of [Re(CO)3L{Mn(CO)5}] using the resonance Raman effect

Abstract

The resonance Raman (r.R.) spectra of a series of [Re(CO)₃L(X)] complexes [L = aryl or alkyl NN′-disubstituted-ethane-1,2-di-imine or 2-(N-monosubstituted-iminomethyl) pyridine; X = Cl or Br], obtained by excitation within the lowest-energy absorption band are reported. The influence of the ligand L and of the halogen atom X is discussed. The excitation profiles of [Re(CO)₃(p-MeC₆H₄NCHCHNC₆H₄Me-p)Cl] are compared with those of the free ligand, NN′-di(p-tolyl)ethane-1,2-di-imine. These spectra revealed that upon excitation within both metal-to-ligand charge-transfer and intraligand transitions also resonance enhancement occurs of a carbonyl stretching mode. The low-temperature r.R. spectra of [Re(CO)₃(NC₅H₄CHNC₆H₄Me-p){Mn(CO)₅}] are reported and used for the characterization of the electronic absorption spectrum and for the explanation of the photochemistry of this complex.