INVESTIGATIONS OF TRANS-RH(PY3)(2)(CO)X (X = NCO, NCS Y, = H, ME, PH)COMPLEXES USING DENSITY-FUNCTIONAL THEORY

In our computational study of trans-Rh(PH3)(2)(CO)X (X = NCO, NCS), we employed the Becke hybrid three-parameter DFT method using the Lee, Y ang and Parr correlation functional (B3LYP) and the double-zeta plus p olarization basis set (DZP). Our optimized complexes have a slightly d istorted square-planar structure with moderate bending of the phosphin e ligands towards the uninegative ligand X-. The predicted structures compare favorably with experimental data for trans-Rh(PPh3)(2)(CO)NCO. Computationally predicted vibrational frequencies nu(C-O) and nu(C-N) for trans-Rh(PPh3)(2)(CO)NCO compare well with solution-phase FTIR da ta. Based upon trends in computed and experimental frequency shifts, w e predict solution-phase nu(C-O) frequencies for trans-Rh(PY3)(2)(CO)N CS (Y = Me, Ph). Performance of B3LYP and BLYP functionals is also dis cussed and compared to results obtained using the Hartree-Fock (HF) me thod. (C) 1998 Elsevier Science B.V.