A DENSITY-FUNCTIONAL STUDY OF PSEUDOTETRAHEDRAL METAL-NITROSYL COMPLEXES

Local and nonlocal density functional computations have been carried o ut to study the electronic structure and the equilibrium geometry of t he isoelectronic series Cr(NO)4, Mn(NO)3(CO), Fe(NO)2(CO)2, and Co(NO) (CO)3 and model compounds Fe(NO)2L2 (L = Cl, HCN, NH3, PH3, and C2H4). The structure of Fe(NO)2(C4H6) is also described. The discussion is f ocused on structural modifications through a change of ligand, in part icular those concerning the metal-nitrosyl conformation (linear vs. be nt). Though this is a preliminary study of metal-nitrosyl properties b y DFT methods and more computations are required to analyze the mechan ism of homogeneous catalysis processes, our results support the hypoth esis that structural reorganization from linear to bent metal-nitrosyl plays a key role in some reactions, such as in butadiene dimerization . (C) 1994 John Wiley & Sons, Inc.