Models for the Molybdenum(VI/V) Centers of the Molybdenum Hydroxylases and Related Enzymes. Geometry, Electronic Structure, and EPR g-Tensor Predictions from ab Initio and Semiempirical Molecular Orbital Studies

Abstract

The geometries and electronic structures of several molybdenum(V) and molybdenum(VI) complexes with tetradentate N 2 S 2 and N 2 O 2 ligands (LH 2 =N,N'-bis(2-mercaptophenyl)-N,N'-dimethyl- 1,2-diaminoethane, N,N'-bis(2-hydroxyphenyl)-N,N'-dimethyl-1,2-diaminoethane) which have been proposed as models for the molybdenum-(VI/V) centers of the molybdenum hydroxylases and related enzymes have been predicted using ab initio and INDO molecular orbital methods. Ab initio and INDO geometrical predictions have been compared with known X-ray crystal structures for three complexes and have been found to be in excellent agreement. In addition, the EPR g tensors of the molybdenum(V) complexes have been estimated using INDO methods