Geometric control of reduction potential in oxomolybdenum centers: Implications to the serine coordination in DMSO reductase

Two isomers (cis and trans) of (L1O)MoOCl2 have been synthesized and separa ted using the heteroscorpinate ligand L1OH, which possesses an N2O donor se t. These geometric isomers differ in the orientation of the phenolate oxyge n with respect to the terminal oxo group. The cis isomer spontaneously conv erts to the thermodynamically more stable trans isomer. Since the reduction potentials of the two isomers differ by similar to 220 mV and crystal stru ctures of DMSOR and TMAOR exhibit a wide range of O-t-Mo-O-ser angles, we s uggest that this angular variation may play a crucial role in gating the el ectron transfer process in the regeneration step.