Comparative molecular chemistry of molybdenum and tungsten and its relation to hydroxylase and oxotransferase enzymes

The similarities and differences in the fundamental coordination chemistry of molybdenum and tungsten mainly in physiological oxidation states MIV–VI are examined in relation to the properties of enzyme sites that catalyze oxygen atom transfer reactions. The comparative aspects of dithiolene complexes, which as synthetic analogues simulate structural and electronic features of these sites, are emphasized. Analogue reaction systems of enzymes are summarized. The mechanism of reduction of the biological substrate Me2SO in one such system as elucidated with density functional calculations is presented as a case study.