New Oxovanadium Bis(1,2-dithiolate) Compounds That Mimic the Hydrogen-Bonding Interactions at the Active Sites of Mononuclear Molybdenum Enzymes

Reaction of VO(acac)2 with 1,2-dithiols in the presence of triethylamine gives pentacoordinate oxovanadium complexes
[HNEt3]2[VO(bdt)2] (1), [HNEt3]2[VO(tdt)2] (2), and [HNEt3]2[VO(bdtCl2)2] (3) (where H2bdt = 1,2-benzenedithiol, H2tdt
= 3,4-toluenedithiol, and H2bdtCl2 = 3,6-dichloro-1,2-benzenedithiol). Compounds 1−3 have been characterized
by IR, UV/visible, EPR, and mass spectroscopies. The X-ray crystal stuctures of 1 and 2 show hydrogen-bonding
interactions between the terminal oxo atom and triethylammonium counterions and between ligand sulfur atoms
and the counterions. These interactions are comparable with those found at the active sites of mononuclear
molybdenum enzymes.