KINETICS AND MECHANISM OF DEOXYGENATION OF ENE-2-AMINOPHENOLATO)-(ETHANOL)DIOXOMOLYBDENUM(VI) BY THIONYL CHLORIDE

The kinetics of deoxygenation of [MoO2(Sap)EtOH] (Sap(2-) = N-salicyli dene-2-aminophenolate dianion) by thionyl chloride have been studied i n acetonitrile and a mixture of tetrahydrofuran and acetonitrile (v/v = 9:1) by spectrophotometry. Under the conditions [MoO2(Sap)EtOH] << [ SOCl2], the reaction of formation of the product MoO(Sap)Cl-2 consists of two consecutive steps. The pseudo-first-order rate constants of th e first-step reaction depended on [SOCl2](1/2) and were significantly affected by the dielectric constant of solvent used, whereas those of the second-step reaction were independent of [SOCl2]. A mechanism is p roposed for the deoxygenation, where the reactant reacted initially wi th MoO2(Sap)EtOH is not SOCl2, but SOCl+ or Cl- ions. (C) 1997 Elsevie r Science Ltd.