Rapid synthesis of Group VI carbonyl complexes by coupling borohydride catalysis and microwave heating

Several Group VI tetracarbonyl phosphine and tertiary amine complexes [M(CO)4 L2, M = Cr, Mo, W, L2 = 2PPh3, dppm, dppe, dppp, dppb, bpy, phen, dppf] were synthesized in minutes in the microwave at moderate temperature, atmospheric pressure, and utilizing NaBH4 as a catalyst. The reactions were optimized by careful solvent selection. The octahedral complexes were isolated in percent yields ranging from 17 to 95. The lower temperatures, shorter reaction times, benign solvents, and lower pressures as compared to the traditional thermal syntheses provide a rapid, eco-friendly synthetic route to these common Group VI complexes.