Oxidations of (R(3)tach)M(CO)(3) Complexes [M = Cr, Mo, W; R(3)tach = 1,3,5-Trialkyl-1,3,5-triazacyclohexane (R = t-Bu, Bn)]. Crystal Structures of (t-Bu(3)tach)MO(3).15H(2)O (M = Mo, W).

Stable Cr, Mo, and W complexes having a metal in oxidation state II, III, or VI, and possessing a facially coordinated 1,3,5-trialkyl-1,3,5-triazacyclohexane (R(3)tach) ligand, can be prepared by oxidation of (R(3)tach)M(CO)(3) with a variety of oxidizing agents. The reaction of the chromium or molybdenum complexes (R(3)tach)M(CO)(3) (M = Cr, R = Bn (benzyl), t-Bu and M = Mo, R = t-Bu) with bromine or thionyl chloride at reflux affords a series of monomeric M(III) trihalide complexes. More controlled oxidation of (t-Bu(3)tach)M(CO)(3) (M = Mo, W) with either bromine or iodine yields the 7-coordinate M(II) cations [(t-Bu(3)tach)M(CO)(3)X](+) (X = Br, I); protonation with trifluoromethanesulfonic acid affords the isolable [(t-Bu(3)tach)M(CO)(3)H](+) cations as their trifluoromethanesulfonate salts.