SOLUTION PHOTOPHYSICS, ONE-ELECTRON PHOTOOXIDATION, AND PHOTOINITIATED 2-ELECTRON OXIDATION OF MOLYBDENUM(III) COMPLEXES

Several six-coordinate Mo(III) complexes phosphoresce and undergo phot ooxidation in room-temperature solution. The phosphorescence of (Me-3[ 9]aneN(3))MoX3 (Me-3[9]aneN(3) = 1,4,7-trimethyl-1,4,7-triazacyclonona ne) in CH3-CN at room temperature occurs with the following maxima, li fetimes, and quantum yields: X = Cl, 1120 nm, 1.0 mu s, and 6.1 x 10(- 5); X = Br, 1130 nm, 0.80 mu s, and 9.6 x 10(-5); and X = I, 1160 nm, 0.40 mu s, and 1.2 x 10(-4), respectively. The phosphorescences are as signed to the {E-2(g), T-2(1g)} --> (4)A(2g) transition. Solutions of HB(Me(2)pz)(3)(MoCl3-)-Cl-III Me(2)pzH = 3,5-dimethylpyrazole) in CH3C N, and solid MoCl3(py)(3) and (Me-3[9]aneN(3))-WCl3, also phosphoresce . (Me-3[9]aneN(3))MoX3 (X Cl, Br, I) complexes undergo reversible one- electron photooxidation upon irradiation in the presence of accepters such as TCNE and chloranil. (Me-3[9]aneN(3))MoX3 (X = Br, I only) are photooxidized irreversibly to [(Me-3[9]aneN(3))(MoX3)-X-IV](+) by C(NO 2)(4) in CH3CN. In CH3CN-H2O (1:1 v/v), photoinitiated two-electron ox idation occurs: the primary photoproduct is Mo(IV), which disproportio nates spontaneously to form [(Me-3[9]aneN(3))(MoOX2)-O-V](+).