SELENOLATES OF ALUMINUM AND GALLIUM - SYNTHESIS AND MOLECULAR-STRUCTURES OF [MES(2)AL(MU-SEME)](2), [PH(2)GA(MU-SEME)](2), AND [ME(2)(PHSE)AL-CENTER-DOT-PPH(3)]

The reaction of triorganoaluminum and -gallium derivatives, R(3)M, (M = Al, R = Me, Mes; M Ga, R = Ph) with the diselenide, R'Se-2(2) (R' = Me, Ph) yields [R(2)M(mu-SeR')](n), (M = Al, R = Me, R' = Me, 1; R = M e, R' = Ph, 2; R = Mes, R' = Me, 3; M = Ga, R = Ph, R' = Me, 4) and th e corresponding selenoether RSeR'. 1 is also prepared by a simple inse rtion reaction of elemental grey selenium into the Al-C bond of trimet hylaluminum. 1 reacts with 4-picoline to give the addition compound, M e(2)(MeSe)Al . Pic, 6. 2 reacts with PPh(3) to yield Me(2)(PhSe)Al . P Pha, 5, with benzaldehyde to yield {Me(2)Al[mu-OC(H)(SEPh)Ph]}(n), 7, and with methyl benzoate to give the selenoester PhC(O)SePh. The resul ting derivatives have been characterized by H-1, C-13, P-31, and Se-77 NMR spectroscopy and by chemical analyses. The structures of 3, 4, an d 5 were determined by single crystal X-ray diffraction techniques. Th e crystal structure parameters of 3 are as follows: orthorhombic space group Cmca (No. 64); cell constants a = 23.419(3) Angstrom; b = 14.83 0(2) Angstrom; c = 12.020(2) Angstrom; and Z = 8; R = 5.3%, R(w) = 4.7 % based on 996 (I > 2.0 sigma(I)) observed reflections. The (AlSe)(2) core is planar, and the aluminum center is in a pseudotetrahedral envi ronment with an Al-Se bond distance of 2.519(2) Angstrom. 4 crystalliz es in the monoclinic space group P2(1)/c (No. 14); cell constants a = 11.170(1) Angstrom; b = 13.637(3) Angstrom; c = 18.311(2) Angstrom; be ta = 96.52(1)degrees; Z = 4; and R = 3.0%, R(w) = 6.0% based on 2205 ( I > 2.0 sigma(I)) observed reflections. The central (GaSe)(2) ring of the dimer is planar with a Ga-Se bond distance of 2.509(1) Angstrom. T he unit cell parameters of 5 are as follows: triclinic space group P ( $) over bar 1 (No. 2); cell constants a = 9.777(2) Angstrom; b = 9.817 (3) Angstrom; c = 14.125(3) Angstrom; alpha = 82.84(2)degrees; beta = 77.53(2)degrees; gamma = 66.40(2)degrees; and Z = 2; R = 4.0%, R(w) = 3.4% based on 3292 (I > 2.0 sigma(I)) observed reflections. The alumin um center is in a pseudotetrahedral environment with an Al-Se bond dis tance of 2.394(1) Angstrom and an Al-P bond distance of 2.517(1) Angst rom.