- Selenolates of aluminum and gallium. Synthesis and molecular structures of [Mes2Al(μ-SeMe)]2, [Ph2Ga(μ-SeMe)]2, and [Me2(PhSe)Al·PPh3]
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The reaction of triorganoaluminum and -gallium derivatives, R3M, (M = Al, R = Me, Mes; M = Ga, R = Ph) with the diselenide, R′2Se2 (R′ = Me, Ph) yields [R2M(μ-SeR′)]n, (M = Al, R = Me, R′ = Me, 1; R = Me, R′ = Ph, 2; R = Mes, R′ = Me, 3; M = Ga, R = Ph, R′ = Me, 4) and the corresponding selenoether RSeR′. 1 is also prepared by a simple insertion reaction of elemental grey selenium into the Al-C bond of trimethylaluminum. 1 reacts with 4-picoline to give the addition compound, Me2(MeSe)Al·Pic, 6. 2 reacts with PPh3 to yield Me2(PhSe)Al·PPh3, 5, with benzaldehyde to yield {Me2Al[μ-OC(H)(SePh)Ph]}n, 7, and with methyl benzoate to give the selenoester PhC(O)SePh. The resulting derivatives have been characterized by 1H, 13C, 31P, and 77Se NMR spectroscopy and by chemical analyses. The structures of 3, 4, and 5 were determined by single crystal X-ray diffraction techniques. The crystal structure parameters of 3 are as follows: orthorhombic, space group Cmca (No. 64); cell constants a = 23.419(3) A?; b = 14.830(2) A?; c = 12.020(2) A?; and Z = 8; R = 5.3%, Rw = 4.7% based on 996 (I > 2.0σ(I)) observed reflections. The (AlSe)2 core is planar, and the aluminum center is in a pseudotetrahedral environment with an Al-Se bond distance of 2.519(2) A?. 4 crystallizes in the monoclinic space group P21/c (No. 14); cell constants a = 11.170(1) A?; b = 13.637(3) A?; c = 18.311(2) A?; β = 96.52(1)°; Z = 4; and R = 3.0%, Rw = 6.0% based on 2205 (I > 2.0σ(I)) observed reflections. The central (GaSe)2 ring of the dimer is planar with a Ga-Se bond distance of 2.509(1) A?. The unit cell parameters of 5 are as follows: triclinic space group P1 (No. 2); cell constants a = 9.777(2) A?; b = 9.817(3) A?; c = 14.125(3) A?; α = 82.84(2)°; β = 77.53(2)°; γ = 66.40(2)°; and Z = 2; R = 4.0%, Rw = 3.4% based on 3292 (I > 2.0σ(I)) observed reflections. The aluminum center is in a pseudotetrahedral environment with an Al-Se bond distance of 2.394(1) A? and an Al-P bond distance of 2.517(1) A?.
- Kumar, Rajesh,Dick, David G.,Ghazi, Shahid U.,Taghiof, Majid,Heeg, Mary Jane,Oliver, John P.
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p. 1601 - 1607
(2008/10/09)
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