SYNTHESIS AND CHARACTERIZATION OF GALLIUM-ARSENIC COMPOUNDS CONTAINING A 4-MEMBERED GA-AS-GA-CL OR GA-AS-GA-AS RING - CRYSTAL-STRUCTURES OF (ME3SICH2)2GAAS(SIME3)2GA(CH2SIME3)2CL AND [(ME3SICH2)2GAAS(SIME3)2]2

The third example of an organogallium four-membered ring compound with arsenic, halogen mixed bridging, (Me3SiCH2)2GaAs(SiMe3)2Ga(CH2SiMe3)2Cl (1), was prepared by the reaction of (Me3Si)3As (2) with two equivalents of (Me3SiCH2)2GaCl. X-ray crystallographic analysis showed that the compound contains a nonplanar Ga-As-Ga-Cl ring. The crystals belong to the monoclinic system space group P2(1/c) (C2h(5)) with four molecules per unit cell of dimensions a 12.476(2), b 15.832(2), c 22.279(3) angstrom, beta 108.87(1)-degrees, V 4164(2) angstrom-3. The dimer [(Me3SiCH2)2GaAs(SiMe3)2]2 (3) was prepared by reaction of LiAs(SiMe3)2 and (Me3SiCH2)2GaCl. Its solid-state dimeric structure was established by single-crystal X-ray analysis. Crystals of 3 belong to the orthorhombic system space group Pbcn (D2h(14)) with four dimers in a unit cell of dimensions a 12.886(1), b 21.172(2), c 18.610(2) angstrom, V 5077(1) angstrom-3. The centrosymmetric dimers contain a planar Ga-As-Ga-As ring with Ga-As bond lengths of 2.572(1) and 2.561(1) angstrom, and As-Ga-As angles of 85.85(3) and 86.32(3), and Ga-As-Ga 93.91(2)-degrees. Compound 3 reacts with two equivalents of (Me3SiCH2)2GaCl to produce 1 as a minor product along with a mixture of other unidentified products. H-1 and C-13{H-1} NMR spectra of the product mixture obtained from the reaction of 3 with two equivalents of Ph2GaCl and that from the reaction of [Ph2GaAs(SiMe3)2]2 with two equivalents of (Me3SiCH2)2GaCl display some common signals, which are believed to be due to Ph2GaAs(SiMe3)2Ga(CH2SiMe3)2Cl.