Synthesis and characterization of four-membered gallium-arsenic ring compounds containing a bridging As(SiMe3)2 group: crystal structures of and

Article abstract of DOI:10.1016/0022-328X(90)85445-5

The first organogallium four-membered ring compounds with arsenic, halogen mixed bridging to be characterized completely, Ph2(X = Cl (1) and X = Br (2) were prepared by the reaction of (Me3Si)3As (3) with Ph2GaCl and Ph2GaBr, respectively.X-ray crystallographic analyses show the compounds to be isostructural with each containing a non-planar Ga-As-Ga-X four membered ring.Isomorphous crystals of 1 and 2 belong to the monoclinic system, space group P2₁/c (C⁵_2h), with four molecules in unit cells of dimensions: a 10.560(3), b 15.797(3), c 20.591(4) Angstroem, β 92.17(2) deg, V 3433(2) Angstroem³ for 1, and a 10.653(1), b 15.777(2), c 20.517(2) Angstroem, β 91.97(1) deg, V 3446(1) Angstroem³ for 2.The non-planarity of the rings is manifested in the halogen atom displacements of 0.256 Angstroem in 1 and 0.293 Angstroem in 2 from the respective Ga-As-Ga' planes.Deviations from overall C_2y symmetry serve to relieve unfavorable intramolecular bulky ring substituent interaction present in such a symmetric form.The dimer 2 (4), obtained from the reaction of Ph2GaCl and LiAs(SiMe3)2, has been characterized by partial elemental analysis, NMR spectroscopy and cryoscopic molecular weight determination.An alternative route to the synthesis of 1 by reaction of 4 and Ph2GaCl was investigated via NMR spectroscopy.