Spectroscopic and crystallographic studies of phosphino adducts of gallium(III) iodide

Abstract

The solid state structures of the compounds GaI3•PPh3 and Ga2I6•dppe ( dppe = 1,2-bis(diphenylphosphino)ethane ) have been determined. For the former, in which the GaI3P core has C3v symmetry, the structure is trigonal, with a = 14.961(2) Å, c = 16.509(3) Å, V = 3199.5(4) Å3, Z = 6, space group [Formula: see text]. In Ga2I6•dppe, the ligand bridges two GaI3P centres; the structure is monoclinic, a = 10.196(7) Å, b = 15.363(1) Å, c = 23.027(9) Å, β = 98.735(4)°, V = 3565.1(3.2) Å3Z = 4, space group P21/n The use of 31P NMR spectroscopy shows that GaI3•PPh3 is slightly dissociated in nonaqueous solution, and the effect of adding Ph3P or I− has been investigated. Similar studies with Ga2I6•dppe are also reported. In each system, four-coordination at gallium is dominant; an equally important factor is the dimerization of uncomplexed GaI3 to Ga2I6 in these solutions. Keywords: gallium(III) iodide, complexes, phosphorus, NMR, crystallography.