The first four-membered ring compound containing two gallium atoms bridged by two different Group 15 elements, I2GaAs(SiMe3)2Ga(I)2P(SiMe3)2 (1) to be completely characterized was synthesized by both the equilibration of [I2GaAs(SiMe3)2]2 (2) and [I2GaP(SiMe3)2]2 (3) in a 1:1 mole ratio, and the direct reaction of Gal3 with As(SiMe3)3 and P(SiMe3)3 in a 2:1:1 mole ratio. Single crystal x-ray structures were determined for both 1 and 3. Crystals of 1 belong to the orthorhombic system, space group Pbca, with a = 17.349(3), b = 13.9187(21), c = 13.7570(24) Ä. V = 3322.0(10) A3, DcaIc = 1.879 g cnr3 for Z = 4; the average Ga-As/P bond length is 2.44 Ä. and crystals of 1 are isomorphous with those of 2. Crystals of 3 belong to the monoclinic system, space group P2\lc, with a = 11.040(9), b = 10.228(4), c = 19.619(9) A, V = 2169.4(22) A3, Dcalc = 1.816 g cm"3 for Z = 4; the average Ga-P bond length is 2.39 Ä
