SYNTHESIS AND CRYSTAL-STRUCTURE OF A MONOMERIC TETRAALKYLDIGALLIUM TELLURIDE WITH A BENT GA-TE-GA GROUP

Tetrakis[bis(trimethylsilyl)methyl]digallane-(4) (1) with a gallium-gallium bond reacts under mild conditions with Et(3)P(+)-Te- to give the title compound R(2)Ga-Te-GaR(2) (2; R = CH(SiMe(3))(2)) in high yield. 2 is stable in solution at room temperature and, due to the high steric shielding, a monomer even in the solid state. A crystal structure determination (orthorhombic; Pcaa; a = 2375.3(2) pm; b = 1658.4(2) pm, c = 1216.6(3) pm; Z = 4) reveals an angled Ga-Te-Ga group (109.8 degrees) and a Ga-Te bond length of 255.21(4) pm, as would be expected for a Ga-Te single bond with the atoms in low coordination numbers. There are no indications for a significant pi-interaction between tellurium lone pairs and the gallium atoms, and the hindered rotation of the bulky substituents observed by Low-temperature NMR is more likely caused by steric restrictions.