METAL DERIVATIVES OF MOLECULAR-COMPOUNDS .4. SYNTHESIS, STRUCTURE, AND REACTIVITY OF LITHIUM [TRIS(TRIMETHYLSILYL)SILYL]TELLANIDE BULLET DME

Lithium tris(trimethylsilyl)silanide . 1,5 DME [3] and tellurium react in 1,2-Dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide . DME (1). An X-ray structure determination {-150 +/- 3-degrees-C; P2(1)/c; a = 1 346.6(4); b = 1 497.0(4); c = 1 274.5(3) pm; beta = 99.22(2)-degrees; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li-Te-Li-Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li-Te 278 and 284; Si-Te 250; Li-O 200 pm (2x); Te-Li-Te 105-degrees; Li-Te-Li 75-degrees; O-Li-O 84-degrees}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 +/- 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane (2), methyl[tris(trimethylsilyl)silyl]tellane (4) and bis[tris(trimethylsilyl)silyl]ditellane (5) are formed.