Organosilyl Compounds of Zinc, Cadmium and Mercury

The zinc and cadmium organosilyl compounds are about equally unstable, in sharp contrast to the mercury compounds. The reaction of lithium tetrakis(trimethylsilyl) aluminate with zinc acetate in diethyl ether yields (25 %) bis(trimethylsilyl) zinc [435]. This compound can be kept for about three weeks under an inert gas at — 20 °C. The reaction of lithium tetrakis(trimethylsilyl) aluminate with cadmium acetate forms bis(trimethylsilyl) cadmium [435] (27%, very unstable, sensitive to light). Bis(tri-t-butylsilyl) cadmium [436] (m. p. 140 °C, slightly yellowish crystals which turn greenish black on exposure to air) can be obtained from tri-r-butylsilane and diethylcadmium (Eq. 3.230)  

However, the organosilyl mercury compounds are more conveniently synthesized from haloorganosilanes and a large excess of a sodium amalgam. The sodium in this amalgam is very dilute, but the amount of amalgam used is such that equivalent molar amounts of sodium and halogen are present. In this way bis(trimethylsilyl)mercury [438] m.p. 104°C (Eq.3.232) and 2,2,4,4,6,6,8,8-octamethyl-2,4,6,8-tetrasila-l,5-dimercura-cyclooctane [438] (56% subl.p. 107°C at 0.013 Pa = 0.0001 m Hg). (Eq. 3.233) are made. 

Alkyltrimethylsilyl mercury compounds are obtained in a good yield from bis(trimethylsilyl) mercury and alkyl mercury chlorides in toluene at a temperature below 0°C [439] (Eq. 3.234)  

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