3,4-dimethyl-2,5-bis(trimethylsilyl)phospha- and 3,4-dimethyl-2,5-bis(trimethylsilyl)arsacyclopentadienides of calcium

The reaction of zirconocene dichloride with 2 equiv of butyllithium and 1-t rimethylsilylpropyne yields yellow 1,1-bis(cyclopentadienyl)-3,4-dimethyl-2 ,5-bis(trimethylsilyl)zirconacyclopenta-2,4-diene, 1. The metathesis reacti on of 1 with PCl3 gives a mixture of 1-chloro- and 1-cyclopentadienyl-3,4-d imethyl-2,5-bis( which was allowed to react in THF with distilled calcium. Crystallization of the product from THF solution gave dimeric bis(tetrahydr ofuran-O)dicalcium bis[3,4-dimethyl-2,5-bis(trimethylsilyl)-1-phosphacyclop enta-2,4- cyclopentadienide chloride, 2. The metathesis reaction of 1 with AsCl3 yielded nearly quantitatively 1-chloro-3,4-dimethyl-2,5-bis(trimethyl silyl)-1-arsacyclopenta-2,4-diene, 3. 3,4-Dimethyl-2,5-bis(trimethylsilyl)- 1-arsacyclopentadienyl bis(tetrahydrofuran-O)calcium chloride, 4, was isola ted from the reduction of 3 with distilled calcium.