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-trimethylsilylpropyne yields yellow 1,1-bis(cyclopentadienyl)-3,4-dimethyl-2,5-bis(trimethylsilyl)zirconacyclopenta-2,4-diene, 1. The metathesis reaction of 1 with PCl3 gives a mixture of 1-chloro-
and 1-cyclopentadienyl-3,4-dimethyl-2,5-bis(trimethylsilyl)-1-phosphacyclopenta-2,4-diene,
which was allowed to react in THF with distilled calcium. Crystallization of the product
from THF solution gave dimeric bis(tetrahydrofuran-O)dicalcium bis[3,4-dimethyl-2,5-bis(trimethylsilyl)-1-phosphacyclopenta-2,4-dienide] cyclopentadienide chloride, 2. The metathesis reaction of 1 with AsCl3 yielded nearly quantitatively 1-chloro-3,4-dimethyl-2,5-bis(trimethylsilyl)-1-arsacyclopenta-2,4-diene, 3. 3,4-Dimethyl-2,5-bis(trimethylsilyl)-1-arsacyclopentadienyl bis(tetrahydrofuran-O)calcium chloride, 4, was isolated from the reduction
of 3 with distilled calcium.