REVERSIBLE REARRANGEMENTS OF CHLOROPHOSPHANE-DICHLOROGERMYLENE YLIDESTO TRICHLOROGERMYLPHOSPHANES - STRUCTURE DETERMINATION OF A TETRANUCLEAR BIS(CHLOROPHOSPHANE)BIS(TRICHLOROGERMYLPHOSPHANE) SILVER BROMIDE COMPLEX

Chlorophosphanes RR'PCl (1a: R,R' = iPr; 1b: R = tBu, R' = iPr, 1c: R = iPr, R' = Et2N, 1d: R = tBu, R' = Et2N) react with the dichlorogermy lene dioxane complex 2 furnishing trichlorogermylphosphanes RR'PGeCl3 4a-d. In the cases of 1c/4c and 1d/4d the insertion reactions remain i ncomplete; similarly, 4a always contains, shortly after isolation in p ure state, small amounts of la that can be detected by NMR. A product with the analytical composition of isomers 3d/4d is provided by the re action of trichlorosilylphosphane tBu(Et2N)PSiCl3 (5 d) with GeCl4. Th e alkyl(dialkylamino)trichlorogermylphosphane 4d exists only in an equ ilibrium with chlorophosphane 1d, which coordinates GeCl2 leading to t he dichlorogermylene complex 3d. A 1:1 mixture of 4a with la is formed by the novel cleavage (''chlorogermylation'') of the P-P bond of tetr aisopropyldiphosphane with germanium tetrachloride. Di-tert-butyl(tric hlorogermyl)phosphane 4e (R, R' = tBu) reacts with silver bromide prov iding a crystalline silver complex 7. A structure determination by X-r ay diffraction reveals that 7 is [Ag4Br4(tBu(2)PCl)(2)(tBu(2)PGeCl(3)) (2)]. 2 C7H8. Two of the Ag atoms of the cubane-like (AgBr)(4) core of 7 are coordinated by chlorophosphane 1e, the other two by trichloroge rmylphosphane 4e.