Phosphanylphosphinidene-Phosphoranes: A Study on Building and Decomposition of Phosphorus-Rich Chains with Two Ylidic Moieties

The reactions of tBu(2)P-P=P(tBu(2))CH2Li at low temperature with dichlorophosphanes RPCl2 (R = Ph, Me, NEt2, tBu) lead to "P-7-chains" as primary products wherein two ylidic moieties are linked by a CH2-PR-CH2 unit. However, if R = tBu the long chain is only a by-product in addition to tBu(2)P-P=P(tBu(2))Me. The thermal decomposition of "P-7-chains" as monitored by P-31 NMR spectroscopy results in tBu(2)P-CH2-PR-CH2-PtBu2 ("P-3-chains") and the phosphanylphosphanylidene {tBu(2)P-P} which is observed as its cyclic trimer or tetramer. In the reactions of tBu(Me3Si)P-P=P(tBu(2))CH2Li with RPCl2 the corresponding "P-7-chains" and the P4CH2-rings are formed. The substituent R strongly determines the ratio of chain to ring as well as the thermal stability of the products. The solid-state structures of one representative of both "P-7-chains", and of the oxidized derivative of the P4CH2-ring with R = tBu were determined by single-crystal X-ray diffraction analysis.