2-DIPHENYLPHOSPHINO-1,3-DIPHOSPHOLIDE ANIONS

The title compounds are easily obtained in four steps from 4,5-disubst ituted 1,3-diphenyl-1,3-diphosphacyclopent-4-enes (1). Metallation of the P-CH2-P unit of 1 followed by reaction with Ph2PCl allows a diphen ylphosphino group to be grafted onto 1 at the C-2 carbon. After remova l of the remaining C2H proton by a base, selective cleavage of the two P-1-Ph and P-3-Ph bonds by lithium in THF affords the corresponding 2 -diphenylphosphino-1,3-diphospholide ions (5). in one case, the reacti on of n-butyllithium with la leads to an opening of the five-membered ring via a nucleophilic attack at phosphorus. A bis-(phosphino)methani de ion (8) is thus obtained. Its chemistry has been investigated brief ly.