PROCEDURE FOR THE DEGRADATION OF 1,2-(PR(2))(2)-1,2-DICARBA-CLOSO-DODECABORANE(12) AND 1-(PR(2))-2-R'-1,2-DICARBA-CLOSO-DODECABORANE(12)

Monophosphines and bisphosphines bearing anionic groups derived from t he 7,8-dicarba-nido-undecaborate unit, such as [7-PR(2)-8-Me-7,8-C2B9H 10](-) and [7,8-(PR(2))(2)(-)7,8-C2B9H10](-) (R = phenyl, ethyl, isopr opyl or ethoxy), were synthesized from closo-carborane precursors 1-PR (2)-2-Me-1,2-C2B10H10 and 1,2-(PR(2))(2)-1,2-C2B10H10, respectively. I n general, the C-c-P bond in the close species is very susceptible deg radation reactions, producing C-c-P cleavage and yielding the [7,8-C2B 9H10](-)(2) anion. Good degradation conditions which retain the C-c-P found are toluene with a carborane-to-piperidine ratio of 1:50 and eth anol with carborane-to-piperidine ratio of 1:10. The aryl phosphines k eep the C-c-P bond best and produce the highest yields. Phosphites als o retain the C-c-P bond, but the phosphorus becomes positive and produ ces a zwitterionic species. All<ylphosphines are intermediate, dependi ng on the bulk and nature of the R group in the -PR(2) unit. The cryst al structure of [NMe(4)][7,8-(PPh(2))(2)-7,8-C2B9H10]. CH3CH2OH is des cribed.