SYNTHESIS AND REACTIONS OF SOME LITHIUM PHOSPHINOFORMATES R(2)PCOOLI AND RHPCOOLI - AB-INITIO CALCULATIONS IN THE H2PCOOH-PH3/CO2 SYSTEM

The preparation of lithiumphosphinoformates R(2)PCOOLi 1 (R = Ph, c-Hexyl, i-Pr, Et) and RHPCOOLi 2 (R = Ph, c-Hexyl) from R(2)PLi or RPHLi and CO2 is described. In the latter reaction RP(COOLi)(2) 3 and RPH(2) are formed in addition to 2. In protic media 1-3 are rapidly decomposed with decarboxylation and formation of R(2)PH and RPH(2), respectively. Reactions of 1 with Mel, (MeO)(2)SO2, Me(3)SiCl and CS2 are similar to those of Ph(2)PCOONa and no significant influence of R was detected. With (MeO)(2)SO2 mixtures of 2 and 3 gave esters RHPCOOMe and RP(COOMe)(2) while with Me(3)SiCl RHPCOOSiMe(3) was obtained as the sole product. Ab initio MO calculations (GAUSSIAN 90 system of programs; HF/3-21G*, HF/6-31G** and MP2/6-31G** basis sets) showed the phosphinoformic acid to be less stable than its decomposition products, from which it is separated by a high barrier of isomerization. Therefore the acid should be stable in the rarefied gas phase.