REACTIONS OF COORDINATED LIGANDS .8. PHOSPHINOFORMIC ACIDS RR'PCOOH (R, R' = ORGANYL, H), THE STILL UNKNOWN P-ANALOGS OF CARBAMINIC ACIDS, STABILIZED AS LIGANDS IN COMPLEXES (CO)5MPRR'COOH (M = CR, W)

Metal carbonyl complexes containing phosphinoformic acids, including the parent compound H2PCOOH, have been made by the following route: (CO)5MPRR'H-->(CO)5MPRR'Li-->(CO)5MPRR'COOLi-->(CO)5MPRR'COOSiMe3-->(CO)5MPRR'COOH (R = organyl, H; M = Cr, W). While the uncoordinated silyl esters RR'PCOOSiMe3 spontaneously decompose to RR'PH, CO2 and Me3SiOH in protic media the last step in the sequence above can be safely brought about by silica gel. So far only chromatography on silica gel has been found to provide the mild conditions necessary to avoid decarboxylation of the ligated esters during protolysis. Some reactions of (CO)5MPRR'COOLi are reported and compared with those of the free ligands RR'PCOOLi. The structures of the complexes have been confirmed by spectroscopic methods (IR, MS, H-1-, P-31-, C-13-NMR).