The reaction of phosphorus ligands with hydridotricarbonyl-π-cyclo-pentadienyl-molybdenum or -tungsten

Abstract

Reaction of HM(CO)3π-C5H5(M = Mo or W) with phosphines or phosphites (L) leads to the formation of the air-stable crystalline complexes HM(CO)2(L)π-C5H5(M = Mo or W). Rate measurements on the reaction of P(C6H5)3 with DW(CO)3π-C5H5 and HW(CO)3π-C5H5 established the bimolecularity of the reaction and the absence of an isotope effect, suggesting that reaction involves direct displacement of carbon monoxide and not the intermediacy of unstable formyl complexes. Examination of the 1H n.m.r. and infrared spectra of the complexes established a cis-stereochemistry, i.e., cis-HM(CO)2(L)π-C5H5(M = Mo or W). The hydrido-complexes react stereospecifically with CCl4 and I2 to give the complexes cis-XM(CO)2(L)π-C5H5(M = Mo or W; X = Cl or I).