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).