REACTION OF [WME(CO)3(ETA-C5H5)] WITH LIBHET3 - FORMATION AND REACTIONS OF THE ANIONIC FORMYL TRANS-[W(CHO)ME(CO)2(ETA-C5H5)] AND THE ANIONIC HYDRIDO ACYL TRANS-[WH(COME)(CO)2(ETA-C5H5)]

Addition of LiBHEt3 to [WMe(CO)3(eta-C5H5)] 5 at -70-degrees-C results in the formation of the formyl trans-[W(CHO)Me(CO)2(eta-C5H5)]- 7. In solution, this species exists as a mixture of two BEt3 adducts and a BEt3-free species. All the formyl species undergo chemical exchange at -50-degrees-C. Warming of the reaction mixture to ambient temperature results in solutions containing the anionic hydrido acyl complex trans-[WH(COMe)(CO)2(eta-C5H5)]- 6 isolable as a boron-free salt [Li(12-crown-4)2][WH(COMe)(CO)2(eta-C5H5)] (12-crown-4 = 1,4,7,10-tetraoxacyclododecane). This moisture-sensitive anion gives [W(CO)3(eta-C5H5)]- on exposure to water and undergoes hydride for halide (X) exchange on low-temperature treatment with CCl4, CBr4 or CHl3 forming the reactive anions [WX(COMe)(CO)2(eta-C5H5)]- 8-10. The major product of warming these halogenoacyl anions is 5. Addition of [Me3O][BF4] to boron-free solutions of [WI(COMe)(CO)2(eta-C5H5)]- 10 results in the new carbene trans-[WI{ = C(OMe)Me}(CO)2(eta-C5H5)] 11, while treatment with SiMe3Cl followed by low-temperature filtration through silica gives the hydroxycarbene trans-[WI{ = C(OH)Me}(CO)2(eta-C5H5)] 12.