DIFFERENT MODES OF REACTION OF LITHIUM PHOSPHIDES WITH CP-ASTERISK-M(NO)(X)CL COMPLEXES OF MOLYBDENUM TUNGSTEN

Treatment of CpM(NO)(X)Cl complexes (M = Mo, W; X, = CH(2)SiMe(3), CH (2)CMe(3), NHCMe(3), OCMe(3), Cl) with lithium phosphides can result i n one of three different types of reactions. Some reactions involve th e starting material undergoing metathesis of a chloro ligand, and othe rs effect reduction of the organometallic reactant, while a third clas s results in a scrambling of the ligands of the starting complex. Reac tions of CPM(NO)(X)Cl with LiPPh(2) lead to formation of the respecti ve phosphido-containing complexes CpM(NO)(X)(PPh(2)) [M = W, X = CH(2 )SiMe(3) (1), CH(2)CMe(3) (2), NHCMe(3) (3), OCMe(3) (4); M = Mo, X = NHCMe(3) (5). In contrast, treatment of the molybdenum complexes CpMo (NO)(X)Cl (X = CH(2)SiMe(3), CH(2)CMe(3), OCMe(3)) with LiPPh(2) under identical conditions affords no isolable products. When metathesis of the chloro ligands in the CpM(NO)Cl-2 complexes of Me and W is attem pted with either LiPPh(2) or LiPPhH, the only isolable products formed are those resulting from the reduction of the organometallic reactant . Thus, treatment of CpW(NO)Cl-2 with 1 equiv of LiPPh(2) leads to is olation of the NO bond-cleaved product, [CpW(NO)(Cl)](mu-N)[Cp*W-(O)C l] (6), in low (15%) yield, while reactions of CpM(NO)Cl-2 (M = Mo, W ) with 2 equiv of either LiPPh(2) or LiPPhH afford modest yields of th e bimetallic products [CpW(NO)(mu-PPh(2))](2) (7), [Cp*Mo(NO)(mu-PPh( 2))](2) (8), and [CpMo(NO)(mu-PHPh)](2) (9). Finally, the reaction of CpW(NO)(NHCMe(3))Cl with LiPPhH induces a Ligand-scrambling process in which an amide Ligand from one molecule of the starting material is transferred to the tungsten center of another to produce CpW(NO)(NHC Me(3))(2) (10). A similar example of ligand scrambling occurs during t he reaction of CpMo(NO)(CH(2)SiMe(3))Cl with LiPPhH In this case the unexpected product {[CpMo(NO)(CH(2)SiMe(3))(2)][Li(THF)]}(2) (11, iso lated in 3% yield) has also undergone a further one-electron reduction at the metal center. The solid-state molecular structures of compound s 9-11 have been established by X-ray crystallographic analyses.