Preparation and properties of cis-[W(N2)2(Ph2PCH2PPh2)2] and trans-[M(N2)2(Ph2PCHCHPPh2)2](M = Mo or W), and the crystal structure of cis-[W(N2)2(PMe2Ph)4]
Abstract
The complexes cis-[W(N2)2(Ph2PCH2PPh2)2](A) and trans-[W(N2)2(Ph2PCHCHPPh2)2](B) have been prepared by reduction of WCl6 or [WCl4(Ph2PCHCHPPh2)] with Mg in tetrahydrofuran (thf) under N2 in the presence of the appropriate phosphine. Dinitrogen is displaced from (A) by CO to give cis-[W(CO)2(Ph2PCH2PPh2)2]. Compound (B) reacts with I2, FeCl3, and CuCl2 to give [W(N2)2(Ph2PCHCHPPh2)2]Y (Y = I3, FeCl4, or CuCl2) and with HCl to give the cation [WCl(NNH2)(Ph2PCHCHPPh2)2]+. Both complexes (A) and (B) undergo reversible one-electron oxidation in thf. The complex trans-[Mo(N2)2(Ph2PCHCHPPh2)2] gives tans-[Mo(N2)(RCN)(Ph2PCHCHPPh2)2](R = Me or Et) on treatment with RCN. X-Ray analysis of the related complex, cis-[W(N2)2(PMe2Ph)4], shows a well defined octahedral structure in which the dinitrogen ligands have different environments and the W–N distances are 1.983 and 2.015(3)Å.