141807-09-2Relevant academic research and scientific papers
Reactions at metal-bound nitrogen atoms. Formation of molybdenum and tungsten phosphoraniminato complexes from silylimido complexes and synthesis of a nitride-bridged tungsten derivative
Lichtenhan, Joseph D.,Ziller, Joseph W.,Doherty, Nancy M.
, p. 2893 - 2900 (2008/10/08)
Tungsten(VI) and molybdenum(VI) phosphoraniminato complexes, M(NPMe3)Cl5, are synthesized in good yield by the reaction of excess Cl2 with tungsten(IV) and molybdenum(IV) silylimido complexes, M(NSiMe3)Cl2(PMe3)3. These reactions are accompanied by loss of ClSiMe3 and PCl2Me3. Related tungsten(IV) and molybdenum(IV) phosphoraniminato complexes, [W-(NPR3)Cl2(PMe3)3]Cl (PR3 = PMe3, PMePh2, PPh3) and [Mo(NPMe3)Cl2(PMe3)3]Cl, are readily prepared by addition of PCl2R3 to M(NSiMe3)Cl2(PMe3)3. The tungsten(IV) derivatives react with excess Cl2 producing W(NPR3)Cl5 and PCl2Me3, with subsequent exchange of the PvR3 and PvMe3 groups occurring. A tungsten(V) phosphoraniminato derivative, W(NPMe3)Cl4-(PMe3), is isolated from the reaction of W(NSiMe3)Cl2(PMe3)3 with limited Cl2 and is found to form by conproportionation of W(NPMe3)Cl5 and [W(NPMe3)Cl2(PMe3)3]Cl. The tungsten(VI) triphenylphosphoraniminato complex can also be prepared by addition of PCl2Ph3 to W(N)Cl3 or from Me3SiNPPh3 and WCl6, with additional Me3SiNPPh3 or Me3SiNPMePh2 producing bis(phosphoraniminato) complexes. In contrast, attempts to synthesize W(NPMePh2)Cl5 by the reaction of WCl6 and Me3SiNPMePh2 instead result in high-yield formation of a reduced mixed-valence nitride-bridged compound, [W2(N)Cl9]2-[PClMePh2]2. Four of the tungsten phosphoraniminato complexes in this system have been structurally characterized and are found to contain approximately linear WNP geometries with short tungsten-nitrogen multiple-bond distances (1.736-1.791 ?). The nitride-bridged tungsten derivative possesses an asymmetric linear W(N)W structure with one short tungsten-nitrogen bond (1.682 ?) suggesting description of this species as an anionic tungsten(VI) nitride acting as a two-electron ligand to tungsten(V) chloride.
