Preparation and properties of dinitrogen complexes of molybdenum and tungsten with trimethylphosphine as coligand : III. Synthesis and properties of cis-[W(N 2) 2(PMe 3) 4], trans-[W(C 2H 4) 2(PMe 3) 4] and [M(N 2)(PMe 3) 5] (M = Mo, W). The crystal and molecular structure of [Mo(N 2)(PMe 3) 5

Abstract

The reduction of [WCl 4(PMe 3) 3] with dispersed sodium, under dinitrogen, gives cis-[W(N 2) 2(PMe 3) 4], while under ethylene trans-[W(C 2H 4) 2(PMe 3) 4] is obtained. The ethylene complex can also be prepared by displacement of the dinitrogen molecules in cis-[W(N 2) 2(PMe 3) 4] by ethylene at room temperature and pressure. Interaction of cis-[M(N 2) 2(PMe 3) 4] complexes (M = Mo, W), with PMe 3, under helium or argon, yields [M(N 2)(PMe 3) 5]. The molybdenum complex crystallizes in the orthorhombic space group Pnma, with a 22.063(6), b 12.106(4), c 9.745(4) Å. The Mo—P distance trans to the dinitrogen ligand (2.483(7) Å) is slightly longer than the average of the other four Mo—P bonds (2.460(5) Å).