| Abstract: | Complex Catalysis. XIX. Synthesis of Nitrosyl Complexes of Tungsten and their Usefulness as Precatalysts for Olefin Metathesis Nitrosylating reduction of WCl6 with NO leads to WCl3(NO)4 that on addition of different donor ligands L yields complexes of the types WCl3(NO)L2 (L = OOh3, HMPT, pyridine) and WX2(NO)2 L2 (L = PPh3, X = Cl; XL = acac) or mixtures of products (L = Dipy, RCN, Et4NCl), respectively. Whereas by carbonylation of WCl3(NO)(OPPh3)2 in the presence of EtAlCl2 only chloro carbonyl tungsten complexes are formed, the reaction of W(CO)6 with NOAlCl4 and subsequent addition of PPh3 gives, in analogy to molybdenum, the nitrosyl carbonyl complexes W(NO)(CO)4(AlCl4) and WCl(NO)(CO)2(PPh3)2. All the nitrosyl tungsten complexes in combination with EtAlCl2 catalyze the metathesis of pent-2-ene, however, with a significantly lower activity than the corresponding nitrosyl molybdenum systems. |
