NEW TUNGSTEN(VI) CARBYNE COMPLEXES AND CA RBENE COMPLEXES FROM THE REACTION OF CHLOROCARBYNE COMPLEXES WITH NUCLEOPHILIC SUBSTANCES - NEW CATALYSTS FOR RING-OPENING METATHETIC POLYMERIZATION OF CYCLOOLEFINS

Tungstenchlorocarbyne complexes [LRCl2W=C-p-tol] of the tripodal oxyge n ligands L-R(-)= [(C5H5)Co{P(O)R-2}(3)](-), R = OMe O-i-Pr, react wit h methanol, ethanol and 1,2-ethanediol to yield the alkoxidocarbyne co mplexes [LOMeCl(OR)W=C-p-tol], OR = OMe, OEt, OCH2CH2OH. [L-OMe(OMe)(2 )W=C-p-tol] has been prepared by the reaction of [LOMeCl2W=C-p-tol] wi th KOMe. The reaction of [LRCl2M=C-p-tol] with aqueous triethylamine o r alumina leads to two isomeric oxocarbene complexes [LRCl(O)W=CH-p-to l]. In the presence of AlCl3, these complexes are highly active cataly sts for the ring opening metathetical polymerisation of cyclooctene. T he oxocarbene complex [LOMeCl(O)W=CH-p-tol] reacts further with Al2O3 to give the dioxoalkyl complex [L-OMe(O)(2)W-CH2-p-tol]. The reaction of [LOMeCl2W=C-p-tol] with HNEt2 yields the amidocarbyne complex [LOMe Cl(NEt2)W=C-p-tol]. With H2N-n-Pr the amidocarbyne complex [LOMeCl(NH- n-Pr)W=C-p-tol] is formed that isomerizes within hours to the imidocar bene complex [LOMeCl(N-n-Pr)W=CH-p-tol]. This conversion proceeds via an isomer of [LOMeCl(N-n-Pr)W=CH-p-tol] in which the p-tolyl-ligand is pointing towards the tripodal oxygen ligand and finally leads to the isomer, in which the p-tolyl-ligand is pointing away from the oxygen l igand. The carbene complexes [LRCl(X)W=CH-p-tol] are oxidised in air t o yield [LRW(X)(O)Cl], R = OMe, O-i-Pr, X = O, N-n-Prop.