133289-14-2Relevant academic research and scientific papers
Formation and structure of heptacoordinate dihalogeno carbene-C,O chelate complexes and dihalogeno carbene-C,O chelate phosphine complexes of molybdenum(II) and tungsten(II): A new class of fischer type carbene complexes
Stumpf, Rüdiger,Jaeger, Monika,Fischer, Helmut
, p. 4040 - 4048 (2001)
The carbene-C,O chelate carbonyl tungsten(O) complex [(CO)4W=C(OMe)C6H4OMe-o] (1) reacts with phosphines by opening of the chelate ring to form [(CO)4(PR3)W=C(OMe)C6H4-OMe-o] (R = Me (5), nBu (6), Ph (7), Cy (8)). Treatment of 5 and 6 with SnX4 affords by oxidative decarbonylation, depending on R and X, either one or two isomers of the carbene-C,O chelate dicarbonyl phosphine tungsten(II) complexes [X2(CO)2(PR3)W=C(OMe)C6H4 OMe-o] (R = Me, X = Cl (9a), Br (9b), I (9c-A/9c-B); R = nBu, X = Cl (10a), Br (10b-A/10b-B), I (10c)). The isomers do not interconvert. In the corresponding reaction of 7 with SnBr4 instead of a carbene-C,O chelate dicarbonyl phosphine tungsten(II) complex the carbene-C,O chelate tricarbonyl tungsten(II) complex [Br2(CO)3W=C(OMe)C6H4OMe-o] (3b) is formed. When 8 is treated with SnBr4, the formation of a carbene-C,O chelate phosphine tungsten-(II) complex cannot be detected any more. Like the o-OMe tungsten(O) complexes 5 and 6 the p-OMe tungsten(O) complex [(CO)4(PnBu3)W=C(OMe)C6H4 OMe-p] (11) and the ring-unsubstitut complex [(CO)4(PnBu3)W=C(OMe)Ph] (13) react with SnBr4 by oxidative decarbonylation and formation of W(II) complexes, [Br2(CO)3(PnBu3)W=C(OMe)R′] (R′ = C6H4OMe-p, Ph) (two isomers each). Dicarbonyl carbene-C,O chelate trimethylphosphine metal(II) complexes [X2(CO)2(PMe3)M=C(OMe)C6 H4OMe-o] (M = Mo, W; X = Cl, Br) are also accessible by substitution of PMe3 for a CO ligand in [X2(CO)3M=C(OMe)C6H4OMe-o]. However, when PMe3 is replaced by the bulkier PPh3 in the reaction with [Br2(CO)3-M=C(OMe)C6H4OMe-o], instead of substitution, the opening of the chelate ring is observed.
