C-O bond activation in carbene-C,O chelate tungsten(II) complexes - MeX elimination in the reaction of [X-2(CO)(3)W=C(C6H4OMe-o)OMe] with L-2 (L-2 = dppe, 2 PMe3)

The heptacoordinated dihalogeno carbene-C,O chelate carbonyl complexes [X-2 (CO)(3) W=C(C6H4OMe-o)OMe] (3a-c, X = Cl (a), Br (b), I (c)) react with Ph2 PCH2CH2PPh2 (dppe) via CO and MeX elimination to give the aryloxycarbene-C, O chelate complexes [X(CO)(2)(dppe) W=C(C6H4O)OMe)OMe] (7a-c). The analogou s reactions of 3a-c with two equivalents of PMe3 and that of the monophosph ine complexes [X-2(CO)(2)(PMe3)W=C(C6H4OMe-o)OMe] (9a-c) with one equivalen t of PMe3 likewise afford aryloxycarbene-C,O chelate complexes [X(CO)(2)(PM e3)(2)W=C(C6H4O)OMe] (8a-c). In contrast to 8a and 8b the structure of 8c i s dynamic. (C) 2001 Published by Elsevier Science B.V.