CARBONYL INSERTIONS INTO METAL NITROGEN BONDS OF GROUP-4 DIALKYLAMIDO COMPLEXES - X-RAY STRUCTURE OF CP(ASTERISK)(ME(2)N)(2)TI[O(ME(2)N)C]W(CO)(5)

[Cp*M(NMe(2))(3)] [Cp* = eta(5)-C(5)Me(5); 1, M = Ti; 2, M = Zr] reacts with metal carbonyls, M'(CO)(n) (n = 6, M' = Cr, Mo, W; n = 5, M' = Fe), to give the corresponding insertion products, Cp*(Me(2)N)(2)M[O(Me(2)N)C]M'(CO)(n-1) (M = Ti; 3, M' = W; 4, M' = Mo; 5, M' = Cr; 6, M' = Fe; M = Zr; 7, M' = W; 8, M' Mo; 9, M' = Cr; 10, M' = Fe), in good yield. When complexes 3-5 were heated at 80 degrees C in toluene for several days, Cp*Ti(mu-NMe(2))(2)[O(NMe(2))C]M'(CO)(3) (11, M' = W; 12, M' = Mo; 13, M' = Cr) were obtained. However, heating 6 under the same conditions gave Cp*(Me(2)N)Ti[O(Me(2)N)C]Fe-2(CO)(3) (14). Reactions of 12 with CO and Bu(t)-NC have been carried out, giving compound 4 in the first case-and Cp*(Me(2)N)2(T)i[O(Me(2)N)C]Mo(CO)(3)(CNBu(t))(2) (15) in the second. The structure of 3 has been proved unequivocally by a X-ray diffraction study (space group P2(1), a = 8.828(2) Angstrom, b = 13.001(4) Angstrom, c = 12.045(2) Angstrom, beta = 98.22(2)degrees, Z = 2, R(1) = 0.044 and wR(2) = 0.109). 3 consists of two moieties, Cp*Ti(NMe(2))(2) and W(CO)(5), bridged by a [O(Me(2)N)C] unit where the oxygen atom is bound to the oxophilic titanium atom, while the carbon is forming a Fischer carbene-like complex with tungsten.