Heterobimetallic complexes with a propynylidene C-3-bridge: General synthetic routes to bimetallic ethynylcarbene complexes

Sequential reaction of the dimethylamino(trimethylsilylethy nyl)carbene complexes [(CO)(5)M'= C(NMe(2))C = CSiMe(3)] [M' = W (1a), M' = Cr (1b)] with KF/THF/MeOH, nBuLi and transition metal halides, [XML(n)], affords heterobimetallic propynylidene complexes of the type [(CO)(5)M' = C(N-Me(2))C = CML(n)] [ML(n) = Ni(PPh(3))Cp (4a, b), Ni(PMe(2)Ph)(2)-(Mes) (Mes = 2,4,6-C(6)H(2)Me(3)) (5a), Rh(CO)(PPh(3))(2) (6a), Fe-(CO)(2)Cp (7a, b)]. In contrast, reaction of 1a with MeLi . LiBr and [IFe(CO)(2)Cp] yields the novel N-metallated complex [(Co)(5)W = C{N(Me)Fe(CO)(2)Cp}C = CSiMe(3)] (8a). The complexes [(CO)(5)M' = C(NMe(2))C = CML(n)] [ML(n) = Fe(CO)(2)Cp (7a, b), Ru(CO)(2)Cp (10a, b), Ru(CO)(PPh(3))Cp (11a), Mn(CO)(5) (12a), Re(CO)(5) (13a)] are accessible by Pd-catalyzed coupling of the C-stannylated carbene complexes [(CO)(5)M' = C-(NMe(2))C = CSnBu(3)] (9a, b) with [XML(n)]. The related mono-methylaminocarbene complexes [(CO)(5)M' = C(NHMe)C = CSnBu(3)] (16a, b), obtained by stannylation of [(CO)(5)M' = C(NHMe)C = CH] (15a, b) with Bu(3)SnNEt(2), react with [IFe(CO)(2)Cp] to give the bimetallic complexes [(Co)(5)M' = C(NHMe)C = CFe(CO)(2)Cp] (17a, b). The complexes 4a, 5a, 7a and 10a were characterized by X-ray structural analyses. The spectroscopic and structural data suggest that the two metal centers in 4-7, 10-13 and 17 interact only weakly.