Synthesis of Heterodinuclear (Carbene)platinum (or palladium) Complex That Gives μ-Alkenyl-Type Complex by Deprotonation

Heterodinuclear platinum (or palladium) complexes having a terminal carbene, (Ph3P)Cl(Me2NHC)M−M′L′n (M = Pt: M′L′n = Co(CO)4 (1), Mn(CO)5 (2), MoCp(CO)3 (3), FeCp(CO)2 (4); M = Pd: M′L′n = Co(CO)4 (33), Mn(CO)5 (34)) and (L)Cl{(PhCH2)YC}Pt−M′L′n (M′L′n = Co(CO)4, L = PMe2Ph: Y = NPh2 (5), OEt (6), OMe (7), OiPr (8); M′L′n = Co(CO)4, L = PPh3: Y = OEt (9); M′L′n = Mn(CO)5, L = PMe2Ph: Y = OEt (10)), are synthesized by metathesis reactions of dichlorocarbene complexes with metalate Na+[M′L′n]−. These complexes are characterized by NMR and IR spectroscopies and elemental analysis, and the molecular structures of 1, 2, and 6 are determined by X-ray structure analysis. Deprotonation of 6−10 with base gives heterodinuclear μ-alkoxystyrylplatinum−metal complexes, (L)(CO){μ-PhHCYC}Pt−M′L′n−1 (M′L′n−1 = Co(CO)3, L = PMe2Ph: Y = OEt (13), OMe (14), OiPr (15); M′L′n−1 = Co(CO)3, L = PPh3: Y = OEt (16); M′L′n−1 = Mn(CO)4, L = PMe2Ph: Y = OEt (12)), where the E isomer is thermodynamically stable. Z isomers of corresponding monomeric alkoxystyrylplatinum(II) complexes are found to be more stable than the corresponding E isomers. In contrast, both the dinuclear diphenylaminostyrylplatinum−cobalt complex and its mononuclear analogue favor the Z configuration.