Metal ion mediated transfer and cleavage of diaminocarbene ligands

Under mild conditions, reactions of (CO)(5)M=C[N(R)CH2](2) [M = W, Mo, Cr; R = Et, allyl, benzyl, 4-pentenyl] with (PhCN)(2)PdCl2, (PhCN)(2)PtCl2, [(C O)(2)RhCl](2), (Me2S)AuCl, [(CH3CN)(4)Cu]BF4, and AgBF4 provide the corresp onding diaminocarbene complexes via carbene ligand transfer. The resulting Pd(II), Pt(II), Rh(I), and Au(I) carbene complexes are stable and were isol ated. The Cu(I) and Ag(I) complexes readily undergo acid-induced M=C cleava ge to yield the imidazolidin-2-ylidinium salts. The carbene-transfer reacti ons were studied for two phosphine donors: (CO)(m)(L)W=C[N(R)CH2](2) CR = E t, benzyl; L = PPh3, m = 4; L = dppe, m = 3). The X-ray crystal structures of (CO)(5)W=C[N(CH2C6H5)CH2](2) (1c), cis-(CO)(4)(PPh3)W=C[N(CH2C6H5)CH2](2 ) (5b), fac-(CO)(3)(dppe)W=C[N(CH2C6H5)CH2](2) (6b), Cl-2(CO)Pt=C[N(CH2C6H5 )CH2](2) (9c), and cis-Cl2Pt{=C[N(CH2C6H5)CH2](2)}(2) (11b) are reported.