Metal Ion Mediated Transfer and Cleavage of Diaminocarbene Ligands

Under mild conditions, reactions of (CO) 5 M C[N(R)CH 2 ] 2 [M = W, Mo, Cr; R = Et, allyl, benzyl, 4-pentenyl] with (PhCN) 2 PdCl 2, (PhCN) 2 PtCl 2, [(CO) 2 RhCl] 2, (Me 2 S)AuCl, [(CH 3 CN) 4 Cu]BF 4, and AgBF 4 provide the corresponding diaminocarbene complexes via carbene ligand transfer. The resulting Pd(II), Pt(II), Rh(I), and Au(I) carbene complexes are stable and were isolated. The Cu(I) and Ag(I) complexes readily undergo acid-induced M C cleavage to yield the imidazolidin-2-ylidinium salts. The carbene-transfer reactions were studied for two phosphine donors: (CO) m (L)W C[N(R)CH 2 ] 2 {R = Et, benzyl; L = PPh 3, m = 4; L = dppe, m = 3}. The X-ray crystal structures of (CO) 5 W C[N(CH 2 C 6 H 5 )CH 2 ] 2 ( 1c ), cis -(CO) 4 (PPh 3 )W C[N(CH 2 C 6 H 5 )CH 2 ] 2 ( 5b ), fac -(CO) 3 (dppe)W C[N(CH 2 C 6 H 5 )CH 2 ] 2 ( 6b ), Cl 2 (CO)Pt C[N(CH 2 C 6 H 5 )CH 2 ] 2 ( 9c ), and cis -Cl 2 Pt{=C[N(CH 2 C 6 H 5 )CH 2 ] 2 } 2 ( 11b ) are reported.