Synthetic, spectroscopic and structural behavior of unsaturated functionalized N-heterocyclic carbene complexes of group 11.

A series of unsaturated functionalized silver(I) N-heterocyclic carbenes [{(?C-C7N2H10)AgCl}2] (1a), [{(?C-C8N2H12)2}2Ag][Ag2Cl4] (1b), [{(?C-C9N2H14)2Ag}2][Ag2Cl4] (1c), and [{(?C-C12N2H14)2Ag}2][Ag2Cl4] (1d) have been synthesized and used as transmetalation agents to form the corresponding Au(I) and Cu(I) complexes. The reactions of 1a-d with [Au(SMe2)Cl] or CuI produced the mixed-metal biscarbene compounds [(?C-C7N2H10)2M][AgCl2] (M = Au 2a; Cu 3a), [{(?C-C8N2H12)2}2M][Ag2Cl4] (M = Au 2b; Cu 3b), [{(?C-C9N2H14)2M}2][Ag2Cl4] (M = Au 2c; Cu 3c), and [{(?C-C12N2H14)2}2M][Ag2Cl4] (M = Au 2d; Cu 3d). The carbene complexes were fully characterized by IR, NMR and mass spectrometry, and the molecular structures of 1a, 1b, 2b and the imidazolium salt [PMIM][PF6] (L2?) were determined by single crystal X-ray diffraction studies. Compounds L4, 1d and 2d were used as monomeric units to carry out free-radical polymerization (FRP) reactions using AIBN as initiator.