Mononuclear and mixed-metal copper(I)—silver(I) complexes containing 2,2′-bibenzimidazole and triphenylphosphane as ligands: crystal structures of [Cu(tmbbimH2)(PPh3)2](MeCOO)·0.2C7H8 and [Ag0.55Cu1.45(μ-bbim)(PPh3)4]·4CH2Cl2

Novel mononuclear [Cu(bbimH2)(PPh3)2](MeCOO) (1), [Cu(tmbbimH2)(PPh3)2](MeCOO)·0.2C7H8(2)·0.2C7H8, and mixed-metal [Ag0.55Cu1.45(μ-bbim)(PPh3)4]·4CH2Cl2(3)·4CH2Cl2 complexes (bbimH2 = 2,2′-bi-(1H)-benzimidazole, tmbbimH2 = 5,5′,6,6′-tetramethyl-2,2′-bi-(1H)-benzimidazole) have been prepared. Compounds (2)·0.2C7H8 and (3)·4CH2Cl2 have been characterized by single-crystal X-ray structure analyses. In the solvate of (2), the CuI ion sits on a distorted tetrahedral site, being coordinated to two nitrogen atoms and two phosphorus atoms. The coordination sphere of (1) is proposed to be analogous to that of (2). In the solvate of (3), there are two equivalent distorted tetrahedral sites, each one consists of 27.5% of AgI and 72.5% of CuI ions, bridged by the planar tetradentate ligand bbim2−. The 1H- and 31P{1H}-n.m.r. data are discussed and related to the structures.