Lewis-Base Adducts of Group 11. Metal(I) Compounds. XXXI. Reaction of 2,6-Bis[l-phenyl-1-(pyridin-2-yl)ethyl]pyridine (L), and Copper(I) Halides in Acetonitrile: Structural Characterization of Salts of the [(MeCN)Cu(meso-L)]+ Cation

Reaction of 2,6-bis[l-phenyl-1-(pyridin-2-yl)ethyl pyridine, L, with copper(I) chloride, bromide, and iodide in acetonitrile solution has been shown to yield salts, structurally characterized by single-crystal X-ray diffraction methods as [(MeCN)CuL]+ [ClCuCl]-, (I), [(MeCN)CuL]+2[XCuX2CuX]2-, X = Br (2), I (3) (both isomorphous), all as yellow needles, and a form of (3), orange blocks, as the hemiacetonitrile solvate, (4), [(MeCN)CuL]+2[ICuI2CuI]2-.MeCN. The same cation is common to all four species, containing four-coordinate copper(I), with L as meso-tridentate ligand; in (4), the most precisely defined example, Cu-N(MeCN) is 1.91965) A, the shortest copper(I) acetonitrile distance known, while Cu-N(L) are 2.065(5)-2.073(5) A. The reason for non-formation of species of the type [LCuX] appears to lie in the tridentate ligand conformation which permits coordination of acetonitrile but not larger halide species.