Lewis-Base Adducts of Group-11 Metal(I) Compounds. XXXI. Reaction of 2,6-Bis[1-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

Abstract

Reaction of 2,6-bis[l-phenyl-1-(pyridin-2-yl)ethyl]pyridine, L, with copper(1) 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 ]^-, (1), [( 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 [IcuI₂Cul]^2-. MeCN . The same cation is common to all four species, containing four-coordinate copper(r), with L as meso -tridentate ligand; in (4), the most precisely defined example, Cu-N( MeCN ) is 1.919(5) Å, the shortest copper(1) acetonitrile distance known, while Cu-N(L) are 2.065(5)-2.073(5) Å. 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.