Copper(I) Complexes with N-allylazomethines. The Role of π- and σ-Coordination in Structure Formation of 2CuBr·R–CH=N–C3H5 (R = 2-furyl) and CuBr·R–CH=N–C3H5 (R = phenyl)

Abstract

Crystals of the complexes 2CuBr·C₄H₃(O)–CH=N–CH₂–CH=CH₂ (I) and CuBr·C₆H₅–CH=N–CH₂–CH=CH₂ (II) were obtained from an ethanol solution of CuBr₂ and N-allyl-2-furylaldimine or N-allylbenzaldimine using the alternating current electrochemical procedure. Their crystal structures were determined (DARCH diffractometer, MoK _α radiation, 1001 (F ≥ 2σ F) and 911 (F ≥ 6 σ F) reflections; R = 0.029 and 0.063, respectively, for I and II. π , σ-Complex I crystallizes in space group A2/a, a = 13.698(6), b = 17.679(5), c = 10.247(4) Å, γ = 114.03(3)°, Z = 8. Crystal data for σ-complex II: space group P2 ₁ /a, a = 19.016(5), b = 13.876(2), c = 4.0272(9) Å, β = 92.90(2)°, Z = 4. The structure of I involves separate π- and σ-coordinations of copper(I) in the form of planar trigons similar to those in the analogous nonisostructural π-complex with copper(I) chloride. The length of the coordinated C=C bond is 1.35(1) Å. The structure of II consists of infinite (CuBr) _n chains σ-coordinated to the nitrogen atom of the ligand molecules. The noncoordinated allyl group is disordered.