Copper(I) complexes with N-allylazomethines. The role of pi- and sigma-coordination in structure formation of 2CuBr center dot R-CH=N-C3H5 (R=2-furyl) and CuBr center dot R-CH=N-C3H5 (R = phenyl)

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, MoKalpha radiation, 1001 (F greater than or equal to2 sigm aF) and 911 (F greater than or equal to6 sigmaF) reflections; R = 0.029 and 0.063, respectively, for I and II. pi, sigma -Complex I crystallizes in sp ace group A2/a, a = 13.698(6), b = 17. 679(5), c = 10.247(4) Angstrom, gamm a = 114.03(3)degrees, Z = 8. Crystal data for sigma -complex II: space grou p P2(1)/a, a = 19.016(5), b = 13.876(2), c = 4.0272(9) Angstrom, beta = 92. 90(2)degrees, Z = 4. The structure of I involves separate pi- and sigma -co ordinations of copper(I) in the form of planar trigons similar to those in the analogous nonisostructural pi -complex with copper(I) chloride. The len gth of the coordinated C=C bond is 1.35(1) Angstrom. The structure of II co nsists of infinite (CuBr)(n) chains sigma -coordinated to the nitrogen atom of the ligand molecules. The noncoordinated allyl group is disordered.