N-allylaldiminium cation as a pi-ligand. Synthesis and crystal structure of the [(CH3)(2)N-C6H4-CH = NH-CH2-CH = CH2]Cu3Cl4 compound

The crystals of the [(CH3)(2)N-C6H4-CH=NH-CH2-CH=CH2]Cu3Cl4 compound were p repared by alternating-current electrochemical synthesis from N-allyl-4-(N' ,N'-dimethylamino)benzaldimine (ADBA) and an ethanol solution of CuCl2 . 2H (2)O in the presence of carbamide and structurally characterized [a DARCh d iffractometer, MoKalpha radiation, space group P2(1)/n, a = 35.267, b = 6.5 11, c = 7.587 Angstrom, gamma = 94.64 degrees, V = 1736 Angstrom(3), Z = 4, R = 0.035 for 1030 independent reflections with F greater than or equal to 4 sigma(F)]. The coordination polyhedron of the Cu(1) atom is a trigonal p yramid formed by three chlorine atoms and the C=C bond; that of Cu(2) is a trigonal pyramid formed by Cl atoms; and that of Cu(3) is a planar triangle formed by chlorine atoms. The length of the coordinated C=C double bond is equal to 1.35(2) Angstrom. The structure is built from the (Cu3Cl4)(n)(n-) chains pi-coordinated to the H(+)ADBA cations and oriented along [010]. Th e geometry of the H(+)ADBA cation corresponds to the purely aromatic resona nce form, whereas, in the previously studied [H(+)ADBA]CuX2 compounds (X = Cl, Br), it is partially converted into the quinoid form due to the +M-effe ct of the (CH3)(2)N group. The calculated effective charges on the atoms in dicate that the positive charge on the H+ADBA cation is stabilized by the h ydrogen bonds.