New π Ligand N,N,N,N′,N′,N′-Hexaallylethylenediaminium (L2+): Synthesis and Crystal Structures of LBr2 • 2H2O and Its Cuprocomplexes L[CuII(Br0.45Cl3.55)], L[Cu4I(Br4.55Cl1.45)], and L[Cu4IBr6]

The alkylation of ethylenediamine with allyl bromide in the presence of a fourfold (with respect to ethylenediamine) molar amount of NaHCO3 in acetone with an ethanol admixture (15 : 1) affords LBr2 +/- 2H(2)O (I), where L2+ is the N,N,N,N',N',N'-hexaallylethylenediaminium cation. Single crystals of complexes L[Cu-II(Br0.45Cl3.55)] (II), L[Cu-4(I)(Br4.55Cl1.45)] (III), and L[(Cu4Br6)-Br-I] (IV) are prepared by ac electrochemical synthesis from an ethanolic solution of LBr2 +/- 2H(2)O, CuCl2 +/- 2H(2)O (or CuBr2) at copper wire electrodes. The crystal structures of compounds I-IV are determined by X-ray diffraction analysis. The crystals of complex I are monoclinic: space group P2(1)/n, a = 8.544(3), b = 10.404(3), c = 13.350(4) angstrom, beta = 97.29(3)degrees, V = 1177.2(6) angstrom(3), Z = 2. The bromine anions in compound I are bonded to the L2+ cations and water molecules through hydrogen contacts (E) H center dot center dot center dot Br (E = O, C) of 2.57(3)-2.86(3) angstrom. The crystals of compounds II-IV are triclinic: space group P (1) over bar. For II: a = 8.762(4), b = 9.163(4), c = 16.500(6) angstrom, alpha = 95.62(4)degrees, beta = 96.39(4)degrees, gamma = 111.46(4)degrees, V = 1211.4(9) angstrom(3), Z = 2; for III: a = 9.074(4), b = 9.435(4), c = 9.829(5) angstrom, alpha = 116.12(4)degrees, beta = 104.14(4)degrees, gamma = 100.22(4)degrees, V = 692.3(6) angstrom(3), Z = 1; for IV isostructural III: a = 9.084(4), b = 9.404(4), c = 9.869(4) angstrom, alpha = 116.31(3)degrees, beta = 104.00(3)degrees, gamma = 100.37(3)degrees, V = 692.1(5) angstrom(3), Z = 1. Unlike the isolated tetrahedral CuX42- anion in structure II, an original chain anion (Cu4X62-)(n) is observed in the structures of pi complexes III and IV.