Activation of -N=CH- bond in a Schiff base by divalent nickel monitored by NMR evidence.

The Schiff base, 2-salicylidene-4-aminophenyl benzimidazole in ethanol undergoes activation of -N=CH- bond by Ni(2+) in the presence of ammonia or primary alkyl amine to produce nickel complexes of the formula Ni{o-C(6)H(4)(O)CH NR}(2) . n H(2)O [R = H, Me; n = 0; R = Et, n = 0.5] and 4-aminophenyl benzimidazole. The products have been identified by elemental analysis, magnetic susceptibility measurements and IR, ESR, mass and extensive NMR spectral studies. The possible mechanism for the activation of -N=CH- bond has also been proposed.

Bis{2-[4-(methyl-sulfan-yl)phen-yl]-1H-benzimidazol-3-ium} tetra-bromido-cadmate(II) ethanol monosolvate.

In the anion of the title compound, (C(14)H(13)N(2)S)(2)[CdBr(4)]·C(2)H(5)OH, the Cd(II) atom is in a distorted tetra-hedral environment and one of the Br atoms is disordered over three sites with site-occupancy factors of 0.828 (5), 0.106 (3) and 0.068 (4). In the crystal, inter-molecular N-H⋯O, C-H⋯O and N-H⋯Br inter-actions result in a two-dimensional polymeric network extending parallel to (010).

2-(4-Methyl-sulfanylphen-yl)-1H-benzimidazol-3-ium bromide.

In the cation of the title compound, C(14)H(13)N(2)S(+)·Br(-), the essentially planar benzimidazole system (r.m.s. deviation = 0.0082 Å) is substituted with a 4-methyl-sulfanylphenyl ring. The dihedral angle between the benzimidazole system and the 4-methyl-sulfanylphenyl ring is 2.133 (2)°. The crystal structure is characterized by strong and highly directional inter-molecular N-H⋯Br hydrogen bonds involving the bromide ion. Moreover, C-H⋯S inter-actions result in chains of mol-ecules along the c axis. The supra-molecular assembly is further stabilized by π-π stacking inter-actions between the benzimidazole system and 4-methyl-sulfanylphenyl rings [centroid-centroid distance = 3.477 (4) Å].

Bis{2-[4-(methyl-sulfan-yl)phen-yl]-1H-benzimidazol-3-ium} tetra-bromido-cuprate(II) dihydrate.

The asymmetric unit of the title compound, (C(14)H(13)N(2)S)(2)[CuBr(4)]·2H(2)O, contains two cations, one anion and two solvent water mol-ecules that are connected via O-H⋯Br, N-H⋯Br and N-H⋯O hydrogen bonds into a two-dimensional polymeric structure. The cations are arranged in a head-to-tail fashion and form stacks along [100]. The central Cu(II) atom of the anion is in a distorted tetra-hedral environment.