Crystal and molecular structure of di-μ-bromobromopentakis(benzimidazole)dicopper(II) monobromide tetrahydrate [Cu2Br3(C7H6N2)5]Br·4H2O

A new complex compound. Cu₂Br₃(C₇H₆N₂)₅]Br·4H₂O, has been synthesized and its crystal structure investigated by single-crystal X-ray methods. The crystals are isostructural with those of the Cu₂Cl₃(C₇H₆N₂)₅]Cl·4H₂O salt. They are orthorombic, space group Pnma with 4 formula units in a cell of dimensions:a+19.923(1),b+17.555(2),c+12.0523(4)Å. The structure was refined by full-matrix least-squares to giveR+0.047 andR _w+0.053 for 3569 intensities above 3σ(I). As in the chloride compound, the complex cation consists of pairs of distorted trigonal bipyramidal Cu(II) centers which share an edge by two equatorial bromide ions. The Cu...Cu nonbonding distance in the complex in 3.4894(7)Å. The two Cu?Br?Cu bridges are not equivalent and their geometry is slightly different from that in the chloride complex. Comparison of the investigated structure to other binulear bis(μ-halide) bridged copper(II) complexes of similar structure has been made.