Ionothermal synthesis and crystal structure of a new organic-inorganic hybrid compound: Catena-poly[bis(1-ethyl-3-methylimidazolium) [hepta-μ-bromido-pentacuprate(I)]]

Abstract

A new organic-inorganic hybrid compound, catena-poly[bis(1-ethyl-3-methylimidazolium) [μ5-bromido-tri-μ3-bromido-tri-μ2-bromido-pentacuprate(I)]], {(C6H11N2)2[Cu5Br7]}n , has been obtained under ionothermal conditions from a reaction mixture containing Ba(OH)2.8H2O, Cu(OH)2.2H2O, As2O5, 1-ethyl-3-methylimidazolium bromide and distilled water. The crystal structure consists of complex [Cu5Br7]2- anions arranged in sinusoidal {[Cu5Br7]2-}n chains running along the a axis, which are surrounded by 1-ethyl-3-methylimidazolium cations. Three of the five unique Br atoms and one of the three CuI atoms occupy special positions with half-occupancy (a mirror plane perpendicular to the b axis, site symmetry m). The CuI ions are in a distorted tetrahedral coordination environment, with four Br atoms at distances ranging from 2.3667 14;(10) to 2.6197 14;(13) 14;Å, and an outlier at 3.0283 14;(12) 14;Å, exceptionally elongated and with a small contribution to the bond-valence sum of only 6.7%. Short C-H⋯Br contacts build up a three-dimensional network. The Cu⋯Cu distances within the chain range from 2.8390 14;(12) to 3.0805 14;(17) 14;Å, indicating the existence of weak CuI⋯CuI cuprophilic interactions.