In situ alkylation of 4,4′-bipyridine in hydrothermal synthesis of one-dimensional copper(I) bromide compounds

Hydrothermal reaction of CuBr2, 4,4′-bipyridine and ethanol/methanol generated two copper (I) bromide complexes with in situ alkylated 4,4′-bipyridium, namely [C14H18N2][Cu5Br7] (1) and [C12H14N2][Cu4Br6] (2). The structure of 1 consists of Cu5Br72- chains and N,N  ′-diethyl-4,4′-bipyridinium. The underlying structural motif in Cu5Br72- of 1 is the Cu5Br capped square pyramid, which is different from the Cu5Br2 pentagonal bipyramidal structural motif in various documented Cu5Br72- anions. The Cu5Br72- in 1 contains untypical μ5-bromide, with which five copper atoms forms a capped square pyramid rather than a pentagonal pyramid as predicted by Subramanian and Hoffmann. Compound 2 is isostructural with [C12H14N2][Cu4Cl6] reported by Willett, and consists of Cu4Br62- chains and N,N  ′-dimethyl-4,4′-bipyridinium. The Cu4Br62- chain is composed of alternating Cu6Br6 and Cu2Br6 units.

Graphical abstractHydrothermal reaction of CuBr2, 4,4′-bipyridine and ethanol/methanol generated two copper(I) halide complexes with in situ synthesized alkylated bipyridine-like cations.Figure optionsDownload full-size imageDownload as PowerPoint slide