Crystal structure of bis-(2,2′ :6′,2″-terpyridyl)cobalt(II) bromide trihydrate

Abstract

The crystal structure of the title compound has been determined by Patterson and Fourier methods from single-crystal X-ray diffractometer data, and refined by least squares to R 0·096 (2704 reflections). Crystals are triclinic, probable space group P, a= 19·763(4), b= 9·563(2), c= 8·537(1)Å, α= 95·96(1), β= 93·48(1), γ= 94·44(1)°, Z= 2. Within the cation, each terpyridyl ligand co-ordinates via the three nitrogen atoms, the central Co–N distance being shorter than the outer [〈Co–N〉, 1·89, 2·10(1)Å respectively] and the ligand being strained to accommodate the bonding; the overall cation symmetry is approximately D_2d. The bromide ions are disordered between lattice sites ca. 2·0 Å apart; the potential barrier between the two sites appears small and may be the determinant of the ‘crossover’ situation which exists in this complex.