Solvent-Induced Cobalt(II) Cyanoguanidine Bromides: Syntheses, Crystal Structure, Optical and Magnetic Properties

Abstract

Two different phase-pure cobalt(II) cyanoguanidine bromide coordination compounds, Co(C2N4H4)2(H2O)4·2Br·2H2O (1) and Co3(C2N4H4)8(H2O)8·6Br (2), were precipitated from aqueous and methanol solutions, respectively, and their structures were solved and refined from X-ray single-crystal data at 100 K. Both 1 and 2 crystallize in the triclinic system with space group P1¯. The structure of 1 consists of two crystallographically distinct isolated CoO4N2 octahedral units plus bromide anions and crystal water molecules, whereas 2 is built from both isolated octahedra and discrete binuclear cluster units made from edge-sharing octahedra. Diffuse reflectance spectra and IR analysis then go on to highlight optical and vibrational differences between these two compounds. The magnetic susceptibility of 1 is consistent with either isolated or very weakly interacting Co2+ centers whereas the magnetic susceptibility of 2 evidences the potential weak antiferromagnetic exchange interactions that may arise from superexchange within the binuclear clusters.