Crystal structure of bis(5-bromo-1,10-phenanthroline-κ2N,N′)bis[dihydrobis(pyrazol-1-yl)borato- κ2N2,N2′]iron(II) toluene disolvate

The structure determination of the title compound was undertaken as part of a project on the modification and synthesis of new spin-crossover (SCO) compounds based on octahedral Fe-II bis(pyrazolyl)borate complexes. In the course of these investigations, the compound [Fe(C6H8BN4)(2)(C12H7BrN2)] was synthesized, for which magnetic measurements revealed an incomplete spin-crossover behaviour. Crystallization of this compound from toluene led to the formation of crystals of the toluene disolvate, [Fe(C6H8N4B)(2)(C12H7N2Br)]center dot-2C(7)H(8). Its asymmetric unit comprises two discrete metal complex molecules and two toluene solvent molecules. One of the latter is severely disordered and its contribution to the diffracted intensities was removed using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18]. In each complex molecule, the FeII cation is coordinated by the two N atoms of a 5-bromo-1,10-phenanthroline ligand and by two pairs of N atoms of chelating dihydrobis(pyrazol-1-yl)borate ligands in the form of a slightly distorted octahedron. The discrete complexes are arranged in columns along the a-axis direction with the toluene solvate molecules located between the columns. The 5-bromo-1,10-phenanthroline ligands of neighbouring columns are approximately parallel and are slightly shifted relative to each other, indicating pi-pi interactions.