High-pressure single crystal X-ray diffraction study of the linear metal chain compound Co3(dpa)4Br2·CH2Cl2

Abstract

The crystal structure of the linear metal chain compound Co₃(dpa)₄Br₂·CH₂Cl₂ (1) has been investigated up to a pressure of 13.6(2) GPa in a diamond anvil cell (DAC) using single crystal X-ray diffraction. The structure remains orthorhombic as the unit cell volume is reduced by 30% at 12.8 GPa. At 13.6(2) GPa the diffraction pattern is of very poor quality and not even reliable unit cell parameters can be determined. Peak broadening resulting from non-hydrostatic conditions was avoided by annealing the loaded DAC prior to data collection, allowing reliable structural models to be refined up to a pressure of 11.8(2) GPa. On increasing pressure, the disordered CH₂Cl₂ crystal solvent molecule gradually becomes redistributed from one site to another. Hirshfeld surface analysis suggests that the redistribution is a result of repulsive H⋯H interactions. Pressure also affects the molecular geometry, in particular the Co–Co and Co–Br bond lengths which decrease by 4% and 12%, respectively, at 11.8(2) GPa.