A variable temperature study of Ru3(CO)12 in the solid state and the generation of alternative crystal structures

Summary The molecular and crystal structure of Ru₃(CO)₁₂ has been reinvestigated on single-crystal X-ray diffraction data collected at 100 and 150 K. Thermal motion analysis on high-order diffraction data have been used to characterize the motion about equilibrium positions of the molecule as a whole and of groups of atoms. It has been shown that, while the molecule undergoes an almost isotropic rigid-body librational and translational motion, the three Ru(CO)₄ units undergo different librational motions about the axes passing between each Ru atom and bisecting the opposite 615-01 bond. Packing potential energy calculations and computer graphics have been used to show that the most favoured packing motif in the experimental crystal is based on interlocking between tetracarbonyl units formed by two pairs of CO ligands at right angles along a 615-02 edge. Starting from the structure of Ru₃(CO)₁₂, alternative crystal arrangements have been generated and compared with the experimental crystal structure in terms of packing efficiency and cohesive energy.