Polymorphs and co-crystal with half-sandwich Ru(ii) dimers [(η6-arene)RuX2]2

The solid-state organization of the two important metallorganic precursors [(g6-p-cymene)RuI2]2 and [(g6- indane)RuCl2]2 is studied herein. Single crystals of [(g6-indane)RuCl2]2 have been obtained by slow evaporation of a dichloromethane solution of the dimeric complex, while two polymorphs of [(g6- p-cymene)RuI2]2 were obtained by modifying the conditions of the crystallization experiments. In addition, the reaction between [(g6-p-cymene)RuCl2]2 and 4-(N-methylamino)benzoic acid in methanol led unexpectedly to the isolation of a co-crystal where the amine ligand interacts with the organometallic dimer through an intermolecular N–H…Cl–Ru hydrogen bond. The most important features of the packing of all these compounds are described and compared with analogous crystal forms already present in the Cambridge Structural Database in order to derive general information on the aggregation modes of [(g6- arene)RuX2]2 systems.