Molecular and Crystal Structures of Cubane-like Ru−O Complexes and the Molecular Orbital Analysis of an Unusual π−π Interaction Stabilized by C−H···O Hydrogen Bonds

The synthesis and structural characterization of the family of the cubane-like complexes [(η 6 -C 6 H 6 )Ru(OH)] 4 [OH] 4 ·12H 2 O ( 1 ), [(η 6 -C 6 H 6 )Ru(OH)] 4 [BF 4 ] 3 [Cl]·2H 2 O ( 2 ), and [(η 6 -C 6 H 6 ) 3 Ru 4 (OH) 4 (Cl) 3 ][BF 4 ] 2 ·3H 2 O ( 3 ) are reported. The relationship between molecular and crystal structure of the complexes has been investigated by means of theoretical calculations of the DFT type. In the solid state, compound 1 shows the presence of benzene−benzene contacts between perfectly eclipsed ligands belonging to neighboring molecules. These are surrounded by a “belt” of water molecules forming C−H···O hydrogen bonds with the coordinated benzene. These H-bonds would appear to be sufficiently strong to compensate the anticipated repulsive benzene−benzene interactions. The role of (M−)Cl···H−O and Cl - ···H−O interactions in 2 and 3 has also been investigated.