Synthesis of ruthenium(II) monosubstituted squarates: 2. Single crystal structures of fac-[Ru(Cl)(dmso)3(H2O)(L)] · xH2O (L=anisole-, anilino-squarate) and fac-[Ru({C6H5}2NC4O3)(Cl)(dmso)3(H2O)] · C4H8O

The three monomeric ruthenium(II) monosubstituted squarate complexes fac-[Ru(Cl)(dmso)3(H2O)(L)] · xH2O [L=CH3OC6H5C4O3 (1), C6H5NHC4O3 (2)] and fac-[Ru({C6H5}2NC4O3)(Cl)(dmso)3(H2O)(L)] · C4H8O (3), obtained by the reactions of cis-[RuCl2(dmso)4] with the sodium salts of the anisole-, anilino- and diphenylamino-squarate ligands, respectively, all have the ruthenium atom showing octahedral geometry. The coordination polyhedron in each complex consists of three S-bonded dmso groups, one chlorine, one aqua and one monosubstituted squarate ligand. In 1, hydrogen bonded chains are formed along the crystallographic c direction but stacking interactions are absent. Molecules of complex 2, however, pack to form almost planar juxtaposed hydrogen bonded, π-stacked sheets, with pairs of molecules being linked by N–H ⋯ O and additional O–H ⋯ O hydrogen bonds, whilst those of 3 pack simply as π-stacked “dimer pairs”.