Isolation and structural comparison of Ru-dnp complexes [dnp = 2,6-bis-(1,8-naphthyridin-2-yl)pyridine] with axially or equatorially coordinating NCS ligands.

The mol-ecular and crystal structures of two ruthenium(II) complexes, -aqua-2,6-bis-(1,8-naphthyridin-2-yl)pyridine-κ ,',''(tri-phen-yl-phosphine-κ)ruthenium(II) hexa-fluorido-phosphate-acetone-water (1/0.5/1), [Ru(NCS)(CHN)(CHP)(HO)]PF·0.5CHO·HO (I) and -[2,6-bis-(1,8-naphthyridin-2-yl)pyridine-κ',','']bis-(pyridine-κ)(thiocyanato-κ)ruthenium(II) thio-cyanate, [Ru(NCS)(CHN)(CHN)]NCS (II), with an N-coordinating thio-cyanato group and a tridentate polypyridyl supporting ligand, are reported. The Ru atom in each of the cationic complexes adopts a distorted octa-hedral coordination sphere, defined by an N atom of the thio-cyanato ligand, three N atoms from the tridentate polypyridyl ligand, and an O and P atom in (I) or two pyridine-N atoms in (II) derived from monodentate ligands. The thio-cyanato ligand in (I) coordinates in an axial manner to the {Ru-dnp} unit [dnp = 2,6-bis-(1,8-naphthyridin-2-yl)pyridine], whereas it coordinates in an equatorial manner in (II). In the crystal structure of compound (I), intra-molecular C-H⋯O, C-H⋯N and O-H⋯N hydrogen bonds as well as π-π contacts are present, in addition to inter-molecular C-H⋯F, C-H⋯O and O-H⋯O hydrogen bonds. In the crystal structure of compound (II), intra-molecular C-H⋯N hydrogen bonds are observed along with inter-molecular C-H⋯N and C-H⋯S hydrogen bonds as well as a π-π inter-action.