Alkene analogues of bis(N-donor)ketone ligands: Ruthenium(II) complexes containing 1-(pyridin-2-yl)-1-(N-methylimidazol-2-yl)ethene and 1,1-bis(N-methylimidazol-2-yl)ethene((mim)(2)C=CH2), and structural studies of [Ru(bpy)(2){(mim)(2)C=CH2}][PF6](2) (bpy equals 2,2'-bipyridine) and the pyridine-2-carboxylate (pyCO(2)(-)) complex [Ru(bpy)(2)(pyCO(2))][PF6]

The complexes [Ru(bpy)2(N~N)][PF6]2 have been synthesized from reactions of cis-[RuCl2(bpy)2]·2H2O (bpy=2,2′-bipyridine) and the bidentate ligands N~N ((mim)2C=CH2 and (py)(mim)C=CH2 where py=pyridin-2-yl and mim=N-methylimidazol-2-yl) in aqueous ethanol; with the analogue (py)(mim)C=O, the pyridine-2-carboxylate complex [Ru(bpy)2(pyCO2)][PF6] is formed. The complexes [Ru(bpy)2{(mim)2C=CH2}][PF6] 2 (1) and [Ru(bpy)2(pyCO2)][PF6] (3), characterized by room-temperature single crystal X-ray studies, were shown to have distorted octahedral geometry for ruthenium(II). The (mim)2C=CH2 ligand is non-planar, with the mim mean planes forming a dihedral angle of 32.2(1)° and forming dihedral angles of 56.5(1) and 60.4(1)° with the 'C=CC2' mean plane, in contrast to the near planarity reported for the ketone analogue (mim)2C=O in other metal complexes. Crystallographic data: for 1, monoclinic, space group C2/c, a=25.123(9), b=13.607(1), c=21.310(1) Å, β=103.61(4)°, Z=8, R=0.040 for No=6065 'observed' reflections, Rw=0.041; for 3, monoclinic, space group P21/c, a=14.463(10), b=11.211(7), c=18.619(13) Å, β=119.97(6)°, Z=4, R=0.045 for No=3031 'observed' reflections, Rw=0.048.