Formation of Ruthenium(II) Complexes with Unsymmetrical Terdentate Ligands

Abstract

Three unsymmetrical terdentate ligands, 2-(2'-quinolyl)-1,10-phenanthroline (4), 2-(1'-isoquinolyl)-1,10-phenanthroline (5), and 3,3'-dimethylene-2-(2'-quinolyl)-1,10-phenanthroline (6), have been prepared by application of the Friedländer condensation. Ligand 4 forms predominantly a pentaaza-coordinated (N5) complex with Ru(II), [Ru(4-N,N',N")(4-N,N')Cl](PF(6)), whose structure was determined by X-ray analysis (C(42)H(26)ClF(6)N(6)PRu: monoclinic, C2/c, a = 29.308(3) Å, b = 15.205(2) Å, c = 19.505(2) Å, beta = 107.312(8) degrees, V = 8298(1) Å(3), Z = 8). Ligand 5 forms predominantly a hexaaza-coordinated (N6) complex, [Ru(5-N,N',N")(2)](PF(6))(2). The bridged species 6 shows intermediate behavior, and the rate for interconversion of the N5 to N6 complex has been measured. The stereochemical features of these two binding modes are examined, and both pi-stacking and steric effects are invoked to explain the observed behavior, leading to the proposal of a backside displacement mechanism for their interconversion.

Ruthenium(II) complexes containing novel asymmetric tridentate ligands: synthesis, structure, electrochemical and spectroscopic properties

“…The proton chemical shifts are assigned with the aid of 1 H-1 H COSY experiments and comparison with those of similar compounds. 3,10,13,23 As expected, on co-ordination of ligands to the ruthenium ion, the chemical shifts of H a , H b and H c were shifted upfield. The pronounced shift for H a is due to the magnetic anisotropy induced by the proximate ring current, but there is a lesser influence on H b and H c .…”

“…Until now, ruthenium() complexes with asymmetric tridentate ligands are scarcely known. 13 In order to obtain more insight into the properties of ruthenium complexes with asymmetric tridentate ligands, we have recently designed three novel asymmetric tridentate ligands, 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine (dppt), 3-(1,10-phenanthrolin-2-yl)-as-triazino [5,6-f ]acenaphthylene (pta) and 3-(1,10-phenanthrolin-2-yl)-as-triazino [5,6-f ]phenanthrene (ptp). Both the asymmetry and the extended π framework of the new ligands will have a different effect on the properties of ruthenium complexes in comparison with tpy and its derivatives.…”

Photoisomerization and thermal isomerization of ruthenium aqua complexes with chloro-substituted asymmetric bidentate ligands

“…We tried to increase the synthetic yield by performing the reaction under high pressure and at high temperature (1 MPa and 150 C), but Ru(tpy) 2 was obtained as the main product. In contrast to the proximal selectivity of thermal reactions with Ru(tpy)Cl 3 and pyqu derivatives observed in this work, it has been reported that the thermal reactions of Ru(tpy)Cl 3 and 2-(2-pyridyl)-1,8-naphthyridine 11b,11d or phenanthroline derivatives 16 with a pendant moiety at the 2-position are distal selective. We previously reported that the d-1H 2 O would be more instable rather than the p-1H 2 O due steric repulsion between the pendant moiety of the pyqu ligand and a monodentate ligand as shown by the solidstate structure.…”

A luminescent Pt(ii) complex with a terpyridine-like ligand involving a six-membered chelate ring

“…The isomeric complex [Pt(2)Cl](PF 6 ) was also prepared using 2-(2 -quinolinyl)-1,10-phenanthroline (2) which had been prepared in earlier work. 20 For comparison, the analogous Pt(II) complex of 2-(2 -pyridyl)-1,10-phenanthroline (3) was also examined. 1 All compounds were characterized by NMR, MS and elemental analysis.…”