Stereochemistry in tris(bidentate ligand)ruthenium(II) complexes containing unsymmetrical polypyridyl ligands

Abstract

+ and [Ru(L')(L~)~]~+ systems where the two ligands L' and L2 are the symmetrical ligand dmbipy [4,4'-dimethyl-2,2'-bipyridine] and the unsymmetrical ligand pmbipy [4-(2,2-dimethylpropyl)-4'-methyl-2,2'-bipyridine].

Tuning the Excited‐State Energy of the Organic Chromophore in Bichromophoric Systems Based on the RuII Complexes of Tridentate Ligands

“…[1,2] The most studied complexes are based on [RuA C H T U N G T R E N N U N G (bpy) 3 ] 2 + (bpy = 2,2'-bipyridine), as they have been shown to have long-lived excited states at room temperature that originate from their metal-to-ligand charge-transfer (MLCT) state. [3][4][5] However, bpy-based complexes induce chirality at the metal centre, and separation of the diastereomers in polymetallic complexes, although possible, [6] can be complicated, thus attention has been turned to achiral tridentate 2,2':6',2''-terpyridine (tpy)-type ligands. [7] Although tpy is a synthetically appealing target, on coordination to the metal ion, the tridentate ligand imposes a small bite angle and consequently its ligand-field strength is lower than that of bpy.…”

“…Complex 2 a crystallised in the triclinic space group P1 with two cations, four PF 6 À ions and four molecules of acetonitrile in the asymmetric unit. The pendant phenyl rings are twisted by 7.6(2) and 9.5(2)8 for both independent cations (Table 1).…”

“…However, the addition of an excess of ammonium tetraphenylborate to a solution of 2 b in acetonitrile allowed salt exchange, and the complex was crystallised as a mixed salt containing one PF 6 À and one BPh 4 À ion per cation. The Ru À N bond lengths and N-Ru-N bond angles are very similar to those of 2 a, thus indicating that the substitution on the periphery has little effect on the metal centre.…”

“…The precipitate was collected and purified by column chromatography using acetonitrile/KNO 3 (saturated) (7:1) as the eluent. The second intense red band was collected and was precipitated as its PF 6 À salt. It was found that a one-pot synthesis of 3 a was more successful than the two-step approach, which would involve the formation of a [RuCl 3 (L1)] intermediate.…”

N‐Sulfinylcarboximidates as a New Class of Chiral Bidentate Ligands: Application to Asymmetric Coordination Chemistry

“…by treating with bpy and Me 3 NO at room temperature (Scheme 3). [17] Finally, to evaluate the applicability of the novel CO/ TFA-precursor complex, we applied it to the asymmetric synthesis of a biologically useful ruthenium complex and we selected Bartons "DNA molecular light switch"…”