Synthesis and electrochemical and photoemission properties of mononuclear and binuclear ruthenium(II) complexes containing 2,2'-bipyridine, 2,9-dimethyl-1,10-phenanthroline, 2,2'-bipyrimidine, 2,2'-biimidazole, and 2-pyridinecarboxaldimine ligands

Abstract

Four new mononuclear ruthenium(II) complexes, [Ru(PTPI)3]2+ (PTPI = 2-p-tolylpyridinecarboxaldimine) and [Ru(bpy)2B]2+ [B = 2,9-dimethyl-1,10-phenanthroline (2,9-Me2phen), 4,4'-dimethyl-2,2'-bipyrimidine (4,4'-Me2bpyrm), and 2,2'-biimidazole (biimH2)], have been prepared as PF6~s alts and their electrochemical and photoemission properties investigated in solution.In addition, the ligand-bridged binuclear species [Ru(bpy)2(B)Ru(bpy)2](PF6)4 (B = bpyrm and 4,4'-Me2bpyrm) have also been obtained as by-products in the synthesis of the mononuclear complexes and separated from their mononuclear analogues by Sephadex chromatography. The mononuclear compounds all exhibit polarograms in acetonitrile consistent with quasi-reversible, one-electron [Ru(II) -* Ru(III)] oxidation processes with Ex¡2 potentials (SCE) ranging from 0.93 to 1.29 V. The E[/2 potentials suggest an ordering in the B ligand x-acceptor ability of biimH2 « 2,9-Me2phen ~bpy < 4,4/-Me2bpyrm < bpyrm. The binuclear [Ru(II),Ru(II)] complexes possess polarograms displaying two, one-electron oxidation processes (AEy/2 = 0.18 V) corresponding to production of the mixed-valence [(Ru(II),Ru(III)] and fully oxidized [Ru(III),Ru(III)] species. At room temperature and in acetonitrile, the mononuclear B = 2,9-Me2phen, bpyrm, 4,4'-Me2bpyrm, and biimH2 complexes have dx* absorption and luminescence spectra similar to that of [Ru(bpy)3]2+, with emission bands occurring between 588 and 600 nm in all cases. Under similar conditions, the bipyrimidine-bridged binuclear complexes do not exhibit emission spectra in the 350-800-nm region. The emission spectrum observed for the [Ru(PTPI)3]2+ complex is probably not of dx* origin, with the emission bands being blue shifted (at ~345 and 400 nm) relative to the 496and 552-nm dx* absorption bands.

Diastereoisomers as probes for solvent reorganizational effects on IVCT in dinuclear ruthenium complexes

“…The complexes [{Ru(bpy) 2 } 2 (l-bpm)] 4+ and [{Ru-(Me 2 bpy) 2 } 2 (l-bpm)] 4+ have been synthesized previously [30,48,49,[70][71][72][73][74][75][76][77], either by a thermal method involving the reaction of the cis-[Ru(bpy) 2 Cl 2 ] AE 2H 2 O precursor with bpm in ethylene glycol under reflux, or a microwaveassisted synthetic procedure. In the present case, the latter method was used for the complexes [{Ru(pp) 2 } 2 (l-bpm)] 4+ {pp = bpy, Me 2 bpy, 5,5 0 -Me 2 bpy, Me 4 bpy}, which resulted in comparable yields to those obtained from the thermal methods but with a significant reduction in the reaction times (typically $10 min rather than 2 h for the thermal procedure).…”

“…The electrochemical and spectroelectrochemical characteristics of [{Ru(bpy) 2 } 2 (l-bpm)] 4+ (as a diastereoisomeric mixture) Table 1 Electrochemical data (in mV relative to the Fc + /Fc 0 couple) for the dinuclear complexes [{Ru(pp) 2 have been detailed in a number of previous studies [30,[71][72][73][74][78][79][80][81][82][83].…”

catena-Poly{μ-(2,2'-bipyrimidine-N,N':N'',N''')-[(nitrato-O,O')copper(II)]-di-(μ-nitrato-μ-O)-[(nitrato-O,O')copper(II)]}, [Cu2(NO3)4(C8H6N4)]

“…This ligand is potentially interesting for two reasons: it can act either as a doubly-bidentate bridging ligand or simply as a bidentate ligand. Mononuclear and binuclear 2,2'-bipyrimidine Ru H complexes are known (Dose & Wilson, 1978;Hunziker & Ludi, 1977;Ruminski & Petersen, 1982). It has also been supposed that this ligand can act as monodentate with CuC12 in polymeric arrays (Tuerstein, Feit & Navon, 1974).…”

The synthesis of dipridyl- and 1,10-phenanthrolylferrocenes and bis-N,N′-(2,2′-dipyridyl(6-ferrocenyl-N,N′-2,2′-dipyridyl))ruthenium dichloride

“…The ruthenium complex was synthesized using a modification of the literature procedure (19) which have an average value of 2.056(6) A, (26). In the latter case, the relatively short bond lengths were explained in terms of considerable T-bonding between the delocalized T*-orbitals on the bipyridine ligands and the ~t h e n i u m core.…”