Syntheses, Characterization, X‐ray Crystal Structure, Redox and Photophysical Properties of Polypyridylruthenium(II) Complexes Containing Carboxylate‐Substituted Pyridyltriazoles

Abstract

The syntheses and properties of two novel [Ru(bpy) 2 (L−LЈ)] n+ complexes with L−LЈ = 3-carboxy-5-(pyrid-2Ј-yl)-1,2,4-triazole (H 2 cpt) or 3-(ethoxycarbonyl)-5-(pyrid-2Ј-yl)-1,2,4-triazole (Hcept) ligands are described. Previous publications on Ru II complexes containing (pyrid-2Ј-yl)-1,2,4-triazoles revealed that their coordination is possible via N1 and N4 of the triazole ring. 1 H NMR spectroscopic data and the crystal structure of [Ru(bpy) 2 (cept)]PF 6 ·H 2 O (2) indicate that the coordination of the Hcpt − and cept − occurs via N1 of the triazole ring. The crystals of 2 are monoclinic and belong to the space group P2 1 /n with a = 12.339(7), b = 16.512 (7), c = 16.802(8) Å , β = 110.29(4)°, and Z = 4. A water molecule is hydrogen-bonded to the carbonyl oxygen atom of the

Energy Transfer Pathways in Dinuclear Heteroleptic Polypyridyl Complexes: Through-Space vs Through-Bond Interaction Mechanisms

“…Analysis of the 1 H NMR data obtained for both mononuclear and dinuclear complexes and comparison of the chemical shifts observed for N1-bound complexes of other similar pyridyltriazole-based systems indicate that coordination takes place via N1. , Crystal structures of analogous pyridyltriazole complexes containing the ligands 3-methyl-5-(2-pyridyl)-4 H -1,2,4-triazole and 3-(2-hydroxyphenyl)-5-(2-pyridyl)-4 H -1,2,4-triazole also indicate that the Ru(bpy) 2 unit is coordinated via N1. Considering steric considerations this finding is not surprising 2 …”

“…Synthesis. The compounds were prepared using literature methods . However, as described in the Experimental Section under the synthetic procedure for mRu , purification of the products obtained is needed to separate the mononuclear from the dinuclear compounds.…”

“…The samples used were all of low concentration (10 -4 −10 -5 M), and degassing was carried out by bubbling nitrogen through the sample for at least 20 min. Luminescent lifetimes at 77 K were measured using an Edinburgh Analytical Instruments nF900 TCSPC described elsewhere 10d. The lifetime are estimated to be ±10%.…”

“…In recent years, the role of bridging ligands based on the 1,2,4-triazolato anion (e.g., 3,5-bis(2-pyridyl)-1 H -1,2,4-triazolato, bpt - ) in mediating ground state interaction (i.e., the degree of delocalization of the singly occupied molecular orbital of the mixed valence complex (M II M III ) over the metal centers) has been examined extensively. 1,2,4-Triazolato anion based ligands hold significant advantages over other bridging systems, due to the possibility of both the formation of coordination isomers and an accessible acid/base chemistry, which enable both synthetic and environmental manipulation of the photochemical and photophysical properties of Ru(II) and Os(II) homo- and heterometallic complexes incorporating these ligands. − Indeed it is clear from these studies that ground state interaction between metal centers in the dinuclear complexes is mediated by the bridge through a hole transfer HOMO assisted superexchange mechanism. A further important attribute of these systems is the ability to modify excited state properties independently of the ground state metal−metal interaction, a feature that is essential to the development of multicomponent systems exhibiting rationally designed properties.…”

The Combination of 4‐Hydroxythiazoles with Azaheterocycles: Efficient Bidentate Ligands for Novel Ruthenium Complexes

“…The Ru–N bond lengths from the thiazole ligand to the metal atom are elongated (Ru1–N1 2.078(5) Å, Ru1–N3 2.085(5) Å). This can be ascribed to a less π* backbonding from the thiazole molecule to the Ru II atom, which was observed for similar complexes like [Ru(bpy) 2 (cept)] + (cept = 3‐(ethoxycarbonyl)‐5‐(pyrid‐2′‐yl)‐1,2,4‐triazolate) 14 and [Ru(bpy) 2 TPZ] 2+ (TPZ = 2‐( 1,H ‐tetrazol‐5‐yl)pyrazine) 15. The bond angle N1–Ru1–N3 of the bidentate thiazole to the Ru II core is slightly diminished (78.4(2)°) compared to the bond angle formed from the bpy ligands (e.g.…”