Synthesis and characterisation of group 8 tris(1-benzyl-1, 2, 3-triazol-4-yl)-p-anisolylmethane complexes. Issue 36 (24th August 2022)

• Record Type: Journal Article
• Authors: Francis, Samuel; Rice, Craig R.; Scattergood, Paul A.; Elliott, Paul I. P.
• Is Part Of: Dalton transactions. Volume 51:Issue 36(2022)
• Page Start: 13692
• Page End: 13702
• Publication Date: 2022-08-24
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d2dt02503e
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Tris(triazolyl)methanes are a largely unexplored class of scorpionate ligand. Homoleptic group 8 complexes are presented with electrochemical and photophysical data. Abstract : The tris(1, 2, 3-triazol-4-yl)methane framework offers a highly versatile architecture for ligand design, yet the coordination chemistry of this class of ligand remains largely unexplored. We report here the synthesis and characterisation of the homoleptic complexes [M(ttzm)2 ](PF6 )2 (ttzm = tris(1-benzyl-1, 2, 3-triazol-4-yl)- p -anisolylmethane; M = Fe (Fe ), Ru (Ru ), Os (Os )). Initial attempts to prepare Ru by reaction of [Ru( p -cymene)Cl2 ]2 and ttzm also led to the isolation of the heteroleptic complex [Ru( p -cymene)(ttzm)](PF6 )2 . The structures of [Ru( p -cymene)(ttzm)](PF6 )2, [Fe(ttzm)2 ] 2+ (as its BPh4 − salt) and Os were solved by X-ray diffraction. The homoleptic Fe(ii ) and Os(ii ) containing cations adopt distorted octahedral geometries due to the steric interactions between the ansiole and triazole rings of the ttzm ligands. The homoleptic complexes all adopt a low-spin d 6 configuration and exhibit reversible M(ii )/M(iii ) processes (+0.35 to +0.72 V vs . Fc/Fc + ). These oxidation processes are cathodically shifted relative to those of related hexatriazole donor based complexes with density functional theory (DFT) calculations showing the metal d-orbitals are destabilised through a π-donor contribution from the triazole rings. The complexes all show prominent UV-visible absorption bands between 350 and 450 nm assigned to transitions of 1 MLCT character. Whilst none of the homoleptic complexes are emissive in room temperature fluid solutions, Os is emissive at 77 K in an EtOH/MeOH glass ( λ max 472 nm).