Structural, electrochemical and photophysical behavior of Ru(ii) complexes with large bite angle sulfur-bridged terpyridyl ligands. Issue 1 (31st October 2019)

• Record Type: Journal Article
• Authors: Brown, Christopher M.; Arsenault, Nicole E.; Cross, Trevor N. K.; Hean, Duane; Xu, Zhen; Wolf, Michael O.
• Is Part Of: Inorganic chemistry frontiers. Volume 7:Issue 1(2020)
• Page Start: 117
• Page End: 127
• Publication Date: 2019-10-31
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9qi01009b
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Sulfur-bridged terpyridyl ligands expand the bite angles in Ru(ii ) species leading to geometries very close to that of a "perfect" octahedron. Altering the donor strength of substituents results in systematic tuning of the redox properties. Abstract : Ruthenium(ii ) terpyridyl species typically suffer from a distortion away from the ideal octahedral geometry due to the rigidity of the terpyridine ligand. In this study we report a series of new sulfur-bridged terpyridyl ligands (1a–c ) which offer enhanced flexibility due to sulfur spacers linking the pyridine rings, in addition to the ability to tune electronic properties with electron-donating (Me) and electron-withdrawing (CF3 ) substituents in the 4 and 4′′-positions of the sulfur-bridged ligands. The resulting Ru(ii ) complexes are detailed herein as both homoleptic (2a–c ) and heteroleptic (3a–c ) species, with the synthesis, structural characterization, photophysical and redox properties discussed, and the sulfur-bridged ligands allowing geometries closer to that of a "perfect" octahedron. All six species were found to be non-emissive at room temperature (with emissivity increasing on cooling to 77 K), and the electrochemical properties were greatly altered due to the increased bite angle of the sulfur-bridged ligands. The electrochemical and photophysical HOMO–LUMO gap can be easily tuned by altering the substituents in the 4 and 4′′-positions.