title: Redox trends in terpyridine nickel complexes.
abstract: A synthesis has been developed that allows the isolation of four-coordinate [(tpy)Ni-Br] (1, tpy = terpyridine) in high yield. Complex 1 has been structurally characterized, and the X-ray data reveal a square-planar geometry, unlike the known [(tpy')Ni-I] (tpy' = 4,4',4''-tri-tert-butyl-terpyridine) but similar to [(tpy)Ni-CH(3)]. In the solid-state, EPR spectroscopy indicates, however, that unlike [(tpy)Ni-CH(3)], the electronic structure of 1 is a metal-centered, not a ligand-centered radical. Density functional theory (DFT) analyses support this assignment. The preparation of 1 also facilitated the analysis of the redox potentials of a series of terpyridine nickel derivatives. It was found that the overall ligand sphere (one vs two coordinated terpyridine ligands) plays more of a role in determining the redox potentials of these derivatives than do the formal oxidation states of the nickel ions in the solution phase.
authors.affiliation: Department of Chemistry, University of Hawaii, 2545 McCarthy Mall, Honolulu, Hawaii 96822, USA.
authors.forename: James T
authors.initials: JT
authors.lastname: Ciszewski
authors.forename: Dmitry Y
authors.initials: DY
authors.lastname: Mikhaylov
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Holin
authors.forename: Marsil K
authors.initials: MK
authors.lastname: Kadirov
authors.forename: Yulia H
authors.initials: YH
authors.lastname: Budnikova
authors.forename: Oleg
authors.initials: O
authors.lastname: Sinyashin
authors.forename: David A
authors.initials: DA
authors.lastname: Vicic
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D009942:Organometallic Compounds; D011725:Pyridines; D009532:Nickel