title: Manipulating magnetism: Ru₂⁵⁺ paddlewheels devoid of axial interactions.
abstract: Variable-temperature magnetic and structural data of two pairs of diruthenium isomers, one pair having an axial ligand and the formula Ru2(DArF)4Cl (where DArF is the anion of a diarylformamidine isomer and Ar = p-anisyl or m-anisyl) and the other one being essentially identical but devoid of axial ligands and having the formula [Ru2(DArF)4]BF4, show that the axial ligand has a significant effect on the electronic structure of the diruthenium unit. Variable temperature crystallographic and magnetic data as well as density functional theory calculations unequivocally demonstrate the occurrence of π interactions between the p orbitals of the chlorine ligand and the π* orbitals in the Ru2(5+) units. The magnetic and structural data are consistent with the existence of combined ligand σ/metal σ and ligand pπ/metal-dπ interactions. Electron paramagnetic resonance data show unambiguously that the unpaired electrons are in metal-based molecular orbitals.
authors.affiliation: Department of Chemistry, Texas A&M University , P.O. Box 30012, College Station, Texas 77842-3012, United States.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Chiarella
authors.forename: F Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Murillo
authors.forename: Karen
authors.initials: K
authors.lastname: Ventura
authors.forename: Dino
authors.initials: D
authors.lastname: Villagrán
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang