title: A tale of hydrogen abstraction, initially detected via X-ray diffraction.
abstract: Reaction of a bis-tetrazinyl pyridine pincer ligand, btzp, with a vanadium(III) reagent gives not a simple adduct but dichlorido{3-methyl-6-[6-(6-methyl-1,2,4,5-tetrazin-3-yl-κN(2))pyridin-2-yl-κN]-1,4-dihydro-1,2,4,5-tetrazin-1-yl-κN(1)}oxidovanadium(IV) acetonitrile 2.5-solvate, [V(C11H10N9)Cl2O]·2.5CH3CN, a species which X-ray diffraction reveals to have one H atom added to one of the two tetrazinyl rings. This H atom was first revealed by a short intermolecular N...Cl contact in the unit cell and subsequently established, from difference maps, to be associated with a hydrogen bond. One chloride ligand has also been replaced by an oxide ligand in this synthetic reaction. This formula for the complex, [V(Hbtzp)Cl2O], leaves open the question of both ligand oxidation state and spin state. A computational study of all isomeric locations of the H atom shows the similarity of their energies, which is subject to perturbation by intermolecular hydrogen bonding found in X-ray work on the solid state. These density functional calculations reveal that the isomer with the H atom located as found in the solid state contains a neutral radical Hbtzp ligand and tetravalent d(1) V center, but that these two unpaired electrons are more stable as an open-shell singlet and hence antiferromagnetically coupled.
authors.affiliation: Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405, USA.
authors.forename: Alice K
authors.initials: AK
authors.lastname: Hui
authors.affiliation: Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405, USA.
authors.forename: Chun Hsing
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Grand Valley State University, 1 Campus Drive, 312 Padnos Hall, Allendale, MI 49401, USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Terwilliger
authors.affiliation: Department of Chemistry, Grand Valley State University, 1 Campus Drive, 312 Padnos Hall, Allendale, MI 49401, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lord
authors.affiliation: Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405, USA.
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Caulton
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D004583:Electrons; D006860:Hydrogen Bonding; D008024:Ligands; D010084:Oxidation-Reduction; D014639:Vanadium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D014639:Vanadium
keywords: crystal structure; hydrogen abstraction; hydrogen bonding; non-innocent; redox; tetrazine; vanadium