Acta Crystallographica Section C

Structural Chemistry

Volume 70, Part 3 (March 2014)

research papers

fa3324 scheme

Acta Cryst. (2014). C70, 250-255    [ doi:10.1107/S2053229614003234 ]

A tale of hydrogen abstraction, initially detected via X-ray diffraction

A. K. Hui, C.-H. Chen, A. M. Terwilliger, R. L. Lord and K. G. Caulton

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-[kappa]N2)pyridin-2-yl-[kappa]N]-1,4-di­hydro-1,2,4,5-tetra­zin-1-yl-[kappa]N1}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 One chloride ligand has also been replaced by an oxide ligand in this synthetic reaction.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 d1 V center, but that these two unpaired electrons are more stable as an open-shell singlet and hence anti­ferromagnetically coupled.

CCDC reference: 986586

Formula: [V(C11H10N9)Cl2O]·2.5C2H3N

Keywords: crystal structure; vanadium; hydrogen bonding; non-innocent; tetra­zine; hydrogen abstraction; redox.

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