A Planar Three-Coordinate Vanadium(II) Complex and the Study of Terminal Vanadium Nitrides from N2: A Kinetic or Thermodynamic Impediment to N–N Bond Cleavage?

We report the first mononuclear three-coordinate vanadium­(II) complex [(nacnac)­V­(ODiiP)] and its activation of N2 to form an end-on bridging dinitrogen complex with a topologically linear V­(III)­N2V­(III) core and where each vanadium center antiferromagnetically couples to give a ground state singlet with an accessible triplet state as inferred by HFEPR spectroscopy. In addition to investigating the conversion of N2 to the terminal nitride (as well as the microscopic reverse process), we discuss its similarities and contrasts to the isovalent d3 system, [Mo­(N­[tBu]­Ar)3], and the S = 1 system [(Ar­[tBu]­N)3Mo]2(μ2-η1:η1-N2).