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 N-2 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 N-2 to the terminal nitride (as well as the microscopic reverse process), we discuss its similarities and contrasts to the isovalent d(3) system, [Mo(N[Bu-t]Ar)(3)], and the S = 1 system [(Ar[Bu-t]N)(3)Mo](2)(mu(2)-eta(1):eta(1)-N-2).