Atom Transfer as a Preparative Tool in Coordination Chemistry. Synthesis and Characterization of Cr(V) Nitrido Complexes of Bidentate Ligands

The transfer of a terminal nitrido ligand from MnV(N)(salen) to Cr(III) complexes is explored as a new preparative
route to CrV nitrido complexes. Reaction of MnV(N)(salen) with labile CrCl3(THF)3 in acetonitrile solution precipitates
[Mn(Cl)(salen)]·(CH3CN) and yields a solution containing a mixture of CrV nitrido species with only labile auxiliary
ligands. From this solution CrV nitrido complexes with bidentate monoanionic ligands can be obtained in high
yields. Five coordinate complexes of 8-hydroxoquinolinate (quin), 1,3-diphenylpropane-1,3-dionate (dbm), and
pyrrolidinedithiocarbamate (pyr-dtc) have been structurally characterized:  Cr(N)(quin)2 (1) crystallizes as compact
orange prisms in the triclinic space group P1̄ with cell parameters a = 7.2450(6) Å, b = 8.1710(4) Å, c = 13.1610(12)
Å, α = 80.519(6)°, β = 75.721(7)°, γ = 75.131(5)°, V = 725.47(10) Å3, Z = 2. Cr(N)(dbm)2 (2) crystallizes as
green rhombs in the orthorhombic space group Pbca with cell parameters a = 14.6940(6) Å, b = 16.4570(18) Å,
c = 19.890(3) Å, V = 4809.8(8) Å3, Z = 8. Cr(N)(pyr-dtc)2 (3) crystallizes as orange prisms in the monoclinic
space group P21/c with cell parameters a = 14.8592(14) Å, b = 8.5575(5) Å, c = 11.8267(12) Å, β = 106.528(7)°,
V = 1441.7(2) Å3, Z = 4. Complexes 2 and 3 represent new coordination environments for first row transition
metal nitrido complexes. The d-orbital energy splitting in these systems with relatively weak equatorial donors
differs significantly from the pattern in vanadyl and the previously known first row transition metal nitrido complexes.
The dx2-y2 orbital in 2 and 3 is lower in energy and well resolved from the M−N π* orbitals {dzx,dyz}.