Atom transfer as a preparative tool in coordination chemistry. Synthesis and characterization of Cr(V) nitrido complexes of bidentate ligands

摘要

The transfer of a terminal nitrido ligand from Mn-V(N)(salen) to Cr(III) complexes is explored as a new preparative route to Cr-V nitrido complexes. Reaction of Mn-V(N)(salen) with labile CrCl3(THF)(3) in acetonitrile solution precipitates [Mn(Cl)(salen)].(CH3CN) and yields a solution containing a mixture of Cr-V nitrido species with only labile auxiliary ligands. From this solution Cr-V 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 P (1) over bar with cell parameters a = 7.2450(6) Angstrom, b = 8.1710(4) Angstrom, c = 13.1610(12) Angstrom, alpha = 80.519(6)degrees, beta = 75.721(7)degrees, gamma = 75.131(5)degrees, Angstrom = 725.47(10) Angstrom(3), Z = 2. Cr(N)(dbm)(2) (2) crystallizes as green rhombs in the orthorhombic space group Pbca with cell parameters a = 14.6940(6) Angstrom, b = 16.4570(18) Angstrom, c = 19.890(3) Angstrom, V = 4809.8(8) Angstrom(3), 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) Angstrom, b = 8.5575(5) Angstrom, c = 11.8267(12) Angstrom, beta = 106.528(7)degrees, V = 1441.7(2) Angstrom(3), 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 d(x)(-y)(2)(2) orbital in 2 and 3 is lower in energy and well resolved from the M-N pi* orbitals {d(zx),d(yz)}. [References: 35]