84174-28-7Relevant articles and documents
Inter-Metal Nitrogen Atom Transfer Reactions between Nitridochromium(V) and Chromium (III) Porphyrins
Neely, Frank L.,Bottomley, Lawrence A.
, p. 5432 - 5434 (2008/10/09)
Reactions of nitridochromium(V) porphyrins with chromium(III) porphyrins resulted in reversible, inter-metal nitrogen atom transfer between the two chromium porphyrin complexes. The progress of these reactions was followed spectrophotometrically. Kinetic analysis of the spectral data obtained over time for a variety of substituted porphyrins showed the reactions to be first order in each of the reactants and second order overall. Equilibrium constants were computed from the spectral data and ranged from 0.56 to 2.1 for the reactions between nitridochromium(V) octaethylporphyrin and a series of chlorochromium(III) tetraphenylporphyrins possessing phenyl ring substituents. Forward rate constants were determined for this reaction series and ranged from 6.8 to 1420 M-11 s-1. Electron-withdrawing substituents enhanced the forward rates but diminished the equilibrium constants. It is proposed that the reactions proceed by nucleophilic attack of the nitridochromium porphyrin donor on the cationic chromium(III) porphyrin nitrogen atom acceptor facilitating a net, two-electron redox process mediated by a homobimetallic μ-nitrido intermediate.
Metal Complexes with Tetrapyrrole Ligands XXXIII. Preparation of Azidochromium(III)-, Azidomanganese(III)-, and Azidoiron(III) Porphyrins and their Photolysis to Terminal or Bridged Nitridometal Porphyrins
Buchler, Johann Walter,Dreher, Christine
, p. 222 - 230 (2007/10/02)
Azidometal(III) porphyrins, e.g.M(TTP)N3 1 Aa - 1 Ca (M = Cr, Mn, Fe), are transformed into nitrido complexes on irradiation with ultraviolet light.Thus, Cr(III) or Mn(III) complexes, e.g.Cr(TTP)N3 or Mn(TTP)N3, yield Cr(V) and Mn(V) complexes with terminal nitride ligands, e.g.Cr(TTP)N (1 Ab) or Mn(TTP)N (1 Bb) with concomitant liberation of 1 mol of N2.However, the Fe(III) complex Fe(TTP)N3 produces the mixed-valence μ-nitrido-bis complex, 2N (1 Cg) and about 1.2 mol of N2 per mol of Fe.The azidometal(III) porphyrins are prepared from the corresponding hydroxo- or μ-oxo-metal(III) porphyrins and hydrazoic acid in benzene. - Key words: Chromium Porphyrins; Manganese Porphyrins; Nitridometal Complexes; Photolysis of Azido Complexes
Metal complexes with tetrapyrrole ligands. 29. Synthesis and electron spin resonance spectra and electron nuclear double resonance investigations of nitridochromium(V) porphyrins
Buchler, Johann W.,Dreher, Christine,Lay, Kiong-Lam,Raap, Adriaan,Gersonde, Klaus
, p. 879 - 884 (2008/10/08)
Mononuclear pentacoordinated nitridochromium(V) porphyrins, nitrido(tetra-p-tolylporphinato)chromium(V), CrN(TTP), and nitrido(octaethylporphinato)chromium(V), CrN(OEP), are prepared by hypochlorite oxidation of the corresponding chromium(III) porphyrins, CrOH(TTP)-2H2O and CrOH(OEP)·1/2H2O, in the presence of ammonia. These remarkably stable species are identified by UV/vis, IR, and mass spectra. An investigation of these paramagnetic compounds by ESR and ENDOR spectroscopy has furnished evidence for the CrV(d1/dxy) state of the central metal and the coordination of a single axial nitrogen. The X- and Q-band ESR as well as the 14N ENDOR spectra are identical for both CrN(TTP) and CrN(OEP): At room temperature we find an isotropic signal at g0 = 1.9825 and an isotropic 53Cr hyperfine splitting a0(53Cr) = 2.83 mT. A superhyperfine splitting a(14N) = 0.27 mT due to five apparently equivalent 14N nuclei is observed. At 77 K an anisotropic ESR signal with g⊥ = 1.9945 and g∥ = 1.9583 and anisotropic hyperfine values of a⊥(53Cr) = 2.24 mT and a∥(53Cr) = 4.01 mT have been determined. 14N ENDOR spectra measured at 3.6 K serve to discern the axial and equatorial superhyperfine splitting constants: For Npyrrole, a⊥1 = 0.36, a⊥2 = 0.14, and a∥ = 0.31 mT, and for Naxial, a⊥1 = 0.37, a⊥2 = 0.34, and a∥ = 0.13 mT. The ESR and ENDOR parameters are characteristic for a d1 system with strong spin localization in the dxy orbital and nearly no spin localization in dz2, which may be the reason for the high stability of these complexes.
