80939-26-0Relevant academic research and scientific papers
INFLUENCE OF HYDROGEN BONDING ON THE PROPERTIES OF IRON PORPHYRIN IMIDAZOLE COMPLEXES. AN INTERNALLY HYDROGEN BONDED IMIDAZOLE LIGAND.
Quinn,Mercer-Smith,Burstyn,Valentine
, p. 4136 - 4144 (2007/10/02)
Two new imidazole derivatives have been synthesized, cis-methyl urocanate and trans-methyl urocanate. The IR properties of these imidazole derivatives have been compared with those of imidazole itself and other imidazole derivatives. A series of complexes of the form Fe**I**I**I(TPP)(L)//2SbF//6, where TPP equals tetraphenylporphyrin and L equals imidazole or a substituted imidazole, have been synthesized and characterized by visible, electron paramagnetic resonance and IR spectroscopy and cyclic voltammetry in order to evaluate the effects of hydrogen bonding of coordinated imidazole ligands on the properties of iron porphyrin complexes.
Crystal structure and properties of a potassium cryptate salt of bis(4-methylimidazolato)(tetraphenylporphinato)iron(III)
Quinn, Robert,Strouse, Charles E.,Valentine, Joan S.
, p. 3934 - 3940 (2008/10/08)
The synthesis and characterization of the potassium cryptate salt of bis(4-methylimidazolato)(tetraphenylporphinato)iron(III) (1) are reported. The salt crystallizes as the toluene solvate, C77FeH82KN10O6, in the triclinic space group P1 with 2 formula units in the unit cell. At 117 K, the unit cell parameters are a = 14.63 (1) ?, b = 14.68 (1) ?, c = 17.20 (1) ?, α = 93.67 (7)°, β = 87.44 (7)°, and γ = 109.69 (7)°. The structure was solved with 3655 observed reflections, and refinement led to conventional and weighted R values of 10.7 and 10.1. The mean Fe-N(porphyrin) bond length, 1.998 (25) ?, is consistent with those of other low-spin ferric porphyrin complexes. The Fe-N(ligand) bond lengths are 1.928 (12) and 1.958 (12) ?. A comparison with Fe-N(ligand) bond lengths of [FeTPP(ImH)2]Cl (TPP = tetraphenylporphyrin; ImH = imidazole) indicates that deprotonation of imidazole may result in a 0.06-? shortening of the axial bond lengths. Visible and EPR spectral results are consistent with the presence of a low-spin, six-coordinate ferric porphyrin complex in dimethylacetamide solution and in the solid. A comparison of the results of cyclic voltammetry of 1 and its protonated analogue, [FeTPP(4MeImH)2]SbF6 (4MeImH = 4-methylimidazole), indicates that reduction of the imidazolate complex occurs at a potential that is 700 mV more negative than that of the imidazole complex.
New Five- and Six-Coordinate Imidazole and Imidazolate Complexes of Ferric Tetraphenylporphyrine
Quinn, Robert,Nappa, Mario,Valentine, Joan S.
, p. 2588 - 2595 (2007/10/02)
The synthesis of several new imidazole and imidazolate complexes of ferric tetraphenylporphyrine (TPP) are reported.The following coplexes have been made with L = imidazole (ImH) or 4-methylimidazole (4MeImH) and L- = imidazolate (Im-) or 4-methylimidazolate (4MeIm-): FeTPP(L)(L-), -2>-, and (SbF6).Addition of Im- to FeTPPCl resulted in the formation first of the imidazolate-bridged complex + and then of -.Similar addition of 4MeIm- to FeTPPCl resulted in the formation first of the high-spin mononuclear complex FeTPP(4MeIm) and then of -.The affinity of (SbF6) for a second 4MeImH was found to be very high, with K >/= 107 M-1 in toluene, 25 deg C.By contrast, 4MeImH was found preferentially to hydrogen bond to Fe(TPP)(4MeIm), with K ca. 5 * 104 M-1 in THF, 25 deg C.Coordination of 4MeImH was only observed at high concentration of ligand (K ca. 50 +/- 10 M-1).The monoimidazole complex (SbF6) was concluded to be high spin after a comparison of the visible spectral properties of a large number of ferric TPP complexes.
