80925-71-9Relevant academic research and scientific papers
New Five- and Six-Coordinate Imidazole and Imidazolate Complexes of Ferric Tetraphenylporphyrine
Quinn, Robert,Nappa, Mario,Valentine, Joan S.
, p. 2588 - 2595 (1982)
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.
