Preparation and Crystal Structures of Manganese, Iron, and Cobalt Complexes of the Bis[di(2-pyridyl)methyl]amine (bdpma) Ligand and Its Oxidative Degradation Product 1,3,3-Tris(2-pyridyl)-3H-imidazo[1,5-a]pyridin-4-ium (tpip); Origin of the bdpma Fragility
摘要:
The synthesis and structural characterization of manganese, iron, and cobalt complexes of bis[di(2-pyridyl)methyl]amine (bdpma) were investigated. The bdpma ligand can give rise to mono- or dimeric complexes. Moreover, bdpma can undergo oxidative degradation leading to 1,3,3-tris(2-pyridyl)-3H-imidazo[1,5-a]pyridin-4-ium (tpip) or to starting materials used for the preparation of bdpma. During attempts to prepare manganese, iron, or cobalt complexes of the tpip ligand, two classes of compounds were obtained. The first class corresponded to the tpip cation with a simple exchange of counterion and the second class led to a new type of complex, which involved a modification of tpip and contained the N-(di(2-pyridyl)methoxymethyl)(di(2-pyridyl)imine) (dpmmdpi) ligand. This work has allowed us to understand the fragility of the bdpma ligand, which is due to the easily activated benzylic C-H bonds in the a position to the heteroatom.
investigation of corresponding iron(III) complexes has revealed the fragility of the BDPMA ligand. Different degradation products of the starting ligand have been crystallized and the distribution of these derivatives strongly depends on the nature of the anion in the iron(III) salts.
distorted trigonal bipyramidal, square pyramidal and octahedral geometries, respectively. FAB mass spectra and ESR spectra of crystalline samples and frozensolutions suggested that the overall structures are not modified for complexes 1–3 on going from the solid to the solutionstates.
Oxidative degradation of chlorinated phenols catalyzed by a non-heme iron(III) complex
作者:Catherine Hemmert、Michael Renz、Bernard Meunier
DOI:10.1016/s1381-1169(98)00131-9
日期:1999.1
A new symmetric pentadentate ligand containing four pyridine groups, bis(di-2-pyridylmethyl)amine (BDPMA), has been synthesized in a good yield. The corresponding non-hemeiron(III) complex, [Fe(BDPMA)](NO3)3, with potassium monopersulfate as oxidant, catalyzed the oxidative degradation of aromatic pollutants chlorinated phenols to yield the corresponding benzoquinones.
Bis[di(2-pyridyl)methyl]amine (BDPMA) has been synthesized by refluxing di-2-pyridyl ketone and di-(2-pyridyl)methylamine in isopropanol in the presence of molecular sieves and acetic acid and subsequent reduction with zinc dust. The established methods for reductive amination, i.e. NaBH3CN, NaBH(OAc)(3) and NaBH4, failed in the synthesis of BDPMA due to a disfavored equilibrium towards the imine formation and therefore long reaction times were required, involving side reactions, The presented method can be used on large-scales and tolerates aromatic heterocycles as functional groups.
Isolation and characterization of an oxidative degradation product of a polypyridine ligand
作者:Michael Renz、Catherine Hemmert
DOI:10.1039/a803255f
日期:——
The origin of the fragility of a polypyridine ligand under oxidizing conditions is discussed.