title: Chelate ring size variations and their effects on coordination chemistry and catechol dioxygenase reactivity of iron(III) complexes.
abstract: The catechol dioxygenase reactivity of iron(III) complexes using tripodal ligands was investigated. Increasing, as well as decreasing, chelate ring sizes in the highly active complex [Fe(tmpa)(dbc)]B(C6H5)4 (tmpa = tris[(2-pyridyl)methyl]amine; dbc = 3,5-di-tert-butylcatecholate dianion), using related ligands, only resulted in decreased reactivity of the investigated compounds. A detailed low-temperature stopped-flow investigation of the reaction of dioxygen with [Fe(tmpa)(dbc)]B(C6H5)4 was performed, and activation parameters of DeltaH++ = 23 +/- 1 kJ mol(-1) and DeltaS++ = -199 +/- 4 J mol(-1) K(-1) were obtained. Crystal structures of bromo-(tetrachlorocatecholato-O,O')(bis((2-pyridyl)methyl)-2-pyridylamine-N,N',N'')-iron(III), (mu-oxo)-bis(bromo)(bis((2-pyridyl)methyl)-2-pyridylamine-N,N',N' ',N''')-diiron(III), dichloro-((2-(2-pyridyl)ethyl)bis((2-pyridyl)methyl)amine-N,N',N' ',N''')-iron(III) and (tetrachlorocatecholato-O,O')((2-(2-pyridyl)ethyl)bis((2-pyridyl)methyl)amine-N,N',N' ',N''')-iron(III) are reported.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Merkel
authors.forename: Matthias
authors.initials: M
authors.lastname: Pascaly
authors.forename: Bernt
authors.initials: B
authors.lastname: Krebs
authors.forename: Jörg
authors.initials: J
authors.lastname: Astner
authors.forename: Simon P
authors.initials: SP
authors.lastname: Foxon
authors.forename: Siegfried
authors.initials: S
authors.lastname: Schindler