title: Titanium and manganese complexes supported by a xanthene-bridged bis(tripodal N2O2) ligand: isomerization, intramolecular hydrogen bonding and metal-binding ability.
abstract: A new bis(N2O2) ligand, L(4-), in which two tripodal diamine-bis(phenolate) moieties are bridged by a xanthene backbone, was prepared. The reaction of H4L with 2 equiv. of [Ti(O(i)Pr)4] produced C2 and Cs symmetrical isomers of the dititanium(IV,IV) complex [Ti2(L)(O(i)Pr)4]. The isolated C2 isomer was slowly converted to the Cs isomer via Ti-N bond cleavage to form a 3 : 2 mixture in equilibrium. A similar dimanganese(III,III) complex [Mn2(L)(OMe)2(MeOH)2] was synthesized from a 1 : 2 mixture of H4L and manganese(II) perchlorate in the presence of triethylamine. An X-ray analysis of [Mn2(L)(OMe)2(MeOH)2] revealed that two Mn-N2O4 octahedrons are connected by intramolecular hydrogen bonds as well as a xanthene bridge to form a C2 symmetrical structure. The dimanganese(III,III) complex further reacted with manganese(II) acetate to form the mixed-valence trimanganese(III,II,III) complex [Mn3(L)(μ-OMe)2(μ-OAc)2]. Electrochemical data of the trimanganese(III,II,III) complex indicated that the xanthene-bridged dimanganese(III,III) unit effectively binds a Mn(II) ion in solution.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan. mhiro@sci.osaka-cu.ac.jp
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hirotsu
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Rika
authors.initials: R
authors.lastname: Tanaka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagai
authors.forename: Keiji
authors.initials: K
authors.lastname: Ueno
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Teki
authors.forename: Isamu
authors.initials: I
authors.lastname: Kinoshita
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D006860:Hydrogen Bonding; D007536:Isomerism; D008024:Ligands; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008968:Molecular Conformation; D009589:Nitrogen Oxides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014966:Xanthenes / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D009589:Nitrogen Oxides; D014966:Xanthenes; D008345:Manganese; D014025:Titanium