title: High-spin chloro mononuclear MnIII complexes: a multifrequency high-field EPR study.
abstract: The isolation, structural characterization, and electronic properties of two six-coordinated chloromanganese (III) complexes, [Mn(terpy)(Cl)3] (1) and [Mn(Phterpy)(Cl)3] (2), are reported (terpy = 2,2':6'2"-terpyridine, Phterpy = 4'-phenyl-2,2':6',2"-terpyridine). These complexes complement a series of mononuclear azide and fluoride Mn(lll) complexes synthesized with neutral N-tridentate ligands, [Mn(L)(X)3] (X = F- or N3 and L = terpy or bpea [N,N-bis(2-pyridylmethyl)-ethylamine)], previously described. Similar to these previous complexes, 1 and 2 exhibit a Jahn-Teller distortion of the octahedron, characteristic of a high-spin Mn(III) complex (S = 2). The analysis of the crystallographic data shows that, in both cases, the manganese ion lies in the center of a distorted octahedron characterized by an elongation along the tetragonal axis. Their electronic properties were investigated by multifrequency EPR (190-475 GHz) performed in the solid state at different temperatures (5-15 K). This study confirms our previous results and further shows that: i) the sign of D is correlated with the nature of the tetragonal distortion; ii) the magnitude of D is not sensitive to the nature of the anions in our series of rhombic complexes, contrary to the porphyrinic systems; iii) the [E/D] values (0.124 for 1 and 0.085 for 2) are smaller compared to those found for the [Mn(L)(X)3] complexes (in the range of 0.146 to 0.234); and iv) the E term increases when the ligand-field strength of the equatorial ligands decreases.
authors.affiliation: High Magnetic Field Laboratory of Grenoble, HMFL, CNRS-MPI UPR 5021 BP 166, F 38042 Grenoble 9, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Mantel
authors.forename: Hongyu
authors.initials: H
authors.lastname: Chen
authors.forename: Robert H
authors.initials: RH
authors.lastname: Crabtree
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
authors.forename: Jacques
authors.initials: J
authors.lastname: Pécaut
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Collomb
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc
mesh_terms: D000838:Anions; D001703:Biophysics / Q000379:methods; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002713:Chlorine / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D004583:Electrons; D005459:Fluorides / Q000737:chemistry; D006860:Hydrogen Bonding; D007477:Ions; D008024:Ligands; D008345:Manganese / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013696:Temperature
chemical_list: D000838:Anions; D007477:Ions; D008024:Ligands; D017895:Manganese Compounds; D008345:Manganese; D002713:Chlorine; D005459:Fluorides