title: Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: Mn(II)(2)Mn(IV) and Mn(II)(2)Mn(III)(6) complexes.
abstract: The employment of the anion of methyl 2-pyridyl ketone oxime (mpko(-)) as a tridentate chelating/bridging ligand in manganese chemistry is described. The inorganic anion (Br(-), ClO(4)(-)) used in the reaction affects the identity of the product. The reaction of MnBr(2) and one equivalent of mpkoH in the presence of a base affords [Mn(3)(OMe)(2)(mpko)(4)Br(2)] (3), which is mixed-valence (2Mn(II), Mn(IV)). The central Mn(IV) atom in each of the two, crystallographically independent, centrosymmetric molecules is coordinated by four oximate oxygen atoms belonging to the eta(1):eta(1):eta(1):mu mpko(-) ligands, and two eta(1):mu MeO(-) groups, while six coordination at each terminal Mn(II) atom is completed by four nitrogen atoms belonging to the 'chelating' part of two mpko(-) ligands, and one Br(-) ion. The Mn(II) atoms have trigonal prismatic coordination geometry. The reaction of Mn(ClO(4))(2).6H(2)O, mpkoH and OH(-) (1:2:1) in MeOH gives [Mn(8)O(4)(OMe)(mpko)(9)(mpkoH)](ClO(4))(4) (4), which is also mixed-valence (2Mn(II), 6Mn(III)) and possesses the novel [Mn(8)(mu(3)-O)(4)(mu-OMe)(mu-OR'')(2)](11+) core. The latter possesses a U-shaped sequence of four fused {Mn(II)Mn(III)(2)(mu(3)-O)}(6+) triangular units, with a Mn(III)-Mn(III) edge being shared between the central triangles. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on complexes 3 and 4 . The dc susceptibility data for 3 in the 5.0-300 K range have been fit to a model with two J values, revealing weak ferromagnetic Mn(II)Mn(IV) (J = +3.4 cm(-1)) and Mn(II)Mn(II) (J' = +0.3 cm(-1)) exchange interactions. Fitting of the magnetization vs. H/T data by matrix diagonalization and including only axial anisotropy (ZFS, D) gave ground state spin (S) and D values of S = 13/2, D = +0.17 cm(-1) for and S = 3, D = -0.09 cm(-1) for 4 . The combined work demonstrates the usefulness of mpko(-) in the preparation of interesting Mn clusters, without requiring the co-presence of carboxylate ligands.
authors.affiliation: Department of Chemistry, University of Patras, 265 04, Patras, Greece.
authors.forename: Constantinos C
authors.initials: CC
authors.lastname: Stoumpos
authors.forename: Theocharis C
authors.initials: TC
authors.lastname: Stamatatos
authors.forename: Harikleia
authors.initials: H
authors.lastname: Sartzi
authors.forename: Olivier
authors.initials: O
authors.lastname: Roubeau
authors.forename: Anastasios J
authors.initials: AJ
authors.lastname: Tasiopoulos
authors.forename: Vassilios
authors.initials: V
authors.lastname: Nastopoulos
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Teat
authors.forename: George
authors.initials: G
authors.lastname: Christou
authors.forename: Spyros P
authors.initials: SP
authors.lastname: Perlepes
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008345:Manganese / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010091:Oximes / Q000138:chemical synthesis / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D010091:Oximes; D011725:Pyridines; C534157:methyl 2-pyridyl ketone oxime; D008345:Manganese; D010100:Oxygen