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Reaction of 1,3-bis(salicylideneamino)-2-propanol (H3L) with manganese(II) acetate tetrahydrate in the presence of ethylenediamine and sodium thiocyanate give a salen complex [Mn(salen)(NCS)] (H2salen = N,N′-disalicylideneethylenediamine), while that in the presence of water and triethylamine gives a binulear manganese(III) complex [Mn2(L)2(H2O)]·3CH3OH. Both complexes have been characterized by X-ray crystal structure analyses, electronic spectra, and magnetic susceptibilities.

Bis(μ-carboxylato-O,O′)-diaquabis(1,10-phenanthroline)dicopper(II) dinitrate tetrahydrates, [Cu(RCOO)(phen)(H2O)]2(NO3)2·4H2O, where R=H, CH3, and (CH3)3C, were prepared and characterized by elemental analyses, electronic spectra, magnetic susceptibilities, and X-ray structure analysis. The magnetic susceptibility data conform to the usual dimer equation. The −2J values are 125 cm−1 for formate, 86 cm−1 for acetate, and 99 cm−1 for 2,2-dimethylpropanoate. The crystal structures of [Cu(HCOO)(phen)(H2O)]2(NO3)2·4H2O (1) and [Cu(CH3COO)(phen)(H2O)]2(NO3)2·4H2O (2) were determined by the single-crystal X-ray diffraction method. The crystallographic data are: Compound 1, monoclinic, I2⁄a, a=18.850(2), b=9.775(2), c=17.752(2) Å, β=99.03(1)°, V=3230.4(8) Å3, Z=4, R=0.055 for 2511 observed unique reflections; Compound 2, monoclinic, C2⁄c, a=18.563(4), b=14.272(5), c=14.126(3) Å, β=106.72(2)°, V=3584(2) Å3, Z=4, R=0.082 for 2092 reflections. The complexes consist of dimeric [Cu(RCOO)(phen)(H2O)]22+)] cations with five-coordinated copper ions linked by two carboxylato ions in a syn-syn bridging arrangement. The Cu···Cu distances are 3.103(2) Å for 1 and 3.063(3) Å for 2.

Two sterically hindered tris-pyridyl methane ligands, tris(6-methyl-2-pyridyl)methane (L1) and bis(6-methyl-2-pyridyl)pyridylmethane (L2), are newly synthesized. Under aerobic conditions, Ln (n = 1 or 2) reacts with CuX2 (X = Cl or Br), oxygenated at the methine position to LnOH or LnOMe. The former alcoholate ligand creates trinuclear Cu(II) complexes [Cu3(X)(LnO)3](PF6)2 [(X, n) = (Br, 1) 1, (C1, 1) 2, (Br, 2) 3, or (C1, 2) 4] in which the alkoxide oxygen atoms bridge copper centers. The crystal structures of 1-4 are presented along with their magnetic susceptibility data. The weak antiferromagnetic coupling between the Cu(II) centers in this trinuclear arrangement is due to weak interaction of the magnetic orbitals (dz2) which are oriented along three alternate sides in a hexagon of the Cu3O3 core in 1-4. Under anaerobic conditions, L1 reacts with CuBr2 to form a square pyramidal complex [CuL1Br2] (9) with the ligand facially capping. [Cu(Br)2(L1OMe)] (10) was obtained after the suspension of 9 in MeOH was stirred under air for 48 h. In the presence of cyclohexene, 9 is converted to [Cu(Br)(L1)]m (m = 1 or 2) 5 quantitatively to give trans- 1,2-dibromocyclohexane, indicating that Br2 is generated during the reaction. The FAB MS spectrum of [18O]-1 prepared by the reaction of L1 with CuBr2 under 18O2 shows that the ligand of [18O]-1 is L1(18O-.) L1(18OH), L1OCD3, and bis(6-methyl-2-pyridyl) ketone were obtained from reaction of L1 with CuBr2 in CD3OD under 18O2. These results indicate that the origins of the O atom in L1OH and L1OMe are O2 and MeOH, respectively. On the basis of these results, a mechanism of the oxygenation of L1 in the present system will be proposed.

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Mononuclear and dinuclear manganese complexes with2,6-bis[N-(2-pyridylethyl)iminomethyl]-4-methylphenol (HL), [MnII2(L)(CH3COO)2(CH3OH)](ClO4) (1), [MnII2(L)(CH3COO)2(NCS)] (2), [MnII(HL)(NCS)2(H2O)] (3), [MnIIMnIII(L)(CH3COO)2(CH3OH)2](ClO4)2 (4), [MnIIMnIII(L)(CH3COO)2(NCS)2] (5), [MnIIMnIII(L)(CH3COO)2(N3)2]·2CH3OH (6), and [MnIII(HL)(N3)3] (7), have been prepared and characterized by infrared, electronic, and ESR spectra, as well as the temperature dependence of the magnetic susceptibilities (80—300 K). The molecular structures of 1, 2, 3, 6, and 7 were determined by single-crystal X-ray structure analyses. Complexes 1 and 2 have a μ-phenoxo-di-μ-acetato-bridged dinuclear structure, in which one manganese atom is five-coordinated and the other six-coordinated. Complex 6 is a μ-phenoxo-di-μ-acetato-bridged dinuclear molecule comprising an octahedral Mn(II) atom and an elongated-octahedral Mn(III) atom. The manganese atoms of 3 and 7 are six-coordinated in a distorted octahedral environment. The spectral and magnetic properties are discussed in relation to the crystal structures.

The structures of six dimeric copper(II) formates and acetates with picoline as an axial ligand, (I)-(VI), have been determined at room temperature and electron density distributions in lithium acetate dihydrate, (VII), and copper(II) formate diurea dihydrate, (VIII), have been studied at 120K. (VI) show no important geometrical differences in the Cu2(COO)4 cage between the copper acetates and formates. The observed deformation-density distributions in the CH3COO-(VII) and HCOO-(VIII) ions are in accord with theoretical expectations. Mulliken population analysis of eight carboxylate ions using STO-6G basis sets indicates that the electron population of the carboxylate group of the bridging ligand correlates with the -2J values of the binuclear copper(II) carboxylates. The key point that determines the strength of the spin-exchange interaction is the 2px orbital population of the carboxylate C atom (x is parallel to the C--R bond axis in the RCOO-ion). The electron population on a carboxylate O atom is shown to exhibit a roughly linear correlation with the pKa value of the parent carboxylic acid. The conundrum of why formate and fluoroacetate are exceptions to the correlation of -2J with pKa value has been solved in this paper.

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