Phenyl 2‐Pyridyl Ketone and Its Oxime in Manganese Carboxylate Chemistry: Synthesis, Characterisation, X‐ray Studies and Magnetic Properties of Mononuclear, Trinuclear and Octanuclear Complexes

摘要: The use of phenyl 2-pyridyl ketone [(ph)(2-py)CO] and its oxime [(ph)(2-py)CNOH] in manganese benzoate chemistry has been investigated. reaction an excess (ph)(2-py)CNOH with Mn(O2CPh)2·2H2O affords the mononuclear complex [MnII(O2CPh)2{(ph)(2-py)CNOH}2]·1.2H2O (1·1.2H2O) high yield. MnII ion is coordinated by two monodentate benzoates N,N′-bidentate chelating molecules a cis-cis-trans fashion. comproportionation between NnBu4MnO4 (3:1) presence MeCN/EtOH/CH2Cl2 leads to isolation mixed-valent cluster [Mn8O2(OH)2(O2CPh)10{(ph)(2-py)CNO}4]· 4CH2Cl2 (2·4CH2Cl2) about 55% A second synthetic procedure that pure 2 involves known starting material (NnBu4)[Mn4IIIO2(O2CPh)9(H2O)] four equivalents ligand CH2Cl2. centrosymmetric octanuclear molecule contains MnIII ions held together μ4-O2− ligands μ3-OH− give unprecedented [Mn8(μ4-O)2(μ3-OH)2]14+ core, peripheral ligation provided ten PhCO2− (two η1, syn,syn η1:η1:μ2 η1:η2:μ3) η1:η1:η1:μ2 (ph)(2-py)CNO− ions. 1:1 (ph)(2-py)CO trinuclear [Mn3(O2CPh)6{(ph)(2-py)CO}2] (3) more than 80% As judged from single-crystal X-ray crystallography, adopts linear structure one η1:η2:μ2 spanning each pair metal terminal are capped bidentate ligands. three complexes have characterised IR spectroscopy. CV study CH2Cl2 reveals irreversible reduction oxidation processes. magnetic properties 3 studied variable-temperature dc magnetic-susceptibility techniques. temperature approaches zero, value χMT product for zero and, thus, S = 0 ground state. This state explained terms behaviour central, butterfly-like [Mn4III(μ3-O)2]8+ subcore. results reveal weak antiferromagnetic coupling, J −2.7 cm−1 adjacent (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)