Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TU Lisbon, Lisbon, Portugal.
Inorg Chem. 2011 Feb 7;50(3):918-31. doi: 10.1021/ic101516k. Epub 2011 Jan 6.
New hydrazone o-HO-phenylhydrazo-β-diketones (OHADB), R(1)NHN═CR(2)R(3) [R(1) = HO-2-C(6)H(4), R(2) = R(3) = COMe (H(2)L(1), 1), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(2), 2), R(2) = COMe, R(3) = COOEt (H(2)L(4), 4); R(1) = HO-2-O(2)N-4-C(6)H(3), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(3), 3), R(2) = COMe, R(3) = COOEt (H(2)L(5), 5), R(2)R(3) = COMe (H(2)L(6), 6A)], and their Cu(II) complexes [Cu(2)(CH(3)OH)(2)(μ-L(1))(2)] 7, [Cu(2)(H(2)O)(2)(μ-L(2))(2)] 8, [Cu(H(2)O)(L(3))] 9, Cu(2)(μ-L(4))(2) 10, [Cu(H(2)O)(L(5))] 11, [Cu(2)(H(2)O)(2)(μ-L(6))(2)] 12A and [Cu(H(2)O)(2)(L(6))] 12B were synthesized and fully characterized, namely, by X-ray analysis (4, 5, 7-12B). Reaction of 6A, Cu(NO(3))(2) and ethylenediamine (en) leads, via Schiff-base condensation, to [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}] (13), and reactions of 12A and 12B with en give the Schiff-base polymer Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)} 14. The dependence of the OHADB tautomeric equilibria on temperature, electronic properties of functional groups, and solvent polarity was studied. The OHADB from unsymmetrical β-diketones exist in solution as a mixture of enol-azo and hydrazo tautomeric forms, while in the solid state all the free and coordinated OHADB crystallize in the hydrazo form. The relative stabilities of various tautomers were studied by density functional theory (DFT). 7-14 show catalytic activities for peroxidative oxidation (in MeCN/H(2)O) of cyclohexane to cyclohexanol and cyclohexanone, for selective aerobic oxidation of benzyl alcohols to benzaldehydes in aq. solution, mediated by TEMPO radical, under mild conditions and for the MW-assisted solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant.
新的腙氧代邻羟基苯基腙β-二酮（OHADB），R(1)NHN═CR(2)R(3) [R(1) = HO-2-C(6)H(4)，R(2) = R(3) = COMe (H(2)L(1)，1)，R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(2)，2)，R(2) = COMe，R(3) = COOEt (H(2)L(4)，4)；R(1) = HO-2-O(2)N-4-C(6)H(3)，R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(3)，3)，R(2) = COMe，R(3) = COOEt (H(2)L(5)，5)，R(2)R(3) = COMe (H(2)L(6)，6A)]，及其 Cu(II)配合物[Cu(2)(CH(3)OH)(2)(μ-L(1))(2)] 7，[Cu(2)(H(2)O)(2)(μ-L(2))(2)] 8，[Cu(H(2)O)(L(3))] 9，Cu(2)(μ-L(4))(2) 10，[Cu(H(2)O)(L(5))] 11，[Cu(2)(H(2)O)(2)(μ-L(6))(2)] 12A 和[Cu(H(2)O)(2)(L(6))] 12B 被合成并进行了充分的表征，即通过 X 射线分析（4、5、7-12B）。6A、Cu(NO(3))(2)和乙二胺（en）的反应通过席夫碱缩合，得到[Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}]（13），而 12A 和 12B 与 en 的反应则得到席夫碱聚合物Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)} 14。研究了 OHADB 互变异构平衡对温度、官能团电子性质和溶剂极性的依赖性。不对称β-二酮的 OHADB 在溶液中作为烯醇-偶氮和腙互变异构形式的混合物存在，而在固态中，所有游离和配位的 OHADB 都以腙形式结晶。通过密度泛函理论（DFT）研究了各种互变异构体的相对稳定性。7-14 显示出在 MeCN/H(2)O 中催化过氧化（环己烷）氧化为环己醇和环己酮的活性，在水相中，在温和条件下，在 TEMPO 自由基介导下，选择性地催化苄醇氧化为苯甲醛，以及在微波辅助无溶剂条件下，以叔丁基过氧化氢为氧化剂，从仲醇合成酮的活性。
