Nesterova Oksana V, Pombeiro Armando J L, Nesterov Dmytro S
Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
Research Institute of Chemistry, Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya st., 117198 Moscow, Russia.
Materials (Basel). 2020 Nov 29;13(23):5435. doi: 10.3390/ma13235435.
New Schiff base complexes [Cu(HL)(L)(N)]∙2HO () and [CuL(N)]∙HO () were synthesized. The crystal structures of and were determined by single-crystal X-ray diffraction analysis. The HL ligand results from the condensation of salicylaldehyde and 1-(2-aminoethyl)piperazine, while a new organic ligand, HL, was formed by the dimerization of HL via a coupling of two piperazine rings of HL on a carbon atom coming from DMF solvent. The dinuclear building units in and are linked into complex supramolecular networks through hydrogen and coordination bondings, resulting in 2D and 1D architectures, respectively. Single-point and broken-symmetry DFT calculations disclosed negligible singlet-triplet splittings within the dinuclear copper fragments in and . Catalytic studies showed a remarkable activity of and towards cyclohexane oxidation with HO in the presence of nitric acid and pyridine as promoters and under mild conditions (yield of products up to 21%). Coordination compound also acts as an active catalyst in the intermolecular coupling of cyclohexane with benzamide using di-tert-butyl peroxide (BuOOBu) as a terminal oxidant. Conversion of benzamide at 55% was observed after 24 h reaction time. By-product patterns and plausible reaction mechanisms are discussed.
合成了新型席夫碱配合物[Cu(HL)(L)(N)]∙2H₂O ( )和[CuL(N)]∙H₂O ( )。通过单晶X射线衍射分析确定了 和 的晶体结构。HL配体由水杨醛与1-(2-氨基乙基)哌嗪缩合而成，而一种新的有机配体HL则是通过HL的两个哌嗪环在来自DMF溶剂的一个碳原子上偶联而二聚形成的。 和 中的双核结构单元通过氢键和配位键连接成复杂的超分子网络，分别形成二维和一维结构。单点和破缺对称性DFT计算表明， 和 中双核铜片段内的单重态-三重态分裂可忽略不计。催化研究表明，在硝酸和吡啶作为促进剂的温和条件下， 和 对H₂O₂氧化环己烷具有显著活性(产物收率高达21%)。配合物 在以二叔丁基过氧化物(BuOOBu)为终端氧化剂的情况下，还可作为环己烷与苯甲酰胺分子间偶联的活性催化剂。反应24小时后，苯甲酰胺的转化率为55%。讨论了副产物模式和可能的反应机理。
