Structure-dependent spectroscopic and redox properties of copper(I) complexes with bidentate iminopyridine ligands
摘要:
A series of iminopyridine ligands; cyclopropylpyridin-2-ylmethyleneamine (A), cyclopentylpyridin-2-ylmethyleneamine (B), cyclohexylpyridin-2-ylmethyleneamine (C), and cycloheptylpyridin-2-ylmethyleneamine, (D) and their copper(I) complexes, [Cu(L)(2)](+) (1a-1d) and [Cu(L)(PPh3)(2)](+) (2a-2d) have been synthesized and characterized by CHN analyses, H-1 NMR and IR and UV-Vis spectroscopy. Structures of 1a, 1b, 1c and 2a were determined by X-ray crystallography. The coordination polyhedron about the Cu-I center in the complexes is best described as a distorted tetrahedron. The dihedral angles between the least-squares planes of the chelate ligands show considerable variation from 86.1 degrees in 1a to 68.3 degrees in 1b, indicating the importance of packing forces in the crystalline environment. The UV-Vis spectra of the complexes are characterized by first metal to ligand charge transfer bands increasing in wavelength with increasing size of the ring substituents in the ligands, except for the cyclopropyl compounds (1a and 2a), in good agreement with the variation of the dihedral angles between the ligand planes. Cyclic voltammetry of the complexes indicates a quasireversible redox behavior for the complexes. The bulkier ligands (PPh3) inhibit the geometric distortion within the oxidized form and the redox potentials of complexes 2a-2d are shifted to more positive values, therefore. (C) 2009 Elsevier B.V. All rights reserved.
合成了一系列在亚胺氮上具有取代基变化的吡啶基嘧啶配体,并与[MoCl 2 O 2 ]核配位。复合物的新的分子结构进行了充分表征通过1 H和13 C NMR,FT-IR,ESI,EA,和X-射线晶体学,和它们的催化活性进行了研究,使用烯烃的环氧化叔叔丁基过氧化氢(TBHP)作为氧化剂。与类似的均相钼配合物相比,新的配合物在环氧化反应中显示出优异的催化活性和优良的选择性。结果表明,取决于吡啶吡啶亚胺配体结构上的烷基臂,催化性能有显着变化。催化结果表明,络合物[MoCl 2 O 2(L)](L:N-(2-吡啶基亚甲基)-1-叔丁基亚胺)C 5是环己烯环氧化的最佳催化前体(TON:92920和TOF :30974 h -1)。
Molybdenum (VI) Complexes Containing Pyridylimine Ligands: Effect of the Imine Nitrogen Substituent in the Epoxidation Reaction
作者:Daniel Martínez‐Martínez、M. León Santiago、Rubén A. Toscano、Manuel Amézquita‐Valencia
DOI:10.1002/ejic.202000790
日期:2021.1.22
A series of pyridylimine ligands with variations of the substituent at the imine nitrogen were synthesized and coordinated to the [MoCl2O2] core. The novel molecular structures of the complexes were fully characterized by 1H and 13C NMR, FT‐IR, ESI, EA, and X‐ray crystallography, and their catalytic activity was studied for the epoxidation of alkenes using tert‐butyl hydroperoxide (TBHP) as the oxidant
合成了一系列在亚胺氮上具有取代基变化的吡啶基嘧啶配体,并与[MoCl 2 O 2 ]核配位。复合物的新的分子结构进行了充分表征通过1 H和13 C NMR,FT-IR,ESI,EA,和X-射线晶体学,和它们的催化活性进行了研究,使用烯烃的环氧化叔叔丁基过氧化氢(TBHP)作为氧化剂。与类似的均相钼配合物相比,新的配合物在环氧化反应中显示出优异的催化活性和优良的选择性。结果表明,取决于吡啶吡啶亚胺配体结构上的烷基臂,催化性能有显着变化。催化结果表明,络合物[MoCl 2 O 2(L)](L:N-(2-吡啶基亚甲基)-1-叔丁基亚胺)C 5是环己烯环氧化的最佳催化前体(TON:92920和TOF :30974 h -1)。
Structure-dependent spectroscopic and redox properties of copper(I) complexes with bidentate iminopyridine ligands
作者:Werner Massa、Saeed Dehghanpour、Khadijeh Jahani
DOI:10.1016/j.ica.2009.01.008
日期:2009.6
A series of iminopyridine ligands; cyclopropylpyridin-2-ylmethyleneamine (A), cyclopentylpyridin-2-ylmethyleneamine (B), cyclohexylpyridin-2-ylmethyleneamine (C), and cycloheptylpyridin-2-ylmethyleneamine, (D) and their copper(I) complexes, [Cu(L)(2)](+) (1a-1d) and [Cu(L)(PPh3)(2)](+) (2a-2d) have been synthesized and characterized by CHN analyses, H-1 NMR and IR and UV-Vis spectroscopy. Structures of 1a, 1b, 1c and 2a were determined by X-ray crystallography. The coordination polyhedron about the Cu-I center in the complexes is best described as a distorted tetrahedron. The dihedral angles between the least-squares planes of the chelate ligands show considerable variation from 86.1 degrees in 1a to 68.3 degrees in 1b, indicating the importance of packing forces in the crystalline environment. The UV-Vis spectra of the complexes are characterized by first metal to ligand charge transfer bands increasing in wavelength with increasing size of the ring substituents in the ligands, except for the cyclopropyl compounds (1a and 2a), in good agreement with the variation of the dihedral angles between the ligand planes. Cyclic voltammetry of the complexes indicates a quasireversible redox behavior for the complexes. The bulkier ligands (PPh3) inhibit the geometric distortion within the oxidized form and the redox potentials of complexes 2a-2d are shifted to more positive values, therefore. (C) 2009 Elsevier B.V. All rights reserved.