136768-57-5Relevant articles and documents
DFT and experimental studies of perchlorate ion coordination in cis/trans-copper(II) complexes of tetradentate pyridyl ligands
Pandiyan, Thangarasu,Guadalupe, Hernandez J.,Cruz, Julian,Bernes, Sylvain,Ugalde-Salvdivar, Victor M.,Gonzalez, Ignacio
, p. 3274 - 3285 (2008)
Spectral and structural studies of N,N′-dimethyl-N,N′-bis- (pyridin-2-ylmethyl)-1,2-diaminoethane (L1), N,N′-dimethyl-N,N′- bis(pyridin-2-ylmethyl)-1,3-diaminopropane (L2), and their copper(II) complexes were carried out by spectroscopic and DFT methods. The DFT results show that conventional and nonconventional H-bonds present in L1 and L2 influence the NMR chemical shifts at different pH values, which thus suggests that the protonation sites at the pyridyl and tertiary nitrogen atoms of the ligands change the chemical environment of the adjacent carbon atoms; this observation is consistent with 13C NMR spectra recorded at different pH values. Furthermore, for their copper complexes, two possible geometrical isomers (cis and trans) are obtained; for example, cis-[CuL 1]2+, where both NCH3 groups are oriented in the same plane, is in equilibrium with its trans isomer and, as a result, a small energy difference (0.9 kcal mol-1) appears. In contrast, trans-[CuL2]2+ does not equilibrate with the cis isomer, because there is a greater energy difference (ΔE = 3.9 kcal mol -1) between the two isomers. Indeed, when [CuL1] 2+ with two perchlorate ions was optimized, it was found that although only cis-[CuL1]2+ was able to accommodate a perchlorate ion in the axial position of the square pyramidal geometry by stabilizing the structure with two cis NCH3 groups through H-bonds, the trans isomer was unable to retain the perchlorate ion in the coordination sphere, because the NCH3 groups were in the trans position; this disfavors the presence of the perchlorate ion in the sphere, because of the absence of H-bonds. This is consistent with the X-ray structure, in which cis-[CuL1(ClO4)]+ is resolved, whereas the trans isomer is not. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Copper(II)-azido complexes constructed from polypyridyl amine ligands
Mautner, Franz A.,Koikawa, Masayuki,Mikuriya, Masahiro,Harrelson, Emily V.,Massoud, Salah S.
, p. 17 - 22 (2013)
A novel 1-D polymer Cu(II) complex bridged by perchlorate ions and azide ligand with the structural formula [Cu(DPA)(N3)(μO,O-ClO 4)]n (1), {[Cu(Ldpdmen)(μ1,3-N 3)]ClO4}n (2), {[Cu2(μ-L py)(μ-1,1,3-N3)(μ-1,3-N3)](ClO 4)2}n (3) and {[Cu2(L T)(μ2-1,3-N3)(N3)(H 2O)](ClO4)2H2O}n (4) where DPA = di(2-pyridylmethyl)amine, Ldpdmen = N,N′-bis(2- pyridylmethyl)-N,N′-dimethylethylenediamine and Lpy = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]pyridine and LT = 3,5-bis[bis(2-pyridylmethyl) aminomethyl]toluene were synthesized. The complexes were characterized by spectroscopic techniques (IR and visible) and by single crystal X-ray crystallography. The magnetic properties were also measured for 1-3 at variable temperatures (4.5-300 K). Compound 1 has the copper center in a 4+2 geometry with the equatorial plane formed through the three N-donors of the DPA and an azido group which acting as a monodentate ligand. The 1-D chain is generated via the axial O,O′-bridging perchlorato groups where the intra-chain Cua??Cu distance is 6.9416(16) A?. In complex 2, the Cu center is ligated by the four N-donor atoms of Ldpdmen amine ligand and two N atoms of the EE bridging azido groups in a cis-coordinated asymmetric EE bonding fashion. The intra-chain Cua??Cu distance in this complex is 5.7949(15) A?.
Copper tetradentate N2Py2 complexes with pendant bases in the secondary coordination sphere: Improved ligand synthesis and protonation studies
Khosrowabadi Kotyk, Juliet F.,Ziller, Joseph W.,Yang, Jenny Y.
, p. 1990 - 2002 (2016)
An improved preparation for a tetradentate neutral N2Py2 ligand with two dimethylamine functionalities in the secondary coordination sphere (LDMA) is reported. This synthetic route uses cheaper and more readily available p
Electrochemical Exploration of Active Cu-Based Atom Transfer Radical Polymerization Catalysis through Ligand Modification
Bernhardt, Paul V.,Melville, Jamie N.
, p. 9709 - 9719 (2021)
The intersection between Cu-catalyzed atom transfer radical polymerization (ATRP) and organometallic mediated radical polymerization (OMRP) has been recently shown to be a result of competition between the CuI and CuII complexes of polyamine ligands for the same organic free radical. The tetradentate ligands N,N′-bis-2′-pyridylmethyl-ethane-1,2-diamine (L1) and N,N′-dimethyl-N,N′-bis-2′-pyridylmethyl-ethane-1,2-diamine (L2) form stable Cu complexes which, depending on their oxidation state, can either liberate or complex organic radicals. Herein, we show that this process may be affected by subtle changes to the ligand system. Switching from a tertiary amine (L2) to a secondary amine (L1) retains ATRP and OMRP activity through a series of cyclic voltammetry measurements in the presence of the initiator bromoacetonitrile.
O-H and (CO)N-H bond weakening by coordination to Fe(ii)
Resa, Sandra,Millán, Alba,Fuentes, Noelia,Crovetto, Luis,Luisa Marcos,Lezama, Luis,Choquesillo-Lazarte, Duane,Blanco, Victor,Campa?a, Araceli G.,Cárdenas, Diego J.,Cuerva, Juan M.
supporting information, p. 2179 - 2189 (2019/02/12)
New N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-ethane-1,2-diamine derivatives bearing covalently linked OH and (CO)NH groups have been synthesized. The coordination of those pendant hydroxyl/amide groups to a Fe(ii) metal center is demonstrated both in solution, even in the presence of chloride as the counterion, and in solid state, by means of X-ray diffraction crystal structures. As a result of this coordination, the experimental bond dissociation free energies (BDFE) of O-H and (CO)N-H bonds are remarkably diminished down to 76.0 and 80.5 kcal mol-1 respectively, which is also in agreement with DFT-based theoretical calculations. These BDFE values are in the range of commonly used hydrogen-atom donor reagents. The strategy presented here allows an unequivocal evaluation of the influence of metal coordination in X-H bond weakening in organic solvents which could be easily extended to other metal centers.
