Molecular squares of Ni(II) and Cu(II): ferromagnetic exchange interaction mediated by syn-anti carboxylate-bridging
Himanshu Arora1, Francesc Lloret, Rabindranath Mukherjee
1Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208 016, India.
Abstract:
The synthesis of four discrete tetranuclear complexes {[Ni(II)(L(2))][ClO(4)]}(4).MeCN (1), {[Cu(II)(L(1))(O(3)SCF(3))]}(4).H(2)O (), {[Cu(II)(L(3))(OClO(3))]}(4).MeCN () and {[Cu(II)(L(4))][ClO(4)]}(4).3MeCN.4H(2)O (4), supported by a closely similar group of carboxylate-appended (2-pyridyl)alkylamine ligands [L(1)(-): 3-[N-methyl-{2-(pyridin-2-yl)ethyl}amino]propionate; L(2)(-): 3-[(2-(pyridin-2-yl)ethyl){2-(pyridin-2-yl)methyl}amino]propionate; L(3)(-): 3-[N-isopropyl-{2-(pyridin-2-yl)methyl}amino]propionate and L(4)(2-): 3-[N-{2-(pyridin-2-yl)methyl}amino]-bis(propionate)] is described. Structural characterization reveals that each Ni(II) centre in 1 has square-pyramidal Ni(II)N(3)O(2) coordination and each Cu(II) centre in 2-4 has distorted square-pyramidal Cu(II)N(2)O(3) coordination, utilizing three N and one carboxylate O in 1 and two N and carboxylate O (one in 2 and 3; two in 4) of the ligand and the fifth/fourth coordination is provided by an oxygen atom belonging to the carboxylate group of an adjacent molecule. A CF(3)SO(3)(-) or a ClO(4)(-) ion provides an O coordination in 2 and 3, respectively. Temperature-dependent magnetic studies reveal the existence of ferromagnetic exchange interaction in each case, due to the presence of equatorial-equatorial syn-anti carboxylate bridge between M(II) centres.
More Related Videos
15:03Synthesis of Functionalized Magnetic Nanoparticles, Their Conjugation with the Siderophore Feroxamine and its Evaluation for Bacteria Detection
Published on: June 16, 2020
07:07Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology
Published on: March 12, 2015
Related Concept Videos
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:42Valence Bond Theory
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
03:45Formation of Complex Ions
02:57Coordination Number and Geometry
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...