Related Experiment Video
Updated: May 17, 2026
Effect of Microwave Synthesis Conditions on the Structure of Nickel Hydroxide Nanosheets
Published on: August 18, 2023
Binuclear nickel complexes with an edge sharing bis(square-pyramidal) N3Ni(μ-S2)NiN3 core: synthesis,
Ulrike Lehmann1, Jochen Lach, Claudia Loose
1Universität Leipzig, Institut für Anorganische Chemie, Johannisallee 29, 04103 Leipzig, Germany.
Abstract:
The synthesis of the novel macrocyclic octadentate amino-thiophenolate ligand H(2)L2 (3,7,11,19,23,27-hexaaza-33,34-dithiol-15,31-di(tert-butyl)-tricyclo[27,3,1(13.17)]-tetratriaconta-1(32),13,15,17(34),29,30-hexane) and its ability to support binuclear nickel(II) complexes with dithiolato-bridged square-pyramidal Ni(II) ions are reported. H(2)L2 is obtained as the hexahydrobromide salt from a Schiff-base condensation reaction between 1,2-bis(4-tert-butyl-2,6-diformylphenylthio)ethane and bis(3-aminopropyl)amine followed by two successive reductions with NaBH(4) and Na/NH(3). The ligand forms a green, paramagnetic, binuclear nickel(II) complex dication [Ni(II)(2)L2](2+), which can be isolated as a ClO(4)(-) (4) or BPh(4)(-) salt (5). The binuclear nickel(II) complex contains a central N(3)Ni(μ-S)(2)NiN(3) core with two square-pyramidal coordinated Ni(II) ions. The [Ni(2)L2](2+) dication does not bind further coligands, in striking contrast to the behaviour of the parent [Ni(2)L1](2+) dication supported by the smaller (L1)(2-) macrocycle (containing diethylenetriamine in place of the dipropylenetriamine units) which readily binds a variety of other coligands (L') to form bisoctahedral [Ni(2)L1(L')](+) structures. The unusual behaviour of 4 relates to two different N configurations which leads to a steric shielding of the third bridging position by the CH(2)-groups of the dipropylenetriamine chains. An analysis of the temperature-dependent magnetic susceptibility data of 5 reveals the presence of a weak antiferromagnetic exchange interaction between the spins of the nickel(II) ions with a value for the magnetic exchange coupling constant J of -23.5 cm(-1) (H = -2JS(1)S(2)). These results are further substantiated by DFT calculations.
Related Concept Videos
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,...
02:57Coordination Number and Geometry
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.
02:34Structural 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...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...