Related Experiment Video
Updated: Jul 6, 2026
Effect of Microwave Synthesis Conditions on the Structure of Nickel Hydroxide Nanosheets
Published on: August 18, 2023
On the origin of paramagnetism in planar nickel(II) complexes
1School of Chemistry, Building F11, Eastern Avenue, The University of Sydney, NSW 2006, Australia. a.bridgeman@chem.usyd.edu.au
Abstract:
The general rule that in Ni(II) d(8) chemistry, tetrahedral (or nearly tetrahedral) complexes have temperature dependent magnetic moments which are usually larger than the spin-only value whilst square planar complexes are diamagnetic is broken for certain Ni[P((t)Bu)(2)(O)NR](2) complexes. These have planar coordination for various alkyl groups but have the spectral and paramagnetic properties normally associated with tetrahedral systems. In contract to previous studies, density functional calculations show the unusual adoption of a high-spin rather than low-spin arrangement in the planar systems is due to the strong pi bonding of the amide group and the preference for a planar coordination is due to greater separation between the bulky nitrogen and phosphorus substituents.
Related Concept Videos
02:42Valence Bond Theory
01:30Paramagnetism
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.
02:46Crystal 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,...
01:26Diamagnetism
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
01:03Precipitation Gravimetry
In determining nickel by gravimetric analysis, a precipitant of ethanolic dimethylglyoxime is added to a hot nickel salt solution. This is quickly followed by the dropwise addition of dilute ammonia solution until precipitation occurs. A...