Related Experiment Video
Updated: Jan 19, 2026
Single Crystal and Powder X-ray Diffraction
Published on: April 30, 2023
Reversible Thermochromism of Nickel(II) Complexes and Single-Crystal-to-Single-Crystal Transformation
Jayaraman Pitchaimani1, Subramanian Karthikeyan2, Narayanan Lakshminarasimhan3
1Department of Chemistry, Karunya Institute of Technology and Science (Deemed to be University), Coimbatore 641114, Tamil Nadu, India.
Abstract:
A molecular Ni(II)-NNN pincer complex (1) exhibited unprecedented reversible single-crystal-to-single-crystal transformation and color change upon heating and cooling due to a subtle change in the N-Ni(II) bond length and ligand conformation. UV-vis, thermogravimetric, differential scanning calorimetry, single-crystal structural data, temperature-dependent powder X-ray diffraction, and Raman and computational studies supported the structural change of the Ni(II) complex with temperature.
Related Concept Videos
08:14Single Crystal and Powder X-ray Diffraction
X-ray crystallography is a technique that uses X-rays to study the structure of molecules. X-ray diffraction (XRD) experiments are routinely carried out with either single-crystal or powdered samples.
Single-crystal XRD:
Single-crystal XRD allows for absolute structure determination. With single-crystal XRD data, the exact atomic positions can be observed, and thus bond lengths and angles can be determined. This...
11:32High Pressure Single Crystal Diffraction at PX^2
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...
07:08Efficient Mammalian Cell Expression and Single-step Purification of Extracellular Glycoproteins for Crystallization
04:51Comparison of Two Different Synthesis Methods of Single Crystals of Superconducting Uranium Ditelluride
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,...