Related Experiment Video
Updated: May 17, 2026
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Structural and electronic comparison of 1st row transition metal complexes of a tripodal iminopyridine ligand
Ashley M McDaniel1, Anthony K Rappé, Matthew P Shores
1Department of Chemistry, Colorado State University , Fort Collins Colorado 80523-1872, United States.
Abstract:
We report the preparation and characterization of a series of divalent 3d transition metal complexes (Cr to Zn, 1-7), featuring the multidentate, tripodal iminopyridine Schiff-base ligand trimethyl 6,6',6″-((1E,1'E,1″E)-((nitrilotris(ethane-2,1-diyl))tris(azanylylidene))tris-(methanylylidene))trinicotinate (L(5-OOMe)). X-ray structural studies carried out on 1-5 and 7 reveal complex geometries ranging from local octahedral coordination to significant distortion toward trigonal prismatic geometry to heptacoordinate environments. Regardless of coordination mode, magnetic and spectroscopic studies show the ligand to provide moderately strong ligand fields: the Fe complex is low-spin, while the Co and Mn complexes are high-spin at all temperatures probed. Cyclic voltammograms exhibit multiple reversible ligand-based reductions, which are relatively consistent throughout the series; however, the electrochemical behavior of the Cr complex 1 is fundamentally different from those of the other complexes. Time-dependent (TD) density functional theory (DFT) and natural transition orbital (NTO) computational analyses are presented for the ligand, its anion, and complexes 1-7: the computed spectra reproduce the major differential features of the observed visible absorption spectra, and NTOs provide viable interpretations for the observed features. The combined studies indicate that all complexes contain neutral ligands bound to M(II) ions, except for the Cr complex 1, which is best described as a Cr(III) species bound to a radical anionic ligand.
More Related Videos
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
14:44Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Related Concept Videos
02:57Coordination Number and Geometry
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...
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,...
02:34Structural 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...
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.