Related Experiment Video
Updated: Dec 2, 2025
Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Isomerism and Biradical Character of Tetrapnictide Dianions: A Computational Study
Peter Coburger1,2, Robert Wolf1, Hansjörg Grützmacher2
1Institute of Inorganic Chemistry University of Regensburg 93040 Regensburg Germany.
Abstract:
We present a computational study on tetrapnictide dianions Pn 4 2- (Pn = P, As, Sb, Bi), using density functional theory (DFT), coupled-cluster [DLPNO-CCSD(T)] and complete active space self-consistent field (CASSCF) methods. Environmental effects such as solvation and coordination of counterions are included. The calculations reveal that out of three isomers (square-planar, butterfly and capped-triangle), the square planar isomers are generally the most stable. The counterion (Li+ and Mg2+) used in the calculations have a substantial effect on the relative stabilities. The square planar isomers show considerable biradical character. Calculated reactions toward alkenes indicate that this unusual electronic structure has significant implications on the reactivity of the Pn 4 2- dianions.
Related Concept Videos
01:18Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
01:07Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
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...
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,...
02:33Stereoisomerism of Cyclic Compounds
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...