Bond length

Summary

In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest of the molecule. Explanation Bond length is related to bond order: when more electrons participate in bond formation the bond is shorter. Bond length is also inversely related to bond strength and the bond dissociation energy: all other factors being equal, a stronger bond will be shorter. In a bond between two identical atoms, half the bond distance is equal to the covalent radius. Bond lengths are measured in the solid phase by means of X-ray diffraction, or approximated in the gas phase by microwave spectroscopy. A bond between a given pair of atoms may vary between different molecules. For example, the carbon to hydrogen bonds in methane are different from those in methyl chloride. It is however possible to make generalizations w

Official source

https://en.wikipedia.org/wiki/Bond_length

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related publications (38)

Related publications

Related people (1)

Related people

Related units (1)

Related units

Related concepts (54)

Related concepts

Related courses (24)

Related courses

Related lectures (43)

Related lectures

Helical versus linear Jahn-Teller distortions in allene and spiropentadiene radical cations

Marc Hamilton Folkmann Garner, Rubén Laplaza Solanas

The allene radical cation can be stabilized both by Jahn-Teller distortion of the bond lengths and by torsion of the end-groups. However, only the latter happens and the allene radical cation relaxes into a twisted D-2 symmetry structure with equal double-bond lengths. Here we revisit the Jahn-Teller distortion of allene and spiropentadiene by assessing the possible implications of their helical pi-systems in the radical cations. We describe a general relation between the structure and the number of pi-electrons in spiroconjugated and linearly conjugated systems. Through constrained optimizations we compare the stabilization achieved by bond-length alternation and axial torsion in the radical cations, which we explain with a simple frontier molecular orbital (MO) picture. While structurally different, allene and spiropentadiene have similar helical frontier MOs. Both cations relax through torsion because the stabilization of their helical frontier MOs is bigger than that which can be achieved by linear pi-conjugation. Electrohelicity thus manifests in molecular systems with partial occupation as a helical pi-conjugation effect, which evidently provides more stabilization than its linear counterpart in terms of the Jahn-Teller distortion. This mechanism may be a driving factor for the relaxation in a range of spiroconjugated and linearly conjugated cationic systems.

ROYAL SOC CHEMISTRY2022

, ,

Despite the close association between tellurium (Te) and gold (Au) in many epithermal, orogenic, and intrusion-related hydrothermal ore deposits, the hydrothermal chemistry of Te remains poorly understood. We studied the protonation/ deprotonation and structure of tellurous acid ((H2TeO3)-O-IV) species in aqueous solutions and in water vapor as a function of pH from room-temperature to 505 degrees C using a number of methods: TeO2(s) solubility in solution and steam, potentiometry, NMR spectroscopy, and in situ XAS spectroscopy. The solubility of TeO2(s) increases by up to a factor 80 between ambient temperature and 200 degrees C. As the temperature increases, the pH range over which the neutral species H2TeO3(aq) dominates to the detriment of the ionic species H3TeO3+, HTeO3-and TeO32-expands. The structure of these species is a trigonal pyramid with the Te atom at its apex, indicating a stereochemically active electron pair. The Te-O bond lengths increase with increasing protonation (i.e., decreasing pH). Although hydrated tellurite species such as TeO2(H2O)(g) and TeO2(H2O)(2)(g) exist in significant concentrations in vapors equilibrated with TeO2(s), these species are unlikely to play a significant role in natural systems, because of the high solubility of Te(IV) in the liquid phase under these conditions. Solubility calculations conducted with the new and existing properties confirm the importance of reduced species for the vapor transport of Te, with a partitioning coefficient (Kd = Te concentration in vapor/Te concentration in liquid) up to >10(5) in favor of the vapor, and ppm concentrations of Te in reduced vapors at 300 degrees C. Thermodynamic calculations show that slightly basic, mildly reduced fluids that can transport Au efficiently as Au(HS)(2)(-) can also carry significant Te (e.g., similar to 100 ppb at 300 degrees C). The calculations also suggest that under magmatic hydrothermal conditions, large amounts of Te can be transported as Te(IV) complexes in oxidized fluids (coexisting with SO2(g)). Reduction of Te(IV) caused by processes such as fluid-rock interaction or fluid mixing will lead to a dramatic decrease in the solubilities of both Te and Au, and to the precipitation of telluride minerals. (C) 2013 Elsevier Ltd. All rights reserved.

Elsevier2013

Jahn-Teller distortion and electronic structure of LiMn2O4

LiMn2O4 is one of the important cathode material for rechargeable lithium batteries. Standard ab initio studies within local density approximation (LDA) and generalized gradient approximation (GGA) are not able to reproduce the intrinsic insulating electronic structure and Jahn-Teller-type local atomic distortion of LiMn2O4. In the present work, GGA+U method is shown to be able to localize electrons to Mn 3d(z2) orbits in the majority spin channel, and open a gap of about 0.5 eV between the Mn 3d(z2) and Mn 3d(x2-y2). Results from GGA+U calculation showed that Mn ions are in the mixed valence state of Mn3+ and Mn4+. This is in good agreements with experimental observations and different to Mn3.5+ obtained from standard GGA calculations. While Jahn-Teller distortion is not observed in Mn4+O6 octahedra, it is clearly seen in Mn3+O6 octahedra, in which Mn-O bond lengths along the z-axis direction are obviously elongated. (C) 2008 Elsevier B.V. All rights reserved.

2009

, ,

Elsevier2013