Anatomy of bond formation. Bond length dependence of the extent of electron sharing in chemical bonds from the analysis of domain-averaged Fermi holes

2007 ◽  
Vol 135 ◽  
pp. 31-42 ◽  
Author(s):  
Robert Ponec ◽  
David L. Cooper
Keyword(s):  
Bond Length ◽  
Bond Formation ◽  
Chemical Bonds ◽  
Length Dependence

scholarly journals Bond-Length Distributions for Ions Bonded to Oxygen: Results for the Transition Metals and Quantification of the Factors Underlying Bond-Length Variation in Inorganic Solids

2020 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Bond Length ◽  
A Priori ◽  
Bond Formation ◽  
Length Variation ◽  
Electronic Effects ◽  
Coordination Polyhedra ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Non Local

Bond-length distributions are examined for 63 transition-metal ions bonded to O2- in 147 configurations, for 7522 coordination polyhedra and 41,488 bond distances, providing baseline statistical knowledge of bond lengths for transi-tion metals bonded to O2-. A priori bond valences are calculated for 140 crystal structures containing 266 coordination poly-hedra for 85 transition-metal ion configurations with anomalous bond-length distributions. Two new indices, Δ𝑡𝑜𝑝𝑜𝑙 and Δ𝑐𝑟𝑦𝑠𝑡, are proposed to quantify bond-length variation arising from bond-topological and crystallographic effects in extended solids. Bond-topological mechanisms of bond-length variation are [1] non-local bond-topological asymmetry, and [2] multi-ple-bond formation; crystallographic mechanisms are [3] electronic effects (with inherent focus on coupled electronic-vibra-tional degeneracy in this work), and [4] crystal-structure effects. The Δ𝑡𝑜𝑝𝑜𝑙 and Δ𝑐𝑟𝑦𝑠𝑡 indices allow one to determine the primary cause(s) of bond-length variation for individual coordination polyhedra and ion configurations, quantify the dis-torting power of cations via electronic effects (by subtracting the bond-topological contribution to bond-length variation), set expectation limits regarding the extent to which functional properties linked to bond-length variations may be optimized in a given crystal structure (and inform how optimization may be achieved), and more. We find the observation of multiple bonds to be primarily driven by the bond-topological requirements of crystal structures in solids. However, we sometimes observe multiple bonds to form as a result of electronic effects (e.g. the pseudo Jahn-Teller effect); resolution of the origins of multiple-bond formation follows calculation of the Δ𝑡𝑜𝑝𝑜𝑙 and Δ𝑐𝑟𝑦𝑠𝑡 indices on a structure-by-structure basis. Non-local bond-topological asymmetry is the most common cause of bond-length variation in transition-metal oxides and oxysalts, followed closely by the pseudo Jahn-Teller effect (PJTE). Non-local bond-topological asymmetry is further suggested to be the most widespread cause of bond-length variation in the solid state, with no a priori limitations with regard to ion identity. Overall, bond-length variations resulting from the PJTE are slightly larger than those resulting from non-local bond-topological asym-metry, comparable to those resulting from the strong JTE, and less than those induced by π-bond formation. From a compar-ison of a priori and observed bond valences for ~150 coordination polyhedra in which the strong JTE or the PJTE is the main reason underlying bond-length variation, the Jahn-Teller effect is found not to have a symbiotic relation with the bond-topo-logical requirements of crystal structures. The magnitude of bond-length variations caused by the PJTE decreases in the fol-lowing order for octahedrally coordinated d0 transition metals oxyanions: Os8+ > Mo6+ > W6+ >> V5+ > Nb5+ > Ti4+ > Ta5+ > Hf4+ > Zr4+ > Re7+ >> Y3+ > Sc3+. Such ranking varies by coordination number; for [4], it is Re7+ > Ti4+ > V5+ > W6+ > Mo6+ > Cr6+ > Os8+ >> Mn7+; for [5], it is Os8+ > Re7+ > Mo6+ > Ti4+ > W6+ > V5+ > Nb5+. We conclude that non-octahedral coordinations of d0 ion configurations are likely to occur with bond-length variations that are similar in magnitude to their octahedral counterparts. However, smaller bond-length variations are expected from the PJTE for non-d0 transition-metal oxyanions.<br>

Angular-Resolved Vleed from O-Cu(001): Valence Bands, Chemical Bonds, Potential Barrier, and Energy States

1997 ◽  
Vol 11 (25) ◽  
pp. 3073-3091 ◽  
Author(s):  
Chang Q Sun
Keyword(s):  
Fine Structure ◽  
Work Function ◽  
Potential Barrier ◽  
Bond Formation ◽  
Chemical Bonds ◽  
Bond Forming ◽  
Comprehensive Information ◽  
New Models ◽  
Energy States ◽  
Valence Bands

It is shown that the VLEED, furnished with appropriate modelling approaches, is able to reveal comprehensive information about the details of a surface. Constructing Brillouin zones from the critical positions on the angular-resolved VLEED spectra yields information about valence bands and in-plane reconstruction of the O-Cu(001) surface. Decoding the fine-structure features with new models [J. Phys. Chem. Solids58 903 (1997) and J. Phys.: Condens. Matt., C9, 5823 (1997)] rewards us with consistent understanding of the bond formation and its consequences. It is interpreted that the bond forming results in the dislocation of surface atoms, the variation of energy states, the nonuniformity and anisotropy of the potential barrier, and the reduction in both work function and inner potential of the surface.

Molecular Theory Considering Nuclear Potential Wells

2021 ◽  
Author(s):  
Dariush Habibollah Zadeh
Keyword(s):  
Bond Length ◽  
Periodic Table ◽  
Computer Software ◽  
Shielding Effect ◽  
Nuclear Potential ◽  
Average Error ◽  
Chemical Bonds ◽  
Model Concept ◽  
Potential Wells ◽  
Additional Tool

Abstract This article introduces potential wells around nuclei and their roles in chemical bonds. The approach uses one-electron Bohr atomic model concept. Multi-electron atoms are converted to one-electron atoms by grounding all inactive, non-reacting electrons using the Apparent Nuclear Charge (ANC) and Electron Shielding Effect (ESE) concepts introduced in earlier publications. Then the resulting two one-electron atoms and their potential wells are utilized to obtain the related chemical bond length. The methodology is applicable to all elements of periodic table without a need for any additional tool. To test the concept, calculated bond lengths were compared to experimental ones for about 90 different bonds which showed an average error of less than 5%. The article discusses some nontraditional views for chemical bonds which may contradict the traditional beliefs in chemistry. Hopefully, readers would consider the calculated results in support of the presented views. Attached to this article is a computer software program which was prepared with sample input and output files for readers. The software can be utilized to obtain any interested bond length. The software is applicable to all elements in the periodic table up to the element Hassium with the atomic number of 108.

Zu einer Bindungslängen-Kristallchemie

1992 ◽  
Vol 200 (3-4) ◽  
Author(s):  
Martin Trömel
Keyword(s):  
Electrical Conductivity ◽  
Bond Strength ◽  
Bond Length ◽  
Chemical Bonds ◽  
Ionic Radii ◽  
Interatomic Distances ◽  
Secondary Bonds ◽  
Oxidizing Power ◽  
Oxygen Bond ◽  
Weak Chemical

AbstractFundamentals of a bond length based crystal chemistry which emerges from the bond valence method and goes beyond the concept of ionic radii are discussed. In many cases, atomic distances can serve as a measure of chemical bonding. Unobserved interatomic distances and ionic radii can be predicted from bond-length – bond-strength relationships. Electrical conductivity appears to be connected with peculiarities of bondlengths. The oxidizing power of oxides and oxo-complexes seems to be correlated with oxygen bond-lengths. Secondary bonds and intermolecular interactions appear as weak chemical bonds.

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