18-Electron Resonance Structures in the BCC Transition
Metals and Their CsCl-type Derivatives
Version 2 2017-02-20, 17:51
Version 1 2017-02-20, 17:48
Posted on 2017-02-20 - 17:51
Bonding in elemental
metals and simple alloys has long been thought of as involving intense
delocalization, with little connection to the localized bonds of covalent
systems. In this Article, we show that the bonding in body-centered
cubic (bcc) structures of the group 6 transition metals can in fact
be represented, via the concepts of the 18-n rule
and isolobal bonding, in terms of two balanced resonance structures.
We begin with a reversed approximation Molecular Orbital (raMO) analysis
of elemental Mo in its bcc structure. The raMO analysis indicates
that, despite the low electron count (six valence electrons per Mo
atom), nine electron pairs can be associated with any given Mo atom,
corresponding to a filled 18-electron configuration. Six of these
electron pairs take part in isolobal bonds along the second-nearest
neighbor contacts, with the remaining three (based on the t2g d orbitals) interacting almost exclusively with first-nearest neighbors.
In this way, each primitive cubic network defined by the second-nearest
neighbor contacts comprises an 18-n electron system
with n = 6, which essentially describes the full
electronic structure of the phase. Of course, either of the two interpenetrating
primitive cubic frameworks of the bcc structure can act as a basis
for this discussion, leading us to write two resonance structures
with equal weights for bcc-Mo. The electronic structures of CsCl-type
variants with the same electron count can then be interpreted in terms
of changing the relative weights of these two resonance structures,
as is qualitatively confirmed with raMO analysis. This combination
of raMO analysis with the resonance concept offers an avenue to extend
the 18-n rule into other transition metal-rich structures.
CITE THIS COLLECTION
DataCite
3 Biotech
3D Printing in Medicine
3D Research
3D-Printed Materials and Systems
4OR
AAPG Bulletin
AAPS Open
AAPS PharmSciTech
Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)
Academic Medicine
Academic Pediatrics
Academic Psychiatry
Academic Questions
Academy of Management Discoveries
Academy of Management Journal
Academy of Management Learning and Education
Academy of Management Perspectives
Academy of Management Proceedings
Academy of Management Review
Vinokur, Anastasiya
I.; Fredrickson, Daniel C. (2017). 18-Electron Resonance Structures in the BCC Transition
Metals and Their CsCl-type Derivatives. ACS Publications. Collection. https://doi.org/10.1021/acs.inorgchem.6b02989
or
Select your citation style and then place your mouse over the citation text to select it.
SHARE
Usage metrics
Read the peer-reviewed publication
AUTHORS (2)
AV
Anastasiya
I. Vinokur
DF
Daniel C. Fredrickson
KEYWORDS
electron pairselectron count18- n ruleCsCl-type Derivatives BondingraMO analysisapproximation Molecular Orbitaltransition metal-rich structuressecond-nearest neighbor contacts18- electron configurationBCC Transition Metalsbcc structure18- Electron Resonance Structurest 2 gresonance structures18- n electron systemgroup 6 transition metals