The preferred valence states of transition metals

1964 ◽  
Vol 17 (8) ◽  
pp. 833 ◽  
Author(s):  
JC Sheldon
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Heat Of Formation ◽  
Valence States ◽  
Elementary Transition ◽  
Binary Compounds ◽  
Transition Metal Fluorides ◽  
D Orbitals ◽  
Related Compounds ◽  
Valence Number

It is proposed that the valence number, n, for bonding in the elemental state may be estimated by n = rΔHf�/C, where r is half the interatomic distance, -ΔHf� is the heat of formation of the elemental state, and C is a constant and approximately 28 and 40 Ǻ kcal g-atom-1 for non-metals and metals respectively. It is shown that the valence states of the elementary transition metals, as given by n, correspond closely to the most stable oxidation states (MSOS) displayed in binary transition metal fluorides, chlorides, and related compounds. It is concluded that the trend of the MSOS of transition metal binary compounds results mainly from each metal possessing a preferred valence state, which is strongly determined by the availability of the (n-l)d orbitals for bonding as judged by their size relative to that of the ns and p orbitals.

The prediction of metal-to-metal bonding in transition metal binary and related compounds

1964 ◽  
Vol 17 (11) ◽  
pp. 1191 ◽  
Author(s):  
JC Sheldon
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Valence State ◽  
Oxidation States ◽  
Metal Bonding ◽  
Binary Oxides ◽  
Lower Oxidation ◽  
D Orbitals ◽  
Related Compounds

The evidence for, and the factors determining, the formation of metal-to-metal (m-m) bonds in transition metal oxides, sulphides, halides, and related complexes are discussed. It is proposed that when metals of high preferred valence state are constrained to low formal oxidation states, m-m bonds will form to allow the metal to exercise a higher valency. It is assumed that (n-l)d orbitals are used for such bonds and predictions of the feasibility of m-m bonding are possible by the comparison of the size of such orbitals with the expected inter-metal distances in polymeric metal oxides and halides. It is concluded that binary oxides and halides (excepting fluorides) of the lower oxidation states of Zr, Hf, Nb, Ta, Mo, W, and Re and of a few neighbouring elements will display m-m bonds.

Reactivity of transition metal fluorides. VIII. Reactions of rhenium heptafluoride and hexafluoride

1971 ◽  
Vol 24 (2) ◽  
pp. 243 ◽  
Author(s):  
JH Canterford ◽  
TA O'Donnell ◽  
AB Waugh
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Exchange Reactions ◽  
Metal Fluorides ◽  
Oxidation Reduction ◽  
Halogen Exchange ◽  
Transition Metal Fluorides

Oxidation-reduction and halogen-exchange reactions of the higher fluorides of rhenium with a series of selected reagents have been investigated. The results correlate with studies of reactivities of higher fluorides of other transition metals previously reported. The reactions reported provide markedly improved preparative routes to the hexachloride, pentabromide, and pentafluoride of rhenium.

scholarly journals Structural and electronic properties of LiMnO2 doped with transition metals: A first-principles study

2021 ◽  
Vol 2145 (1) ◽  
pp. 012035
Author(s):  
Nontawat Chaiyaocha ◽  
Worasak Sukkabot
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Electronic Properties ◽  
Density Functional ◽  
Electronic Conductivity ◽  
Diffusion Channel ◽  
Volumetric Expansion ◽  
Structural And Electronic Properties ◽  
Metal Doped ◽  
D Orbitals

Abstract A spin density functional calculations of structural and electronic properties of LiMnO2 doped with several transition metals (Sc, V and Tc) are reported. The physical properties of LiMnO2 material are sensitive with the transition-metal dopants. Transition metal dopants enhance the lattice parameters and volumes, thus increasing the Li diffusion channel. The computations underscore that d orbitals of transition metals are located around the Fermi level. V doping in LiMnO2 demonstrates the enhancement in the electronic conductivity due to the volumetric expansion. Finally, these results deliver a valuable information for the transition-metal doped LiMnO2 cathode materials to improve the performance of lithium batteries.

Intercalation of First Row Transition Metals inside Covalent-Organic Frameworks (COF): a Strategy to Fine Tune the Electronic Properties of Porous Crystalline Materials

2018 ◽  
Author(s):  
Srimanta Pakhira ◽  
Jose Mendoza-Cortes
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Electronic Properties ◽  
High Surface ◽  
Electronic Devices ◽  
High Surface Area ◽  
Main Role ◽  
Covalent Organic Frameworks ◽  
Porous Network ◽  
Crystalline Materials

<div>Covalent organic frameworks (COFs) have emerged as an important class of nano-porous crystalline materials with many potential applications. They are intriguing platforms for the design of porous skeletons with special functionality at the molecular level. However, despite their extraordinary properties, it is difficult to control their electronic properties, thus hindering the potential implementation in electronic devices. A new form of nanoporous material, COFs intercalated with first row transition metal is proposed to address this fundamental drawback - the lack of electronic tunability. Using first-principles calculations, we have designed 31 new COF materials <i>in-silico</i> by intercalating all of the first row transition metals (TMs) with boroxine-linked and triazine-linked COFs: COF-TM-x (where TM=Sc-Zn and x=3-5). This is a significant addition considering that only 187 experimentally COFs structures has been reported and characterized so far. We have investigated their structure and electronic properties. Specifically, we predict that COF's band gap and density of states (DOSs) can be controlled by intercalating first row transition metal atoms (TM: Sc - Zn) and fine tuned by the concentration of TMs. We also found that the $d$-subshell electron density of the TMs plays the main role in determining the electronic properties of the COFs. Thus intercalated-COFs provide a new strategy to control the electronic properties of materials within a porous network. This work opens up new avenues for the design of TM-intercalated materials with promising future applications in nanoporous electronic devices, where a high surface area coupled with fine-tuned electronic properties are desired.</div>

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

Electronic properties of quasi two-dimensional transition metals chalcogenides with low-dimensional magnetism

Doklady BGUIR ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 87-95
Author(s):  
M. S. Baranava ◽  
P. A. Praskurava
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Exchange Interaction ◽  
Electronic Properties ◽  
Metal Atom ◽  
Transition Metal Atom ◽  
Two Dimensional ◽  
Transition Metal Atoms ◽  
Ground Magnetic ◽  
Low Dimensional

The search for fundamental physical laws which lead to stable high-temperature ferromagnetism is an urgent task. In addition to the already synthesized two-dimensional materials, there remains a wide list of possible structures, the stability of which is predicted theoretically. The article suggests the results of studying the electronic properties of MAX3 (M = Cr, Fe, A = Ge, Si, X = S, Se, Te) transition metals based compounds with nanostructured magnetism. The research was carried out using quantum mechanical simulation in specialized VASP software and calculations within the Heisenberg model. The ground magnetic states of twodimensional MAX3 and the corresponding energy band structures are determined. We found that among the systems under study, CrGeTe3 is a semiconductor nanosized ferromagnet. In addition, one is a semiconductor with a bandgap of 0.35 eV. Other materials are antiferromagnetic. The magnetic moment in MAX3 is localized on the transition metal atoms: in particular, the main one on the d-orbital of the transition metal atom (and only a small part on the p-orbital of the chalcogen). For CrGeTe3, the exchange interaction integral is calculated. The mechanisms of the formation of magnetic order was established. According to the obtained exchange interaction integrals, a strong ferromagnetic order is formed in the semiconductor plane. The distribution of the projection density of electronic states indicates hybridization between the d-orbital of the transition metal atom and the p-orbital of the chalcogen. The study revealed that the exchange interaction by the mechanism of superexchange is more probabilistic.

COx-free hydrogen production via ammonia decomposition over mesoporous Co/Al2O3 catalysts with highly dispersed Co species synthesized by a facile method

2021 ◽  
Author(s):  
Yingqiu Gu ◽  
Di Xu ◽  
Yun Huang ◽  
Zhouyang Long ◽  
Guojian Chen
Keyword(s):  
Fuel Cells ◽  
Hydrogen Production ◽  
Transition Metal ◽  
Transition Metals ◽  
Ammonia Decomposition ◽  
Metal Catalyst ◽  
Facile Synthesis ◽  
Transition Metal Catalyst ◽  
Highly Dispersed ◽  
Free Hydrogen

Transition metals have been considered as potential catalysts for ammonia decomposition to produce COx-free hydrogen for fuel cells. However, the facile synthesis of transition metal catalyst with small size active...

Organic synthesis with the most abundant transition metal–iron: from rust to multitasking catalysts

2021 ◽  
Author(s):  
Sujoy Rana ◽  
Jyoti Prasad Biswas ◽  
Sabarni Paul ◽  
Aniruddha Paik ◽  
Debabrata Maiti
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Organic Synthesis ◽  
Present Review ◽  
Synthetic Chemistry ◽  
Late Transition Metals ◽  
Iron Chemistry ◽  
Late Transition

The promising aspects of iron in synthetic chemistry are being explored for three-four decades as a green and eco-friendly alternative to late transition metals. This present review unveils these rich iron-chemistry towards different transformations.

Endo- and exohedral chloro-fulleride as η5 ligands: A DFT study on the first-row transition metal complexes

2021 ◽  
Author(s):  
Sebastian Anila ◽  
Cherumuttathu Hariharan Suresh
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Dft Study ◽  
C60 Fullerene ◽  
Ring Fusion ◽  
Coordination Modes

C60 fullerene coordinates to transition metals in η2-fashion through its C-C bond at [6,6] ring fusion whereas other coordination modes η3, η4, η5 and η6 are rarely observed. The coordination...

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