Dinuclear first-row transition metal–(C8Me6)2complexes: metal–metal and metal–ligand bonds determined by the d electron configuration of the metal atom

2016 ◽  
Vol 40 (3) ◽  
pp. 1988-1996 ◽  
Author(s):  
Xiuli Yan ◽  
Xiaoyan Li ◽  
Zheng Sun ◽  
Qingzhong Li ◽  
Lingpeng Meng

The nature and strength of the metal–metal and metal–ligand bonds depend on the d electron configuration of the transition metal.

1992 ◽  
Vol 272 ◽  
Author(s):  
Dieter Fenske

In the widest sense, a cluster is an aggregate of molecules or atoms. Many clusters contain metal atom groups Mn in which the metals are chemically bonded to each other. To decide whether metal-metal bonds are present, the comparison with bonding in pure metals is often made.


Doklady BGUIR ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 87-95
Author(s):  
M. S. Baranava ◽  
P. A. Praskurava

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.


ChemInform ◽  
1987 ◽  
Vol 18 (51) ◽  
Author(s):  
M. DI VAIRA ◽  
P. STOPPIONI ◽  
M. PERUZZINI

RSC Advances ◽  
2016 ◽  
Vol 6 (46) ◽  
pp. 40155-40161 ◽  
Author(s):  
Wei Wang ◽  
Yan-Dong Guo ◽  
Xiao-Hong Yan

Two-probe systems of transition metal atom (X)-encapsulated B40fullerene contacted with Au electrodes, where X = Fe, Mn, Ni, and Co.


1984 ◽  
Vol 39 (9) ◽  
pp. 807-829
Author(s):  
Michael C. Böhm

The band structure of the metal-ligand-metal (M-L-M) bridged quasi one-dimensional (1D) cyclopentadienylmanganese polymer, MnCp 1, has been studied in the unoxidized state and in a partly oxidized modification with one electron removed from each second MnCp fragment. The tight-binding approach is based on a semiempirical self-consistent-field (SCF) Hartree-Fock (HF) crystal orbital (CO) model of the INDO-type (intermediate neglect of differential overlap) combined with a statistical averaging procedure which has its origin in the grand canonical ensemble. The latter approximation allows for an efficient investigation of violations of the translation symmetries in the oxidized 1D material. The oxidation process in 1 is both ligand- and metal-centered (Mn 3d-2 states). The mean-field minimum corresponds to a charge density wave (CDW) solution with inequivalent Mn sites within the employed repeat-units. The symmetry adapted solution with electronically identical 3d centers is a maximum in the variational space. The coupling of this electronic instability to geometrical deformations is also analyzed. The ligand amplitudes encountered in the hole-state wave function prevent extremely large charge separations between the 3d centers which are found in ID systems without bridging moieties (e.g. Ni(CN)2-5 chain). The symmetry reduction in oxidized 1 is compared with violations of spatial symmetries in finite transition metal derivatives and simple solids. The stabilization of the valence bond-type (VB) solution is physically rationalized (i.e. left-right correlations between the 3d centers). The computational results derived for 1 are generalized to oxidized transition metal chains with band occupancies that are simple fractions of the number of stacking units and to 1D systems that deviate from this relation. The entropy-influence for temperatures T ≠ 0 is shortly discussed (stabilization of domain or cluster structures).


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