Peculiarities of electronic structure and chemical bonding in iron and cobalt metal complexes of porphyrazine and tetra(1,2,5-thiadiazole)porphyrazine

2020 ◽  
Vol 24 (09) ◽  
pp. 1146-1154 ◽  
Author(s):  
Yuriy A. Zhabanov ◽  
Valery V. Sliznev ◽  
Igor V. Ryzhov ◽  
Pavel A. Stuzhin
Keyword(s):  
Metal Complexes ◽  
Electronic Structures ◽  
Geometrical Structure ◽  
Ground States ◽  
Electronic States ◽  
Cobalt Metal ◽  
Crystal Field Theory ◽  
Complete Active Space ◽  
Dynamic Correlation ◽  
Metal Atoms

The geometrical and electronic structures of iron and cobalt metal complexes of porphyrazine and tetra(1,2,5-thiadiazole)porphyrazine in ground and low-lying excited electronic states were determined by DFT calculations and the complete active space (CASSCF) method with following accounting dynamic correlation by multiconfigurational quasidegenerate second-order perturbation theory (MCQDPT2). A geometrical structure of D[Formula: see text] symmetry has been obtained for all four complexes. According to data obtained by the MCQDPT2 method, the complexes of cobalt and iron possess the ground states 2A[Formula: see text] and 3A[Formula: see text], respectively, and wave functions of the ground states have the form of a single determinant. It is shown that the crystal field theory (CFT) can be used to describe the sequence of electronic states of the investigated complexes. The nature of the bonds between metal atoms and nitrogen atoms has been described using the analysis of the electron density distribution in the frame of Bader’s quantum theory of atoms in molecule (QTAIM).

Electronic States of Fe2S-/0/+

2003 ◽  
Vol 68 (2) ◽  
pp. 405-422 ◽  
Author(s):  
Olaf Hübner ◽  
Joachim Sauer
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Electronic States ◽  
Spin Coupling ◽  
Heisenberg Spin ◽  
Complete Active Space ◽  
Dynamic Correlation ◽  
High Spin States ◽  
Consistent Field ◽  
Self Consistent Field

The relative energies of a multitude of low-lying electronic states of Fe2S-/0/+ are determined by complete active space self-consistent field (CASSCF) calculations. The numerous states obtained are assigned to spin ladders. For selected states, dynamic correlation has been included by multireference configuration interaction (MRCI) and the structures of some high-spin states have been optimized by CASSCF/MRCI. Comparison is made with structures obtained by density-functional theoretical calculations. The ground states of Fe2S-/0/+ are 10B2, 1A1 and 8A2, respectively, and the total splittings of the lowest-energy spin ladders are about 0.18, 0.07 and 0.13 eV, respectively. The spin ladders of Fe2S qualitatively reflect the picture of Heisenberg spin coupling. While both Fe2S- and Fe2S+ show an Fe-Fe distance of about 270 pm, that of Fe2S is about 100 pm longer. The calculated adiabatic electron affinity of Fe2S is 1.2 eV and the ionization energy 6.6 eV. An interpretation of the observed photoelectron spectrum of Fe2S- is given.

scholarly journals Superatomic Nature of Metal Encapsulated Dodecahedrane: The Case of M@C20H20 (M = Li, Na, Mg+)

2021 ◽  
Author(s):  
Isuru Ariyarathna
Keyword(s):  
Angular Momentum ◽  
Shell Model ◽  
Electronic Structures ◽  
Ground States ◽  
Electronic States ◽  
Building Blocks ◽  
Quantum Calculations ◽  
Solvated Electron ◽  
High Level

The idea of designing unprecedented materials made of superatomic building blocks, motivated the present study on endohedral M@C20H20 (M = Li, Na, Mg+) species. Ground and excited electronic structures of M@C20H20 (M = Li, Na, Mg+) were analyzed by means of high-level quantum calculations. In their ground states, one electron occupies a defuse superatomic s-orbital that lies around the C20H20 cage. These entities populate higher angular momentum p-, d-, f-, g-superatomic orbitals in their low-lying electronic states. The proposed superatomic Aufbau shell model for Li@C20H20 and Na@C20H20 is 1s, 1p, 1d, 2s, 1f, 2p, 2d, 1g, 2f slightly different from that of Mg@C20H20+ which is 1s, 1p, 1d, 2s, 1f, 2p, 2d, 1g, 3s, 2f, 2g, 3p. These introduced superatomic orbital series resemble the Aufbau principle of solvated electron precursors.

scholarly journals Atoms in Highly Symmetric Environments: H in Rhodium and Cobalt Cages, H in an Octahedral Hole in MgO, and Metal Atoms Ca-Zn in C20 Fullerenes

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1281
Author(s):  
Zikri Altun ◽  
Erdi Ata Bleda ◽  
Carl Trindle
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Coordination Number ◽  
Electronic Structures ◽  
Density Functional ◽  
Functional Theory ◽  
Metal Atoms ◽  
Tetragonal Pyramidal ◽  
Non Covalent Interactions ◽  
Covalent Interactions

An atom trapped in a crystal vacancy, a metal cage, or a fullerene might have many immediate neighbors. Then, the familiar concept of valency or even coordination number seems inadequate to describe the environment of that atom. This difficulty in terminology is illustrated here by four systems: H atoms in tetragonal-pyramidal rhodium cages, H atom in an octahedral cobalt cage, H atom in a MgO octahedral hole, and metal atoms in C20 fullerenes. Density functional theory defines structure and energetics for the systems. Interactions of the atom with its container are characterized by the quantum theory of atoms in molecules (QTAIM) and the theory of non-covalent interactions (NCI). We establish that H atoms in H2Rh13(CO)243− trianion cannot be considered pentavalent, H atom in HCo6(CO)151− anion cannot be considered hexavalent, and H atom in MgO cannot be considered hexavalent. Instead, one should consider the H atom to be set in an environmental field defined by its 5, 6, and 6 neighbors; with interactions described by QTAIM. This point is further illustrated by the electronic structures and QTAIM parameters of M@C20, M=Ca to Zn. The analysis describes the systematic deformation and restoration of the symmetric fullerene in that series.

History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 154-155
Author(s):  
H. Ade
Keyword(s):  
Electronic Structures ◽  
Chemical Shifts ◽  
Electronic States ◽  
Inorganic Materials ◽  
Chemical Bonds ◽  
Fundamental Physics ◽  
X Ray ◽  
Disciplinary Perspective ◽  
Core Electrons ◽  
X Ray Absorption

In Near Edge X-ray Absorption Fine Structure (NEXAFS) microscopy, excitations of core electrons into unoccupied molecular orbitals or electronic states provide sensitivity to a wide variety of chemical functionalities in molecules and solids. This sensitivity complements infrared (IR) spectroscopy, although the NEXAFS spectra are not quite as specific and “rich” as IR spectra. The sensitivity of NEXAFS to distinguish chemical bonds and electronic structures covers a wide variety of samples: from metals to inorganics and organics. (There is a tendency in the community to use the term NEXAFS for soft x-ray spectroscopy of organic materials, while for inorganic materials or at higher energies X-ray Absorption Near Edge Spectroscopy (XANES) is utilized, even though the fundamental physics is the same.) The sensitivity of NEXAFS is particularly high to distinguish saturated from unsaturated bonds. NEXAFS can also detect conjugation in a molecule, as well as chemical shifts due to heteroatoms.

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