Saddle-shaped six-coordinate iron(iii) porphyrin complex with unusual intermediate-spin electronic structure

2009 ◽  
pp. 2180 ◽  
Author(s):  
Ru-Jen Cheng ◽  
Chia-Wei Chao ◽  
Ya-Ping Han ◽  
Yen-Chou Chen ◽  
Chiao-Han Ting
Keyword(s):  
Electronic Structure ◽  
Porphyrin Complex ◽  
Intermediate Spin ◽  
Spin Electronic

scholarly journals Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO2Reduction

2017 ◽  
Vol 56 (8) ◽  
pp. 4745-4750 ◽  
Author(s):  
Christina Römelt ◽  
Jinshuai Song ◽  
Maxime Tarrago ◽  
Julian A. Rees ◽  
Maurice van Gastel ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Porphyrin Complex

scholarly journals First-Principles Study on Redox Magnetism and Electrochromism of Cyclometalated Triarylamine-Core Triruthenium Complex

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 57
Author(s):  
Lin Li ◽  
Yue Wang ◽  
Meng-Yang Chen ◽  
Jian Zhang ◽  
Jian-Quan Liang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Spin Density ◽  
First Principles ◽  
Density Functional ◽  
Redox State ◽  
Visible Region ◽  
Geometric Optimization ◽  
Energy Splitting ◽  
Redox States ◽  
Spin Electronic

Spin electronic states and optical properties of a circular ruthenium (Ru) terpyridine complex with a triarylamine core (CTTC) are theoretically investigated by first-principles calculations within an all-electron numerical orbital scheme based on spin density functional theory (SDFT), which demonstrate five well-defined redox states for electrochromic functions. Atomic structure of CTTC molecule is obtained by geometric optimization, and its electronic structure with a decreasing semiconductor band-gap exhibits five consecutive single-electron redox states of Ru-coordinated centers. Except for CTTC in (Ru)3+4 redox state exhibiting a net spin of 2.25 (ћ/2), the other redox states are almost zero in total spin. Density distribution and energy-splitting of spin states indicate that the ferromagnetic coupling of Ru cations coordinating with terpyridine/triarylamine ligands originates dominantly from the spin polarization of Ru 4d-orbitals coordinated by N- and C-2p electrons of triarylamine. CTTC molecule in each redox state represents a well-discriminated absorption in visible region, with the highest characteristic peaks locating at 24.2, 20.2, 21.3, and 19.3/21.7 (103 cm−1) and a manifold of peaks at 13.4~25.3 (103 cm−1) for +2~+6 redox states, respectively. Theoretical electronic structure and optics of CTTC complex are used to evaluate the underlying physical mechanism of realizing a multi-color visible electrochromism by four couples of redox pairs, which is suggested to be applied for monitoring electrical information.

Electronic structure of five- and six-coordinate iron(III) tetraazaporphyrin complexes: pyrrole-Cαchemical shift as a useful probe

2008 ◽  
Vol 12 (09) ◽  
pp. 1041-1049 ◽  
Author(s):  
Takahisa Ikeue ◽  
Satoshi Kurahashi ◽  
Makoto Handa ◽  
Tamotu Sugimori ◽  
Mikio Nakamura
Keyword(s):  
Electronic Structure ◽  
Spin State ◽  
Electron Configuration ◽  
Hydrogen Atoms ◽  
Nmr Studies ◽  
Chloride Complexes ◽  
H Nmr ◽  
Intermediate Spin ◽  
Intermediate Spin State ◽  
C Nmr

Electronic structure of a series of five-coordinate Fe ( OArTAzP ) X ( OAr = octaaryltetraazaporphyrin , X = Cl-, Br-, I-; Ar = 4-tert-butylphenyl) have been examined on the basis of1H NMR,13C NMR, and EPR spectroscopy as well as SQUID magnetometry. These complexes adopt the intermediate-spin state as in the case of analogous complexes reported by Fitzgerald et al. (Inorg. Chem. 1992; 31: 2006-2013) and Stuzhin et al. (Inorg. Chim. Acta 1995; 236: 131-139). The13C NMR studies using13C -enriched complexes at the pyrrole α positions have revealed that the pyrrole- Cαsignals appear at extraordinary upfield positions, i.e. -130 to -250 ppm at 273 K, due to the dz2-a2 uand dπ-3 eginteractions. The Curie plots of the pyrrole- Cαsignals have further revealed that the iodide complex adopts a much purer intermediate-spin state than the bromide and chloride complexes. In contrast to the case of Fe ( OArTAzP ) X , six-coordinate [ Fe ( OArTAzP )( CN )2]-showed the pyrrole- Cαsignal at 47 ppm at 273 K, which indicates that the complex adopts the low-spin state with the ( dxy)2( dxz, dyz)3electron configuration. Thus, the13C NMR chemical shift of the pyrrole- Cαsignal turns out to be quite a good probe to elucidate the spin state and electron configuration of iron(III) tetraazaporphyrins, where the1H NMR spectroscopy is less useful because of the absence of the hydrogen atoms as well as the alkyl or aryl groups directly attached to the meso positions.

scholarly journals A Theoretical Study of the Occupied and Unoccupied Electronic Structure of High- and Intermediate-Spin Transition Metal Phthalocyaninato (Pc) Complexes: VPc, CrPc, MnPc, and FePc

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 54
Author(s):  
Silvia Carlotto ◽  
Mauro Sambi ◽  
Francesco Sedona ◽  
Andrea Vittadini ◽  
Maurizio Casarin
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Density Functional ◽  
Spin Transition ◽  
Electronic States ◽  
Spectroscopic Properties ◽  
Open Shell ◽  
Excitation Energies ◽  
Intermediate Spin ◽  
Charge Transfer Transitions

The structural, electronic, and spectroscopic properties of high- and intermediate-spin transition metal phthalocyaninato complexes (MPc; M = V, Cr, Mn and Fe) have been theoretically investigated to look into the origin, symmetry and strength of the M–Pc bonding. DFT calculations coupled to the Ziegler’s extended transition state method and to an advanced charge density and bond order analysis allowed us to assess that the M–Pc bonding is dominated by σ interactions, with FePc having the strongest and most covalent M–Pc bond. According to experimental evidence, the lightest MPcs (VPc and CrPc) have a high-spin ground state (GS), while the MnPc and FePc GS spin is intermediate. Insights into the MPc unoccupied electronic structure have been gained by modelling M L2,3-edges X-ray absorption spectroscopy data from the literature through the exploitation of the current Density Functional Theory variant of the Restricted Open-Shell Configuration Interaction Singles (DFT/ROCIS) method. Besides the overall agreement between theory and experiment, the DFT/ROCIS results indicate that spectral features lying at the lowest excitation energies (EEs) are systematically generated by electronic states having the same GS spin multiplicity and involving M-based single electronic excitations; just as systematically, the L3-edge higher EE region of all the MPcs herein considered includes electronic states generated by metal-to-ligand-charge-transfer transitions involving the lowest-lying π* orbital (7eg) of the phthalocyaninato ligand.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

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