Bildung von Fe3S4?FeS2 durch hydrothermale Reaktion

A mixture of Fe₃S₄ (greigite) and FeS₂ (pyrite) is formed at 200°C on hydrothermal treatment of freshly precipitated iron sulphide. Its electron diffraction diagramm was recorded, which corresponded to an incomplete solid solution of Fe₃S₄ and FeS₂. The surface and the interior of the spherical particles of the samples (size about 500 Å) consisted of Fe₃S₄ and FeS₂, respectively.     

Darstellung von μ-Schwefeldisulfoniumsalzen [(CH3)2S?Sx?S(CH3)2]2+2A− (x = 1–3, A− = AsF6−, SbF6−, SbCl6−). Über die Analogie im Reaktionsverhalten zwischen Sulfanen und Sulfoniumsalzen

Preparation of μ-Sulfurdisulfonium Salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺2A^? (x = 1–3, A^? = AsF₆^?, SbF₆^?, SbCl₆^?). On the Analogy of the Reactivity of Sulfanes and Sulfonium Salts The preparation of the μ-sulfurdisulfonium salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺(A^?)₂ with x = 1–3 and A^? = AsF₆^?, SbF₆^?, SbCl₆^? is reported. The salts are formed by reaction of (CH₃)₂SH⁺A^? and (CH₃)₂SSH⁺A^? with SCl₂ and S₂Cl₂, resp. They are characterized by vibrational spectroscopic measurements. [(CH₃)₂S? S₂? S(CH₃)₂]²⁺(SbF₆^?)₂ crystallizes in the space group C2/c with a = 1 884.5(7) pm, b = 1 302.8(5) pm, c = 1 477.2(5) pm, β = 98.62(3)° und Z = 8.     

Theoretical studies on a possible synthesis reaction pathway on N8 (CS) clusters

The potential energy surfaces of N₈ clusters were investigated by density functional theory (DFT) and a possible synthesis reaction pathway for N₈ (C_S) was suggested. The species involved were fully optimized up to the B3LYP/6‐311+G* level of theory. Relative energies were further calculated at the QCISD/6‐311+G*//B3LYP/6‐311+G* level. The reaction rate constants of these steps from the 1 (N₅⁺?N₃^?, complex, C_S) to 2 (N₈, C_S), 2 (N₈, C_S) to 3 (N₈, C_S), 3 (N₈, C_S) to 4 (N₈, D_2d), and 4 (N₈, D_2d) to 5 (N₈, C_S) reactions were predicted by the VTST theory. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1334–1339, 2001     

Phase relations of ternary compounds in the BaFeS system

The phase relations of the ternary phases at 900 and 700°C were determined by heating mixtures in the regions BaSFeSFeS₂ and FeFeSBaS and identifying the products by powder X-ray diffraction. The stable ternary phases at 900°C are BaFe₂S₃, Ba₂FeS₃, Ba₆Fe₈S₁₅, a solid solution BaFeS₂Ba₇Fe₆S₁₄, Ba₂FeS₄, the infinitely adaptive series $\text{Ba}{}_3\text{Fe}{}_{\mathrm{1+x}}\text{S}{}_5\text{,}\text{1}\text{3}\text{≤ x ≤}\text{2}\text{5}$, and Ba₉Fe₁₆S₃₂ which belongs to the infinitely adaptive series Ba_1+xFe₂S₄. At 700°C the stable ternary phases are: BaFe₂S₃, Ba₂FeS₃, BaFeS₂Ba₇Fe₆S₁₄ (solid solution), Ba₆Fe₈S₁₅, Ba₂FeS₄, Ba₅Fe₄S₁₁, and two infinitely adaptive series: Ba₃Fe_1+xS₅ and Ba_1+xFe₂S₄. A stable ternary phase at 700 and 900°C with probable composition Ba₂Fe₄S₅ was found in the FeFeSBaS section.     

Cerium iron sulfide,Ce3Fe1.94S7

Tricerium(III) diiron(II,III) hepta­sulfide, Ce₃Fe_1.94S₇, crystallizes in the polar hexagonal space group P6₃ and adopts the Ce₆Al_3.33S₁₄ structure type. The Fe atoms occupy both tetrahedral and octahedral sites. Isolated FeS₄ tetrahedra, all pointing in the same direction, are stacked along the threefold rotation axes. Chains of face‐sharing FeS₆ octahedra propagate along the 6₃ axis. Vacancies resulting from the partial oxidation of Fe²⁺ to Fe³⁺ occur exclusively in the octahedral Fe sites. The Ce atoms are coordinated by [7+1] S atoms, which form bicapped trigonal prisms.     

Na3Fe2S4, ein Thioferrat mit gemischt valenter sk∞/1[FeS2]-Kette

Na₃Fe₂S₄ has been prepared from Na₂S, S and Fe. It crystallizes in space group Pnma,a=6.6333 (5) Å,b=10.675 (1) Å,c=10.677 (2) Å,Z=4. The crystal structure, as determined from single crystal four-circle diffractometer data (R=2.8%), consists of sk/1[FeS₂]-chains formed by slightly distorted edge sharing [FeS₄]-tetrahedra, the iron atoms having a formal valency of +2.5. The sodium ions are approximately octahedrally coordinated. Exposed to air, Na₃Fe₂S₄ readily takes up water to form a hydrate by a pertially topochemical reaction.

     

Theoretical prediction of the contact distance dependence of the electron transfer reactivity of the ClO/ClO− coupling system

On the basis of the structures and properties of the ClO/ClO^? system obtained at the density functional theory (DFT) (UB3LYP) level, employing the 6‐311+G(3df) standard basis set, the electron transfer reactivity of this system is investigated. The results indicate that there are five possible stable coupling complexes that correspond to the generous minima on the global potential energy surfaces (PES). The most stable coupling complex is planar EC4, in which there is a O? O linkage with two trans‐Cl atoms. Their stabilization energies are calculated to be 20.57 (EC1: C₁), 20.54 (EC2: C₂, ²B), 20.69 (EC3: C₁), 20.70 (EC4: C_s, ²A′), and 20.69 (EC.5: C_2h, ²B_u) kcal/mol at the B3LYP/6‐311+G(3df) level; with the correction of the basis set superposition error (BSSE), the stability order of these encounter complexes is EC4 > EC.5 > EC3 > EC1 > EC2. Based on the five encounter complexes, five coupling modes are designed for the study of the electron transfer reactivity of this system. The dissociation energy curves at the activated states and the corresponding activation energies of these five coupling modes are obtained and are compared at the B3LYP/6‐311+G(3df) and MP2/6‐311+G* levels. The inapplicability of DFT methods has also been discussed in this article in predicting the energy curves, especially with a long contact distance, in which DFT methods give the abnormal behavior for the dissociations of the complexes caused by the “inverse symmetry breaking” problem. On the basis of the golden rule of the time‐dependent perturbation theory, the electron transfer reactivity and the contact distance dependence of the various electron transfer kinetics parameters (e.g., activation energy, coupling matrix element) have been analyzed at the UMP2(full)/6‐311+G* level. The electron transfer can take place over a range of contact distances, but the most effective coupling distance corresponds to only a small range. The coupling orientation analyses also indicate that the most favorable coupling mode to the electron transfer does not always correspond to the most stable encounter complex mechanism. Some highly energetic coupling modes are more favorable for the electron transfer. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Crystal structure,Mössbauer,and magnetic behavior of mixed valence compounds in the BaFeS system: Ba3(Ba1−xAlx)Fe2S6[S1−y(S2)y]

The compounds $\text{Ba}{}_4\text{Fe}{}_2\text{S}{}_6\text{[S}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{(}\text{S}{}_2\text{)}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{]}$ and Ba_3.6Al_0.4Fe₂S₆[S_0.6(S₂)_0.4], designated I and II, were prepared by reacting BaS, Fe, and S powders and Al foils in graphite containers sealed in evacuated quartz ampoules at approximately 1100°C. The crystal structure of I was determined using 1682 independent, nonzero X-ray reflections, while 3589 were used for II. They are triclinic, $\text{A}\text{l}$:

$\text{a=9.002(2)}\text{A}\text{?}\text{,b=6.7086(8)}\text{A}\text{?}\text{,c=24.658(4)}\text{A}\text{?}\text{α91.49(2)°,}$

$\text{β=105.10(2)°y=90.74(2)°,ψ}{}_{\mathrm{calc}}\text{=4.15g/cm}{}^3\text{,for I:}$

$\text{a=8.993(6)}\text{A}\text{?}\text{,b=6.708(7)}\text{A}\text{?}\text{,c=24.70(1)}\text{A}\text{?}\text{α91.11(6)°,}$

$\text{β=105.04(6)°y=90.90(9)°,ψ}{}_{\mathrm{calc}}\text{=3.90g/cm}{}^3\text{,for II:}$

BaS₆ trigonal prisms share edges to form distorted hexagonal rings which form one-dimensional chains leaving two free lateral edges. The chains link in a stairstep manner with the rings offset along the [301] direction. These stairsteps join in a complicated manner to form a three-dimensional network. Fe ions are in two sites forming isolated FeS₄ tetrahedra and isolated Fe₂S₆ dimers by edge-sharing tetrahedra. The Al substitution occurs in the trigonal prisms which have free edges with Al replacing Ba. Room-temperature Mössbauer isomer shifts are 0.20 mm/sec. for I and 0.30 mm/sec for II. These data indicate that upon Al substitution charge compensation occurs by reducing Fe³⁺. Valence calculations indicate that Fe in edge-sharing tetrahedra are reduced while the Fe in the isolated tetrahedron remains unchanged. The effective charge distribution in the Al substituted compound is approximately Fe³⁺, Fe^2.5+ with electron delocalization across the shared edge. Room temperature electrical resistivity is 10⁵ ohm/cm. The compositions of the crystals are best represented by the formulas $\text{[}\text{Ba}{}_4\text{Fe}{}_2\text{S}{}_7\text{]}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{·[}\text{Ba}{}_4\text{Fe}{}_2\text{S}{}_6\text{(S}{}_2\text{)]}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}$ and [Ba₃AlFe₂S₇]_0.4·[Ba₄Fe₂S₇]_0.2·[Ba₄Fe₂S₆(S₂)]_0.4. The replacement of a sulfide by a disulfide ion is thought to be strongly dependent on the sulfur activity during the preparation.     

Isomerization of B6, B6 − and B6 + clusters

The interconversions between isomers with the same spin multiplicity of neutral B₆ and charged B₆ ^? and B₆ ⁺ clusters have been investigated at the B3LYP/6-311+G* level of theory, including determination of the minimum energy pathways with transition states connecting the corresponding reactants and products. In dynamic calculations, 26 isomers were optimized, including 11 novel isomers. In order to further refine the energies, single-point B3LYP/6-311+G(3df) calculations were carried out on the corresponding B3LYP/6-311+G* geometries of all isomers of B₆, B₆ ^? and B₆ ⁺ and the corresponding isomerization transition states. The stability of each isomer of B₆ (singlet and triplet states), B₆ ^? (doublet state) and B₆ ⁺ (doublet state) was analyzed from both thermodynamic and dynamic viewpoints.     

Density functional theory study of the free and tetraprotonated spheroidal macrotricyclic ligands and the complexes with halide anions: F−, Cl−, Br−

Theoretical studies of the macrotricyclic tetramine hexaether (SC), its tetraprotonated form SC‐4H⁺, and the corresponding complexes X^??SC‐4H⁺ (This expression represents the structural properties of the halide inclusion complex formed though the free ligand SC‐4H⁺ and the halide anion X^?: the spherical halide anion X^? is held by a tetrahedral array of ⁺N? H ··· X^? hydrogen bonds inside the intramolecular cavity of the tetraprotonated form SC‐4H⁺) of SC‐4H⁺ with the halide anions: F^?, Cl^?, and Br^? have been performed using density functional theory (DFT) with B3LYP/6‐31G method implemented in the Gaussian 03 program package. The optimized geometric structures obtained from DFT calculations are used to perform Natural Bond Orbital (NBO) analysis. The three main types of hydrogen bonds ⁺N? H ··· F^?, ⁺N? H ··· Cl^?, and ⁺N? H ··· Br^? are investigated. The results indicate that hydrogen bonding interactions are dominant and the halide anions: F^?, Cl^?, and Br^? offer lone pair electrons to the contacting σ* (N? H) antibond orbital of SC‐4H⁺. For all the structures, the most pronounced changes in geometric parameters upon interaction are observed in the proton‐donor molecule. The intermolecular interaction energies are predicted by using B3LYP/6‐31G methods with basis set superposition error (BSSE) and zero‐point energy (ZPE) correction. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Über [Ag(S9)]−, ein symmetrisches zehngliedriges Ringsystem Darstellung,Struktur und spektroskopische Charakterisierung der schwefelreichen Verbindung [(PPh3)2N][Ag(S9)] · S8

About [Ag(S₉)]^?, a Symmetric Ten-Membered Ring System; Preparation, Structure, and Spectroscopic Characterization of the Sulfur Rich Compound [(PPh₃)₂N][Ag(S₉)] · S₈ Orange [(PPh₃)₂N][Ag(S₉)] · S₈ ( 1 ) could be obtained by reaction of a definite S_x^2?-solution with AgNO₃ and characterized by vibrational spectra (IR/Raman) and X-ray structure analysis. The anion [Ag(S₉)]^? shows a symmetric conformation of a ten-membered ring system. 1 crystallizes in the triclinic space group P1 (a = 1383.8(4), b = 1429.5(4), c = 1540.5(5) pm, α 62.38(2), β 68.05(2), γ 65.86(2)°, V = 2399.1 · 10⁶ pm³, Z = 2; R = 0.077 for 5433 independent reflections (F₀ > 3.92 σ(F₀))).     

Über die Darstellung der Pnikogenoniumsalze AsH4+SbF6−, AsH4+AsF6−, SbH4+SbF6−

On the Preparation of Pnikogenonium Salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^?, SbH₄⁺SbF₆^? The preparation of the pnikogenonium salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^? and SbH₄⁺SbF₆^? by protonation from the hydrides AsH₃, SbH₃ in superacidic systems HF/SbF₅ and HF/AsF₅, resp. is reported. The salts are characterized by vibrational and mass spectra. A general valence force field is calculated. The following onium ions are know as hexafluoroantimonate:      

Die kubischen Phasen Na16(ARb6)Sb7, Verbindungen mit den Anionen A = Rb−, Na−, Au−, I−

The Cubic Phases Na₁₆(ARb₆)Sb₇, Compounds with the Anions A = Rb^?, Na^?, Au^?, I^? The novel compounds Na₁₆(ARb₆)Sb₇ have been synthesized from the elements in sealed Nb ampoules at 873 K (A = Rb) and 823 K (A = I, Na, Au). They form brittle cuboctahedra (silver metallic; A = Rb) and irregular polyhedra (silver metallic lustre; A = Na, I; golden metallic lustre; A = Au). They rapidly decompose in moist air to gray products. Their crystal structures have been determined by single crystal X-ray crystallography (A = Rb: a = 1565.8(2) pm; A = I: a = 1563.3(2) pm; A = Na: a = 1562.6(2) pm; A = Au: a = 1560.7(2) pm). They crystallize cubically in the space group Fm3 m (no. 225) with Z = 4 formula units and are isotypic with Sc₁₁Ir₄. The compounds are ZINTL phases and their structures can be described as an eightfold defect variant of the Li₃Bi type of structure (cF128-8; a = 2a′(Li₃Bi)). The Sb atoms form a network of cuboctahedra, centered alternatingly by a SbNa₈ cube or a ARb₆ octahedron. Main structural features are the anions A^? within the Rb₆ octahedron. Supporting the existence of A^? are the isotypical compounds with the more common anion forming elements (A = Au, I), as well as electrostatic potential considerations together with calculations of the volume increments. The semiconducting properties (E_g = 0.33 eV) of Na₁₆(RbRb₆)Sb₇, as well as the diamagnetism χ_mol = ?508 × 10^?6 cm³ mol^?1, are in accordance with those to be expected from the Zintl concept.     

Spectroscopic constants and molecular properties of CN−, SiH−, PO−, SO−, SF−, and SiS−: Density functional study

Spectroscopic constants and molecular properties of selected diatomic anions namely CN^?, SiH^?, PO^?, SO^?, SF^?, and SiS^? in their ground states have been studied in detail using the hybrid HF/DF B3LYP method. The consistency of the calculated values has been verified with four different basis sets, with improved quality. The spectroscopic constants and molecular properties calculated with the aug‐cc‐pVTZ basis set agree very well with the experimental and theoretical values wherever available. Most of the spectroscopic constants and molecular properties of the selected diatomic anions, particularly the spectroscopic constants and molecular properties of SO^? and SiS^? are reported for the first time. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

The polar mixed-valent lanthanum iron(II, III) sulfide La3Fe2−δS7: Synthesis, crystal and electronic structure, Fe Mößbauer spectra, magnetic susceptibility and electrical resistivity

La₃Fe_2−δS₇ (δ=0.042(6)) was synthesized through a reaction of the elements in a LiCl/KCl flux at 970 K, and its structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the polar hexagonal space group P6₃ with a=10.1906(6), c=5.9543(4) Å and Z=2, and adopts the Ce₆Al_10/3S₁₄ structure type. The structure contains both octahedral and tetrahedral iron sites: one-dimensional rods of face-sharing FeS₆ octahedra run along the 6₃ screw axis of the cell; FeS₄ tetrahedra, all pointing in the same direction, are stacked along the threefold rotation axes. The iron-centered polyhedra are linked by lanthanum atoms, which are coordinated by [7+1] sulfur atoms in a bicapped trigonal prismatic arrangement. ⁵⁷Fe Mößbauer spectroscopy confirms that Fe^III and Fe^II cations occupy the tetrahedral and octahedral iron sites, respectively. Magnetic susceptibility data indicate an antiferromagnetic transition at T_N≈155 K. Density functional band structure calculations within the local density approximation reveal two covalent Fe-S subsystems within the compound that mix only weakly. A large anisotropy is indicated by bands that disperse predominantly along the hexagonal axis. The electronic band structure suggests pseudo-one-dimensional metallic conductivity along the rods of face-sharing FeS₆ octahedra. However, due to the defects on the Fe^II positions, La₃Fe_2−δS₇ shows an activated conducting behavior.     

An investigation on the reaction mechanism of the F2+Cl2→2ClF using the B3LYP method

The reaction mechanism of F₂+Cl₂→2ClF has been investigated with the density functional theory at the B3LYP/6‐311G* level. Six transition states have been found for the three possible reaction paths and verified by the normal mode vibrational and IRC analyses. Ab initio MP2/6‐311G* geometry optimizations and CCSD(T)/6‐311G(2df)//MP2/6‐311G* single‐point energy calculations have been performed for comparison. It is found that when the F₂ (or Cl₂) molecule decomposes into atoms first and then the F (or Cl) atom reacts with the molecule Cl₂ (or F₂) nearly along the molecular axis, the energy barrier is very low. The calculated energy barrier of F attacking Cl₂ is zero and that of Cl attacking F₂ is only 15.57 kJ?mol^?1 at the B3LYP level. However, the calculated dissociation energies of F₂ and Cl₂ are as high as 145.40 and 192.48 kJ?mol^?1, respectively. When the reaction proceeds through a bimolecular reaction mechanism, two four‐center transition states are obtained and the lower energy barrier is 218.69 kJ?mol^?1. Therefore, the title reaction F₂+Cl₂→2ClF is most probably initiated from the atomization of the F₂ molecule and terminated by the reaction of F attacking Cl₂ nearly along the Cl? Cl bond. MP2 calculations lead to the same conclusion, but the geometry of TS and the energy barrier are somewhat different. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002     

Electronic structure of the Fe3S4 cluster and its quasi-aromaticity

The localized molecular orbitals and their energy levels for the clusters [Fe₃S₄(SH)₃]^2–, [(HS)₃Fe₃S₄·Ni(PH₃)]^2–, [Mo₃S₄(OH₂)₉]⁴⁺, and [Mo₃S₄·Ni]⁴⁺ have been calculated by mean of the Edmiston-Ruedenberg energy localization technique under the CNDO/2 approximation in order to reveal the resemblance between [Fe₃S₄]⁺ and [Mo₃S₄]⁴⁺ in the geometrical configurations and the addition reactivities with heterometal atoms. It is shown that in these two cluster species with core {M ₃(₃-S)(-S)₃} of similar structure (M = Mo, Fe) there exist three synergically connected three-centered two-electron (M-S-M) -bonds around the puckered six-membered {M₃S₃} rings on account of delocalization of a lone electron pair on each bridging S atom; these (M-S-M) -bonds are thus capable of forming cubane-like heterometal clusters with intruder metal atoms through the ( M) bonding. It is therefore seen that unlike the [Mo₃S₄]⁴⁺ with appreciable bonding between the Mo atoms, the extra d-electrons on the metal atoms in the [Fe₃S₄]⁺ cluster are localized on the Fe atoms, exhibiting an electronic structure significantly different from that of the [Mo₃S₄]⁴⁺ cluster.     

Analysis of methods for calculating the transition frequencies of the torsional vibration of acrolein isomers in the ground (S 0) electronic state

B3LYP, MP2, CCSD(T), and MP4/MP2 in the 6-311G(d, p), 6-311++G(d, p), cc-pVTZ, aug-cc-pVTZ bases used to calculate the transition frequencies of torsional vibration of trans- and cis-isomers of acrolein in the ground electronic state (S ₀) are analyzed. It is found that for trans-isomers, all methods of calculation except for B3LYP in the cc-pVTZ basis yield good agreement between the calculated and experimental values. It is noted that for the cis-isomer of acrolein, no method of calculation confirms the experimental value of the frequency of torsional vibration (138 cm^?1). It is shown that the calculated and experimental values for obertones at 273.0 cm^?1 and other transitions of torsional vibration are different for this isomer in particular. However, it is established that in some calculation methods (B3LYP, MP2), the frequency of the torsional vibration of the cis-isomer coincides with another experimental value of this frequency (166.5 cm^?1). It is concluded that in analyzing the vibrational structure of the UV spectrum, the calculated and experimental values of its obertone (331.3 cm^?1) coincide, along with its frequency. It is also noted that the frequency of torsional vibration for the cis-isomer (166.5 cm^?1) can also be found in other experimental works if we change the allocation of torsional transition 18 ₁ ¹ .     

Synthesis,Crystal Structure and Density Functional Studies on 1N‐Phenyl‐3‐(2,4‐Dichlorophenyl)‐5‐(4‐Chlorophenyl)‐2‐Pyrazoline

1N‐Phenyl‐3‐(2,4‐dichlorophenyl)‐5‐(4‐chlorophenyl)‐2‐pyrazoline has been synthesized and characterized by elemental analysis, IR, UV‐Vis and X‐ray single crystal diffraction. Density functional calculations have been carried out for the title compound by using the B3LYP method with a 6‐311G** basis set. The calculated results show that the predicted geometry can reproduce well the structural parameters. The electronic absorption spectra calculated in the gas phase are better than those calculated in EtOH solvent to model the experimental electronic spectra. Natural Bond Orbital (NBO) analyses suggest that the above electronic transitions are mainly assigned to π → π* transitions. On the basis of vibrational analyses, the thermodynamic properties of the compound at different temperatures have been calculated, revealing the correlations between C⁰_{p, m}, S⁰_m, H⁰_m and temperature.     

Theoretical and experimental study of the absolute configuration of helical structure of (2R,3S)-Rubiginone A2 analog

A novel analogue of (2R,3S)-Rubiginone A₂ was synthesized as a chiral helical model compound via an eight-step procedure (2.7% overall yield). Quantum methods, such as density functional theory (DFT) at different basis sets of 6-311+(d), 6-311++G(2d,p), were used to compute its optical rotation and electronic circular dichroism at the B3LYP/6-311++G(2d,p) level in the gas phase and in solution using PCM model, respectively. UV corrections were performed in electronic circular dichroism (ECD) simulations to match the experimental ECD well. The suitable computational methods, e.g., B3LYP/6-311++G(2d,p)//B3LYP/6-311++G(2d,p) in the gas phase using zero-point energy in Boltzmann statistics, were found and suggested for optical rotation and circular dichroism computations that can be used for absolute configuration determination of chiral helical compounds.