Study of hydrogen bonds in N-methylacetamide by DFT calculations of oxygen, nitrogen, and hydrogen solid-state NMR parameters

Solid-state nuclear magnetic resonance (NMR) parameters of ¹⁷O, ¹⁴N/¹⁵N, and ²H/¹H nuclei were evaluated in two available neutron crystalline structures of N-methylacetamide (NMA) at 250 and 276 K, NMA-I and NMA-II, respectively. Density functional theory calculations were performed by B3LYP method and 6-311++G** and IGLO-II type basis sets to calculate the electric field gradient (EFG) and chemical shielding (CS) tensors at the sites of mentioned nuclei. In order to investigate hydrogen bonds (HBs) effects on NMR tensors, calculations were performed on four-model systems of NMA: an optimized isolated gas-phase, crystalline monomers, crystalline dimers, and crystalline trimers. Comparing the calculated results reveal the influence of N–H···O=C and C–H···O=C HB types on the NMR tensors which are observable by the evaluated parameters including quadrupole coupling constant, C _Q, and isotropic CS, σ _iso. Furthermore, the results demonstrate more influence of HB on the EFG and CS tensors of NMA at 276 K rather than that of 250 K.     

Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid

Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln₂L₃·nH₂O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na₂L·H₂O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na₂L·H₂O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm⁻¹ disappear on complex spectra and ν_as and ν_s of COO⁻ groups appear thus indicating that complexation process took place.     

Syntheses,weak interactions, 3D network structures and magnetic properties of two salts based on bis(maleonitriledithiolate)copper(II) anion and substituted triphenylphosphonium cation

Two new salts, [BzTPP]₂[Cu(mnt)₂] (1) and [4NO₂BzTPP]₂[Cu(mnt)₂] (2) (BzTPP⁺ = benzyltriphenylphosphonium and mnt²⁻ = maleonitriledithiolate) have been prepared and characterized by elemental analyses, UV, IR, molar conductivity and single-crystal X-ray diffraction. The single-crystal structure analysis shows that 1 crystallizes in the monoclinic space group P2₁/n, while 2 crystallizes in the triclinic space group P−1. The effects of weak intramolecular interactions such as C–H···O, C–H···S, C–H···N, C–H···Cu hydrogen bonds and p···π, π···π stacking interactions in the solids generate a 3D network structure. It is noted that the change in the molecular topology of the counteraction when the 4-substituted group in the benzyl ring is changed from H to NO₂ results in differences in the crystal system, space group, weak interactions and the stacking mode of the cations and anions of 1 and 2. The magnetic susceptibilities of these salts measured in the temperature range 2.0 to 300 K show weak ferromagnetic coupling features with θ = 2.05 × 10⁻² K for 1 and 5.13 × 10⁻³ K for 2.     

Investigation of desolvation process in lanthanide dinicotinates

The desolvation process in lanthanide pyridine-3,5-dicarboxylates of the formulae [Tb₂pdc₃(dmf)₂]·dmf (1), [Ho₂pdc₃(dmf)₂]·dmf (2), [Erdc₃(dmf)₂]·dmf (3), and [Yb₂pdc₃(dmf)₂]·dmf (4) where pdc-C₅H₃N(COO)₂²⁻, dmf-N,N′-dimethylformamide) has been investigated by means of the TG–DSC, TG–FTIR, IR and XRD methods. Heating of the complexes in the range 30–260 °C lead to evolution of weakly bonded dmf molecules included in the channels as well those directly bonded with lanthanide atoms. The kinetic analysis revealed a multistep desolvation pattern.     

Hydrothermal Synthesis and Characterization of a Polymeric Network Constructed by Tetranuclear [Yb<Subscript>4</Subscript>(μ<Subscript>3</Subscript>-OH)<Subscript>4</Subscript>]<Superscript>8+</Superscript> Cluster and 2,2′-bipyridine-3,3′-dicarboxylate

Abstract  

A new lanthanide coordination polymer, {[Yb₄(μ ₃ -OH)₄(bpdc)₄(H₂O)₆]}₂·17(H₂O) (1), which contains the tetranuclear lanthanide cluster of cubane-like [Yb₄(μ ₃ -OH)₄]⁸⁺, was obtained by hydrothermal reaction. As building blocks, [Yb₄(μ ₃ -OH)₄]⁸⁺ clusters were further assembled into two-dimensional network structure through the linking of 2,2′-bipyridine-3,3′-dicarboxylate (bpdc) with different four coordination modes. It is unprecedented that the adjacent [Yb₄(μ ₃ -OH)₄]⁸⁺ clusters are in the arraying form of ···AABB···(Yb1–Yb4 unit as A and Yb5–Yb8 unit as B). The thermal stability and magnetic property of compound 1 were investigated further.     

Experimental evidence, stability, and the most probable structure of protonated p-tert-butylcalix[4]arenetetrakis(N,N-dimethylacetamide)

Abstract  

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium H₃O⁺(aq) + 1·Na⁺(nb) \leftrightarrows \leftrightarrows 1·H₃O⁺ (nb) + Na⁺ (aq) taking place in the two-phase water–nitrobenzene system (1 = p-tert-butylcalix[4]arenetetrakis(N,N-dimethylacetamide); aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (H₃O⁺, 1·Na⁺) = −0.1 ± 0.1. Further, the stability constant of the 1·H₃O⁺ complex in water-saturated nitrobenzene was calculated for a temperature of 25 °C as log β _nb (1·H₃O⁺) = 10.9 ± 0.2. By using quantum mechanical DFT calculations, the most probable structure of the 1·H₃O⁺ cationic complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is bound partly to one phenoxy oxygen atom and partly to two carbonyl oxygens of 1 by strong hydrogen bonds and obviously by other electrostatic interactions.     

Synthesis, structural characterization and thermal properties of three copper(II) complexes based on aryl hydrazide ligands

The thiosemicarbazide and hydrazide Cu(II) complexes, [Cu₃L₂¹(py)₄Cl₂] (1), [Cu(HL²)py] (2) and [Cu(HL³)py] (3), (H₂L¹ = 1-picolinoylthiosemicarbazide, H₃L² = N′-(2-hydroxybenzylidene)-3-hydroxy-2-naphthohydrazide, H₃L³ = 2-hydroxy-N′-((2-hydroxy-naphthalen-1-yl)methylene)benzohydrazide) have been prepared and characterized through physicochemical and spectroscopic methods as well as X-ray crystallography. Complex 1 has a centrosymmetric structure with –N–N– bridged Cu₃ skeleton. Neighboring molecules are linked into a 3D supermolecular framework by π–π stacking interactions, N–H···Cl and C–H···Cl hydrogen bonds. Complexes 2 and 3 have similar planar structures but different dimers formed by concomitant Cu···N and Cu···O interactions, respectively. Solvent accessible voids with a volume of 391 ?³ are included in the structure of complex 2, indicating that this complex is a potential host candidate. Thermogravimetric analysis shows that the three complexes are stable up to 100 °C.     

Extraction and DFT study on the complexation of the cesium cation with a hexaarylbenzene-based receptor

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + A⁻(aq) + 1(nb) ⇆ 1·Cs⁺(nb) + A⁻ (nb) taking part in the two-phase water–nitrobenzene system (A⁻ = picrate, 1 = hexaarylbenzene-based receptor; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺, A⁻) = 2.8 ± 0.1. Further, the stability constant of the hexaarylbenzene-based receptor·Cs⁺ complex (abbrev. 1·Cs⁺) in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 4.7 ± 0.1. By using quantum mechanical DFT calculations, the most probable structure of the 1·Cs⁺ complex species was solved. In this complex having C ₃ symmetry, the cation Cs⁺ synergistically interacts with the polar ethereal oxygen fence and with the central hydrophobic benzene bottom via cation–π interaction. Finally, the calculated binding energy of the resulting complex 1·Cs⁺ is −220.0 kJ/mol, confirming relatively high stability of the considered cationic complex species.     

Formation enthalpies of molecules and negative ions of ytterbium bromides

A procedure for determining the formation enthalpies of LnX _n (n = 1–3) molecules of thermally unstable lanthanide di- and trihalides that is based on measuring the equilibrium constants of reactions in Ln-X systems of various content and solving a system of thermochemical equations is suggested. The procedure is used to determine the enthalpies of formation Δ_f H ₂₉₈^o of molecules and negative ions found in the vapors of ytterbium bromides: YbBr (20 ± 3), YbBr₂ (−135 ± 10), YbBr₃ (−233 ± 12), YbBr₃⁻ (−615 ± 31), and YbBr₄⁻ (−766 ± 23) kJ/mol.     

Experimental and theoretical study on the complexation of the cesium cation with dibenzo-30-crown-10

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺ (aq) + A⁻ (aq) + 1(nb) \rightleftarrows \rightleftarrows 1·Cs⁺(nb) + A⁻(nb) taking place in the two-phase water–nitrobenzene system (A⁻ = picrate, 1 = dibenzo-30-crown-10; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺, A⁻) = 4.0 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 5.9 ± 0.1. Finally, by using quantum–mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was derived.     

A combined experimental and DFT study on the complexation of Mg<Superscript>2+</Superscript> with beauvericin

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Mg²⁺(aq) + 1·Sr²⁺(nb) ⇆ 1·Mg²⁺(nb) + Sr²⁺(aq) taking place in the two-phase water–nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (Mg²⁺, 1·Sr²⁺) = 0.0 ± 0.1. Further, the stability constant of the 1·Mg²⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C as log β_nb (1·Mg²⁺) = 9.1 ± 0.2. By using quantum mechanical DFT calculations, the most probable structures of the non-hydrated 1·Mg²⁺ and hydrated 1·Mg²⁺·3H₂O complex species were predicted.     

Studies on mono- and dinuclear bisoxime copper complexes with different coordination geometries

Two new mono- and dinuclear Cu(II) complexes, namely [CuL¹]·0.5H₂O (1) and [(Cu₂(L²)₂)(DMF)]·0.5DMF (2) (H₂L¹ = 1,2-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)]methylene-aminooxy}ethane; H₂L² = 1,3-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)] methyleneaminooxy}propane), have been synthesized and characterized by X-ray crystallography. The unit cell of complex 1 contains two crystallographically independent but chemically identical [CuL¹] molecules and one crystalline water molecule, showing a slightly distorted square-planar coordination geometry and forming a wave-like pattern running along the a-axis via hydrogen bonding and π···π stacking interactions. Complex 2 has a dinuclear structure, comprising two Cu(II) atoms, two completely deprotonated phenolate bisoxime (L²)²⁻ moieties (in the form of enol), and both coordinated and hemi-crystalline DMF molecules. Complex 2 has square-planar and square-pyramidal geometries around the two copper centers, whose basic coordination planes are almost perpendicular and form an infinite three-dimensional supramolecular network structure involving intermolecular C–H···N, C–H···O, and C–H···π(Ph) hydrogen bonding and π···π stacking interactions of neighboring pyrazole rings.     

Thermochemical study on ternary complex of dysprosium <Emphasis Type="Italic">m</Emphasis>-nitrobenzoic acid with <Emphasis Type="Italic">o</Emphasis>-phenanthroline

A ternary binuclear complex of dysprosium chloride hexahydrate with m-nitrobenzoic acid and 1,10-phenanthroline, [Dy(m-NBA)₃phen]₂·4H₂O (m-NBA: m-nitrobenzoate; phen: 1,10-phenanthroline) was synthesized. The dissolution enthalpies of [2phen·H₂O(s)], [6m-HNBA(s)], [2DyCl₃·6H₂O(s)], and [Dy(m-NBA)₃phen]₂·4H₂O(s) in the calorimetric solvent (V_DMSO:V_MeOH = 3:2) were determined by the solution–reaction isoperibol calorimeter at 298.15 K to be \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2phen·H₂O(s), 298.15 K] = 21.7367 ± 0.3150 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [6m-HNBA(s), 298.15 K] = 15.3635 ± 0.2235 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2DyCl₃·6H₂O(s), 298.15 K] = −203.5331 ± 0.2200 kJ·mol⁻¹, and \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = 53.5965 ± 0.2367 kJ·mol⁻¹, respectively. The enthalpy change of the reaction was determined to be \Updelta_\textr H_\textm^q = 3 6 9. 4 9 ±0. 5 6   \textkJ·\textmol ^{- 1} . \Updelta_{\text{r}} H_{\text{m}}^{\theta } = 3 6 9. 4 9 \pm 0. 5 6 \;{\text{kJ}}\cdot {\text{mol}}^{ - 1} . According to the above results and the relevant data in the literature, through Hess’ law, the standard molar enthalpy of formation of [Dy(m-NBA)₃phen]₂·4H₂O(s) was estimated to be \Updelta_\textf H_\textm^q \Updelta_{\text{f}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = −5525 ± 6 kJ·mol⁻¹.     

Crystallographic and theoretical studies of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid (1/1) with intermolecular O–H···N hydrogen bonds and S···O heteroatom interactions

Abstract  The molecular and crystal structure of a 1:1 co-crystal of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P2₁/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) ?, β = 104.988(8)°, V = 962.5(10) ?³ and Z = 2. In the crystal structure, two components connect via the intermolecular O–H···N hydrogen bonds [2.804(4) ?] and S···O heteroatom interaction [2.945(3) ?] with R ₂ ²(7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances of the intermolecular O–H···N and S···O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the crystal. The calculated binding energies corrected BSSE and ZPE are −4.487 (HF), −7.473 (MP2), and −5.640 (B3LYP) kcal/mol. The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in (1). The NBO analysis has revealed that the n(N) → σ*(O–H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular S···O contact is n(O) → σ*(S–N). Index Abstract  In the crystal structure of the title compound, the molecules are linked by intermolecular O–H···N hydrogen bonds and short S···O heteroatom interactions with R ₂ ²(7) couplings to construct a unique and infinite one-dimensional supramolecular tape structure.      

Syntheses,molecular structures and magnetic properties of two hybrid organic–inorganic salts of bis(maleonitriledithiolato)copper(II) and substituted benzyl-4-dimethylaminopyridinium cations

Two new hybrid organic–inorganic salts, [BzDMAP]₂[Cu(mnt)₂](1) and [NO₂BzDMAP]₂[Cu(mnt)₂] (2) ([BzDMAP]⁺ = 1-benzyl-4′-dimethylaminopyridinium, [NO₂BzDMAP]⁺ = 1-(4′-nitrobenzyl)-4′-dimethylaminopyridinium, and mnt²⁻ = maleonitriledithiolate) have been characterized structurally and magnetically. The [BzDMAP]⁺ or [NO₂BzDMAP]⁺ cations (C) and the [Cu(mnt)₂]²⁻ anions (A) in 1 and 2 stack into a 1D alternating CC-A-CC-A-CC column. The Cu···N, π···π, C–H···N, C–H···O, and C–H···S weak interactions play important roles in the molecular stacking and generate a 2D or 3D structure of 1 and 2. The magnetic susceptibilities of these salts measured in the temperature range 2.0–300 K show weak antiferromagnetic coupling features with θ = −2.370 K for 1 and −0.222 K for 2.     

Thermochemical properties of MnNb<Subscript>2</Subscript>O<Subscript>6</Subscript>

Homogeneous manganocolumbite (MnNb₂O₆) was synthesized from Nb₂O₅ and MnO oxides. Powder sample was orthorhombic with unit cell parameters: α = 0.5766 nm, b = 1.4439 nm, c = 0.5085 nm and V = 0.4234 nm³. Heat capacity over the temperature range of 313–1253 K was measured in an inert atmosphere with combined thermogravimetry and calorimetry using NETZSCH STA 449C Jupiter thermoanalyzer. Melting point was 1767 ± 3 K, enthalpy of melting was 144 ± 4 kJ mol⁻¹. Experimental heat capacity of MnNb₂O₆ is fitted to polynomial C _pm = 221.46 + 3.03 · 10⁻³ T + −39.79 · 10⁵ T ⁻² + 40.59 · 10⁻⁶ T ².     

NMR spectra and the structure of the guest sublattice in the monocationic forms of clinoptilolite and heulandite

The¹H NMR spectra of the hydrated monocationic forms of clinoptilolite M₆[Al₆Si₃₀O₇₂]·nH₂O (M=Li, Na, K, Cs, NH₄; n=12–22) and M ₃ ^′ [Al₆Si₃₀O₇₂]·nH₂O (M′=Mg, Ca, Sr, Ba; n=20–24) and heulandite M₈[Al₈Si₂₈O₇₂]·21H₂O (M=Na, K) are divided into three types differing in the symmetry of tensors of magnetic dipole-dipole interactions of protons in zeolite water molecules. On the basis of model calculations it is shown that water molecules in the Cs, K, and Ba forms of clinoptilolite and the K form of heulandite are ordered in structural positions. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Zeorex Ltd., Sofia. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 5, pp. 891–900, September–October, 1996. Translated by L. Smolina     

Phase equilibrium system of RbCl-PrCl3-HCl(12.86 mass %)-H2O at 298.15 K and standard molar enthalpy of formation of new solid-phase compound

The equilibrium solubility of the quaternary system RbCl-PrCl₃-HCl-H₂O was determined at 298.15 K and the corresponding equilibrium diagram was constructed in this paper. The quaternary system is complicated with three equilibrium solid phases, RbCl, RbPrCl₄ · 4H₂O (1:1 type) and PrCl₃ · 6H₂O, of which the new compound RbPrCl₄ · 4H₂O was found to be congruently soluble in the system. The new compound obtained was identified and characterized by the methods of X-ray diffraction, thermogravimetry, and differential thermogravimetry. The compound loses its crystal water by one step at 343 K to 453 K. The standard molar enthalpy of solution of RbPrCl₄ · 4H₂O in deionized water was measured to be −24.53 ± 0.22 kJ mol⁻¹ by heat conduction microcalorimetry. Its standard molar enthalpy of formation was calculated to be −2743.20 ± 1.09 kJ mol⁻¹.     

Different orientations of C=O versus P=O in P(O)NHC(O) skeleton: the first study on an aliphatic diazaphosphorinane with a gauche orientation

Different orientations of P(O) versus C(O) in P(O)NHC(O) skeleton have been discussed in two new phosphorus(V)-nitrogen compounds with formula XP(O)Y and XP(O)Z₂ where X = NHC(O)C₆H₄(4-F) and Y = NHCH₂C(CH₃)₂CH₂NH (1), Z = NHC₆H₄(4-CH₃) (2). Compound 1 is the first example of an aliphatic diazaphosphorinane with a gauche orientation which has been studied by X-ray crystallography; the P=O bond is in the equatorial position of the ring. Both compounds show ⁿ J(F,C) and ^m J(F,H) coupling constants (n = 1, 2, 3 and 4; m = 3 and 4) and ³ J(P,C) > ² J(P,C). Quantum chemical calculations were performed with HF and Density Functional Theory (DFT) methods using 6−31+G(d,p) basis set. A tentative assignment of the observed vibrational bands for these molecules is discussed. Compound 1 shows a deshielded C atom of the carbonyl moiety (in ¹³C NMR spectrum) relative to that of 2, which is supported by IR spectroscopy in which the considerably lower C=O frequency is observed for 1. Comparing the X-ray crystallography and IR spectra of 1 and 2 shows that the acyclic compound 2, containing P=O and C=O bonds in an anti position, are involving in a stronger N–H···O=P hydrogen bond in crystal network. This leads to a weaker P=O and N_C(O)NHP(O)–H bonds and stronger N···O interaction. The N_amide–H is involved in an intramolecular N–H···O hydrogen bond.     

Formation and Stability of Gaseous WS2Cl2, WS2Br2 and WS2I2 – A Combined Experimental and Theoretical Study

Gaseous WS₂Cl₂ and WS₂Br₂ are formed by the reaction of solid WS₂ with chlorine resp. bromine at temperatures of about 1000 K. This could be shown by mass spectrometric measurements. The heats of formation and entropies of WS₂Cl₂ and WS₂Br₂ have been determined by means of mass spectrometry (MS) and quantum chemical calculations (QC). WS₂I₂ could not be detected by experimental methods. This is in line with the quantum chemically determined equilibrium constant of the formation reaction. The following values are given:, Δ_fH⁰₂₉₈(WS₂Cl₂) = –230.8 kJ · mol^–1 (MS), Δ_fH⁰₂₉₈(WS₂Cl₂) = –235.0 kJ · mol^–1 (QC),, S⁰₂₉₈(WS₂Cl₂) = 370.7 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂Cl₂) = 103.78 + 7.07 × 10^–3 T – 0.93 × 10⁵ T^–2 – 3.25 × 10^–6 T² (298.15 K < T < 1000 K) (QC). Δ_fH⁰₂₉₈(WS₂Br₂) = –141.9 kJ · mol^–1 (MS), Δ_fH⁰₂₉₈(WS₂Br₂) = –131.5 kJ · mol^–1 (QC),, S⁰₂₉₈(WS₂Br₂) = 393.9 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂Br₂) = 104.84 + 5.32 × 10^–3 T – 0.75 × 10⁵ T^–2 – 2.45 × 10^–6 T² (298.15 K < T < 1000 K) (QC). Δ_fH⁰₂₉₈(WS₂I₂) = –18.0 kJ · mol^–1 (QC), S⁰₂₉₈(WS₂I₂) = 409.9 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂I₂) = 105.17 + 4.77 × 10^–3 T – 0.67 × 10⁵ T^–2 – 2.19 × 10^–6 T² (298.15 K < T < 1000 K) (QC). These molecules have the expected C_2v‐symmetry.