Structure cristalline de Ca(ReO4)2 · 2H2O

The crystal structure of Ca(ReO₄)₂ · 2H₂O was determined from single-crystal X-ray diffractometer data. The compound is monoclinic, space group C2, with unit cell parameters a = 18.90(4), b = 7.066(3), c = 14.17(2) Å, β = 115.4(4)°, Z = 8. The structure was solved from 4043 observed reflections and refined to an index R of 0.057. The rhenium atoms are tetrahedrally coordinated and the calcium atoms with eight coordination give rise to Ca₂(H₂O)₄O₁₀ polyhedra.     

Discrete Variational (DV)-Xα Calculations of Incomplete Cubane-Type Molybdenum Clusters [Mo3X4(H2O)9]4+ (X= O,S)1

Electronic structures of two incomplete cubane-type clusters [Mo₃X₄(H₂O)₉]⁴⁺ (X =O, S) have been calculated by the discrete-variational (DV)-X method. The calculations explain the experimental results of valence-band X-ray photoelectron spectra, electronic spectra, and reactivity difference toward acetylene. The net charge of Mo in [Mo₃S₄(H_2O)₉]⁴⁺(S) is more negative than that of Mo in [MO₃O₄H₂O)⁴⁺] (O), and the bridging sulfur atoms are the main negative charge-source for the molybdenum atoms in the cluster S. As for S,levels of HOMO (45e) and LUMO (46e) consist mainly of Mo 4d and-S 3p atomic orbitals, and contribution of ₃-S 3p to the orbitals is not large. The existence of Mo-Mo, Mo--S, and Mo- ₃-S bounds is clear from the contour maps of the orbitals. As for O levels of HOMO (40e) and LUMO (41c) consist mainly of Mo 4d and-O 2p atomic orbitals. Contribution of ₃-O 2p to the orbitals is not large except in the orbital 30a₁,. The existence of Mo-Mo, Mo--O, and MO- ₃-O bonds also is appreciable from the contour maps of the orbitals.Dedicated to Professor Jiaxi Lu on the occasion of his 80th birthday.     

Two binuclear complexes containing the enrofloxacinate anion: Cd2(C19H21N3O3F)4(H2O)2 · 4H2O and Pb2(C19H21N3O3F)4 · 4H2O

The syntheses and crystal structures of the closely related but non-isostructural Cd₂(C₁₉H₂₁N₃O₃F)₄(H₂O)₂?·?4H₂O (1) and Pb₂(C₁₉H₂₁N₃O₃F)₄?·?4H₂O (2) are described, where C₁₉H₂₁N₃O₃F^? is enrofloxacinate (enro). Both compounds contain centrosymmetric, binuclear, neutral complexes incorporating a central diamond-shaped M₂O₂ (M?=?Cd, Pb) structural unit. The Cd²⁺ coordination polyhedron in 1 is a CdO₆ trigonal prism, including one coordinated water. The Pb²⁺ coordination polyhedron in 2 can be described as a very distorted square-based PbO₅ pyramid, although two additional short Pb?···?O (<3.1?Å) contacts are also present. In the crystal of the cadmium complex, O–H?···?O hydrogen bonds lead to a layered structure. In the lead compound, O–H?···?O and O–H?···?N interactions lead to chains in the crystal. Crystal data: 1: C₇₆H₉₆Cd₂F₄N₁₂O₁₈, M _r?=?1766.45, triclinic, P 1, a?=?12.185(2)?Å, b?=?12.306(3)?Å, c?=?14.826(3)?Å, α?=?68.15(3)°, β?=?70.28(3)°, γ?=?86.11(3)°, V?=?1938.2(7)?ų, Z?=?1, T?=?298 K, R(F)?=?0.030, wR(F ²)?=?0.079. 2: C₇₆H₈₈F₄N₁₂O₁₆Pb₂, M _r?=?1920.00, triclinic, P 1, a?=?12.0283(4)?Å, b?=?12.7465(4)?Å, c?=?13.0585(4)?Å, α?=?83.751(1)°, β?=?74.635(1)°, γ?=?81.502(1)°, V?=?1904.3(1)?ų, Z?=?1, T?=?298?K, R(F)?=?0.021, wR(F ²)?=?0.049.     

Crystal structure of Ir(III) complexes with 1,10-phenanthroline: K[Ir(phen)Cl4]·H2O and (Me4N)[Ir(phen)Cl4]

The crystal structure of two salts of the complex [Ir(phen)Cl₄]^? anion with K⁺ (K[Ir(phen)Cl₄]·H₂O, 1) and Me₄N⁺ ((Me₄N)[Ir(phen)Cl₄], 2) cations is determined. The iridium(III) ion is in a distorted octahedral environment consisting of chloride anions and a bidentate heterocyclic ligand of 1,10-phenanthroline (phen). A crucial role in the formation of the crystal structure of complex 1 belongs to K…Cl contacts, while in the crystal structure of complex 2, the stacking interactions dominate.     

Heat capacity of polynuclear Fe(HTrz)3(B10H10)·H2O and trinuclear [Fe3(PrTrz)6(ReO4)4(H2O)2](ReO4)2 complexes (HTrz=1,2,4-triazole, PrTrz=4-propyl-1,2,4-triazole) manifesting 1A1⇔5T2 spin transition

Low-temperature heat capacity of polynuclear Fe(HTrz)₃(B₁₀H₁₀)·H₂O (I) and trinuclear [Fe₃(PrTrz)₆(ReO₄)₄(H₂O)₂](ReO₄)₂ (II) spin crossover coordination compounds was measured in 80–300 K temperature range using a vacuum adiabatic calorimeter. For I, an anomaly of heat capacity with a maximum at T _trs=234.5 K (heating mode) was observed, Δ_trs H=10.1±0.2 kJ mol^?1 Δ_trs S=43.0±0.8 J mol^? K^?1. For II, a smooth anomaly between 150 and 230 K was found, Δ_trs H=2.5±0.25 kJ mol^?1 Δ_trs S=13.6±1.4 J mol^? K^?1. Anomalies observed in both compounds correspond to ¹A₁?⁵T₂ spin transition.     

Synthesis and structure of tetra-p-tolylantimony complexes [(4-MeC6H4)4Sb] 2 + [Hg2I6]2−, [(4-MeC6H4)4Sb] 2 + [HgI4]2−, [(4-MeC6H4)4Sb] 3 + [Sb3I12]2−, and [(4-MeC6H4)4Sb]+[ReO4]−

Complexes [(4-MeC₆H₄)₄Sb] ₂ ⁺ [Hg₂I₆]^2? (I), [(4-MeC₆H₄)₄Sb] ₂ ⁺ [HgI₄]^2? (II), [(4-MeC₆H₄)₄Sb] ₃ ⁺ [Sb₃I₁₂]^2? (III), were synthesized by reactions of tetra-p-tolylantimony iodide with mercury iodide and antimony iodide, respectively. Tetra-p-tolylantimony perrhenate [(4-MeC₆H₄)₄Sb]⁺[ReO₄]^? (IV) was prepared from tetra-p-tolylantimony chloride and sodium perrhenate in acetone. Crystal structures of complexes I, II, and IV were determined by X-ray crystallography. Mercury and rhenium atoms have tetrahedral coordinations in these complexes. The Hg-I and Re-O distances in the structures of I, II, and IV vary within 2.7719(13)–2.7908(12)Å, 2.7028(3)–2.9163(3) Å, and 1.693(3)–1.744(3) Å, respectively. Antimony atoms in two crystallographically independent trinuclear centrosymmetric [Sb₃I₁₂]^2? anions of complex III have an octahedral environment. Each terminal SbI₃ fragment (Sb-I_t, 2.8265(9)–2.8333(10)Å) is bound to the central atom through tree bridging iodine atoms (Sb(2)-I_br, 3.2275(9)–3.3620(10)Å). The distances between the central Sb atom and bridging iodine atoms are much shorter (Sb(1)-I_br, 3.0153(6)–3.0316(6) Å; Sb(3)-I_br, 2.9926(6)–3.0074(6) Å).     

Tansition metal complexes with 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL): Synthesis and crystal structure of [Co(L)2(H2O)4] · 6H2O and [Cu(L)2(H2O)2] · 4H2O

Transition metal complexes of 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL), namely [Co(L)₂(H₂O)₄] · 6H₂O (I) and [Cu(L)₂(H₂O)₂] · 4H₂O (II), have been synthesized by a hydrothermal procedure and characterized by X-ray crystallography, CIF files CCDC nos. 1007524 (I), 1007525 (II). Both I and II are mononuclear molecules. In I, the Co²⁺ ion is in octahedral coordiantion environment and surrounded by four O atoms from water molecules and two carboxylate O atoms of two deprotonated ligand (L^?) occupied six culmination. While in II, the Cu²⁺ ion is located in a square-planar geometry, bounded to two aqua O atoms and two carboxylate O atoms from L^?.     

Nonadiabatic dynamics of O(1D) + N2(X1Σg+) → O(3P) + N2(X1Σg+) on three coupled potential surfaces: symmetry, Coriolis, spin-orbit, and Renner-Teller effects

We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O((1)D) + N(2)(X(1)Σ(g)(+)) → O((3)P) + N(2)(X(1)Σ(g)(+)) on the N(2)O X(1)A', ?(3)A", and b(3)A' coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections σ(j(0)) for the ground vibrational and the first two rotational states of N(2), j(0) = 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum K value associated with any electronic state, showing that ?(3)A" is uncoupled in the centrifugal-sudden (CS) approximation at j(0) = 0. The dynamics is resonance-dominated, the probabilities are larger at low K, σ(j(0)) decrease with the collision energy and increase with j(0), and the CS σ(0) is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the X(1)A'-b(3)A' SO effects are those most important while the ?(3)A"-b(3)A' RT ones are negligible.     

Chemical dynamics of the CH(X2Π) + C2H4(X1A1g), CH(X2Π) + C2D4(X1A1g), and CD(X2Π) + C2H4(X1A1g) reactions studied under single collision conditions

The crossed beam reactions of the methylidyne radical with ethylene (CH(X(2)Π) + C(2)H(4)(X(1)A(1g))), methylidyne with D4-ethylene (CH(X(2)Π) + C(2)D(4)(X(1)A(1g))), and D1-methylidyne with ethylene (CD(X(2)Π) + C(2)H(4)(X(1)A(1g))) were conducted at nominal collision energies of 17-18 kJ mol(-1) to untangle the chemical dynamics involved in the formation of distinct C(3)H(4) isomers methylacetylene (CH(3)CCH), allene (H(2)CCCH(2)), and cyclopropene (c-C(3)H(4)) via C(3)H(5) intermediates. By tracing the atomic hydrogen and deuterium loss pathways, our experimental data suggest indirect scattering dynamics and an initial addition of the (D1)-methylidyne radical to the carbon-carbon double bond of the (D4)-ethylene reactant forming a cyclopropyl radical intermediate (c-C(3)H(5)/c-C(3)D(4)H/c-C(3)H(4)D). The latter was found to ring-open to the allyl radical (H(2)CCHCH(2)/D(2)CCHCD(2)/H(2)CCDCH(2)). This intermediate was found to be long lived with life times of at least five times its rotational period and decomposed via atomic hydrogen/deuterium loss from the central carbon atom (C2) to form allene via a rather loose exit transition state in an overall strongly exoergic reaction. Based on the experiments with partially deuterated reactants, no compelling evidence could be provided to support the formation of the cyclopropene and methylacetylene isomers under single collision conditions. Likewise, hydrogen/deuterium shifts in the allyl radical intermediates or an initial insertion of the (D1)-methylidyne radical into the carbon-hydrogen/deuterium bond of the (D4)-ethylene reactant were found to be-if at all-of minor importance. Our experiments propose that in hydrocarbon-rich atmospheres of planets and their moons such as Saturn's satellite Titan, the reaction of methylidyne radicals should lead predominantly to the hitherto elusive allene molecule in these reducing environments.     

The Unprecedented [S4N2O10]2− Anion in the Molecular Gold Complexes [Au2Br2(S4N2O10)2] and [Au2Cl2(S4N2O10)2](S2O5Cl2)

The reaction of hexachlorophosphazene, P₃N₃Cl₆, with SO₃ and the gold halides AuCl₃ and AuBr₃, respectively, leads to the new cyclic anionic tetramer, [S₄N₂O₁₀]²⁻, which is coordinated to Au³⁺ in the dimeric complexes [Au₂X₂(S₄N₂O₁₀)₂] (X=Cl, Br). The [S₄N₂O₁₀]²⁻ anion can be seen as the condensation product of two sulfate anions, [SO₄]²⁻_, and two amidosulfate anions, [NH₂SO₃]⁻.     

Preparative chemistry with [Ru(η6-arene)(H2O)3]2+: bis-arene and monobenzene complexes with O,N and S donors

The preparation, and electronic, ¹H and ¹³C NMR spectra of the complex ions [Ru(η⁶-C₆H₆)L₃]²⁺ (L = acetonitrile, dimethylsulphoxide, dimethylsulphide or tetrahydrothiophene) from [Ru(η⁶-C₆H₆)(H₂O)₃]²⁺ are reported. The NMR data of coordinated benzene are discussed in terms of the π-backbonding capacity of the monodentate ligand.     

Coordination of N2 ligands to lanthanum: the complexes La (N2)1–8

Structural Chemistry - The structures and bonding properties of La(N2)x (x?=?1–8) complexes were investigated by density functional theory (DFT) computations using the B3LYP...     

State-to-state quantum dynamics of the N(4S) + OH(X2Π) → H(2S) + NO(X 2Π) reaction

Quantum state-to-state dynamics for the N((4)S) + OH(X(?2)Π) → H((2)S) + NO(X(?2)Π) reaction is reported on an accurate ab initio potential energy surface of the lowest triplet electronic state (a(3)A(")) of HNO∕HON. It was found that the reaction is dominated by long-lived resonances supported by the HNO and HON wells. Significant non-reactive scattering was observed, indicating substantial deviations from the statistical limit. Due to the large exothermicity of the reaction, the NO product has hot internal state distributions: its rotational state distribution is inverted and peaks near the highest accessible rotational level; and its vibrational state distribution extends to υ = 10 and decays monotonically with the vibrational quantum number. In particular, the predicted product vibrational distribution is in reasonably good agreement with experiment. The calculated differential cross section is dominated by scattering in both the forward and backward directions, consistent with the formation of reaction intermediates.     

Electronic properties and crystal structure of aqua (mepirizole-oxalato)copper(II)monohydrate: [Cu(C11H14N4O2)C2O4·H2O]H2O

A Cu(ll) complex with mepirizole: 4-methoxy-2-(5-methoxy-3-methyl-pyrazoll-yl)-6-methylpyrimidine (L) and oxalate as ligands with the formula [CuL(C₂O₄)(H₂O)]·H₂O has been synthesized. The crystal structure has been determined by X-ray diffraction analysis: monoclinic, space group P2₁/n, Z = 4, a = 7.707(1), b = 14.951(3), c = 14.986(2) Å,β = 92.40(2)°, V = 1725.2(8) ų, D_m = 1.61(1) g cm⁻³, D_c = 1.62 g cm⁻³, R = 0.032 and R_w = 0.035 for 2016 observed reflections. The CuN₂O₂O′chromophore can be described as square pyramidal strongly distorted towards trigonal bipyramidal. The basal coordination positions are occupied by the two oxygen atoms of the bidentate oxalate group, the coordinated water molecule and one nitrogen atom of the bidentate mepirizole group; the other coordinated nitrogen atom occupies the apical position. Magnetic moment, IR, electronic reflectance and ESR spectra are interpreted in accordance with the proposed stereochemistry.     

Thermal analysis of manganese(II) complexes of general formula (Bu4N)2[MnBrnCl4−n]

Thermal decomposition of compounds consisting of tetrahalogenomanganese(II) anions, [MnBr_nCl_4?n]^2? (n = 0–4), and a tetrabutylammonium cation has been studied using the DSC, TG-FTIR, TG–MS and DTA techniques. The measurements were carried out in an argon and static air atmospheres over the temperature ranges 173–450 K (DSC) and 300–1073 K (TG). Solid products of the thermal decomposition were identified by FT-FIR spectroscopy as well as X-ray powder diffractometry.     

Polymeric (NO)3(N2O) n , (NO)3(N2O) n + , and (NO)3(N2O) n − : an interpretation of experimental observations

Semi-empirical and ab initio calculations are reported which provide a possible explanation for reported experimental results on 2-photon ionization of NO containing a few percent of N₂O, which found (NO)₃(N₂O) _n ^+or? clusters to be significantly more abundant than other (NO) _m (N₂O) _n products. It is found that the observed abundances of (NO)₃(N₂O) _n ionic clusters may be accounted for by the existence of covalent cyclic trimers of nitric oxide attached to oligomers of nitrous oxide. The extra stability of NO trimers in the observed clusters appears to arise from (NO) ₃ ⁺ rather than (NO)₃. Attachment of an (N₂O) _n side chain to (NO) ₃ ⁺ occurs exothermically. It is suggested that the addition of N₂O to cyclic-(NO) ₃ ⁺ might provide a means of making a polymer of nitrous oxide, which could have useful properties.     

K3[Fe3.26V0.74(OH)O(PO4)4(H2O)2]·2H2O: a synthetic leucophosphite

A new iron(III)/vanadium(III) phosphate, K₃[Fe_3.26V_0.74(OH)O(PO₄)₄(H₂O)₂]·2H₂O (1), has been obtained by hydrothermal synthesis and characterized by single crystal X-ray diffraction, Scanning electron microscopy–energy dispersive X-ray spectroscopy, Inductively coupled plasma atomic emission spectroscopy (ICP), thermogravimetric analysis, and FTIR spectroscopy. Single crystal X-ray diffraction reveals a 3D open framework (monoclinic, space group P2₁/n, a?=?9.6391(7)?Å, b?=?9.8063(7)?Å, c?=?9.7268(7)?Å, β?=?100.71(1)°, and V?=?903.38(11)?ų). This structure presents Fe^III and V^III in a 4.4?:?1?M ratio with the metal ions in two different crystallographic sites. Both metallic centers have distorted octahedral environments, linked by PO₄ tetrahedra, forming channels along the a-axis. The asymmetric unit of K₃[Fe_3.26V_0.74(OH)O(PO₄)₄(H₂O)₂]·2H₂O presents a {M₄(OH)O(PO₄)₄(H₂O)₂}^3? anionic entity, charge balanced by three K⁺, which are located within the channels. It is also possible to distinguish M₄O₂ units whose M^III polyhedra are linked by vertex and edges.     

[Bu4N]2[Fe2(μ-S2O3)2(NO)4]: Synthesis,Structure, Redox Properties,and EPR Study

The [n-Bu₄N]₂[Fe₂(-S₂O₃)₂(NO)₄] complex was studied using X-ray diffraction analysis, cyclic voltammetry, and EPR spectroscopy, and its crystal structure was determined. The redox properties of the [Fe₂(-S₂O₃)₂(NO)₄]^2–anion in CH₃CN and CH₂Cl₂solutions were studied. An addition of excess reducer (sodium thiosulfate) to the thiosulfate complex was shown to produce an EPR signal with g= 2.03 typical of the mononuclear iron dinitrosyl complexes. The mechanism for [Fe₂(-S₂O₃)₂(NO)₄]^2–reduction was suggested.     

[NH4][(CH3)2NH2]2[Ta(C2O4)4]·2H2O: the first (oxalato)tantalate(V) complex structurally characterized

Abstract  The compound [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O has been synthesized and characterized by elemental and TG/DTA analyses, IR spectroscopy and by the single-crystal X-ray diffraction study. The structure comprises the [Ta(C₂O₄)₄]³⁻ anion, NH₄ ⁺ and [(CH₃)₂NH₂]⁺ cations and crystallization water molecules. The Ta atom is octacoordinated by oxygen atoms from four bidentate oxalate groups forming a coordination polyhedron close to the triangular dodecahedron. The charge-assisted hydrogen bonds from both cations connect the [Ta(C₂O₄)₄]³⁻ anions into a three-dimensional framework. Graphical Abstract  The synthesis and properties of [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O, the first structurally characterized compound with the tetra(oxalato)tantalate(V) anion, is reported.