Octahedral Anions Research Articles

Tetraphenylbismuth(V) Derivatives Ph4BiCl, [Ph4BiDMSO-O][PtBr3DMSO-S] and [Ph4Bi]2[PtCl6]: Synthesis and Structure

The product of the reaction between tetraphenylbismuth chloride Ph4BiCl (I) synthesized via the dephenylation of pentaphenylbismuth with hydrochloric acid and potassium hexabromoplatinate (2 : 1 mol/mol) in water after recrystallization from dimethylsulfoxide is О-dimethylsulfoxydotetraphenylbismuth S-dimethylsulfoxidotribromoplatinate [Ph4BiDMSO-O][PtBr3DMSO-S] (II). Recrystallization of the complex synthesized from compound I and potassium hexachloroplatinate from acetonitrile gives tetraphenylbismuth hexachloroplatinate [Ph4Bi]2[PtCl6] (III). Structures I–III have been studied by X-ray diffraction. The coordination polyhedron of bismuth atoms in compounds I and II (a crystal contains two types of crystallographically independent ions) is a distorted trigonal bipyramid with heteroatoms in axial positions, and the CBiCl and CBiО axial angles are 175.8(1)°, 177.4(3)°, and 177.3(4)°, respectively; the Bi–Cl distances are 2.912(2) A (I), and Bi–О is 2.78(1) and 2.76(1) A (II); in the equatorial plane, the Bi–C bonds and the CBiC angles are, respectively, 2.204(4)–2.224(4) A and 113.42(16)°–123.35(15)° in I, 2.170(13)–2.181(12) A, 2.155(12)–2.187(13) A and 110.9(4)°–123.8(4)°, 111.0(4)°–123.3(5)° in II. The cation in structure III is a distorted tetrahedron, Bi–C bonds vary within a range of 2.199(4)–2.231(4) A, and the CBiC angles are 102.6(2)°–126.5(2)°. The platinum atoms in the anions of compound II are tetracoordinated, the trans-BrPtBr and trans-SPtBr angles are ranged within 176.51(11)°–177.62(6)°; the Pt–Br bonds are 2.402(3)–2.424(3) A, and the Pt–S distances are 2.200(4) and 2.182(4) A. In the centrosymmetric octahedral anions of compound III, the trans-ClPtCl angles are 180°, and the cis-ClPtCl angles are 88.71(6)°–91.29(6)°; the Pt–Cl bonds are 2.329(2)–2.3350(18) A.

Crystal structure, optical property and Hirshfeld surface analysis of bis-[1-(prop-2-en-1-yl)-1H-imidazol-3-ium] hexa-chlorido-stannate(IV).

A new 0D organic-inorganic hybrid material bis-[1-(prop-2-en-1-yl)-1H-imidazol-3-ium] hexa-chlorido-stannate(IV), (C6H9N2)2[SnCl6], has been prepared and characterized by single-crystal X-ray diffraction, Hirshfeld surface analysis and UV-visible spectroscopy. The structure consists of isolated [SnCl6]2- octa-hedral anions separated by layers of organic 1-(prop-2-en-1-yl)-1H-imidazol-3-ium cations. The 1-(prop-2-en-1-yl) fragment in the organic cation exhibits disorder over two sets of atomic sites having occupancies of 0.512 (9) and 0.488 (9). The crystal packing of the title compound is established by inter-molecular N/C-H⋯Cl hydrogen bond and π- π stacking inter-actions. Hirshfeld surface analysis employing three-dimensional mol-ecular surface contours and two-dimensional fingerprint plots has been used to analyse the inter-molecular inter-actions present in the structure. The optical properties of the crystal were studied using UV-visible absorption spectroscopy, showing one intense band at 208 nm, which is attributed to π-π* transitions in the cations.

Hafnium Complexes $$[{\mathbf{P}}{{{\mathbf{h}}}_{{\mathbf{3}}}}{\mathbf{PR}}]_{{\mathbf{2}}}^{ + }$$[HfCl6]2–, where R = Et, CH2C6H4CN-4, or CH2C6H4F-4: Synthesis and Structure

The complexes $${\text{[P}}{{{\text{h}}}_{{\text{3}}}}{\text{PR]}}_{{\text{2}}}^{{\text{ + }}}$$ [HfCl6]2–, where R = Et (I), CH2C6H4CN-4 (II), or CH2C6H4F-4 (III), have been synthesized by the reaction between hafnium tetrachloride and tetraorganylphosphonium chlorides in acetonitrile and structurally characterized. According to X-ray diffraction data, the phosphorus atoms in tetraorganylphosphonium cations have a distorted tetrahedral coordination: the CPC angles are 108.07(8)°–110.89(8)° (I), 105.0(3)°–113.8(3)° (II), and 99.5(4)°–115.7(4)° (III), and the P–С bond lengths are 1.7958(17)–1.8042(19) A (I), 1.758(6)–1.834(6) A (II), and 1.714(8)–1.930(10) A (III). In the centrosymmetric octahedral anions [HfCl6]2– of complex I, the Hf–Cl distances are 2.4549(8)–2.4584(10) A. In complexes II and III, the octahedral configuration of anions is distorted: the trans-ClHfCl angles are 177.23(13)°–180.00° and 177.73(9)°, 178.07(10)°, 178.84(9)°, respectively, and the Hf–Cl bonds are 2.3949(18)–2.4976(17) A (II) and 2.411(2)–2.527(5) A (III). The structural organization of crystals is formed by weak hydrogen bonds Cl⋅⋅⋅Н–С (2.75–2.92, 2.63–2.94, and 2.75–2.83 A) between anions and cations.

(Invited) Novel Approaches for the Study of Local Processes in Rocksalt Oxyfluoride Cathodes

Cation-disordered rocksalt (DRX) lithium transition metal oxides have recently emerged as a new class of high energy density lithium-ion cathodes, but in most cases suffer from rapid performance degradation upon electrochemical cycling. Unlike layered lithium transition metal oxides, these DRXs are amenable to bulk fluorination (as demonstrated by 19F NMR spectroscopy) and significant improvements in their electrochemical properties, especially cyclability, have been observed upon partial oxygen substitution by fluorine.1 We present here our findings on the impact of fluorine doping on the local cation order and structural and electrochemical properties of several DRX cathodes, using a combination of solid-state NMR experiments and theoretical calculations. Specifically, the impact of F insertion on the distribution of Li and F species in the as-synthesized cathodes is evaluated, and changes in the local structure upon electrochemical cycling are monitored. Ex situ 19F NMR spectra collected on cathode samples stopped at different stages of (dis)charge are particularly difficult to interpret, due to the presence of paramagnetic transition metals leading to very large shifts and broad resonances. In addition, the intrinsic disorder on the cation sublattice leads to a large number of F environments with similar shifts, resulting in broad and overlapping signals. To assist the interpretation of the NMR data, we use Monte Carlo simulations and ab initio calculations of the paramagnetic NMR parameters to determine the distribution of F environments in the materials and predict the chemical shift for these various F sites.Monte Carlo simulations clearly indicate short-range order in the as-synthesized materials, with the incorporation of F in octahedral anion sites with at least five Li nearest-neighbors, in good agreement with 19F NMR results (see Fig. 1). Yet, first principles calculations of NMR parameters reveal that 19F NMR signals from F nuclei directly bonded to the redox-active (and paramagnetic) transition metal species are too broad to be observed.2 Hence, all experimentally-observed 19F NMR signals arise from F sites that are not directly bonded to the paramagnetic metal. These initial insights clearly reveal the strength of our combined experimental and theoretical approach but also suggest that further insight into short-range order in these complex materials requires new experimental (NMR) approaches and complementary techniques. Figure 1. a) Distribution of F environments in the model Li1.166Ni0.333Ti0.5O1.833F0.166 DRX structure obtained from Monte Carlo simulations at an equilibration temperature of 973 K. This distribution is used as a proxy for the distribution of F environments in the Li1.15Ni0.45Ti0.3Mo0.1O1.85F0.15material synthesized at 700°C. b) 19F spin echo NMR spectrum obtained at 11.7 T and at a magic angle spinning (MAS) speed of 60 kHz. The observed 19F signal arises from F nuclei with no Ni nearest-neighbor. Figures adapted from Clément et al.2

Reversible Phase Transition, Switchable Second‐Order Nonlinear Optical and Dielectric Properties in a Bismuth(III)‐Based Compound: (R)‐3‐(Fluoropyrrolidinium)2BiBr5

A new Bi(III)‐based hybrid organic‐inorganic compound, (R)‐3‐(fluoropyrrolidinium)2BiBr5 (1), has been synthesized by solution evaporation. It undergoes a drastic reversible phase transition that appears above the room temperature centered at 407 K, exhibiting a recognizable second‐order nonlinear optical response and noteworthy dielectric anomaly. Variable‐temperature single‐crystal structural analyses exhibit its structure consists of one‐dimensional zigzag chains of [BiBr5]∞ containing cis‐connected anionic octahedra and (R)‐3‐(Fluoropyrrolidinium) cations. We speculate, the existence of phase transition properties of 1 triggered by thermal stimulus probably originates from the deformation of anions and order‐disorder transition of the cations in the crystal lattice. All of those findings will provide a new way to design and fabricate of hybrid organic‐inorganic multifunctional stimuli‐responsive materials.

Tetravalent Platinum Complexes: Synthesis, Structure, and Antimicrobial Activity

The complexes [(C2H5)2NH2]2[PtCl6], [(C2H5)4N]2[PtCl6], and [(CH3)3NH]2[PtCl6] were prepared by the reaction of hexachloroplatinic acid with organylammonium chlorides in acetonitrile. Structure of these compounds was determined by X-ray analysis and infrared spectroscopy. The synthesized crystals consist of tetrahedral organylammonium cations and hexachloroplatinate octahedral anions. The antimicrobial activity of the synthesized complexes against the Escherichia coli strain M-17 was studied.

Field-induced slow magnetic relaxation in low-spin S = 1/2 mononuclear osmium(v) complexes.

Photochemical reactions of (PPh4)[OsVI(N)(L)(CN)3] (NO2-OsN) with piperidine and pyrrolidine afforded two osmium(v) hydrazido compounds, (PPh4)[OsV(L)(CN)3(NNC5H10)] ([PPh4]1) and (PPh4)[OsV(L)(CN)3(NNC4H8)] ([PPh4]2), respectively. Their structures consist of isolated, mononuclear distorted octahedral osmium anions that are well-separated from each other by PPh4+. Their low spin S = 1/2 and L = 1 ground state was confirmed by magnetometry and DFT calculations. Interestingly, both compounds exhibit slow magnetic relaxation under a bias dc-field. These osmium(v) complexes are potentially useful building-blocks for the construction of molecule-based architectures with interesting magnetic properties. In contrast, the structurally related (PPh4)[OsIII(L)(CN)3(NH3)] ([PPh4]3), which also has a low-spin S = 1/2 ground state but with a different electronic configuration (5d5), does not exhibit slow magnetic relaxation, due to the absence of any orbital moment (L = 0). Furthermore, the structurally different osmium(v) hydrazido compound reported by Meyer, [OsV(tpy)(Cl)2(NNC5H10)](PF6) (4[PF6]), also does not exhibit slow magnetic relaxation due possibly to a change in magnetic anisotropy from axial for [PPh4]1 and [PPh4]2 to planar.

Crystal structure, thermal studies, vibrational properties, atomic Hirshfeld surface, and electrical and dielectric studies of [C9H14N]3BiCl6 single crystal

The present research under study makes in attention the synthesis of a new organic inorganic hybrid material of formula [C9H14N]3BiCl6 by slow evaporation at room temperature. It is characterized by the following techniques: X-ray diffraction (XRD), IR absorption, Raman scattering, UV–Vis spectrum, Hirschfield surface analysis, thermal analysis, AC conductivity and dielectric measurements. The studied compound belongs to the centrosymmetric Pī space group of the triclinic system. The crystal structure is built up of one octahedral anion [BiCl6]3- and three monoprotonated cations [C9H14N]+. They give between them alternating anionic layers and cationic ones. The DSC revealed a phase transition at the temperature 380 K and the decomposition of the compound at 400 k. Raman and infrared spectra were recorded in the 50–400 and 400-4000 cm−1 frequency regions respectively. The optical properties were investigated by optical absorption and show three bands at 211, 266 and 321 nm. Hirshfeld surface analysis of close intermolecular interactions in this compound enables the identification and the examination of molecular shapes. The AC electrical conductivity and the dielectric relaxation properties of the [C9H14N]3BiCl6 material have been carefully studied by means of impedance spectroscopy measurements over 200 Hz–5 MHz frequencies and 330–400 K temperatures ranges. Nyquist plots (-Z″ versus Z′) results is well explained by an equivalent circuit which is modeled by a combination of a parallel Rp//CPE. Besides, the Arrhenius law is followed by temperature dependence of the electrical conductivity in the different phases and the Jonscher's universal dynamic law is also followed by the frequency dependence of σ (ω). Moreover, it is clear that the activation energy responsible for relaxation has been depicted and shown to be close to the DC conductivity. Finally, the modulus plots can be characterized by the non-experiential decay function ∅(t)=exp(−tτσ)β.

An unexpected rhenium(IV)-rhenium(VII) salt: [Co(NH3)6]3[ReVIIO4][ReIVF6]4·6H2O.

The title hydrated salt, tris-[hexa-amminecobalt(III)] tetraoxidorhenate(VII) tetra-kis-[hexa-fluorido-rhenate(IV)] hexa-hydrate, arose unexpectedly due to possible contamination of the K2ReF6 starting material with KReO4. It consists of octa-hedral [Co(NH3)6]3+ cation (Co1 site symmetry 1), tetra-hedral [ReVIIO4]- anions (Re site symmetry 1) and octa-hedral [ReIVF6]2- anions (Re site symmetries 1and ). The [ReF6]2- octa-hedral anions (mean Re-F = 1.834 Å), [Co(NH3)6]3+ octa-hedral cations (mean Co-N = 1.962 Å), and the [ReO4]- tetra-hedral anion (mean Re-O = 1.719 Å) are slightly distorted. A network of N-H⋯F hydrogen bonds consolidates the structure. The crystal studied was refined as a two-component twin.

SYNTHESIS AND STRUCTURE OF TRIPHENYLBUT-2-ENYL- AND TRIPHENYLMETOXYMETHYLPHOSPHONIUM HEXACHLOROZIRCONATES

Triphenylbut-2-enyl- (1a) and triphenylmetoxymethylphosphonium (1b) hexachlorozirconates have been synthesized by the reactions of zirconium tetrachloride with the triphenylalkylphosphonium chlorides in acetonitrile for the first time and characterized by the IR, NMR spectroscopy and X-ray analysis. The most intensive bands in IR spectra correspond to the valence vibrations of the CAr-H and the СAr-СAr bonds in the triphenylalkylphosphonium cations. The splitting of carbon atoms signals is observed due to the presence of 13C – 31P coupling. SSCC for carbon atoms directly connected with phosphorus are about 48–85 Hz. According to the X-Ray data, compound 1a crystallizes in the monoclinic crystal lattice (the P21/c space symmetry group). Hexachlorozirconate 1b forms the triclinic crystals belong to the P-1 space symmetry group. Crystals of compound 1a is characterized by the less dense molecular packing in the crystal lattice in comparison with compound 1b. Calculated densities for the structures 1a,b are 1.355 g/cm3 and 1.466 g/сm3, respectively. Structural organization of the complexes in crystals is caused by the formation of hydrogen bonds between chlorine atoms of the anion and hydrogens of phenyl and alkyl groups of the cations. The phosphorus atoms in the triphenylalkylphosphonium cations have distorted tetrahedral coordination (CPC 107.01(4)°-114.10(6)° for 1а, 107.38(9)°-112.06(7)° for 1b, the P-С bonds are 1.790(14)-1.865(14) Å for 1а, 1.7838(12)-1.8293(18) Å for 1b). In centrosymmetric octahedral anions [ZrCl6]2− (trans-ClZrCl 180°) the Zr-Cl distances are 2.4654(15)-2.4952(17) Å for 1а and 2.4641(14)-2.4711(12) Å for 1b.

Synthesis and Structure of Platinum Diethyl Sulfoxide Complexes

The reaction of tetraorganylphosphonium and tetraethylammonium chlorides with hexachloroplatinic acid hydrate in a mixture of acetonitrile and diethyl sulfoxide produced [Ph3PEt][PtCl5(deso-S)] and [Et4N][PtCl5(deso-S)] complexes containing tetrahedral tetraorganylphosphonium or tetraethylammonium cations and octahedral diethylsulfoxidopentachloroplatinate anions.

Синтез и строение комплексов циркония [Ph3PCH=CHMe]2[ZrCl6] и гафния [Ph3PCH2C(O)Me]2[HfCl6

The interaction of zirconium (IV) chloride and hafnium (IV) cloride with tetraorganylphosphonium chlorides in solutions of acetonitrile synthesized the following complexes: [Ph 3 PCH=CHCH 3 ][ZrCl 6 ] ( 1 ), [Ph 3 PCH 2 C(O)CH 3 ][HfCl 6 ] ( 2 ). The structures 1 and 2 were determined by XRDA and IR. The X-ray diffraction patterns of crystals 1 and 2 were obtained at 293 K on an automatic diffractometer D8 Quest Broker (MoK α radiation, λ = 0.71073 Å, graphite monochromator) the phosphorus atoms of complexes 1 and 2 have a distorted tetrahedral configuration in the cations. [C 42 H 40 P 2 Cl 6 Zr ( 1 ), M = 910.60; the triclinic syngony, the symmetry group P ; cell parameters: a = 10.189(8), b = 14.428(7), c = 15.229(8) Å; a = 83.31(2) degrees, β = 73.77(3) degrees, g = 87.75(3) degrees; V = 2135(2) Å 3 ; the crystal size is 0.72 × 0.36 × 0.3 mm; intervals of reflection indexes –12 ≤ h ≤ 12, –18 ≤ k ≤ 18, –19 ≤ l ≤ 19; total reflections 36133; independent disclosures 7367; R int = 0.0326; GOOF = 1.180; R 1 = 0.0907; w R 2 = 0.2675; residual electron density ­­–0.91/ 0.827 e/Å 3 , C 42 H 40 P 2 Cl 6 O 1 Hf ( 2 ), M = 1029.87; the triclinic syngony, the symmetry group P ; cell parameters: a = 10.323(3), b = 10.721(3), c = 11.122(3) Å; a = 67.634(13) degrees, β = 78.219(17) degrees, g = 73.041(14) degrees; V = 1082.7(5) Å 3 ; the crystal size is 0.57 × 0.39 × 0.22 mm; intervals of reflection indexes –19 ≤ h ≤ 19, –20 ≤ k ≤ 20, –21 ≤ l ≤ 21; total reflections 118390; independent disclosures 16166; R int = 0.0486; GOOF 1.009; R 1 = 0.0447; w R 2 = 0.0772; residual electron density ­–1,013/0,910 e/Å 3 ]. The СРС valence angles are 107.95(16)°–110.94(15)° and 106.72(17)°–113.51(17)° for 1 , 105.85(15)°–110.97(15)° for 2 , distance P-С 1.771(6)–1.801(6) Å и 1.781(6)–1.801(6) Å in 1 ; 1.790(2)–1.821(2) Å in 2 . In octahedral anions [ZrCl 6 ] 2− and [HfCl 6 ] 2– trans-angles ClZrCl and ClHfCl equal 180.0º, distance 2.462(3)–2.476(3) Å и 2.462(2)– 2.468(2) Å in a crystal solvate in 1 , 2.4513(10)–2.462(2) Å in 2 . Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Structural Data (No. 1913593 for 1 , 1919938 for 2 , deposit@ccdc.cam.ac.uk; http://www.ccdc. cam.ac.uk).

Metal–organic frameworks based on polynuclear lanthanide complexes and octahedral rhenium clusters

A series of MOFs comprising tetrahedral lanthanide complexes, isonicotinate linkers, and the octahedral cluster anion [Re6S8(CN)6]4–demonstrate structure-directing effects of the rhenium cluster.

Zirconium Complexes [Ph3PR] 2 + [ZrCl6]2–, R = Et, CH2Ph, CH2C(O)OMe: Synthesis and Structure

The complexes [Ph3PR] 2 + [ZrCl6]2–, R = Et (I), CH2Ph (II) (1: 1 solvate with acetonitrile), and CH2C(O)OMe (III) have been synthesized by the reaction between zirconium tetrachloride and triphenylorganyl phosphonium chlorides in acetonitrile and structurally characterized. The phosphorus atoms in triphenylorganyl phosphonium cations have a distorted tetrahedral coordination: the CPC angles are 108.29(9)°–110.84(8)° (I), 106.91(8)°—112.21(8)° (II), and 107.26(9)°–112.83(9)° (III), and the P–C bond lengths are 1.793(2)–1.803(2) A (I), 1.791(2)–1.824(2) A (II), and 1.784(2)–1.811(2) A (III). The Zr–Cl distances in the centrosymmetric octahedral anions [ZrCl6]2– of complex I are 2.4625(11)–2.4634(11) A. The octahedral configuration of anions in complexes II and III is distorted: the trans-ClZrCl angles are 176.80(2)°, 177.12(2)°, 179.80(2)° (II) and 175.53(3)°, 175.97(2)°, 177.75(2)° (III), and the Zr–Cl bonds are 2.4489(11)–2.4953(15) A (II) and 2.4510(8)−2.4864(9) A (III).

Modulation of σ-Alkane Interactions in [Rh(L2)(alkane)]+ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η2,η2-σ-Alkane Rh(I), η1-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation.

Solid/gas single-crystal to single-crystal (SC-SC) hydrogenation of appropriate diene precursors forms the corresponding σ-alkane complexes [Rh(Cy2P(CH2) nPCy2)(L)][BArF4] ( n = 3, 4) and [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(L)][BArF4] ( n = 5, L = norbornane, NBA; cyclooctane, COA). Their structures, as determined by single-crystal X-ray diffraction, have cations exhibiting Rh···H-C σ-interactions which are modulated by both the chelating ligand and the identity of the alkane, while all sit in an octahedral anion microenvironment. These range from chelating η2,η2 Rh···H-C (e.g., [Rh(Cy2P(CH2) nPCy2)(η2η2-NBA)][BArF4], n = 3 and 4), through to more weakly bound η1 Rh···H-C in which C-H activation of the chelate backbone has also occurred (e.g., [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(η1-COA)][BArF4]) and ultimately to systems where the alkane is not ligated with the metal center, but sits encapsulated in the supporting anion microenvironment, [Rh(Cy2P(CH2)3PCy2)][COA⊂BArF4], in which the metal center instead forms two intramolecular agostic η1 Rh···H-C interactions with the phosphine cyclohexyl groups. CH2Cl2 adducts formed by displacement of the η1-alkanes in solution ( n = 5; L = NBA, COA), [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(κ1-ClCH2Cl)][BArF4], are characterized crystallographically. Analyses via periodic DFT, QTAIM, NBO, and NCI calculations, alongside variable temperature solid-state NMR spectroscopy, provide snapshots marking the onset of Rh···alkane interactions along a C-H activation trajectory. These are negligible in [Rh(Cy2P(CH2)3PCy2)][COA⊂BArF4]; in [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(η1-COA)][BArF4], σC-H → Rh σ-donation is supported by Rh → σ*C-H "pregostic" donation, and in [Rh(Cy2P(CH2) nPCy2)(η2η2-NBA)][BArF4] ( n = 2-4), σ-donation dominates, supported by classical Rh(dπ) → σ*C-H π-back-donation. Dispersive interactions with the [BArF4]- anions and Cy substituents further stabilize the alkanes within the binding pocket.

Impact of Chloride Concentration on Ligand Substitution Reactions of Zinc(II) Complexes with Biologically Relevant Nitrogen Nucleophiles

The mole-ratio method was used to determine the metal–ligand stoichiometry between [ZnCl2(en)] and [ZnCl2(terpy)] (where en = 1,2-diaminoethane or ethylenediamine and terpy = 2,2′:6′,2″-terpyridine) and imidazole at pH 7.2 in the presence of different chloride concentrations. The results indicated step-wise formation of 1:1 and 1:2 complexes in the presence of 0.010 M NaCl and 1:1 complexes in the presence of 0.001 M NaCl for the [ZnCl2(en)] complex. These results are correlated with additional coordination of chlorides in the first coordination sphere and with changes in coordination geometry. In the presence of 0.001 M NaCl the five-coordinate complex anion [ZnCl3(en)]- is formed initially and then a substitution reaction with imidazole occurs. In the presence of 0.010 M NaCl the octahedral complex anion [ZnCl4(en)]2- is formed. Additional coordination of chloride in the [ZnCl2(terpy)] complex is not found and the metal–ligand stoichiometry is 1:2. The kinetics of ligand substitution reactions of zinc(II) complexes and biologically relevant nitrogen nucleophiles such as imidazole, 1,2,3-triazole and L-histidine were investigated at pH 7.2 as a function of nucleophile concentration in the presence of 0.001 M and 0.010 M NaCl. The reactions were followed under pseudo first-order conditions by UV-Vis spectrophotometry. The substitution reactions included two steps of consecutive displacement of chlorido ligands with changes only in the coordination geometry of the [ZnCl2(en)] complex. The order of reactivity of the investigated nucleophiles for the first reaction step towards both complexes was L-histidine > 1,2,3-triazole > imidazole, while in the presence of 0.010 M NaCl the most reactive ligand was 1,2,3-triazole towards the [ZnCl2(en)] complex.

Selective Anion Recognition by a Dynamic Quadruple Helicate.

An M2 L4 quadruple helicate, formed by wrapping four molecules of 1,4-bis(3-pyridyloxy)benzene (L1 ) about two palladium(II) centers, is shown to bind anions within its internal cavity. 1 H NMR exchange experiments provide a quantitative measure of anion selectivity and reveal a preference for ClO4 - over the other tetrahedral anions BF4 - and ReO4 - and the octahedral anion PF6 - . X-ray crystal structures of [Pd2 (L1 )4 ]4+ helicates containing ClO4 , BF4 - and I- reveal that the cavity size can dynamically change in response to the size of the guest.

Synthesis and Structure of Ruthenium Complexes $$\rm[{Ph_{3}PR]_2^+[RuCl_6]^{2-}}$$ [ P h 3 P R ] 2 + [ R u C l 6 ] 2 − (R = C2H5, CH=CHCH3, CH2CH=CHCH3, CH2OCH3), and $$\rm[{Ph_{3}PCH_2CH=CHCH_2{PPh_3}]_2^{2+}[Ru_2Cl_{10}O]^{4-}}$$ [ P h 3 P C H 2 C H = C H C H 2 P P h 3 ] 2 2 + [ R u

Complexes \(\rm[{Ph_{3}PR]_2^+[RuCl_6]^{2-}}\), where R = C2H5 (I), CH=CHCH3 (II), CH2CH=CHCH3 (III), and CH2OCH3 (IV), have been prepared by the reaction between ruthenium(III) chloride hydrate and triphenylorganylphosphonium chlorides in dimethylsulfoxide in the presence of hydrochloric acid. A hydrochloric acid solution of ruthenium(III) chloride hydrate when mixed with an aqueous solution of 2-butylene-1,4- bis(triphenylphosphonium dichloride) followed by recrystallization from dimethylsulfoxide results in complex \(\rm[{Ph_{3}PCH_2CH=CHCH_2{PPh_3}]_2^{2+}[Ru_2Cl_{10}O]^{4-}}\)· 4H2O (V). According to X-ray diffraction data, phosphorus atoms in mono- and binuclear cations have slightly distorted tetrahedral coordination (CPC 105.54(13)°−113.00(8)°, P−C 1.758(9)−1.839(7) A). In slightly distorted octahedral anions [RuCl6]2− of complexes I–IV, the Ru−Cl bond lengths vary in the range 2.3222(6)−2.340(2) A; the cis-ClRuCl and trans-ClRuCl angles are 89.133(18)°–90.867(18)° and 179.53(13)°–180°, respectively. In the binuclear [(RuCl5)2O]4− anion of complex V, RuCl5 fragments are bonded by a bridging oxygen atom. The Ru–Cl bond lengths fall in the range 2.3375(8)−2.3957(8) A; the Ru–O bond length is 1.7832(2) A. The cis-ClRuCl, trans-ClRuCl, cis-ORuCl, and trans-ORuCl angles are 86.67(3)°−91.28(3)°, 174.60(3)°−174.83(3)°, 91.49(2)°−93.65(2)°, and 178.39(2)°, respectively. In crystals I–V, interionic hydrogen bonds Cl···Hcation (2.63−2.95 A), Cl··· \({\rm{H}_{{H_2}O}}\) (2.35−2.79 A), and Hcation···\({\rm{O}_{{H_2}O}}\) (1.72−1.93 A) (for V) are found.

Emergent SU(4) Symmetry in α-ZrCl_{3} and Crystalline Spin-Orbital Liquids.

While the enhancement of spin-space symmetry from the usual SU(2) to SU(N) is promising for finding nontrivial quantum spin liquids, its realization in magnetic materials remains challenging. Here, we propose a new mechanism by which SU(4) symmetry emerges in the strong spin-orbit coupling limit. In d^{1} transition metal compounds with edge-sharing anion octahedra, the spin-orbit coupling gives rise to strongly bond-dependent and apparently SU(4)-breaking hopping between the J_{eff}=3/2 quartets. However, in the honeycomb structure, a gauge transformation maps the system to an SU(4)-symmetric Hubbard model. In the strong repulsion limit at quarter filling, as realized in α-ZrCl_{3}, the low-energy effective model is the SU(4) Heisenberg model on the honeycomb lattice, which cannot have a trivial gapped ground state and is expected to host a gapless spin-orbital liquid. By generalizing this model to other three-dimensional lattices, we also propose crystalline spin-orbital liquids protected by this emergent SU(4) symmetry and space group symmetries.

Synthesis, crystal structure, DFT (B3LYP/LanL2DZ) and photoluminescence study of new stanate (IV) based inorganic-organic hybrid

A novel interesting metal hybrid compound, named as hexachlorostanate (II) 4.4′ bipyridinium and formulated as (C10H10N2) SnCl6, was synthesized at room temperature by slow evaporation and then characterized by a single X-ray diffraction, spectroscopic measurements, Scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence technique. It crystallizes in the space group C2/c with the following unit cell parameters: a = 17.9611 (13) Å, b = 12.9274 (5) Å, c = 7.6305 (6) Å and β = 117.860 (10) °. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated [SnCl6]2- octahedral anions and 4.4′ bipyridinium (C10H10N2) cations, which are connected via N-H⋯Cl hydrogen bonds forming a chain network. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the present compound were theoretically examined by the DFT/B3LYP method with the LanL2DZ basis set. The X-ray powder is in agreement with the X-ray structure. 13C NMR spectrum shows three signals, confirming the solid state structure determined by X-ray diffraction. Photoluminescence measurements showed a strong emission line at 2.95 eV associated with radiative recombinations of excitons confined within the [SnCl6]2- which were investigated at room temperature.