Alcohol adducts of zinc dichloride: Molecular structure of [ZnCl2(THF){1-HOC(C6H11)2-2-NMe2C6H4}]

The aminoalcohols 1-HOCR₂-2-NMe₂C₆H₄ [R = Ph (1), R = C₆H₁₁ (2)] and 1-HOCPh₂CH₂-2-NMe₂C₆H₄ (3) react with ZnCl₂ in tetrahydrofuran to give the alcohol adducts [ZnCl₂(THF){1-HOCR₂-2-NMe₂C₆H₄}] [R = Ph (4), R = C₆H₁₁ (5)] and [ZnCl₂(THF){1-HOCPh₂CH₂-2-NMe₂C₆H₄}] (6). The complexes 4–6 were characterized by ¹H and ¹³C NMR spectroscopy, and 5 was also structurally characterized by X-ray crystallography.     

Synthesis, Crystal Structure, and Characterizations of tetra(N-Benzoylmethyl-benzimidazole)dibromide cadmium(II) Complex: CdBr2(C7H5N2CH2COPh)4

The structure of CdBr₂(C₇H₅N₂CH₂COPh)₄ has been determined by X-ray crystallography. It crystallizes in the tetragonal system, space group P4/n, with lattice parameters a = 14.904(3) ?, b = 14.904(3) ?, c = 11.817(2) ?, and Z = 2. The crystal structure consists of monomeric molecules of [CdBr₂(C₇H₅N₂CH₂COPh)₄] with distorted octahedron geometry for the CdBr₂N₄ chromophore. It is also characterized by elemental analysis, IR spectrum, electronic spectrum, and thermogravimetric-differential scanning calorimetry (TG-DSC).     

Application of the ABEEM/MM model in studying the properties of the water clusters (H2O) n ( n =7?10)

ABEEM/MM model has been applied to compute the various properties characterizing water clusters (H₂O) _n (n = 7−10), such as optimized geometries, the hydrogen bonds number, cluster interaction energies, stabilities, ABEEM charge distributions, dipole moments, structural parameters, and so on, and to describe the transition reflected by the hexamer region from two-dimensional (from dimer to pentamer) to three-dimensional structures (for clusters larger than the hexamer). Supported by the National Natural Science Foundation of China (Grant No. 20373021)     

Thermal decomposition mechanisms of MgCl2·6H2O and MgCl2·H2O

The thermal decomposition mechanisms and the intermediate morphology of MgCl₂·6H₂O and MgCl₂·H₂O were studied using integrated thermal analysis, X-ray diffraction, scanning electron microscope and chemical analysis. The results showed that there were six steps in the thermal decomposition of MgCl₂·6H₂O: producing MgCl₂·4H₂O at 69 °C, MgCl₂·2H₂O at 129 °C, MgCl₂·nH₂O (1 ≤ n ≤ 2) and MgOHCl at 167 °C, the conversion of MgCl₂·nH₂O (1 ≤ n ≤ 2) to Mg(OH)Cl·0.3H₂O by simultaneous dehydration and hydrolysis at 203 °C, the dehydration of Mg(OH)Cl·0.3H₂O to MgOHCl at 235 °C, and finally the direct conversion of MgOHCl to the cylindrical particles of MgO at 415 °C. To restrain the sample hydrolysis and to obtain MgCl₂·H₂O, MgCl₂·6H₂O was first calcined in HCl atmosphere until 203 °C when MgCl₂·H₂O was obtained; HCl gas was then turned off and the calcination process continued, producing Mg₃Cl₂(OH)₄·2H₂O calcined at 203 °C, Mg₃(OH)₄Cl₂ at 220 °C and MgO at 360 °C. The temperature of producing MgO from calcination of MgCl₂·H₂O was lower (360 °C) than that from MgCl₂·6H₂O (415 °C) because of its more reactive intermediate products: the irregular shape and tiny needle-like Mg₃Cl₂(OH)₄·2H₂O particles and the uneven surface porous Mg₃(OH)₄Cl₂ particles. The MgO particles obtained at 360 °C had a flake structure.     

Electronic absorption spectrum of Ba(MnO4)2·3H2O/Ba(ClO4)2·3H2O

Polarized absorption spectra of Ba(MnO₄)₂·3H₂O/Ba(ClO₄)₂·3H₂O mixed single crystals are reported at 4.2°K. Previous ¹T₂ → ¹A₁ assignments for the 5200 Å and 3000 Å absorption bands of MnO₄⁻ are substantiated; further support is provided for the ¹T₁ → ¹A₁ assignment of the 3600 Å absorption band of MnO₄⁻. The site-splitting of the 5200 Å ¹T₂ state is E(¹E)−E(¹A) ≈ −150 cm⁻¹; that of the 3000 Å ¹T₂ state is E(¹E)−E(¹A) ≈ 300 cm⁻¹. A significant e vibronic intensity component is observed in the 5200 Å ¹T₂ state.     

Thermochemical properties of Ln(Gly)4Im(ClO4)3·nH2O (Ln = Gd, Tb, Dy, Y)

The enthalpies of dissolution in water of new ternary complexes of four late trivalent lanthanide ions Ln(Gly)₄Im(ClO₄)₃·nH₂O (Ln=Gd, Tb, Dy, Y; Gly: glycine; Im: imidazole and n=1 or 2) were measured by means of a Calvet microcalorimeter. Empirical formulae for the calculation of the enthalpies of dissolution (Δ_dissH), relative apparent molar enthalpies (Δ_dissH (app)), relative partial molar enthalpies (Δ_dissH (partial)) and enthalpies of dilution (Δ_dilH_1,2) were obtained from the experimental data of the enthalpies of dissolution of these complexes. The plot of Δ_dissH_m^Θ, Δ_dissH (app) and Δ_dissH (partial) versus the values of the ionic radius of the lanthanide element (r) showed a grouping effect of the lanthanide elements, indicating that the coordinated bond between the lanthanide ions and the ligands has some covalent character. The unknown value of the standard enthalpy of dissolution for the similar complex: Ho(Gly)₄Im(ClO₄)₃·H₂O was estimated according to the plot of Δ_dissH_m^Θ versus r.     

Solution enthalpies of hydrates LnCl3·xH2O (Ln=Ce–Lu)

Trichlorides of the lanthanide elements Ln=Ce–Lu form: (a) isotypic hexahydrates LnCl₃·6H₂O with a coordination number (CN) 8 for the Ln³⁺ ions. (b) Two isotypic groups of trihydrates LnCl₃·3H₂O, in the first group Ln=Ce-Dy the CN is 8; the structure of the second group Ln=Er–Lu is unknown. With Ho no trihydrate exists; a dihydrate is formed. (c) Two isotypic groups of monohydrates LnCl₃·H₂O with unknown structure – Ln=Ce–Dy and Ln=Ho–Lu. For all compounds and for anhydrous chlorides LnCl₃ solution enthalpies were measured with an isoperibolic calorimeter. The Δ_solH⁰ values do not depend only on the difference (lattice enthalpies/hydration enthalpies), but also on the state in solution. According to Spedding the CN of the Ln³⁺ ions against water changes from 9 to 8 between Nd and Sm, causing minima in the series of solution enthalpies. Dihydrates LnCl₃·2H₂O are found for Ln=Ce, Pr, Nd, Sm and presumably for Eu and Gd. They are not yet well characterised.     

Infrared study of νOD modes in isotopically dilute (HDO) isostructural compounds M(HCOO)2·2H2O (M=Mn,Fe,Co,Ni,Cu,Zn) with matrix-isolated guest ions (Cu in M(HCOO)2·2H2O and M in Cu(HCOO)2·2H2O)

The infrared spectra of isotopically dilute (matrix-isolated HDO molecules) isostructural compounds M(HCOO)₂·2H₂O (M=Mn,Fe,Co,Ni,Zn,Cu) are presented and discussed in the region of the OD stretching modes. According to the structural data the compounds under study are divided into two groups: in M(HCOO)₂·2H₂O (M=Mn,Ni,Zn) the H₂O(1) molecules form stronger hydrogen bonds as compared to H₂O(2); in M(HCOO)₂·2H₂O (M=Fe,Co,Cu) the H₂O(2) molecules form stronger hydrogen bonds as compared to the H₂O(1) molecules. The influence of the metal–water interactions (synergetic effect) and the unit-cell volumes (repulsion potential of the lattice) on the hydrogen bond strength within the isostructural series is discussed. The wavenumbers of the uncoupled OD stretching modes of the HDO molecules influenced by guest ions (Cu²⁺ ions matrix-isolated in M(HCOO)₂·2H₂O and M²⁺ ions matrix-isolated in Cu(HCOO)₂·2H₂O) are presented and commented. For example, the analysis of the spectra reveals that when Cu²⁺ ions are included in the structure of M(HCOO)₂·2H₂O the hydrogen bonds of the type M–OH₂OCHO–Cu are considerably weaker as compared to those of the same type formed when M²⁺ ions are included in the structure of Cu(HCOO)₂·2H₂O if the cations remain unchanged.     

2∞[Yb2(NH2)2( Pz )4][Yb(NH3)2( Pz )3 Pz H]: Electride Induced Synthesis of a 2D-Ytterbium-Pyrazolate Network

Summary. ² _∞[Yb₂(NH₂)₂(Pz)₄][Yb(NH₃)₂(Pz)₃ PzH], Pz ⁻ = pyrazolate anion, PzH = pyrazole, C₃H₄N₂ is obtained by the reaction of ytterbium metal with pyrazole in liquid ammonia and subsequent increase of the temperature to 200°C resulting in the formation of colorless single crystals of the compound. The X-ray single crystal analysis reveals that the structure consists of ² _∞[Yb₂(NH₂)₂(Pz)₄] planes with neutral [Yb(NH₃)₂(Pz)₃ PzH] monomeric molecules that are located between the planes and ytterbium is trivalent. This is the first example of a two-dimensional network structure of an organic amine of the rare earth elements that derives from an electride induced synthesis. The product decomposes under release of ammonia outside its sealed reaction vessel, viz. if the NH₃ pressure is removed.     

Two New Octahedral Cd(II) Complexes [Cd(L)2] and {[Cd(LH)2(SCN)2]H2O} [L = C6H5C(OH)NN = C(CH3)C5H4N]: Synthesis and Structural Studies

Two new octahedral Cd(II) complexes [Cd(L)₂] (1) and {[Cd(LH)₂(SCN)₂]H₂O} (2) [where LH = C₁₄H₁₃N₃O] are synthesized using a tridentate hydrazone ligand (LH) and they are characterized by elemental analysis, IR spectra, NMR spectra, thermal studies and finally the structures have been determined by single crystal X-ray diffraction. Complex 1 crystallizes in monoclinic system, space group C2/c with a = 22.565(6) ?, b = 10.252(3) ?, c = 12.187(4) ?, β = 118.851(2)^∘, and Z = 4. Complex 2 also crystallizes in the monoclinic system, space group P2₁/c with a = 9.257(9)?, b = 17.809(2)?, c = 9.548(9)?, β = 107.439(4)^∘, and Z = 2. In 1 the ligand binds the Cd(II) ion in tridentate fashion, whereas in 2 it acts as a bidentate ligand.     

Hydrothermal synthesis and structure of one-dimensional Co(dien)2(VO3)3·(H2O) (dien=diethylenetriamine)

One-dimensional Co(dien)₂(VO₃)₃·(H₂O) was prepared from the hydrothermal reaction of NH₄VO₃, Co₂O₃, diethylenetriamine (dien) and H₂O at 130 °C. The compound crystallizes in the monoclinic system, space group P2₁/c with a=16.1581(6) Å, b=8.7006(3) Å, c=13.9893(4) Å, β=103.1483(11)°, V=1915.13(11) Å³, Z=4, and R₁=0.0268 for 3060 observed reflections. Single crystal X-ray diffraction revealed that the structure is composed of infinite one-dimensional chains formed by corner-sharing VO₄ tetrahedra with Co(dien)³⁺ complex cations and crystallization water molecules occupying the interchain positions, which are held together to a three-dimensional network via extensive hydrogen-bonding interactions. The compound, with a new zig-zag conformation of metavanadate chains, is the first example of vanadium oxides incorporating trivalent transition metal coordination groups. Other characterizations by elemental analysis, IR and thermal analysis are also described.     

Mercury(II) halide adducts of an olefinic double betaine: [{Hg2L2X4·6HgX2}n] [X = Cl, Br; L = cis-(p-Me2NC5H4N)2C2(COO)2]

Two polymeric mercury(II) halide adducts of an olefinic double betaine, cis-(p-Me₂NC₅H₄N⁺)₂C₂(COO⁻)₂ (L), have been prepared and characterized by X-ray crystallography. [{Hg₂L₂Cl₄·6HgCl₂}_n] (1) crystallizes in the monoclinic space group C2/c with Z = 4, and [{Hg₂L₂Br₄·HgBr₂}_n] (2) in the triclinic space group P with Z = 1. Complexes 1 and 2 are structurally similar, being composed of centrosymmetric fourteen-membered rings and nearly linear HgX₂ (X = Cl, Br) moieties that are further inter-linked by weak HgX [HgCl = 2.930–3.136(9) Å, HgBr = 3.057–3.310(6) Å] and HgO [2.64, 2.75(3) Å] bonds to generate a two-dimensional polymeric network.     

Proton solvates, H·nH2O·mL, formed by diphosphine dioxides with chlorinated cobalt(III) dicarbollide acid

Interaction of hydrated proton, H₅O₂⁺·(H₂O)₄, in dichloroethane solutions with diphosphine dioxides (L) having methyl (Ph₄Me), ethyl (Ph₄Et) and polyoxyethylene chains (Ph₄PEG) linking two diphenyl phosphine oxide groups has been investigated. A bulky counter ion: chlorinated cobalt(III) bis(dicarbollide), [Co(C₂B₉H₈Cl₃)₂]⁻, minimizes perturbation of the cation. At low concentrations, Ph₄Et and Ph₄PEG form anhydrous 1:1 complexes with (P)O–H⁺–O(P) fragment having very strong symmetrical H-bonds. At these conditions Ph₄Me form another compound, H₅O₂⁺·L(H₂O)₂, due to lower PO basicity and optimal geometry of the chelate cycle. At higher concentrations, Ph₄Me and Ph₄Et form isostructural complexes H₅O₂⁺·L₂, whereas Ph₄PEG forms only a 1:1 complex with proton dihydrate, H₃O⁺·H₂O. In excess of free Ph₄Me and Ph₄Et a water molecule is introduced to the first coordination sphere of H₅O₂⁺ and the average molar ratio L/H₅O₂⁺ of the complexes exceeds 2. The composition of these complexes as a function of L and its concentration is discussed.     

Vibrational spectra of α-Ge(HPO4)2·H2O compound

We have measured Raman and infrared spectra of α-Ge(HPO₄)₂·H₂O compound at room temperature. The analysis of vibrational modes indicated the presence of two non-equivalent HPO₄²⁻ units in agreement with ³¹P nuclear magnetic resonance measurements. A tentative assignment of all the observed modes is proposed based on the previous works reported for other hydrogenphosphate-based compounds.     

Dimethylindium hydrazides [Me2In-NH-NHR]2 (R = CMe3, C6H5)

Trimethylindium reacted with phenyl- and tert-butylhydrazine by the release of methane and the formation of the corresponding dimethylindium hydrazides (1 and 2, respectively). Both products form dimers and possess four-membered In₂N₂ heterocycles with two exocyclic N-N bonds in their molecular cores. Interestingly, one compound (1) crystallizes with centrosymmetric molecules in which the N-N bonds are located on different sides of the In₂N₂ ring (C_2h), while both N-N bonds are on the same side in 2 (C_2v). In contrast, the reaction of tri(tert-butyl)indium with tert-butylhydrazine yielded a quite unexpected product. Partial decomposition occurred, and in a low yield the adduct of tribenzylindium with the unchanged tert-butylhydrazine was isolated. In a remarkable reaction, the trialkylindium derivative did not react with the relatively acidic hydrazine, but by the release of the corresponding alkane with the solvent toluene.     

Studies on gas-phase cyclometalations of [ArNi(PPh3)n]+ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Gas-phase cyclometalation of [ArNi(PPh₃)n]⁺ (n = 1, 2) complexes have been studied by ESI-MS/MS. The electron-donating substituents of aromatic iodides in the para position were found to inhibit the cyclometalation process of losing ArH, while the electron-withdrawing substituents in the para position were found to enhance it. These results indicate that the cyclometalation process of losing ArH is favored by electron-deficient aromatic groups. In addition, the detailed dissociation pathways of the cationic nickel complexes were studied, and among these pathways, the process of aryl-aryl interchange was also found to proceed in ESI-MS/MS.     

Blue-shifted hydrogen-bonded complexes. II. CH3F(HF)1 n 3 and CH2F2(HF)1 n 3

The equilibrium structures, binding energies, and vibrational spectra of the clusters CH₃F(HF)_{1 n 3} and CH₂F₂(HF)_{1 n 3} have been investigated with the aid of large-scale ab initio calculations performed at the Møller–Plesset second-order level. In all complexes, a strong C–FH–F halogen–hydrogen bond is formed. For the cases n = 2 and n = 3, blue-shifting C–HF–H hydrogen bonds are formed additionally. Blue shifts are, however, encountered for all C–H stretching vibrations of the fluoromethanes in all complexes, whether they take part in a hydrogen bond or not, in particular also for n = 1. For the case n = 3, blue shifts of the ν(C–H) stretching vibrational modes larger than 50 cm⁻¹ are predicted. As with the previously treated case of CHF₃(HF)_{1 n 3} complexes (A. Karpfen, E. S. Kryachko, J. Phys. Chem. A 107 (2003) 9724), the typical blue-shifting properties are to a large degree determined by the presence of a strong C–FH–F halogen–hydrogen bond. Therefore, the term blue-shifted appears more appropriate for this class of complexes. Stretching the C–F bond of a fluoromethane by forming a halogen–hydrogen bond causes a shortening of all C–H bonds. The shortening of the C–H bonds is proportional to the stretching of the C–F bond.     

Measurement and correlation of the solubility of MnSO4·H2O in ethanol + water + MgSO4·7H2O solutions

Data on the solubility of manganese sulphate monohydrate in water, and in aqueous alcohols is essential for salting-out crystallisation studies. The solubilities of the quaternary system MnSO₄·H₂O + MgSO₄·7H₂O + H₂O + EtOH were determined in the temperature range 293.2–323.2 K over the ethanol mole fraction range of 0.00–0.12. The solubility data were used for modelling with the modified extended electrolyte non-random two-liquid (NRTL) equation. The present extension uses ion-specific parameters instead of the electrolyte-specific NRTL binary interaction parameters. This approach has feasibility for many electrolytes and mixed aqueous solution systems in principle. The model was found to correlate the solubility data satisfactorily.     

Supramolecular nano drug delivery systems mediated via host-guest chemistry of cucurbit[n]uril (n = 6 and 7)

As a novel family of macrocyclic molecules,cucurbit[n]urils(CB[n]s) have emerged as promising building blocks of supramolecular nano drug delivery systems(SNDDS) in recent years.Direct encapsulation of amphiphilic guests by CB[6] and CB[7] can modulate their amphiphilicity,resulting in formation of supramolecular amphiphiles that self-assemble into supramolecular nanoparticles for drug delivery.Additionally,CB[n]'s host-guest chemistry on the surface of mesoporous nanoparticles makes CB[n] an ideal blocking agent to control drug release from delivery vehicles.These SNDDS possess intrinsic stimuli responsiveness towards external guest or host,which can further incorporate re s ponsiveness to a variety of other stimuli including pH,thermal,redox,photo and enzyme,to realize multiple stimuli-responsive drug release.Moreover,the recent breakthrough in direct functionalization of CB[n]s has provided a feasible method for preparing superior CB[6] and CB[7] derivatives that can be employed to build multifunctional SNDDS with unoccupied macrocycles located on surface,which could be decorated with various functional "tags" through host-guest chemistry.In this review,we summarized the recent progress of CB[6] and CB[7] based SNDDS through formation of supramolecular amphiphiles,supramolecular nanovalves as well as supramolecularly tailorable surface,which we hope to further promote the development of CB[n]s family as building blocks for advanced SNDDS.