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To investigate the halogen substitution effect on the anionic spin crossover (SCO) complexes, azobisphenolate ligands with 5,5′-dihalogen substituents from fluorine to iodine were synthesized, and their anionic FeIII complexes 1F, 1Cl, 1Br, and 1I were isolated. The temperature dependence of magnetic susceptibility and crystal structure revealed that 1F, 1Cl, and 1Br are all isostructural and exhibit SCO with the rotational motion of the cation and ligands, whereas 1I shows incomplete SCO. Note that 1Cl and 1Br showed irreversible and reversible cooperative SCO transitions, respectively. Short intermolecular contacts between the FeIII complex anions were found despite Coulomb repulsions for all the complexes. The topological analysis of the electron density distributions revealed the existence of X···X halogen bonds, C–H···X, C–H···N, and C–H···O hydrogen bonds, and C–H···π interactions are evident. The dimensionality of intermolecular interactions is suggested to be responsible for the cooperative SCO transitions in 1Cl and 1Br, whereas the disorder due to the freezing of ligand rotations in 1Cl is revealed to inhibit the SCO cooperativity. [ABSTRACT FROM AUTHOR]

To investigate the halogen substitution effect on the anionic spin crossover (SCO) complexes, azobisphenolate ligands with 5,5′-dihalogen substituents from fluorine to iodine were synthesized, and their anionic FeIII complexes 1F, 1Cl, 1Br, and 1I were isolated. The temperature dependence of magnetic susceptibility and crystal structure revealed that 1F, 1Cl, and 1Br are all isostructural and exhibit SCO with the rotational motion of the cation and ligands, whereas 1I shows incomplete SCO. Note that 1Cl and 1Br showed irreversible and reversible cooperative SCO transitions, respectively. Short intermolecular contacts between the FeIII complex anions were found despite Coulomb repulsions for all the complexes. The topological analysis of the electron density distributions revealed the existence of X···X halogen bonds, C–H···X, C–H···N, and C–H···O hydrogen bonds, and C–H···π interactions are evident. The dimensionality of intermolecular interactions is suggested to be responsible for the cooperative SCO transitions in 1Cl and 1Br, whereas the disorder due to the freezing of ligand rotations in 1Cl is revealed to inhibit the SCO cooperativity.

The processes of alkaline hydrolysis of an amide solvent and the dehydrochlorination reaction of 2,2-di(4-chlorophenyl)-1,1,1-trichloroethane in NaOH–DMF system were simulated. A quantum-chemical analysis of the thermodynamic parameters of the processes proceeding with the participation of competing reagents such as the hydroxide anion and the intermediate anion of the DMF alkaline hydrolysis process in the system was carried out. The most probable dehydrochlorinating reagent and the reaction mechanism were proposed. [ABSTRACT FROM AUTHOR]

The nature of intrinsic emission and the formation mechanisms of electron-hole trapping centers in a CaSO 4 crystal irradiated by UV photons (4.9–11 eV) over a wide temperature range from 15 to 300 K are investigated by vacuum-ultraviolet and thermoactivated spectroscopy. It is shown that the emission of 4.3 eV, 3.64 eV and 3.8 eV are produced by recombination of electrons from the s states of the conduction band with various nonequivalently located S O 4 − - centers near top of the valence band of the CaSO 4 crystal. Long-wavelength emission at 3.0–3.1 eV, 2.6–2.7 eV, 2.2–2.4 eV, and 1.7–2.0 eV is connected to electronic transitions on the trapping centers. The trapping centers are created when electrons and holes are localized on anionic complexes or during the decay of excited anionic complexes. • The intrinsic emission arises in the recombination of electrons with hole S O 4 − - centers. • The trapping centers are created when electrons are localized on S O 4 2 − complexes. • Defects are created by the decay of excited anionic complexes. [ABSTRACT FROM AUTHOR]

Macrocyclic compounds have been widely used as anion carriers, as they play important functions in chemical and biological systems. This work reports a theoretical study on free 1,4,7,10,13,16-hexaazacyclooctodeca-2,5,8,11,14,17-hexaene (HAC), as well as its complex with fluoride, chloride, bromide and acetate anions, with and without the presence of the sodium counterion, in the gas phase and implicit solvents (cyclohexane and acetonitrile), at the ωB97X-D/6-311G(d,p) level. The negative ∆G values indicate that the crown-anion complex is prone to be formed due to hydrogen bonds in all tested media. Nevertheless, such interactions weaken as the solvent polarity increases. The ΔG values decrease when the counterion is taken into account, reinforcing the formation of the Na-HAC-X complex. However, the complexation is disfavored in polar solution, since the presence of the counterion increases the HAC-anion distance. Natural bond orbital analysis, the quantum theory of atoms in molecules and non-covalent interactions methods explored the nature and strength of the hydrogen bond interactions, while spin-spin coupling constant calculations for the fluoride-based complex ( J ) gave insight into the potential of this NMR parameter to experimentally probe the complexation of HAC with fluoride. [ABSTRACT FROM AUTHOR]

To investigate the π-extension effect on an unusual negative-charged spin crossover (SCO) FeIII complex with a weak N2O4 first coordination sphere, we designed and synthesized a series of anionic FeIII complexes from a π-extended naphthalene derivative ligand. Acetonitrile-solvate tetramethylammonium (TMA) salt 1 exhibited an SCO conversion, while acetone-solvate TMA salt 2 was in a high-spin state. The crystal structural analysis for 2 revealed that two-leg ladder-like cation-anion arrays derived from π-stacking interactions between π-ligands of the FeIII complex anion and Coulomb interactions were found and the solvated acetone molecules were in one-dimensional channels between the cation-anion arrays. A desolvation-induced single-crystal-to-single-crystal transformation to desolvate compound 2' may be driven by Coulomb energy gain. Furthermore, the structural comparison between quasi-polymorphic compounds 1 and 2 revealed that the synergy between Coulomb and π-stacking interactions induces a significant distortion of coordination structure of 2. [ABSTRACT FROM AUTHOR]

Use of a silylamido–magnesium chloride and a magnesium bis-silylamide where the Si–N–Si core is crafted in a cyclic structure, toward magnesium battery application is demonstrated. Reaction between prepared silylamido–magnesium compounds and a Lewis acid in tetrahydrofuran solvent furnishes the desired electrolytes. Embedding the Si–N–Si core into cyclic structure enhances the oxidation potentials of the ‘in situ’ electrolytes (without any purification) against Mg/Mg 2+ compare to the acyclic analogue. Theoretical calculation provides insight into the ionic species present in the electrolyte systems. [ABSTRACT FROM AUTHOR]

A new anionic 8-hydroxyquinolinatopalladate(II) complex with malonate has been synthesized and characterized by elemental analysis, conductivity, FT-IR, UV-Vis and 1H NMR techniques to enhance the development of potential anticancer agents. Cytotoxicity was determined against the human leukemia cells, molt, by MTT assay. The novel antitumor Pd(II) complex was evaluated for its binding to calf thymus DNA (ctDNA) in physiological buffer (pH 7.0) by using absorption spectroscopy, fluorescence titration spectra, ethidium bromide displacement and gel chromatography studies. The results obtained from these analyses indicated that the water-soluble complex can bind to DNA cooperatively through a static quenching procedure at low concentrations. Thermodynamic parameters obtained from fluorescence experiments at different temperatures revealed the hydrogen binding and van der Waals force in the binding process which was supported by Scatchard's plots. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hemicucurbit[n]urils (n =6 and higher) adapt flexibly to the needs of a ligand. [•] Anionic guests lead to characteristic hemicucurbit[n]uril proton NMR shift pattern. [•] Odd hemicucurbit[n]urils contain a characteristic proton NMR absorption. [•] Larger hemicucurbit[n]urils (n =8 and higher) tend to twisted conformations. [•] Twisted hemicucurbit[12]uril can be regarded as a twofold hemicucurbit[6]uril. [ABSTRACT FROM AUTHOR]

Noncovalent interactions of cucurbit[6]uril (CB[6]) with haloacetate and halide anions are investigated in the gas phase using electrospray ionization ion mobility mass spectrometry. Strong noncovalent interactions of monoiodoacetate, monobromoacetate, monochloroacetate, dichloroacetate, and trichloroacetate on the exterior surface of CB[6] are observed in the negative mode electrospray ionization mass spectra. The strong binding energy of the complex allows intramolecular S2 reaction of haloacetate, which yields externally bound CB[6]-halide complex, by collisional activation. Utilizing ion mobility technique, structures of exteriorly bound CB[6] complexes of haloacetate and halide anions are confirmed. Theoretically determined low energy structures using density functional theory (DFT) further support results from ion mobility studies. The DFT calculation reveals that the binding energy and conformation of haloacetate on the CB[6] surface affect the efficiency of the intramolecular S2 reaction of haloacetate, which correlate well with the experimental observation. [ABSTRACT FROM AUTHOR]

The anionic ruthenium and iron complexes Li[(η5-C5Me5)M(CO)2] (M=Ru (1-Ru), Fe (1-Fe)) were generated by deprotonation of the transition metal hydride (η5-C5Me5)M(CO)2H with n-BuLi in tetrahydrofuran (THF). The reaction proceeded at −45 °C immediately. Reactions of 1 with various electrophiles (Me3SiCl, pTol2HSiCl, Me2SiCl2, MeSiCl3, SiCl4, Me3SiSiMe2Cl, and Ph2GeCl2) afforded the corresponding nucleophilic substitution products (η5-C5Me5)M(CO)2ER3 (E=Si, Ge) via salt-elimination. [Copyright &y& Elsevier]

The structures of anionic pyridine-2,6-dicarboxylato (pdc2−) complexes of cobalt, nickel, and copper have been studied. The stoichiometries and structures are very much dependent on whether KOH, Et4NOH, or NaOH is used in the synthesis to deprotonate the H2pdc ligand. Crystallographic results are: ( 1) K2[Co(pdc)2] · 7H2O, orthorhombic, Pnna, Z = 4, a = 20.637(2)Å, b = 13.480(1)Å, c = 8.200(1)Å ( 2) K2[Ni(pdc)2] · 7H2O, orthorhombic, Pnna, Z = 4, a = 20.648(1)Å, b = 13.375(1)Å, c = 8.2393(8)Å ( 3) [Co2(H2O)5(pdc)2] · 2H2O, monoclinic, P21/ c, Z = 4, a = 8.3880(6)Å, b = 27.384(2)Å, c = 9.6110(8)Å, β = 98.271(6)° ( 4) [Ni(Hpdc)2] · 3H2O, monoclinic, P21/ c, Z = 4, a = 13.679(1)Å, b = 10.0450(9)Å, c = 13.767(2)Å, β = 115.184(7)° ( 5) Na6[Co(H2O)6][Co(pdc)2]4 · 28H2O, monoclinic, P21/ n, Z = 2, a = 13.363(1)Å, b = 8.437(1)Å, c = 40.689(3)Å, β = 91.288(5)° ( 6) Na[Ni(Hpdc)(pdc)] · 11.5H2O, monoclinic, C2/ m, Z = 4, a = 15.200(2)Å, b = 22.299(2)Å, c = 8.3596(7)Å, β = 118.894(7)° ( 7) Na[Cu(Hpdc)(pdc)] · 3H2O, monoclinic, P21/ n, Z = 4, a = 9.516(4)Å, b = 14.917(6)Å, c = 12.247(5)Å, β = 92.00(5)°. The potassium and sodium complexes have extensive K+—H2O and Na+—H2O networks. The fact the Et4N+ ion does not appear in any of the complexes is likely due to the fact that it is incapable of forming the intricate cation—water and hydrogen-bonding networks observed in all of the other structures. [ABSTRACT FROM AUTHOR]