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1.
A new tetranuclear CuII–HgII–HgII–CuII complex, [Cu2Hg2Cl4(C18H18N2O2)2], has been prepared by means of a copper complex found in the literature. The molecular structure of this complex was determined by X‐ray diffraction and the Cu–Hg–Hg–Cu chain was seen to be non‐linear. The change in magnetic susceptibility with temperature was recorded for this complex and observed to abide by the Curie–Weiss law. The coordination around the HgII ions is square pyramidal. The Cu?Hg bridging distance is 3.5269 (7) Å.  相似文献   

2.
The formation of the Hg–N3(T) bond between the 1-methylthymine (T) molecule and the hydrated Hg2+ cation was explored with the combined quantum mechanics/molecular mechanics (QM/MM) method including Free Energy Perturbation corrections. The thermodynamic properties were determined in the whole pH range, when these systems were explicitly investigated and considered as the QM part: (1) T + [Hg(H2O)6]2+, (2) T + [Hg(H2O)5(OH)]+, (3) T + Hg(H2O)4(OH)2, and (4) N3-deprotonated T + Hg(H2O)4(OH)2. The MM part contained only solvent molecules and counterions. As a result, the dependence of Gibbs-Alberty reaction free energy on pH was obtained along the reaction coordinate. We found that an endoergic reaction in acidic condition up to pH < 4–5 becomes exoergic for a higher pH corresponding to neutral and basic solutions. The migration of the Hg2+ cation between N3 and O4/2 positions in dependence on pH is discussed as well. For the verification, DFT calculations of stationary points were performed confirming the qualitative trends of QM/MM MD simulations and NMR parameters were determined for them.  相似文献   

3.
A new binuclear mercury(I) complex, [Hg2(L)2(NO3)2] (L = (4-nitrophenyl)pyridin-2-ylmethyleneamine), 1, has been synthesized and characterized by CHN analyses, IR, UV–vis spectroscopy and X-ray crystal structure analysis. The complex contains a metal–metal bonded core, [Hg–Hg]2+, in which a single bidentate imine ligand is coordinated to each mercury atom. The Hg atoms have an additional interaction with the oxygen atom of the NO3 ? ion. Theoretical studies show that the interaction energy between the two {Hg(L)NO3} fragments is about 45–59 kcal/mol depending on the level of calculation. The Mayer-Mulliken and Wiberg bond indices (WBI) for Hg–Hg bond at different levels of theory are about 0.75–0.88 and 0.60–0.70, respectively, and are significantly larger than that for Hg–N and Hg–O bonds. The NBO calculations by using different methods and basis sets also show that the S character in Hg–Hg bond is very large (94.65–97.81 %). All above data for this complex are compared with those for linear Hg2X2 (X = F,Cl, Br, I, Ph) complexes. Interestingly, the bond order for Hg–Hg bond in complex 1 is comparable with that for Hg2F2 and larger than those in above linear complexes. This is consistent with the experimental data indicating that the Hg–Hg bond in 1 is shorter than that in all above complexes, except Hg2F2.  相似文献   

4.
Yellowish single crystals of acidic mercury(I) phosphate (Hg2)2(H2PO4)(PO4) were obtained at 200 °C under hydrothermal conditions in 32% HF from a starting complex of microcrystalline (Hg2)2P2O7. Refinement of single crystal data converged at a conventional residual R[F2 > 2σ(F2)] = 3.8% (C2/c, Z = 8, a = 9.597(2) Å, b = 12.673(2) Å, c = 7.976(1) Å, β = 110.91(1)°, V = 906.2(2) Å3, 1426 independent reflections > 2σ out of 4147 reflections, 66 variables). The crystal structure consists of Hg22+‐dumbbells and discrete phosphate groups H2PO4 and PO43–. The Hg22+ pairs are built of two crystallographically independent Hg atoms with a distance d(Hg1–Hg2) = 2.5240(6) Å. The oxygen coordination sphere around the mercury atoms is asymmetric with three O atoms for Hg1 and four O atoms for Hg2. The oxygen atoms belong to the different PO4 tetrahedra, which in case of H2PO4‐groups are connected by hydrogen bonding. Upon heating over 230 °C, (Hg2)2(H2PO4)(PO4) condenses to (Hg2)2P2O7, which in turn disproportionates at higher temperatures into Hg2P2O7 and elemental mercury.  相似文献   

5.
Mercury fluoride ions formed during the laser ablation of HgF2( s ) show the formation of six different cluster ion series viz., HgFn±, HgnFn–2±, HgnFn–1±, (HgF)n±, HgnFn+1±, and HgnFn+2±. Among the different ion series, the observation of high valent HgFn±(n±=3,4; n=6–8) indicates the existence of corresponding molecules which signify the remarkable participation of 5d Hg electrons in the chemical bonding with F atoms and thus make Hg a truly transition metal. Further, molecular orbital calculations show a large HOMO-LUMO energy gap (≥3 eV) and high electron affinity (≥5 eV) that indicates highly stable HgFn=3,4,6,8 with super halogen properties.  相似文献   

6.
Polycationic Hg–As Frameworks with Trapped Anions. II Synthesis, Crystal Structure, and Magnetism of (Hg6As4)[MoCl6]Cl, (Hg6As4)[TiCl6]Cl, and (Hg6As4)[TiBr6]Br (Hg6As4)[MoCl6]Cl is obtained by reaction of Hg2Cl2, Hg, As, and MoCl4 in closed, evacuated glass ampoules in a temperature gradient 450 → 400 °C in form of dark red cubelike crystals. (Hg6As4)[TiCl6]Cl and (Hg6As4)[TiBr6]Br are also formed in closed, evacuated ampoules from Hg2X2 (X = Cl, Br), Hg, As, and Ti metal at 275 °C and 245 °C in form of dark green and black crystals, respectively. All three compounds are air and light sensitive. They crystallize isotypically (cubic, Pa 3, a = 1207.8(4) pm for (Hg6As4)[MoCl6]Cl, a = 1209.4(3) pm for (Hg6As4)[TiCl6]Cl, a = 1230.9(3) pm for (Hg6As4)[TiBr6]Br, Z = 4). The structures consist of a three‐dimensionally connected Hg–As framework which is made up of As2 groups (As–As distance averaged 242 pm) each connected via six Hg atoms to six neighbouring As2 groups. There are two cavities of different size in the polycationic framework. The bigger cavity is filled with [MoCl6]3–, [TiCl6]3–, and [TiBr6]3– ions of nearly ideal octahedral shape, the smaller cavity with discrete halide ions. The magnetic properties of the two Ti containing compounds are in accordance with a d1 paramagnetism. The temperature dependence and the magnitude of the magnetic moment can be interpreted with consideration of the spin‐orbit coupling. The so far known representatives of this structure type can be characterised by the ionic formula (Hg6Y4)4+[MX6]3–X (Y = As, Sb; M = Sb3+, Bi3+, Mo3+, Ti3+; X = Cl, Br).  相似文献   

7.
The mercury perrhenates with the empirical formulas HgReO4 and Hg2ReO5 were prepared by annealing powdered mixtures of mercury(II)oxide and mercury(II)metaperrhenate Hg(ReO4)2 in sealed silica tubes. Their crystal structures were determined from single-crystal X-ray data. HgReO4 crystallizes dimeric with nearly linear O3Re? O? Hg? Hg? O? ReO3 molecular units and Hg2ReO5 has a solid state structure, where Hg(I) and Hg(II) together with oxygen atoms form 14-membered rings, which are condensed to two-dimensionally infinite polycationic nets of composition (Hg22+ · 2 HgO)n. These nets are separated from each other by tetrahedral ReO4? anions.  相似文献   

8.
The mer operon in bacteria encodes a set of proteins and enzymes that impart resistance to environmental mercury toxicity by importing Hg2+ and reducing it to volatile Hg(0). Because the reduction occurs in the cytoplasm, mercuric ions must first be transported across the cytoplasmic membrane by one of a few known transporters. MerF is the smallest of these, containing only two transmembrane helices and two pairs of vicinal cysteines that coordinate mercuric ions. In this work, we use molecular dynamics simulations to characterize the dynamics of MerF in its apo and Hg2+-bound states. We find that the apo state positions one of the cysteine pairs closer to the periplasmic side of the membrane, while in the bound state the same pair approaches the cytoplasmic side. This finding is consistent with the functional requirement of accepting Hg2+ from the periplasmic space, sequestering it on acceptance, and transferring it to the cytoplasm. Conformational changes in the TM helices facilitate the functional interaction of the two cysteine pairs. Free-energy calculations provide a barrier of 16 kcal/mol for the association of the periplasmic Hg2+-bound protein MerP with MerF and 7 kcal/mol for the subsequent association of MerF's two cysteine pairs. Despite the significant conformational changes required to move the binding site across the membrane, coarse-grained simulations of multiple copies of MerF support the expectation that it functions as a monomer. Our results demonstrate how conformational changes and binding thermodynamics could lead to such a small membrane protein acting as an ion transporter. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

9.
Rb5Hg19: A New Defect Variant of the BaAl4 Structure Type The hitherto unknown, silver metallic, air sensitive Rb5Hg19 can be prepared directly from the elements. It crystallizes tetragonally with lattice constants a = 1156.1 pm, c = 1051.0 pm (Z = 2, space group I4/m, No. 87, melting temperature 467 K) in a new defect variant of the BaAl4 structure type. The structure is based on distorted 44 nets of Hg4 rectangles and squares forming rectangular and square pyramids together with additional Hg atoms. The vertices of the pyramids point in alternate directions with respect to [001]. Opposite vertices show relatively short contacts dHg–Hg = 292.3 pm along [001]. The defect character of the Rb5Hg19 structure shows up by single Hg atoms substituting each fifth Hg–Hg group in an ordered way and serving as common vertices for two subsequent square pyramids along [001]. The replacement of Hg–Hg groups by single Hg atoms explains the vertical and horizontal distortions of the 44 nets and explains the differences of the Rb coordination with respect to Ba (bicapped tetragonal hexagonprism) in the BaAl4 type, in which a hypothetical RbHg4 could eventually crystallize. The symmetry relations of Rb5Hg19 and α‐La3Al11 (the only defect variant of BaAl4 except Rb5Hg19) to the aristo type BaAl4 are discussed.  相似文献   

10.
The reaction of [1,3‐bis(2‐ethoxy)benzene]triazene, [ HL ], with Hg(SCN)2 and Hg(CH3COO)2, resulted in the formation of the complexes [Hg L (SCN)] ( 1 ) and [Hg L 2] · CH3OH ( 2 ). They were characterized by means of X‐ray crystallography, CHN analysis, FT‐IR, 1H NMR, and 13C NMR spectroscopy. The structure of compound 1 consists of two independent complexes in which the HgII atoms are stacked along the crystallographic a axis to form infinite chains. Each HgII atom is chelated by one L ligand and one SCN ligand, whereas in compound 2 , the HgII atom is surrounded by two L ligands. In addition, 1D chains formed by metal–π interactions are connected to each other by C–H ··· π stacking interactions in the structure of 1 , which results in a 2D architecture. An interesting feature of compound 2 is the presence of C–H ··· π edge‐to‐face interactions.  相似文献   

11.
A new electronic systems has been observed from excited Hg vapour, which is assigned to collisionally induced emission from the Hg2 O±g first excited states of the dimer: Hg2O±g + M → 2Hg(6 1S0) + M + hvmax 3950 A). For M = N2, the rate coefficient is 5.3(±0.7) × 10?19 cm3 molecule?1 at 298 K. From time resolved measurements of the luminescence in the afterglow following pulsed excitation, the decay rate of the green emission, in an excess of N2, is shown to be a linear function of [Hg][N2]. It is concluded that the reaction which controls the decay of the excitation is formation of an excited trimer in a termolecular reaction; the trimer is the carrier of the green emission: Hg2 O±g + Hg(6 1S0 + Hg(61S0 + N2 → Hg33Πu + N2. The rate coefficient is 1.10(±0.07) × 10?30 cm6 molecule?2 s?1 at 298 K.  相似文献   

12.
About 60 molecular species composed of up to 10 mercury atoms and of oxygen atoms and/or of some other elements or groups (such as halogen, OH2, OH, H, alkali, NO3) have been investigated quantum chemically. Different density functional approaches and the ab initio SCF‐MP2 method were applied, comparing different basis sets and different atomic core sizes. It is important not to treat the Hg 5s, p, d as inactive core shells, and to use sufficiently many polarization functions. The shape of the 〉O‐Hg‐Hg‐O〈 units is not favorable concerning the formation of lattices composed of HgI, O and OH only. Despite its bulkiness, the OHgHgO units can easily come into contact with each other and then disproportionate. This is prevented in the so‐called ternary M‐HgI oxides by the embedded oxometallate (oxoacidic) anions. Furthermore, the HgI and HgII oxide bond energies are less favorable towards the stability of HgI oxo compounds, as compared to Hg halidic or oxoacidic compounds. Both points are not promising concerning the search for HgI oxides/hydroxides, although the preparation of such compounds, including spacer groups, by topochemical reactions can still not be excluded. So far, experimental efforts towards the synthesis of such a new class of compounds have only demonstrated that HgII is strictly preferred over HgI in the formation of solids of binary Hg‐O or ternary A‐Hg‐O composition (A = electropositive metal such as alkali, in contrast to M = transition or semi‐metal). This is so even if compounds containing ‘electron rich Hgδ— atoms’ (i.e. A‐Hg amalgams) are oxidized under mild conditions.  相似文献   

13.
About Cesium Trichloromercurate(II) CsHgCl3: Solution of a Complex Superstructure and Behaviour under High Pressure By solving the crystal structure of CsHgCl3 a new uncommon distortion variant of the cubic perovskite type with extremely (2 + 2 + 2)‐distorted HgCl6 octahedra has been found. The trigonal superstructure with space group P32 and ninefold cell contents differs from the aristotype only so far, as 2/3 of the Cl‐atoms are moved away from their ideal positions leading to 3 pairs of different Hg–Cl distances with about 2.35 Å, 2.71 Å and 3.15 Å. The cations Cs+ and Hg2+ and the chloride ions with medium Hg–Cl distance keep the ideal positions of a cubic perovskite lattice. Due to the evenly distribution of the three different bonds in the three directions of cubic space the cell shows an almost perfect cubic metric. Raman spectra and powder diffraction experiments up to pressures of 5 GPa demonstrated that the ideal perovskite arrangement is stabilized with increasing pressure. The shift of the FT‐Raman bands show in agreement with spectra simulations that the Hg–Cl bonds are equalized, leading to a regular octahedral co‐ordination of the Hg atoms. The disappearance of the Raman spectrum at P > 3.4 GPa indicates that the high pressure phase forms an ideal cubic perovskite (a = 5.204(1) Å, Hg–Cl = 2.60 Å).  相似文献   

14.
Chitosan and pectic acid have been modeled as disaccharides or oligosaccharides for Hg2+ and Pb2+ adsorption. Reasonable models of both biopolymers were used. Several adsorption sites of both polysaccharides were considered, mainly NH2 in chitosan and CO2 in pectic acid. Hg2+ has several points of anchorage on chitosan. The most important one is NH2 . The Molecular Mechanic modeling permit us to compare in relative terms the different conformations of models of pectic acid and chitosan and their effect in heavy metal coordination. Using the Parameterized Model version 3 (PM3), we report the formation enthalpy of inter‐ and intramolecular compounds with Hg and Pb. The Extended Huckel method (EHM) results seem to indicate that electrostatic interaction (leading to adsorbed cation on NH2 and on sites different to NH2) could be the reason for the high uptake found for Hg2+ using chitosan. Besides NH2, the OH near the amine group is the preferred site for Hg2+ adsorption, especially if it is ionized. In the case of Pb2+ adsorption, several sites of chitosan present no interaction with this cation. Only the NH2 group and the ionized OH group mentioned above seem to be the preferred sites, following the EH modified (EHMO) results. The Hg‐ and Pb‐adsorption modeling on pectic acid permit us to conclude that the best site is the same for both metals: the bridge oxygen between monomers of galacturonic acid. the carbonyl group from carboxylate is the best second site for Hg2+, whereas the internal oxygen bridge is the best second site for Pb2+. Considering the Hg 2+ chemistry in aqueous solution, we evaluated the HgOH+ and HgCl+ or HgCl3 adsorption on both copolymers, using EHMO. The energetic of adsorption changed on both biopolymers for these species, comparing them with Hg2+.  相似文献   

15.
There is widespread interest in non‐covalent bonding and weak interactions, such as electrostatic interactions, hydrogen bonding, solvophobic/hydrophobic interactions, metal–metal interactions, and π–π stacking, to tune the molecular assembly of planar π‐conjugated organic and inorganic molecules. Inspired by the roles of metal–aromatic interaction in biological systems, such as in ion channels and metalloproteins, herein, we report the first example of the use of Hg2+–aromatic interactions to selectively control the assembly and disassembly of zinc–salen complexes in aqueous media; moreover, this process exhibited significant “turn on” fluorescent properties. UV/Vis and fluorescence spectroscopic analysis of the titration of Hg2+ ions versus complex ZnL1 revealed that the higher binding affinity of Hg2+ ions (compared to 13 other metal ions) was ascribed to specific interactions between the Hg2+ ions and the phenyl rings of ZnL1 ; this result was also confirmed by 1H NMR spectroscopy and HRMS (ESI). Further evidence for this type of interaction was obtained from the reaction of small‐molecule analogue L1 with Hg2+ ions, which demonstrates the proximity of the N‐alkyl group to the aromatic protons during Hg2+‐ion binding, which led to the consequential H/D exchange reaction with D2O. DFT modeling of such interactions between the Hg2+ ions and the phenyl rings afforded calculated distances between the C and Hg atoms (2.29 Å) that were indicative of C? Hg bond‐formation, under the direction of the N atom of the morpholine ring. The unusual coordination of Hg2+ ions to the phenyl ring of the metallosalen complexes not only strengthened the binding ability but also increased the steric effect to promote the disassembly of ZnL1 in aqueous media.  相似文献   

16.
KCl coated denuders were employed for the measurement of divalent mercury (Hg2+) species in the air. Laboratory tests show that gaseous Hg2+ can be collected by the denuder with an average efficiency of 98% and elemental Hg will pass through it freely. Hg2+ trapped in the denuder can be quantitatively extracted by 1 mol/L HCl and analyzed by the method of SnCl2 reduction-CVAFS determination. Hg2+ concentrations of 0.04–0.15 ng m–3 corresponding to about 2–9% of the total gaseous mercury in the ambient air were determined at several sampling locations.  相似文献   

17.
A recently proposed electroanalytical method, using differential pulse voltammetry (DPV) on the rotating Au-disk electrode, and electrospray ionization mass-spectrometry (ESI-MS) has been applied to study the binding of the pharmaceutical chelating agents meso-2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropanesulfate (DMPS) and d-penicillamine (d-Pen) with Hg2+. From the use of voltammetric titrations it was possible to obtain a detailed picture of the complexation processes at concentrations much lower than in previous studies. Predominant species were Hg(Pen)2, Hg2(DMSA)2 and Hg(DMPS)2. For Pen, Hg(Pen) was also deduced from DPV data, while Hg2(Pen)4 from ESI-MS. For DMSA and DMPS, Hg2L species were detected by DPV, and Hg2L3, Hg3L3 as well as Hg2(DMPS)2 and Hg(DMSA)2 by ESI-MS. When possible, DPV data were analyzed by multivariate curve resolution with alternating least squares (MCR-ALS).  相似文献   

18.
Contributions on Crystal Structures and Thermal Behaviour of Anhydrous Phosphates. XXIII. Preparation, Crystal Structure, and Thermal Behaviour of the Mercury(I) Phosphates α-(Hg2)3(PO4)2, β-(Hg2)3(PO4)2, and (Hg2)2P2O7 Light-yellow single crystals of (Hg2)2P2O7 have been obtained via chemical vapour transport in a temperature gradient (500 °C → 450 °C, 23 d) using Hg2Cl2 as transport agent. Characteristic feature of the crystal structure (P2/n, Z = 2, a = 9,186(1), b = 4,902(1), c = 9,484(1) Å, β = 98,82(2)°, 1228 independent of 5004 reflections, R(F) = 0,066 for 61 variables, 7 atoms in the asymmetric unit) are Hg22+-units with d(Hg1–Hg1) = 2,508 Å and d(Hg2–Hg2) = 2,519 Å. The dumbbells Hg22+ are coordinated by oxygen, thus forming polyhedra [(Hg12)O4] and [(Hg22)O6]. These polyhedra share some oxygen atoms. In addition they are linked by the diphosphate anion P2O74– (ecliptic conformation; ∠(P,O,P) = 129°) to built up the 3-dimensional structure. Under hydrothermal conditions (T = 400 °C) orange single crystals of the mercury(I) orthophosphates α-(Hg2)3(PO4)2 and β-(Hg2)3(PO4)2 have been obtained from (Hg2)2P2O7 and H3PO4 (c = 1%). The crystal structures of both modifications have been refined from X-ray single crystal data [α-form (β-form): P21/c (P21/n), Z = 2 (2), a = 8,576(3) (7,869(3)), b = 4,956(1) (8,059(3)), c = 15,436(3) (9,217(4)) Å, β = 128,16(3) (108,76(4))°, 1218 (1602) independent reflections of 4339 (6358) reflections, R(F) = 0,039 (0,048) for 74 (74) variables, 8 (8) atoms in the asymmetric unit]. In the structure of α-(Hg2)3(PO4)2 three crystallographically independent mercury atoms, located in two independent dumbbells, are coordinated by three oxygen atoms each. Thus, [(Hg2)O6] dimers with a strongly distorted tetrahedral coordination of all mercury atoms are formed. Such dimers are present besides [(Hg2)O5]-polyhedra in the less dense crystal structure of β-(Hg2)3(PO4)2 (d(Hg–Hg) = 2,518 Å). The mercury(I) phosphates are thermally labile and disproportionate between 200 °C (β-(Hg2)3(PO4)2) and 480 °C (α-(Hg2)3(PO4)2) to elemental mercury and the corresponding mercury(II) phosphate.  相似文献   

19.
Colourless single crystals of [Hg(OH)](NO3)(H2O) were obtained by slow evaporation of an aqueous solution of Hg(NO3)2 and Bi(NO3)3. The crystal structure (orthorhombic, Pbca, Z = 8, a = 943.2(2), b = 697.6(1), c = 1349.0(2) pm, R1(all) = 0.0780) contains [Hg(OH)] = …OH–Hg–OH–Hg… zig zag chains (O–Hg–O angle: 168°, Hg–O–Hg angle: 112°, Hg–OH distance: 212 pm) to which one water molecule is attached loosely. The [Hg(OH)](H2O) chains are connected via bis‐monodentate‐bridging nitrate ions to corrugated layers that are stacked in the [001] direction. Hg2+ has an effective 2+2+2(+1) coordination.  相似文献   

20.
The formal potentials of the Hg2+/Hg 2 2+ , Hg 2 2+ /Hg and Hg2+/Hg redox couples and the apparent equilibrium constants of the reaction Hg2+ + Hg ∝ Hg 2 2+ in conc. aqueous solutions of Mg(ClO4)2 and Ca(ClO4)2 have been determined from emf measurements performed using cells with liquid junction. Based on these data, the hydration numbers of the Hg2+ and Hg 2 2+ ions were estimated.  相似文献   

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