Bis(N,N′‐dimethylimidazol‐2‐yl­idene)mercury chlorotriiodo­mercury dimethyl sulfoxide solvate

The double mercury salt [Hg(C₅H₈N₂)₂][HgClI₃]·C₂H₆OS was prepared and its structure characterized. The [Hg(C₅H₈N₂)₂]²⁺ cation lies about an inversion centre and the [HgClI₃]^2? anion lies on a mirror plane. Cations and anions are linked to form a one‐dimensional polymer by weak Hg?Cl interactions [Hg?Cl 3.3744 (3) Å]. The mercury–carbene bond distance [2.076 (7) Å] is typical of a dicationic mercury–carbene species.     

Synthesis and crystal structure of diiodobis(thiourea)mercury (ii)-bis(diazafluoren-9-one)

The title compound, [HgI₂(CH₄N₂S)₂]·2C₁₁H₆N₂O, is comprised of the Hg(II)–thiourea complex and free 4,5-diazafluoren-9-one (DAFONE). The complex assumes a distorted tetrahedral geometry at mercury formed by two thiourea molecules and two I^? ions, the S–Hg–S angle [103.7°] being significantly smaller than S–Hg–I angles (115.2 and 114.3°). The complex and DAFONE molecules link to each other via hydrogen bonding to form a supramolecular structure. Significant π–π stacking is observed between neighboring DAFONE molecules.     

Benzeneselenolates of Mercury(II). Crystal and Molecular Structures of [Hg(SePh)2] and (Bu4N)[Hg(SePh)3]

The reaction of dibenzenediselenide, (SePh)₂, with mercury in refluxing xylene gives bis(benzeneselenolato)mercury(II), [Hg(SePh)₂], in a good yield. (ⁿBu₄N)[Hg(SePh)₃] is obtained by the reaction of [Hg(SePh)₂] with a solution of [SePh]^– and (ⁿBu₄N)Br in ethanol. The solid state structures of both compounds have been determined by X-ray diffraction. The mercury atom in [Hg(SePh)₂] (space group C2, a = 7.428(2), b = 5.670(1), c = 14.796(4) Å, β = 103.60(1)°) is linearly co-ordinated by two selenium atoms (Hg–Se = 2.471(2) Å, Se–Hg–Se = 178.0(3)°). Additional weak interactions between the metal and selenium atoms of neighbouring molecules (Hg…Se = 3.4–3.6 Å) associate the [Hg(SePh)₂] units to layers. The crystal structure of (ⁿBu₄N)[Hg(SePh)₃] (space group P2₁/c, a = 9.741(1), b = 17.334(1), c = 21.785(1) Å, β = 95.27(5)°) consists of discrete complex anions and (ⁿBu₄N)⁺ counter ions. The coordination geometry of mercury is distorted trigonal-planar with Hg–Se distances ranging between 2.5 and 2.6 Å.     

The first phosphoramide–mercury(II) complex with a Cl2Hg–OP[N(C)(C)]3 segment

Mercury(II) exhibits a strong preference for linear coordination which has been attributed to relativistic effects splitting the 6p orbitals and promoting sp hybridization. If the two ligands attached to the mercury(II) ion are weak donors, the metal ion can act as a good Lewis acid and expand its coordination number. Moreover, mercury has a special affinity for softer bases, such as S and N atoms, and has much less affinity for hard bases, such as those including an O atom. The asymmetric unit of dichlorido[tris(piperidin‐1‐yl)phosphane oxide‐κO]mercury(II)–dichloridomercury(II) (2/1), [HgCl₂{(C₅H₁₀N)₃PO}]₂·[HgCl₂], is composed of one HgCl₂{(C₅H₁₀N)₃PO} complex and one half of a discrete HgCl₂ entity located on an inversion centre. The coordination environment around the Hg^II centre in the complex component is a distorted T‐shape. Bond‐valence‐sum calculations confirm the three‐coordination mode of the Hg^II atom of the complex molecule. The noncovalent nature of the Hg…Cl and Hg…O interactions in the structure are discussed.     

Solvent–metal interactions in bis[1,2‐dicarba‐closo‐dodecaboran(12)‐1‐yl]mercury(II) dichloromethane solvate and bis[1,12‐dicarba‐closo‐dodecaboran(12)‐1‐yl]mercury(II) tetrahydrofuran solvate

The title compounds, bis­[1,2‐dicarba‐closo‐dodecaboran(12)‐1‐yl]­mercury(II) di­chloro­methane solvate, [Hg(C₂B₁₀H₁₁)₂]·CH₂Cl₂, (I), and bis­[1,12‐dicarba‐closo‐dodecaboran(12)‐1‐yl]­mercury(II) tetra­hydro­furan solvate, [Hg(C₂B₁₀H₁₁)₂]·C₄H₈O, (II), were prepared in excellent yields using a robust synthetic procedure involving the reaction of HgCl₂ with the appropriate monoli­thiocarborane. X‐Ray analysis of the products revealed strong interactions between the Hg atoms in both complexes and the respective lattice solvent. The distances between the Hg^II centers and the Cl atoms of the dichloromethane solvent molecule in the ortho‐carborane derivative, (I), and the O atom of the tetra­hydro­furan molecule in the para‐carborane complex, (II), are shorter than the sums of the van der Waals radii for Hg and Cl (3.53 Å), and Hg and O (3.13 Å), respectively, indicating moderately strong interactions. There are two crystallographically independent mol­ecules in the asymmetric unit of both compounds, which, in each case, are related by differing relative positions of the cages.     

Homoligand and mixed-ligand complexes of mercury(II) with aspartic acid and iminodiacetic acid and its derivatives

The formation of homoligand mercury(II) complexes with aspartic acid (H₂Asp) and aspartate-chelant mixed-ligand mercury(II) complexes with iminodiacetic acid (H₂Ida, IDA), 2-hydroxyethyliminodiacetic acid (H₂Heida, HEIDA), and nitrilotriacetic acid (H₃Nta, NTA) in an aqueous perchlorate medium was studied by spectrophotometry and pH-potentiometric titration. The following complexes were identified: [Hg(OH)Asp]^?, [HgAsp₂]^2?, [Hg(Asp)Ida]^2?, [Hg(Asp)Heida]^2?, and [Hg(Asp)Nta]^3?. The logarithms of their stability constants are, respectively, 11.74 ± 0.12, 20.18 ± 0.17, 20.11 ± 0.10, 19.82 ± 0.09, 19.48 ± 0.11, and 20.58 ± 0.07 (μ = 0.1 (NaClO₄), t = (20 ± 2)°C). The hydrogen and hydroxyl competition regions were located in the systems, and relationships between the molar yields of complex species and the reactant concentrations were established. The protonation and dissociation constants of aspartic acid were derived from pH-potentiometric titrations. Experimental data were analyzed using mathematical models allowing one to judge the existence of various complex species in the solution and to identify the species that are sufficient to reproduce the observed data.     

Synthesis and crystal structure of (dibenzo-18-crown-6)bis(thiocyanato-S)mercury(II)

A new host-guest complex (dibenzo-18-crown-6)bis(thiocyanato-S)mercury(II), [Hg(SCN)₂(DB18C6], was synthesized and studied by X-ray diffraction method. The crystal structure (space group P2₁/n, a = 19.372, b = 8.199, c = 31.799 Å, β = 103.58°, Z = 8) was solved by the direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.092 for 6392 independent reflections; CAD-4 autodiffractometer, λMoK _α. In two independent similar complex molecules, the Hg²⁺ cation lies in the cavity of the DB18C6 crown ligand and is coordinated by all the six O atoms and is covalently bonded to two S atoms of the SCN^? ligands lying on the opposite sides of the mean plane of the six O atoms of the DB18C6 ligand. The coordination polyhedron of two independent Hg atoms is a distorted hexagonal bipyramid. Both independent DB18C6 ligands have the “butterfly” conformation with the approximate C _2v symmetry.     

Homo- and heteroleptic mercury(II) complexes with monoamino complexones in aqueous solution

Reactions of mercury(II) with iminodiacetic (H₂Ida), 2-hydroxyethyliminodiacetic (H₂Heida), and nitrilotriacetic acids (H₃Nta) were studied by spectrophotometry and pH potentiometry. The resulting complexes included [HgIda], [Hg(OH)Ida]^?, [HgIda₂]^2?, [HgHeida], [Hg(OH)Heida]^?, [Hg(Heida)₂]^2?, [HgNta]^?, [HgNta₂]^4?, [Hg(Ida)Heida]^2?, [Hg(Ida)Nta]^3?, and [Hg(Heida)Nta]^3?. The logarithms of their stability constants calculated for I = 0.1 (NaClO₄) and T = 20 ± 2°C were 11.14 ± 0.07, 20.33 ± 0.08, 19.40 ± 0.10, 11.42 ± 0.04, 19.68 ± 0.11, 18.48 ± 0.09, 13.42 ± 0.05, 20.80 ± 0.08, 19.05 ± 0.06, 20.64 ± 0.11, and 20.53 ± 0.16, respectively. The experimental data were analyzed in terms of the mathematical models that predict the existence of a wide spectrum of complex species in solution and allow one to consider only those species that are sufficient for accurate reproduction of the observed pattern.     

Determination of sulfite by reaction with mercury(I) chloride and spectrophotometric measurement of mercury(II) complexes

Sulfite ion was determined in the 0.4 to 12-ppm range by reaction with insoluble mercury(I) chloride to form the soluble Hg(SO₃)₂^staggered2? ion and elemental mercury. The uv absorption of the sulfite complex or an anion species, HgX₄^staggered2?, formed on adding an excess of KBr, KCl, KI, or KSCN is measured. The mercury(II) in solution can also be determined by lowering the pH, adding KCl, and forming the crystal violet adduct of the HgCl₃^staggered? ion. This adduct is extracted into benzene and the absorbance measured at 605 nm.     

Synthesis,characterization, and solution behavior of mercury(II) chloride complexes with phosphine tellurides

The reaction of mercury(II) chloride with neutral phosphine telluride ligands (R₃PTe) produced new mercury(II) complexes, HgCl₂(R₃PTe)₂ [R = Me₂N (1), Et₂N (2), C₄H₈N (3), C₅H₁₀N (4) or ^n-Bu (5)]. Attempts to isolate the complex of HgCl₂ with the morpholinyl ligand, (OC₄H₈N)₃PTe, were unsuccessful. Complexes 1–5 have been characterized by elemental analyses, IR, and multinuclear (³¹P, ¹²⁵Te, and ¹⁹⁹Hg) NMR spectroscopy. The solution behavior of the complexes was investigated using variable temperature NMR spectroscopy in the presence of excess ligand and indicated fast ligand exchange on the NMR timescale at room temperature. The metal–ligand exchange barriers in these complexes were estimated to be in the range 8–11 kcal/mol. The results suggest that a slight change in the nature of the substituents on the phosphorus of the ligand can contribute considerably to the lability of the complex obtained. The NMR data are discussed and compared with those obtained for related phosphine chalcogenide systems.     

A new complex of HgBr2 and pyrimidine‐2‐thione: (pyrimidine‐2‐thionato‐κS)(pyrimidinium‐2‐thionato‐κS)mercury(II) tetrabromomercury(II)

The title compound, [Hg(C₄H₄N₂S)(C₄H₃N₂S)]₂[HgBr₄], con­sists of [Hg(pymt)(pymtH)]⁺ complex cations (pymtH is pyrimidine‐2‐thione) lying across twofold rotation axes in space group Fddd, with linearly coordinated mercury at an Hg—S distance of 2.357 (3) Å, and [HgBr₄]²⁻ anions lying at sites of 222 symmetry. The Hg atom is additionally coordinated by two N and two Br atoms, forming a 2+4 effective coordination sphere. The protonated ligand is connected via N—H⋯N hydrogen bonds to the neighbouring unprotonated ligand, thus forming infinite chains of cations.     

Silver(I) and mercury(II) complexes of meta- and para-xylyl linked bis(imidazol-2-ylidenes)

Mononuclear silver and mercury complexes bearing bis-N-heterocyclic carbene (NHC) ligands with linear coordination modes have been prepared and structurally characterised. The complexes form metallocyclic structures that display rigid solution behaviour. A larger metallocycle of the form [L₂Ag₂]²⁺ [where L = para-bis(N-methylimidazolylidene)xylylene] has been isolated from the reaction of para-xylylene-bis(N-methylimidazolium) chloride and Ag₂O. Reaction of silver- and mercury-NHC complexes with Pd(NCCH₃)₂Cl₂ affords palladium-NHC complexes via NHC-transfer reactions, the mercury case being only the second example of a NHC-transfer reaction using a mercury-NHC complex.     

Spectroscopic,thermal and structural studies of a new mercury(II) one-dimensional coordination polymer, [Hg(3-bpo)2(SCN)2], 3-bpo = 2,5- bis (3-pyridyl)-1,3,4-oxadiazole

A new mercury(II)-organic polymeric complex generated from 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) as an angular dipyridyl derivative ligand, [Hg(3-bpo)₂(SCN)₂], was prepared from reactions of ligand 3-bpo with mercury(II) thiocyanate. The compound was characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR-spectroscopy and structurally determined by X-ray single crystal diffraction. The thermal stability of [Hg(3-bpo)₂(SCN)₂] was studied by thermal gravimetric (TG) and differential thermal analyses (DTA).     

A Mercury Iodide Adduct with 1,1‐Bis(diphenylphosphino)ferrocene – Synthesis,Crystal Structure,and Nonlinear Refractive Properties

A new mercury iodide complex of dppf, [HgI₂(dppf)] (adduct 1 , dppf = 1,1‐bis(diphenylphosphino)ferrocene) was prepared and characterized. Single crystal X‐ray diffraction analysis established that the compound crystallizes in the monoclinic system, space group C2c, with a = 34.992(3), b = 10.236(5), c = 18.765(4) Å, β = 99.410(2)°, Z = 8, V = 6631.2(9) ų. The coordination about the mercury atom is tetrahedral with two equivalent Hg–I and Hg–P bonds. Dppf functions as a chelating ligand. The nonlinear optical (NLO) properties were studied with an 8 ns‐pulsed laser at 532 nm. Its optical responses to the incident light exhibit weak optical absorptive and strong refractive effects, with n₂ = 6.86 × 10^–18 m² · W^–1 in a 2.48 × 10^–4 mol · dm^–3 DMF solution.     

Gravimetric and spectrophotometric determination of mercury with n-benzoyl-n-phenylhydroxylamine

N-Benzoyl-N-phenylhydroxylamine (BPHA) is suggested for the gravimetric determination of mercury(II) at pH 3.0–6.0; the precipitate, Hg(C₁₃H₁₀O₂N)₂, is dried at 105° and weighed. Separation from NH₄⁺, Pb, Bi, Sb, As, Cd, Sn, etc. is possible, but chloride, cyanide and (EDTA) interfere. Mercury(II) can also be extracted with a BPHA solution in chloroform: the extracted mercury complex is yellow and shows an absorbance maximum at 340 mμ. The optimum concentration range for determination is 15–52 μg Hg/ml, the molar extinction coefficient is 2693 ±10 and the sensitivity is 0.075 μg/cm². Interferences are similar to those found in the gravimetric method.     

Bis­(acetato‐κ2O,O′)(2,9‐di­methyl‐1,10‐phenanthroline‐κ2N,N′)mercury(II) in two differently hydrated crystal forms

Two differently hydrated crystal forms of the title compound, viz. bis­(acetato‐κ²O,O′)(2,9‐di­methyl‐1,10‐phenanthroline‐κ²N,N′)­mercury(II), [Hg(C₂H₃O₂)₂(C₁₄H₁₂N₂)] or [HgAc₂(dmph)] [dmph is 2,3‐di­methyl‐1,10‐phenantroline (neocuproine) and Ac is acetate], (I), and tris­[bis­(acetato‐κ²O,O′)(2,9‐di­methyl‐1,10‐phenanthroline‐κ²N,N′)­mercury(II)] hexadecahydrate, [Hg(C₂H₃O₂)₂(C₁₄H₁₂N₂)]₃·16H₂O or [HgAc₂(dmph)]₃·16H₂O, (II), are presented. Both structures are composed of very simple monomeric units, which act as the building blocks of complex packing schemes stabilized by a diversity of π–π and hydrogen‐bonding interactions.     

Synthesis and Crystal Structure of Mercury(II) Metal Crown Ether with N‐Heterocyclic Carbene Linkage

The mercury(II) metal crown ether ( 2a ) was obtained in high yield by reaction of the carbene precursor 1,2‐bis[N‐(1‐naphthylmethylene)imidazoliumethoxy]benzene dihexafluorophosphate ( 1 ) and Hg(OAc)₂. Addition of NaI to the acetone solution of 2a resulted in precipitation of pale yellow solid 2b . The structures of 2a and 2b were determined by single‐crystal X‐ray diffractometry. Both molecules display a helical conformation with a torsional cycle. The mercury atom in complex 2a is tricoordinated by two intramolecular carbene carbon atoms and an acetate oxygen atom. The mercury atom in complex 2b is tetracoordinated by two intramolecular carbene carbon atoms and two cis‐iodine atoms.     

Heteroligand mercury(II) complexes with aspartic,tartaric, and citric acids

Mercury(II) complexes with aspartic (H₂Asp) and tartaric acids (H₂Tart) and heteroligand mercury(II) complexes with H₂Asp, H₂Tart, and citric acids (H₃Cit) were studied by spectrophotometry in aqueous solutions with I = 0.1(NaClO₄) at 20 ± 2°C. It was found that the complexation in both binary and ternary systems depends on the concentrations of the reagents and the pH of the medium. The resulting complexes included [HgAsp], [Hg(OH)Asp]^?, [HgAsp₂]^2?, [HgTart], [Hg(OH)Tart]^?, [Hg(OH)₂Tart]^2?, [HgAspCit]^3?, [HgAspTart]^2?, and [Hg(OH)AspTart]^3?. The logarithms of their stability constants were 11.74 ± 0.12, 20.18 ± 0.17, 20.11 ± 0.10, 5.40 ± 0.11, 15.52 ± 0.09, 24.70 ± 0.12, 19.19 ± 0.12, 14.55 ± 0.16 and 23.80 ± 0.14, respectively. The experimental data were analyzed in terms of the mathematical models that predict the existence of a wide spectrum of complex species in solution and allow one to consider only those species that are sufficient for accurate reproduction of the observed pH-dependence of the optical density.     

Investigation of the mercury(II) complex with triethylenetetramine by means of glass and mercury electrodes

A comprehensive study by means of a mercury pool and a glass pH electrode was made of the equilibria involved in aqueous solutions containing varied concentrations of mercury(II) and triethylenetramine, in the pH range 2.0–12.0 at 25°C with potassium nitrate used to adjust the ionic strength to unity. Only the 1:1 complex, Hg(II) trien²⁺, having a stability constant of 10^24.53±0.10 was found in the entire pH range using the entirely independent Bjerrum and Leden methods.     

A 1:2 complex of mercury(II) chloride with 1,3‐imidazole‐2‐thione

The Hg atom in the title monomeric complex, di­chloro­bis(3‐imidazolium‐2‐thiol­ato‐S)­mercury(II), [HgCl₂(C₃H₄N₂S)₂], is four‐coordinate having an irregular tetrahedral geometry composed of two Cl atoms [Hg—Cl 2.622 (2) and 2.663 (2) Å] and two thione S atoms [Hg—S 2.445 (2) and 2.462 (2) Å]. The monodentate thione ligand adopts a zwitterionic form and exists as the 3‐imidazolium‐2‐thiol­ate ion. The bond angle S1—Hg—S2 of 130.87 (8)° has the greatest deviation from ideal tetrahedral geometry. Intermolecular hydrogen bonds between two of the four N—H groups and one of the Cl atoms [3.232 (8) and 3.238 (7) Å] stabilize the crystal structure, while the other two N—H groups contribute through the formation of N—H?Cl intramolecular hydrogen bonds with the other Cl atom [3.121 (7) and 3.188 (7) Å].