Synthesis,spectroscopic and X-ray structural studies of mercury(II) halide complexes of 4-methoxybenzoylmethylenetriphenylphosphorane

The reactions of the title ylide {(C₆H₅)₃PCHCOC₆H₄OCH₃)} (MBPPY) with mercury(II) chloride and mercury(II) bromide in equimolar ratios using methanol as the solvent produces crystals of [(MBPPY) · HgCl₂]₂ (1) and [(MBPPY) · HgBr₂]₂ (2), respectively. Single crystal X-ray analyses reveal the presence of centrosymmetric dimeric structures containing the ylide and HgX₂ (X = Cl or Br) in both cases. The IR and NMR data of the product [(MBPPY) · HgI₂]₂ (3), formed by the reaction of mercury(II) iodide with the same ylide, are similar to those of 1 and 2. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.     

[TMPA]4[Si8O20] · 34 H2O and [DDBO]4[Si8O20] · 32 H2O are heteronetwork clathrates with 1,1,4,4-tetramethylpiperazinium (TMPA) and 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane (DDBO) guest cations

[TMPA]₄[Si₈O₂₀] · 34 H₂O ( 1 ) and [DDBO]₄[Si₈O₂₀] · 32 H₂O ( 2 ) have been prepared by crystallization from aqueous solutions of the respective quaternary alkylammonium hydroxide and SiO₂. The crystal structures have been determined by single-crystal X-ray diffraction. 1 : Monoclinic, a = 16.056(2), b = 22.086(6), c = 22.701(2) Å, β = 90.57(1)° (T = 210 K), space group C2/c, Z = 4. 2 : Monoclinic, a = 14.828(9), b = 20.201(7), c = 15.519(5) Å, β = 124.13(4)° (T = 255 K), space group P2₁/c, Z = 2. The polyhydrates are structurally related host-guest compounds with three-dimensional host frameworks composed of oligomeric [Si₈O₂₀]^8? anions and H₂O molecules which are linked via hydrogen bonds. The silicate anions possess a cube-shaped double four-ring structure and a characteristic local environment formed by 24 H₂O molecules and six cations (TMPA, [C₈H₂₀N₂]²⁺, or DDBO, [C₈H₁₈N₂]²⁺). The cations themselves reside as guest species in large, irregular, cage-like voids. Studies employing ²⁹Si NMR spectroscopy and the trimethylsilylation method have revealed that the saturated aqueous solutions of 1 and 2 contain high proportions of double four-ring silicate anions. Such anions are also abundant species in the saturated solution of the heteronetwork clathrate [DMPI]₆[Si₈O₁₈(OH)₂] · 48.5 H₂O ( 3 ) with 1,1-dimethylpiperidinium (DMPI, [C₇H₁₆N]⁺) guest cations.     

Copper(I) and mercury(II) halide complexes of 1,2-bis(diphenylthioylphosphino)hydrazine

The reaction of 1,2-bis(diphenylthioylphosphino)hydrazine (L) with copper(I) and mercury(II) halides affords the complexes, [{CuLX}₂] (X = I, Br or Cl), [HgLX₂] (X = Cl or Br) and the tetrametallic complex, [{L(HgI₂)₂}₂]. Single crystal X-ray structures have been performed on the uncoordinated ligand, L, as well as the complexes [{CuLX}₂] (X = I, Br and Cl), [HgLBr₂] and [{L(HgI₂)₂}₂. The molecules of L exist as dimers as a result of pairs of N–HS hydrogen bonds. The copper(I) complexes are centrosymmetric dimetallic species, the two copper atoms being bridged by L and the X atoms. In all cases the coordination sphere around the Cu atoms is approximately trigonal pyramidal with an ‘S₂X₂’ donor set. The complex, [HgLBr₂], is a distorted tetrahedral monomer with an ‘S₂Br₂’ donor set and L acting as a bidentate thus forming a seven-membered chelate ring. The tetramercury iodo complex, [{L(HgI₂)₂}₂], contains two ‘L(HgI₂)₂’ units linked centrosymmetrically via an I atom from each moiety. The geometry around the Hg atoms is distorted tetrahedral. The influence of hydrogen bonding between the hydrazine backbone hydrogens of L and the coordinated halide ions in for the structures of the metal complexes is discussed.     

Synthesis and spectral characterization of mercury(II) complexes with the bidentate Schiff base ligand N,N′-bis(2,3-dimethoxybenzylidene)-1,2-diaminoethane: The crystal structures of [Hg((23-MeO-ba)2en)I2] and [Hg((23-MeO-ba)2en)Br2]

Three mercury(II) complexes, [Hg((23-MeO-ba)₂en)X₂] (X = I (1), Br (2) and Cl(3)), and the ligand (23-MeO-ba)₂en ((23-MeO-ba)₂en = N,N′-bis(2,3-dimethoxybenzylidene)-1,2-diaminoethane) have been synthesized and characterized by elemental analyses, FT-IR and ¹H NMR spectroscopy. The crystal and molecular structures of 1 and 2 were determined by X-ray crystallography from single-crystal data. The metal-to-ligand ratio was found to be 1:1. The mercury(II) center in 1 and 2 has a distorted tetrahedral geometry with HgN₂I₂ and HgN₂Br₂ chromophores, respectively. The Schiff base ligand (23-MeO-ba)₂en acts as a chelating ligand, coordinating via the two nitrogen atoms to the mercury(II) center, and it adopts an E,E conformation. The coordination sphere of the mercury(II) center in 1 and 2 is completed by the two I and Br atoms, respectively. In complex 1 an inter-molecular non-classical hydrogen bond of the type C-H?O was found, while in complex 2 inter- and intra-molecular non-classical hydrogen bonds of the type C-H?X (X = O and Br) were found. The ¹H NMR spectra of the complexes exhibit downfield as well as upfield shifts of the free ligand resonances, reflecting changes in the ligand’s geometry during its coordination.     

Structure and Spectroscopic Studies of 4,8-bis(2-Hydroxybenzyl)-cis-octahydro[1,4]-oxazino [3,2-b]-1,4-oxazine

The title compound 4,8-bis(2-Hydroxybenzyl)-cis-octahydro [1,4]-oxazino [3,2-b]-1,4-oxazine (1) has been synthesized by the reaction of N-(2-hydroxybenzyl)-2-amino-1-ethanol with glyoxal. This novel compound was characterized by elemental analysis, IR, and ¹H NMR. The structure was also confirmed by a single crystal X-ray study. The compound crystallizes in monoclinic C2/C space group with unit cell dimensions: a = 18.318(4), b = 8.6110(17), c = 13.267(3) Å, = 119.90(3), V = 1814.1(6) ų, Z = 4. The two fused six-membered rings in 1 adopt chairlike conformations slightly flattened around the nitrogen atoms. In the central fusion bond, the geometry is a staggered conformation, with the two angular hydrogen atoms in the cis positions with respect to the rings, the nitrogen atoms antiperiplanar to each other, while the oxygen atoms remain gauche to each other and antiperiplanar to the hydrogen atoms. The ring conformations in 1 have been discussed on the basis of the anomeric effects and the presence of two strong intramolecular hydrogen bonds between the phenolic hydrogens and the amino groups.     

Synthesis and characterization of new nitrate-bridged polymeric complexes of mercury(II) with phosphorus ylides

Reaction of phosphorus ylides of the type X-C₆H₄-COCHPAr₃ (X = Cl and NO₂; Ar = phenyl and p-tolyl) with Hg(NO₃)₂ · H₂O in equimolar ratios using methanol as solvent are reported. X-ray crystal structure analysis of [Hg(ClC₆H₄C(O)CHPPh₃)(NO₃)(μ-NO₃)]_n · (DMSO)_n shows that the 1:1 complex adopts the noncentrosymmetric polymeric structure in the solid state with NO^-₃ anion bridges. Variation of temperature or concentration in a ³¹P NMR study indicates that the disappearance of satellites, due to coupling to ¹⁹⁹Hg, occurs at increasing temperature or decreasing concentration.     

(±)Alkyl 3-hydroxy-1-azabicyclo[2.2.2]octane-3-carboxylates: conformational preferences of the alkoxycarbonyl group

Molecular mechanics, ab initio (RHF) and density functional (DFT/B3LYP) methods are applied to investigate the conformational preferences of the methoxycarbonyl group of the (±)methyl 3-hydroxy-1-azabicyclo[2.2.2]octane-3-carboxylate. ¹H and ¹³C chemical shifts are also calculated by the GIAO/DFT approach and compared with experimental values. Both theoretical and experimental data account for almost eclipsed conformations with different degrees of distortion from the ideal geometry. It is found that calculations at the B3LYP/6-311G(d,p) level are relatively more reliable to explain the behaviour of the alkoxycarbonyl moiety of 2-hydroxyesters derived from the (±)3-hydroxy-1-azabicyclo[2.2.2]octane-3-carboxylic acid.     

Synthesis and Crystal Structure of 1,3-Trans-1,4-cis- 3,4-di(4-bromophenyl)-1',2',3'-trihydro-1-hydroxy- benzo[g]bicyclo[3.3]octane-2-spiro-2'-indene-1'-one

1 INTRODUCTION Low-valent titanium reagents have exceedinglyhigh abilities to promote reductive coupling of car-bonyl compounds and they are attracting increasinginterest in organic synthesis[1]. Many other func-tional groups can also be coupled[2~8]. Recently, wehave reported some intermolecular reductive cou-pling reactions[9~12] and some new intramolecular re-ductive coupling reactions[13~16] induced by low-va-lent titanium reagents. The spiro[4.4]nonane skeleton has been found inmany…     

Diazabicyclo[2.2.2]octane-1,4-diium occluded in cubic anionic coordinated framework: the role of trifurcated hydrogen bonds of N–HO and C–HO

A unique coordinated molecular capsule compound is synthesized and characterized by X-ray diffraction. The compound crystallizes in cubic space group of Pa-3 with a=14.348(1), b=14.348(1), c=14.348(1) Å, V=2953.8(4) ų, Z=8. The diazabicyclo[2.2.2]octane-1,4-diium is occluded in the cubic anionic coordinated framework of K⁺ and (ClO₄)⁻ in a dimension of 7.174(1) Å, and assumes ordered feature. All of hydrogen atoms take parts in trifurcated hydrogen bonds of N–HO and C–HO type, respectively, the later being reported for the first time. The IR spectrum of the title compound shows significant shift of CH₂ vibrational bands, and are correlated with X-ray structural data.     

Structural, theoretical and multinuclear NMR study of mercury(II) complexes with a new ambidentate phosphorus ylide

The reaction of the new ambidentate ylide, Ph₃PCHCOCH₂COOC₂H₅ (EAPPY), with HgX₂ (X = Cl, Br and I) in equimolar ratios using methanol as the solvent leads to binuclear complexes of the type [EAPPY·HgX₂]₂ (X = Cl (1), Br (2) and I (3)). Single crystal X-ray analysis reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgX₂ (X = Br or I)_. The IR and NMR data of the product [(EAPPY)·HgCl₂]₂ (1), formed by the reaction of mercury(II) chloride with the same ylide, are similar to those of 2 and 3. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products. Theoretical studies indicate that the nature of the R group in ylides of the type Ph₃PCHCOR has a weak effect on the Hg-C(ylide) bond length in binuclear Hg₂L₂I₄ complexes.     

Coordination modes of 3-hydroxypicolinic acid: Synthesis and structural characterization of polymeric mercury(II) complexes

Novel mercury(II) compounds of 3-hydroxypicolinic acid (HpicOH; IUPAC name: 3-hydroxy-2-pyridinecarboxylic acid) were synthesized and characterized. HgCl(picOH) (1) and HgBr₂(HpicOH) (2) were obtained as reaction products from the reaction of the corresponding mercury(II) halide with HpicOH, irrespective of the molar ratio of the reactants. From the reaction of HpicOH and mercury(II) acetate, Hg(picOH)₂ (3) was obtained, while mercury(II) nitrate monohydrate gave the 1/1 solvate with water Hg(picOH)₂ · H₂O (3a). Infrared, ¹H and ¹³C NMR spectroscopic data were analyzed for complexes 1, 2 and 3. X-ray crystal structure analysis of 1 and 2 revealed their polymeric nature and different coordination modes of HpicOH. In 1 the deprotonated picolinic acid is N,O-chelating and bridging, while in 2 HpicOH is a O-monodentate weakly bound ligand. Compound 1 consists of HgCl(picOH) moieties with two linear covalent bonds, Hg–N 2.143(4) and Hg–Cl 2.298(1) Å, and four additional Hg?O contacts (2.460(3)–2.904(3) Å) in which both oxygen atoms from the carboxylic group are bridging and involved in coordination to three neighboring mercury atoms, thus forming infinite layers. The coordination of mercury is 2 + 4. 2 consists of {HgBr₂(HpicOH)} moieties, which are linked into chains by means of mercury to bromine secondary long range interactions. The coordination sphere of mercury can be described as irregular 2 + 3 formed by two covalently bonded bromine atoms (Hg–Br 2.277(1) and 2.366(1) Å), two bridging bromine atoms (Hg?Br 3.309(1) and 3.247(1) Å) and by the HpicOH ligand attached to mercury in the zwitterionic form via the carboxylic oxygen atom (Hg?O 2.602(7) Å).     

Mn (II) and Zn (II) complexes of a benzimidazole ligand having undecyl chains: Crystal structures,photophysical and thermal properties

A new tridentate benzimidazole ligand (L‐C¹¹) containing undecyl chains and its Mn (II) and Zn (II) complexes were synthesised and characterized by spectroscopic and analytical methods. Molecular structures of complexes [Mn(L‐C¹¹)Cl₂] and [Zn(L‐C¹¹)Cl₂] were evaluated by X‐ray diffraction studies. The X‐ray data showed metal ions in both complexes are five‐coordinate with distorted square pyramidal geometry around the metal centres. The undecyl chains in the structure of the complexes are aligned in an interdigitated manner (head to tail) forming a non‐polar domain. The aggregation properties of the ligand and its complexes were investigated by UV–Vis. absorption and emission spectroscopies in DMF‐water mixtures. The emission spectral data revealed that the compounds showed aggregation induced quenching (AIQ) in DMF‐water solutions. Moreover, thermal properties of the compounds were investigated by TG, DTG and DSC analysis.     

[2-(N,N-Dimethylaminomethyl)ferrocenyl] as a ligand towards mercury

The diorganomercurial bis[2-(N,N-dimethylaminomethyl)ferrocenyl]mercury(II), (FcN)₂Hg (3), can be obtained by the symmetrisation of the heteroleptic (FcN)HgCl (2) with Na₂S₂O₃ or in the transmetallation reaction of 2 with (FcN)Li. By crystallisation only the crystals of rac-(FcN)₂Hg were obtained. X-ray diffraction analysis revealed linear coordinated mercury atom with two η¹-bonded FcN ligands. Additionally, weak chelate interactions exist between mercury and nitrogen atoms of the ---CH₂NMe₂ side chains. According to the ¹H-NMR findings, these interactions are not preserved in solution. Diorganomercurial 3 appears in solution as a mixture of two diastereomers with rac/meso-(FcN)₂Hg ratio of 1:1. This diastereomeric ratio in solution remains constant within a wide temperature range and in different solvents. The NMR spectroscopic data of the heteroleptic organomercurials [(FcN)HgCl]₂·H₂O (1) and (FcN)HgCl (2) indicate the chelate-free structure of this compounds in solution within the studied temperature interval (−80 to 90 °C).     

Preparation and Spectral Investigation of Bis[N(2-methyl-phenyl) 4-Nitro-thiobenzamidato] mercury(II), Bis[N(2-methoxy-phenyl) 4-Nitro-thiobenzamidato]mercury(II), and Bis[N(2-chloro-phenyl) 4-Nitro-thiobenzamidato]mercury(II) Complexes

Several preparative routes to bis[N(substituted-phenyl) 4-nitro-thiobenzamidato] mercury(II) complexes are presented, including the reaction of mercury(II) oxide, fluoride, chloride, bromide, cyanide, acetate, and nitrate with N(substituted-phenyl) 4-nitro-thiobenzamide derivatives. ¹ H-NMR, Raman, and IR measurements confirmed the complexation of mercury to sulphur.     

Crystal engineering with 2,1,3-benzoselenadiazole and mercury(II) chloride

The reactions of HgCl₂ with 2,1,3-benzoselenadiazole (bsd) in methanol afforded the polymeric complexes [HgCl₂(bsd)₂]_n (1) and [HgCl₂bsd]_n (2) in good yields. The crystal structures of 1 and 2 have been determined by single-crystal X-ray crystallography. Complex 1 is an one-dimensional (1D) polymer and consists of (HgCl₂)_n chains running parallel to the c-axes. Complex 2 is a two-dimensional (2D) polymer and consists of (HgCl₂)_n chains running parallel to the a-axes and being further bridged by bsd molecules to create a layer lying parallel to the ab plane. Both crystal structures are dominated by π···π interactions between the bsd molecules, while the presence of N···Se interactions increases the dimensionality in 1. Characteristic IR data are discussed in terms of the nature of bonding in the structures of the two complexes.     

New organometallic Ru(II) and Fe(II) complexes with tetrathia-[7]-helicene derivative ligands

A series of organometallic complexes possessing new tetrathia-[7]-helicene nitrile derivative ligands [TH-7] as chromophores, of general formula [MCp(P–P)(NC{TH-[7]-Y}Z)][PF₆] (M = Ru, Fe, P–P = DPPE, Y = H, NO₂, Z = H, C≡N; M = Ru, L–L = 2PPh₃, Y = H, Z = H) has been synthesized and fully characterized. ¹H NMR, FT-IR and UV–Vis. spectroscopic data were analyzed with in order to evaluate the existence of electronic delocalization from the metal centre to the coordinated ligand to have some insight on the potentialities of these new compounds as non-linear optical molecular materials. Slow crystallization of compound [RuCp(PPh₃)₂(NC{TH-[7]-H}H)][PF₆] 2Ru revealed an interesting isomerization of the helical ligand with formation of two carbon-carbon bonds between the two terminal thiophenes, leading to the total closure of the helix (2*Ru).     

X-ray crystal structure and spectral characterization of pseudo five-coordinate Hg(II) polymeric and four-coordinate binuclear complexes of an ambidentate sulfonium ylide

The reaction of ambidentate sulfonium ylide (Me)₂SCHC(O)C₆H₄-p-OCH₃(Y) with HgX₂ [X = Cl (1), Br (2) and I (3)] in equimolar ratios using methanol as the solvent leads to two types of products. Single-crystal X-ray diffraction analysis reveals (i) a two-dimensional polymer, [{HgCl₂(Y)}₄]_n, in which the mercury(II) atom is five-coordinated and ligand Y displays C-coordination as well as an additional interaction, including O-coordination to different mercury centers and (ii) an asymmetric halide-bridged binuclear structure of the type [HgBr₂(Y)]₂, in which the mercury(II) center is four-coordinate and ligand Y displays C-coordination to the metal. The characterization of these compounds by IR, ¹H- and ¹³C NMR spectroscopy confirms the coordination of the ylide to the metal through the carbon atom. Analytical data indicate a 1:1 stoichiometry between the ylide and the Hg(II) halide in all complexes.     

Crystal structure of tris[(2.2.2-cryptand)× (nitrato-O,O′)lead(II)] pentakis(nitrato-O,O′)lead(II)

A novel coordination compound tris[(2.2.2-cryptand)(nitrato-O,O′)lead(II)] pentakis(nitrato-O, O′)lead(II), 3[Pb(NO₃)(Crypt-222)]⁺·[Pb(NO₃)₅]^3? (I) has been prepared and studied by the single crystal X-ray diffraction technique. The crystals of I are monoclinic: space group Pc, a = 25.944 Å, b = 18.389 Å, c = 17.145 Å, β = 93.33°, Z = 4. The structure of I has been solved by the direct and heavy atom methods and refined in a full-matrix anisotropic-isotropic approximation to R = 0.122 for the total of 11145 measured reflections (automated diffractometer CAD-4, λMoK _α). The structure of I includes six independent host-guest complex cations [Pb(NO₃)(Crypt-222)]⁺ and two independent complex anions [Pb(NO₃)₅]^3?. Coordination number of the cation Pb²⁺ equals ten in all these complex ions, and its coordination polyhedron in the first of them is a strongly distorted “hexagonal bipyramid” with two forked vertices, while for the latter ones it is a strongly distorted “square pyramid” with all five vertices forked.     

Synthesis,structures, and characterization of copper(II), nickel(II), and cobalt(III) metal complexes derived from an asymmetric bidentate Schiff-base ligand

An asymmetric bidentate Schiff-base ligand (2-hydroxybenzyl-2-furylmethyl)imine (L–OH) was prepared. Three complexes derived from L–OH were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of metallic salt. Three complexes, Cu₂(L–O^?)₂Cl₂ (1), Ni(L–O^?)₂ (2) and Co(L–O^?)₃ (3), have been structurally characterized through elemental analysis, IR, UV spectra and thermogravimetric analysis. Single crystal X-ray diffraction shows metal ions and ligands reacted with different proportions 1?:?1, 1?:?2 and 1?:?3, respectively, so copper(II), nickel(II), and cobalt(III) have different geometries.