Synthesis of mono and doubly alkynyl substituted ferrocene and its crystal engineering using -C-H···O supramolecular synthon

Mono and doubly alkynyl substituted ferrocene complexes, [Fc(CH₂OCH₂CCH)_n], 2-3 (2: n = 1; 3: n = 2; Fc = ferrocene) have been synthesized from the room temperature reaction of mono and 1,1′-dihydroxymethyl ferrocene, Fc(CH₂OH)_n , 1a-b (1a: n = 1; 1b: n = 2) and propargyl bromide, in modest to good yields. These new ferrocene derivatives have been characterized by mass, IR, ¹H, ¹³C NMR spectroscopy, and molecular structures of compound 2 and 3 were unequivocally established by single crystal X-ray diffraction study. The crystal structure analysis revealed that 2 and 3 consist of infinite 1D zig-zag hydrogen bonded chains and 2D microporous hydrogen bonded network of molecules, linked by intermolecular C-H···O hydrogen bonding. The molecular structures of both 2 and 3 are further stabilized by C-H···π interactions.     

Metal complexes derived from hydrazoneoxime ligands: IV. Molecular and supramolecular structures of some nickel(II) complexes derived from diacetylmonoxime S-benzyldithiocarbazonate

Four new nickel(II) complexes, [{Ni(L)}₂], [NiL · HPyr], [NiL · HIm] and [Ni(HL)₂] · H₂O, derived from diacetylmonoxime-S-benzyldithiocarbazonate (H₂L) have been synthesized and characterized by elemental analyses, field desorption and electrospray ionization mass spectra, UV–Vis, infrared absorption spectra, as well as ¹H NMR spectra. X-ray molecular structures showed that the Ni(II) in both [NiL · HPyr] and [NiL · HIm] are in a distorted square planar environment and is coordinated to the dianionic NNS tridentate hydrazoneoxime ligand via deprotonated oximate nitrogen, hydrazone imine nitrogen, and thiolate sulphur. The fourth coordination sites are occupied, respectively, by the pyrazole and imidazole nitrogens. The oximate O1 of [NiL · HPyr] is involved in intramolecular hydrogen bond with the pyrazole NH proton as well as intermolecular hydrogen bond pyrazole C6H proton, forming a helical chain propagating along the b-axis. The structure is stabilized by a set of π?π and CH?π interactions. The molecular units in [NiL · HIm] are linked together by hydrogen bond formation between the oximate oxygen and imidazole NH proton, giving rise to an infinite zigzag chain extended along the a-axis. The chains are interconnected by π?π and CH?O interactions. In [Ni(HL)₂] · H₂O, the Ni(II) is in a distorted octahedral environment. The two mononegative hydrazoneoxime ligands are coordinated in the meridional configuration where the two thiol sulphur atoms and the two oxime nitrogen atoms are cis to each other, while the imine nitrogen atoms are trans. The oxime proton O2H is involved in a reciprocal bifurcated hydrogen bond formation with both N2 and S3 of the adjacent molecule giving rise to hydrogen bonded dimer. This dimeric structure is further stabilized by a pair of reciprocal CH?O interactions. A one dimensional chain of alternating dimeric unit and water molecule propagating along the c-axis is formed via hydrogen bond formation between the oxime O1 oxygen and the bridged water molecule proton.     

Novel silver(I)-saccharinate complexes exhibiting Ag···π and C-H···Ag close interactions with a new coordination mode of saccharinate

Two novel silver(I) complexes, namely [Ag₂(μ₃-sac)₂(μ-nmpen)]_n (1) and [Ag(sac)(mpr)]₂ (2) (sac = saccharinate; nmpen = N-methyl-1,3-propanediamine; mpr = 2-methyl-1-pyrroline) have been synthesized and characterized by IR spectra, thermal (TG, DTG and DTA) analysis and single crystal X-ray diffraction techniques. Complexes crystallize in the monoclinic system with the space group C2/c and P2₁/c, respectively. In 1, Ag(I) ion exhibits a distorted tetrahedral geometry by tridentate μ₃-bridging sac and μ₂-bridging nmpen ligands. The sac ligand exhibits a new μ₃-coordination mode by means of μ₂-bridging O atom of sulfonyl group and N atom of imino group. Furthermore, complex 1 exhibits a two-dimensional polynuclear structure. In 2, the silver(I) ion is linearly coordinated by the N atoms of a sac and a mpr ligands, forming mononuclear species. The individual molecules are linked into dimers by Ag···C_sac (η¹) interactions between silver(I) ion and phenyl ring of the adjacent complex and these dimers are assembled into two-dimensional layered networks through weak Ag···Ag (3.507 Å), SO···Ag (2.961 Å) and π···π interactions. The most interesting structural features of complexes is the presence of obvious C-H···M hydrogen-bonding interactions between the Ag centers and H atoms of nmpen or mpr ligands.     

Supramolecular assemblies in the crystals of carboxylate salts prepared from a ferrocene β-aminoalcohol

(Ferrocenylmethyl)(2-hydroxyethyl)amine (1) reacts with mono- (CH₃CO₂H and PhCO₂H) and dicarboxylic acids (HO₂C(CH₂)_nCO₂H (n = 0-2), (E)- and (Z)-HO₂CCHCHCO₂H) to give the respective carboxylates, viz [1H](RCO₂) (2, R = CH₃; 3, R = Ph), [1H]₂(O₂C(CH₂)_nCO₂) (4, n = 0; 5, n = 1; 6, n = 2), [1H]₂((E)-O₂CCHCHCO₂) (7) and [1H]₂((Z)-HO₂CCHCHCO₂) (8), as defined crystalline solids. Crystal structures of 2-8 have been determined by single-crystal X-ray diffraction analysis, revealing extensive hydrogen bonding interactions based predominantly on charge-supported N⁺-H···O⁻ and O-H···O⁻ hydrogen bonds, and on C-H···O contacts. Whereas the crystal assemblies of the monocarboxylate salts propagate preferentially in one dimension (2: cross-linked chains, 3: columnar stacks), those of the salts prepared from the dicarboxylic acids (including hydrogenmaleate 8) are best described as layered composite arrays resulting via alternation of polar, hydrogen-bonded layers and of non-polar sheets constituted by the ferrocenyl substituents.     

Synthesis and structural characterization of metal complexes based on pyrazole/imidazolium chlorides

A series of imidzoalium salt, L · HCl, for the potentially bidentate pyrazole/N-heterocyclic carbene was synthesized. Reactions of a 2:1 mixture between L · HCl bearing bulky N-substitution and Ag₂O produced Ag(L)Cl, whereas a novel compound with unique stoichiometry AgL₂(AgCl)_0.5Cl was produced from L · HCl bearing N-methyl group under identical condition. Reactions of L · HCl with PdCl₂ produced zwitterionic Pd^IICl₃L · H. Selected structural determinations on L · HCl, Ag(L)Cl, AgL₂(AgCl)_0.5Cl, and Pd^IICl₃L · H revealed intriguing crystal chemistry in which the less-stable gauche rotamers were obtained exclusively. A preliminary application of the zwitterionic complexes, Pd^IICl₃L · H, in Heck coupling reaction of aryl bromide with n-butyl acrylate shows effective activity.     

Synthesis of ferrocenoyl amino acid derivatives via homogeneous catalytic aminocarbonylation

Palladium-catalysed aminocarbonylation of iodoferrocene with amino acid esters as nucleophiles results in the selective formation of N-ferrocenoyl amino acid esters in the presence of Et₃N as the base. At the same time, the use of DBU leads to the formation of new N-ferrocenylglyoxyl amino acid derivatives with reasonable selectivity. In the latter reactions two new side products, formed via acylation of DBU, were also isolated and characterised.     

[Zn(μ-l)Cl2]∞: a one-dimensional (1-D) zigzag coordination chain exhibiting unique two-dimensional (2D) hydrogen-bonding supramolecular architecture

Self-assembly of the versatile bridging ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (l) with ZnCl₂ in CHCl₃-H₂O medium affords a neutral one-dimensional zigzag coordination polymer [Zn(μ-l)Cl₂]_∞ (1), which has been characterized by IR, elemental analyses, thermogravimetric analysis (TGA) and X-ray diffraction techniques. The crystal structure of 1 reveals that the ligand molecules bridge the tetrahedral Zn^II centers (ZnN₂Cl₂) in the unprecedented transoid conformation, forming a one-dimensional zigzag coordination chain. The inter-chain C-H···Cl hydrogen bonds between the pyridine rings and the coordinated chloride anions extend these 1-D coordination frameworks to result in a novel 2-D supramolecular architecture, and there exist significant edge-to-edge π-π stacking interactions between the inter-chain neighboring pyridyl rings of the ligand, which may further stabilize this structure.     

Two-stage formation of chloro (N-o-chlorobenzamido-meso-tetraphenylporphyrinato) zinc(II) methylene chloride solvate: Zn(N-NHCO(o-Cl)C6H4-tpp)Cl · CH2Cl2

The coordinating properties of N-o-chlorobenzamido-meso-tetraphenylporphyrin (N-NHCO(o-Cl)C₆H₄-Htpp; 11) have been investigated for the Zn²⁺ ion. Insertion of Zn results in the formation of the zinc complex Zn(N-NCO(o-Cl)C₆H₄-tpp)(MeOH) · MeOH (12 · MeOH). The diamagnetic 12 · MeOH can be transformed into the diamagnetic Zn(N-NHCO(o-Cl)C₆H₄-tpp)Cl · CH₂Cl₂ (13 · CH₂Cl₂) in a reaction with aqueous hydrogen chloride (2%). X-ray structures for 12 · MeOH and 13 · CH₂Cl₂ have been determined. The coordination sphere around the Zn²⁺ ion in 12 · MeOH is a distorted trigonal bipyramid with N(2), N(4) and O(2) lying in the equatorial plane, whereas for the Zn²⁺ ion in 13 · CH₂Cl₂, it is a square-based pyramid in which the apical site is occupied by the Cl(1) atom.     

The synthesis, structural characterization and in vitro anti-cancer activity of novel N-(3-ferrocenyl-2-naphthoyl) dipeptide ethyl esters and novel N-(6-ferrocenyl-2-naphthoyl) dipeptide ethyl esters

N-(3-ferrocenyl-2-naphthoyl) dipeptide esters (5-7) and N-(6-ferrocenyl-2-naphthoyl) dipeptide esters (8-10) were prepared by coupling either 3-ferrocenylnaphthalene-2-carboxylic acid 2 or 6-ferrocenylnaphthalene-2-carboxylic acid 4 to the dipeptide ethyl esters GlyAla(OEt) (5, 8), AlaGly(OEt) (6, 9), and AlaAla(OEt) (7, 10) using the standard N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), 1-hydroxybenzotriazole (HOBt) protocol. All the compounds were fully characterized using a combination of ¹H NMR, ¹³C NMR, DEPT-135 and ¹H-¹³C COSY (HMQC) spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and cyclic voltammetry (CV). In vitro, the cytotoxic effects of compounds 5-10 show improvements over the corresponding N-(ferrocenyl)benzoyl derivatives, with IC₅₀ values against the H1299 lung cancer cells ranging from 1.2 μM to 8.0 μM. N-(6-ferrocenyl-2-naphthoyl)-glycine-l-alanine ethyl ester 8 was found to be the most active derivative of the naphthoyl series so far, displaying an IC₅₀ value of 1.3 ± 0.1 μM. This value is slightly lower than that found for the clinically employed anti-cancer drug cisplatin (IC₅₀ = 1.5 ± 0.1 μM against H1299).     

An unprecedented coordination mode of the orotate ligand in novel polynuclear cadmium(II)–orotate complexes

Two novel carboxylate-bridged Cd(II)–orotate polynuclear complexes with 2-(2-ethylamino)pyridine (2-etapy), [Cd(μ-HOr)(2-etapy)]_n (1), and N,N-diethylethylenediamine (N,N-eten) ligands, {[Cd(μ-HOr)(H₂O)(N,N-eten)]·H₂O}_n (2) (H₃Or = orotic acid), have been synthesized and characterized by TGA–evolved gas analysis (TGA–EGA), IR spectroscopy and single crystal X-ray diffraction techniques. The orotate ligand acts as a bridging ligand with two different coordination modes, showing an unprecedented tetradentate coordination mode. The HOr ligand simultaneously chelates Cd(II) ions through the carboxylate oxygen, deprotonated pyrimidine nitrogen atoms and carboxyl oxygen atoms as a tetradentate ligand in 1. In complex 2, the HOr ligand bridges two Cd(II) ions through the carboxylate oxygen and deprotonated pyrimidine nitrogen atoms and oxygen atom of a carboxylate group of a neighbouring complex unit. Three-dimensional (3D) supramolecular structures are generated by hydrogen-bonding, and π···π and C–H···π interactions between the closest chains in both complexes.     

Preparation,spectroscopic characterization and X-ray crystal and molecular structures of nickel(II), copper(II) and zinc(II) complexes of the Schiff base formed from isatin and S-methyldithiocarbazate (Hisa-sme)

Complexes of general formula, [M(isa-sme)₂] · n(solvate) [M = Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺; isa-sme = monoanionic form of the Schiff base formed by condensation of isatin with S-methyldithiocarbazate; n = 1 or 1.5; solvate = MeCN, DMSO, MeOH or H₂O] have been synthesized and characterized by a variety of physicochemical techniques. An X-ray crystallographic structure determination of the [Ni(isa-sme)₂] · MeCN complex reveals a six-coordinate, distorted octahedral geometry. The two uninegatively charged, tridentate, Schiff base ligands are coordinated to the nickel(II) ion meridionally via the amide O-atoms, the azomethine N-atoms and the thiolate S-atoms. By contrast, the crystal structure of [Zn(isa-sme)₂] · MeOH shows a four-coordinate distorted tetrahedral geometry. The two dithiocarbazate ligands are coordinated as N, S bidentate chelates with the amide O-atom not coordinated. The structure of the copper(II) complex [Cu(isa-sme)₂] · DMSO is complicated and comprises two different complexes in the asymmetric unit, one four- and the other five-coordinate. The four-coordinate copper(II) has a distorted (flattened) tetrahedral geometry as seen in the Zn(II) analogue whereas the five-coordinate copper(II) has a distorted square-pyramidal geometry with one ligand coordinated to the copper(II) ion as a tridentate (N, S, O) ligand and the other coordinated as a bidentate N, S chelate. EPR spectroscopy indicates that in solution only one form is present, that being a distorted tetrahedral complex.     

N-[1-(Benzotriazol-1-yl)alkyl]amides from N-acyl-α-amino acids or N-alkylamides

A variety of N-(1-methoxyalkyl)amides react with benzotriazole in the presence of PPh₃·HBF₄ and organic bases (Hünig's base, DBU or DABCO) or solid-state-supported bases (SiO₂-Pip or IRA-67) in CHCl₃ to give N-[1-(benzotriazol-1-yl)alkyl]amides in good yields. The most convenient and efficient procedure for obtaining N-[1-(benzotriazol-1-yl)alkyl]amides consists, however, of the addition of benzotriazole sodium salt to a solution of crude 1-(N-acylamino)alkyltriphenylphosphonium salt, obtained in situ from N-(1-methoxyalkyl)amides and PPh₃·HBF₄. A combination of these reactions with the recently described electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids in the presence of SiO₂-Pip enables an effective two-pot transformation of N-acyl-α-amino acids to N-[1-(benzotriazol-1-yl)alkyl]amides.     

Uranyl ion complexes with long chain aminoalcoholbis(phenolate) [O,N,O,O′] donor ligands

The reaction between uranyl nitrate hexahydrate and phenolic ligand precursor [(N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-4-amino-1-butanol) · HCl], H₃L1 · HCl, leads to a uranyl complex [UO₂(H₂L1)₂] (1a) and [UO₂(H₂L1)₂] · 2CH₃CN (1b). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-4-amino-1-butanol)H₃L2 · HCl], H₃L2 · HCl, yields a uranyl complex with a formula [UO₂(H₂L2)₂] · CH₃CN (2). The ligand [(N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-5-amino-1-pentanol) · HCl], H₃L3 · HCl, produces a uranyl complex with a formula [UO₂(H₂L3)₂] · 2CH₃CN (3) and the ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-5-amino-1-pentanol) · HCl], H₃L4 · HCl, leads to a uranyl complex with a formula [UO₂(H₂L4)₂] · 2CH₃CN (4). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-6-amino-1-hexanol) · HCl], H₃L5 · HCl, leads to a uranyl complex with a formula [UO₂(H₂L5)₂] · 4toluene (5). The complexes 1–5 are obtained using a molar ratio of 1:2 (U to L) in the presence of a base (triethylamine). The molecular structures of 1a, 1b, 3, 4 and 5 were verified by X-ray crystallography. All complexes are neutral zwitterions and have similar centrosymmetric, mononuclear, distorted octahedral uranyl structures with the four coordinating phenoxo ligands in an equatorial plane. In uranyl ion extraction studies from water to dichloromethane with ligands H₃L1 · HCl–H₃L5 · HCl, ligands H₃L1 · HCl, H₃L4 · HCl and H₃L5 · HCl are the most effective ones.     

Co(II), Ni(II) and Zn(II)-orotate complexes with N-methylimidazole: Synthesis, crystal structures and antimicrobial activities

Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV-Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H₂O)₂(Nmeim)₂]₃·H₂O (1), [Ni(HOr)(H₂O)₂(Nmeim)₂] (2) and [Zn(HOr)(H₂O)(Nmeim)₂] (3) were determined by the single crystal X-ray diffraction technique (H₃Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C-H?π and π?π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300-2400 μg/mL.     

A simple procedure for the esterification of alcohols with sodium carboxylate salts using 1-tosylimidazole (TsIm)

An efficient and selective method for esterification of alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of RCO₂Na (R: alkyl and aryl), TsIm, and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in DMF to afford the corresponding esters in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.     

Aminoalkylbis(phenolate) [O,N,O] donor ligands for uranyl(VI) ion coordination: Syntheses,structures, and extraction studies

The syntheses of five new aminoalkylbis(phenolate) ligands (as hydrochlorides) and their uranyl complexes are described. The reaction between uranyl nitrate hexahydrate and phenolic ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-1-aminopropane) · HCl], H₂L1 · HCl, forms a uranyl complex [UO₂(HL1)₂] · 2CH₃CN (1). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-1-aminobutane) · HCl], H₂L2 · HCl, forms a uranyl complex with a formula [UO₂(HL2)₂] · 2CH₃CN (2). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methyl benzyl)-1-aminohexane) · HCl], H₂L3 · HCl, yields a uranyl complex with a formula [UO₂(HL3)₂] · 2CH₃CN (3) and the ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-cyclohexylamine) · HCl], H₂L4 · HCl, yields a uranyl complex with a formula [UO₂(HL4)₂] (4). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-benzylamine) · HCl], H₂L5 · HCl, forms a uranyl complex with a formula [UO₂(HL5)₂] · 2MeOH (5). The molecular structures of 1, 2′ (2 without methanol), 3, 4 and 5 were verified by X-ray crystallography. The complexes 1–5 are neutral zwitterions which form in a molar ratio of 1:2 (U to L) in the presence of a base (triethylamine) and bear similar mononuclear, distorted octahedral uranyl structures with the four coordinating phenoxo ligands forming an equatorial plane and resulting in a centrosymmetric structure for the uranyl ion. In uranyl ion extraction studies from water to dichloromethane with ligands H₂L1 · HCl–H₂L5 · HCl, the ligands H₂L2 · HCl and H₂L4 · HCl are the most effective ones.     

Reactivity of M(en)Cl2 (M = Pd/Pt,en = 1,2-diaminoethane) with N,N′-bis(salicylidene)-p-phenylenediamine: Binding with hexafluorobenzene

Schiff base N,N′-bis(salicylidene)-p-phenylenediamine (LH₂) complexed with Pt(en)Cl₂ and Pd(en)Cl₂ provided [Pt(en)L]₂ · 4PF₆ (1) and Pd(Salen) (2) (Salen = N,N′-bis(salicylidene)-ethylenediamine), respectively, which were characterized by their elemental analysis, spectroscopic data and X-ray data. A solid complex obtained by the reaction of hexafluorobenzene (hfb) with the representative complex 1 has been isolated and characterized as 3 (1 · hfb) using UV–Vis, NMR (¹H, ¹³C and ¹⁹F) data. A solid complex of hfb with a reported Zn-cyclophane 4 has also been prepared and characterized 5 (4 · hfb) for comparison with complex 3. The association of hfb with 1 and 4 has also been monitored using UV–Vis and luminescence data.     

The structures of (phenylato)(N-2-thiophenecarboxamido-meso-tetraphenylporphyrinato)mercury(II) and bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin

The reaction of PhHgOAc with N-NHCO-2-C₄H₃S-Htpp (5) and N-p-HNSO2C6H4^tBu-Htpp (4) gave a mercury (II) complex of (phenylato) (N-2-thiophenecarboxamido-meso-tetra phenylporphyrinato)mercury(II) 1.5 methylene chloride solvate [HgPh(N-NHCO-2-C₄H₃S-tpp) · CH₂Cl₂ · 0.5C₆H₁₄;  6 · CH₂Cl₂ · 0.5C₆H₁₄] and a bismercury complex of bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin, [(HgPh)2(N-p-NSO₂C₆H₄^tBu-tpp); 7], respectively. The crystal structures of 6 · CH₂Cl₂ · 0.5C₆H₁₄ and 7 were determined. The coordination sphere around Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 is a sitting-atop derivative with a seesaw geometry, whereas for the Hg(1) in 7, it is a linear coordination geometry. Both Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 acquire 4-coordination with four strong bonds [Hg(1)–N(1) = 2.586(3) Å, Hg(1)–N(2) = 2.118(3) Å, Hg(1)–N(3) = 2.625(3) Å, and Hg(1)–C(50) = 2.049(4) Å for 6 · CH₂Cl₂ · 0.5C₆H₁₄; Hg(2)–N(1) = 2.566(6) Å, Hg(2)–N(2) = 2.155(6) Å, Hg(2)–N() = 2.583(6) Å, and Hg(2)–C(61) = 2.064(7) Å for 7]. The plane of the three pyrrole nitrogen atoms [i.e., N(1)–N(3)] strongly bonded to Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and to Hg(2) in 7 is adopted as a reference plane 3N. For the Hg²⁺ complex in 6 · CH₂Cl₂ · 0.5C₆H₁₄, the pyrrole nitrogen bonded to the 2-thiophenecarboxamido ligand lies in a plane with a dihedral angle of 33.4° with respect to the 3N plane, but for the bismercury(II) complex in 7, the corresponding dihedral angle for the pyrrole nitrogen bonded to the NSO₂C₆H₄^tBu group is found to be 42.9°. In the former complex, Hg(1)²⁺ and N(5) are located on different sides at 1.47 and −1.29 Å from its 3N plane, and in the latter one, Hg(2)²⁺ and N(5) are also located on different sides at −1.49 and 1.36 Å form its 3N plane. The Hg(1)?Hg(2) distance in 7 is 3.622(6) Å. Hence, no metallophilic Hg(II)?Hg(II) interaction may be anticipated. NOE difference spectroscopy, HMQC and HMBC were employed to unambiguous assignment for the ¹H and ¹³C NMR resonances of 6 · CH₂Cl₂ ·  0.5C₆H₁₄ in CD₂Cl₂ and 7 in CDCl₃ at 20 °C. The ¹⁹⁹Hg chemical shift δ for a 0.05 M solution of 7 in CDCl₃ solution is observed at −1074 ppm for Hg(2) nucleus with a coordination number of four and at −1191 ppm for Hg(1) nucleus with a coordination number of two. The former resonance is consistent with that chemical shift for a 0.01 M solution of 6 in CD₂Cl₂ having observed at −1108 ppm for Hg(1) nucleus with a coordination number of four.     

Apparent molar volumes and apparent molar heat capacities of aqueous N-acetyl-d-glucosamine at temperatures from 278.15 K to 368.15 K and of aqueous N-methylacetamide at temperatures from 278.15 K to 393.15 K at the pressure 0.35 MPa

We determined apparent molar volumes V_? from densities measured with a vibrating-tube densimeter at 278.15 ? (T/K) ? 368.15 and apparent molar heat capacities C_p,? with a twin fixed-cell, differential, temperature-scanning calorimeter at 278.15 ? (T/K) ? 363.15 for aqueous solutions of N-acetyl-d-glucosamine at m from (0.01 to 1.0) mol · kg⁻¹ and at p = 0.35 MPa. We also determined V_? at 278.15 ? (T/K) ? 368.15 and C_p,? at 278.15 ? (T/K) ? 393.15 for aqueous solutions of N-methylacetamide at m from (0.015 to 1.0) mol · kg⁻¹ and at p = 0.35 MPa. Empirical functions of m and T for each compound were fitted to our results, which are then compared to those for N,N-dimethylacetamide. Estimated values of Δ_rV_m(m, T) and Δ_rC_p,m(m, T) for formation of aqueous N-acetyl-d-glucosamine from aqueous d-glucose and aqueous acetamide are calculated and discussed.     

On the influence of the heterocyclic ring substituents on the structure of dimethylthallium pyrimidine-2-thionato complexes. Crystal structure of dimethyl-(4-trifluoromethylpyrimidine-2-thionate)thallium(III): a compound with intermolecular C-H ? π interactions

The complex [Me₂Tl(4-CF₃pymS)] has been prepared by reacting 4-trifluoromethylpyrimidine-2-thione (4-CF₃pymSH) with dimethylthallium(III) hydroxide in methanol. The resulting compound has a polymeric chain structure, with the thallium atom coordinated by two nitrogen and two sulfur atoms from two different ligands, which act as bridges between two metal atoms, as well as by two carbon atoms of the methyl groups. An intermolecular C-H ? π interaction is observed between an H atom of each methyl group and one of the pyrimidine rings of the neighbouring chain. The structure of the complex is discussed in terms of the IR absorptions, the ¹H, ¹³C and ²⁰⁵Tl NMR spectra and FAB data.