Z. Kosturkiewicz

Four-coordinate copper(I) iodide complexes with triphenylphosphine and heterocyclic thione ligands. The crystal structure of [Cu(PPh3)2(pymtH)I]

Abstract [Cu(PPh3)I]4 reacts with heterocyclic thiones (L) [L = pyrimidine-2-thione (pymtH), 1,3-thiazoline-2-thione (tzdtH), 1,3-imidazoline-2-thione (imtH), benz-1,3-imidazoline-2-thione (bzimtH2) and benz-1,3-thiazoline-2-thione (bztztH)] in the presence of triphenylphosphine to give mononuclear complexes of the general formula [Cu(PPh3)2 (L)I]. These complexes have been characterized by various physicochemical methods. The crystal structure of [Cu(PPh3)2(pymtH)I] has been determined by single-crystal X-ray diffraction methods. The molecule is mononuclear, with a distorted tetrahedral geometry and bond lengths CuS = 2.338(4), CuI = 2.674(2), CuP = 2.296(4) and 2.303(4) A.

Conformational analysis of N-methylpiperidine betaine studied by X-ray diffraction, FTIR spectroscopy and ab initio calculations

Abstract N-methylpiperidine betaine crystallized either as anhydrous or monohydrate. The crystal of the anhydrous form are monoclinic, space group C2/c, a =18.512(2) A, b =11.3017(10) A, c =9.2212(10) A, β=118.48(1) o . The molecule in crystals has a conformation with the N + ⋯O intermolecular distance of ca. 2.90 A. Structures of isolated molecule optimized with BLYP and MP2 methods are very similar to this observed in the crystal.

X-ray, FT-IR and PM3 studies of hydrogen bonds in complexes of some pyridines with trifluoroacetic acid

Abstract The crystal structures of trifluoroacetic acid complexes with 4-NMe 2 -, 4-Me- and 4-CN-pyridines were determined by X-ray analysis; the NH⋯O bonds are 2.724(3), 2.702(4) and 2.587(5) A respectively. The H-bonds are nearly linear for 4-NMe 2 , 177(4)°; 4-Me, 177(4)°; and 4-CN, 174(6)°. IR spectra (Nujol) show continuous absorption, whose intensity decreases with elongation of the H-bond length. The continuous absorption is not observed in D 2 O spectra. The solid-state spectra in the 1700 cm −1 region are more complex than those in D 2 O; the characteristic overtones of the pyridine rings borrow intensity from the continuous absorption via Fermi resonance. The overtones indicate modified structure in the 1700 cm −1 region. The results of both diffraction and FT-IR experiments are comparable. The structural parameters of the complexes were also determined by quantum-mechanical calculations with the semiempirical MNDO—PM3 method. A solvent effect was taken into account using a self-consistent reaction field theory.

On the molecular structure of gold(I) complexes with heterocyclic thiones. The structure of bis(1,3-thiazolidine-2-thione) gold(I) chloride hydrate

Abstract The preparation of a seies of gold(I) coordination compounds with heterocyclic thiones is reported. The crystal structure of the coordination compound with 1,3-thiazolidine-2-thione (tztH) was determined. The S—Au—S angle is 176.52(2)° and the two Au—S distances are 2.281(5) and 2.288(5) A, respectively, giving rise to the usual linear gold(I) environment. Extended Huckel computations on both the model and the observed Au(thione)2 cationic unit are used in an attempt to unravel the factors influencing the local and overall molecular structure observed, which is determined by an extended hydrogen-bond network. On the grounds of these computations and the existing strutural evidence, it is concluded that hydrogen bonds formed by the coordinated thione ligands determine the geometry adopted by these and analogous compounds.

Reaction of acylaminocyanoesters with 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide leading to substituted aminothiazoles. Crysta

Abstract 2-Acylamino-2-cyanoacetic acid ethyl esters 2a-c react with 2,4-bis (4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane 2,4-disulfide 1 in refluxing benzene with formation of 2-alkyl(aryl)-5-aminothiazole-4-carboxylic acid ethyl esters 3a-c . Structure 3 was established by spectroscopic means and an X ray crystallographic investigation of 3a . X-Ray analysis revealed that the thiazole ring, exocyclic nitrogen and carbonyl group forming a hydrogen-bonded cycle are nearly coplanar. A resonance interaction is manifested by distinctly shortened /1.447 (3)/ C(carbonyl)-C(thiazole) distance.

Hydrogen bonds in 1:2 complexes of substituted pyridine N-oxides with pentachlorophenol

Abstract Pyridine N-oxides form two types of crystalline complexes with phentachlorophenol, with 1:1 and 1:2 base-to-acid ratios. The 1:2 complex of 2,6-dimethylpyridine N-oxide with pentachlorophenol crystallizes in space group P1 with a = 7.335(1) A , b = 11.324(2) A , c = 15.824(2) A , α = 100.38(1)°, β = 94.63(1)°, γ = 106.60(1)°, V = 1226.7(6) A 3 and Z = 2. The structure has been refined to R = 0.046 for 3408 observed Mo Kα reflections. The oxygen atom of the N-oxide group accepts hydrogen bonds from two molecules of pentachlorophenol, with Otctdot;O distances of 2.639(5) and 2.642(5) A and OHO angles of 141.2° and 157.6°, respectively. Both NOtctdot;HO bridges are formed in, or near, the directions of the electron lone-pairs of the N-oxygen atom. The two pentachlorophenol rings (A and B) are nearly parallel to each other and they are almost perpendicular to the pyridine ring. FTIR spectra of eleven 1:2 complexes in the solid state are similar and independent of the proton acceptor properties of the N-oxides. Five lines in the 35 Cl NQR spectra of the 1:2 complexes provide evidence that both molecules of pentachlorophenol are equivalent. In CHCl 3 solution, all the 1:2 complexes exist as a mixture of the 1:1 complex and pentachlorophenol.

FT-IR, UV—visible and X-ray studies of complexes of pyridine N-oxides with pentachlorophenol

Abstract The crystal structure of the 4-methoxy-2,6-dimethylpyridine N -oxide·pentachlorophenol complex has been determined by X-ray analysis. The O ··· O distance is 2.439(6) A, the OHO angle is 152.3° and the hydrogen-bonded proton is close to the phenol molecule. The FT-IR spectra of pentachlorophenol complexes with some substituted pyridine N -oxides in the solid state and seven aprotic solvents of different polarity (ϵ from 2.27 to 37.5) show a broad absorption. The broad absorption shows weak dependence upon solvent polarity and is classified as type (ii). UV spectra show that in the investigated complexes protons are not transferred from the phenol to the N -oxides. Formamide ( ϵ = 111) is a much stronger proton acceptor than the pyridine N -oxides. Pentachlorophenol in formamide is converted to the phenolate ion.

Conformation of 1-benzyloxy-4-methoxypyridinium perchlorate: X-ray, AM1 and PM3 studies

The crystal structure of 1 -benzyloxy-4-methoxypyridinium perchlorate has been deduced from single-crystal X-ray diffraction data. The crystals are monoclinic, space group P21/a, with a= 9.254 0(7), b= 21.532(2), c= 7.335 2(8)A, β= 102.69(1)° and Z= 4. The final R value is 0.084 for 1593 observed reflections. The molecule is extended with a trans conformation around the central C(1)–O(1) bond linking the phenyl and pyridine residues. The aromatic ring planes are almost perpendicular to the linking C(1)–O(1) bond and the rings are twisted 9.1 (2)° to each other. The N–O distance [1.401 (7)A] is much longer than that found in pyridine N-oxides and is typical for an N–O single bond. Both the PM3 and AM1 methods predict that the trans conformer is less stable (by ca. 3 kcal mol–1) than the gauche conformer in the gas phase. The problem of the conformation of the phenyl group (D) and pyridinium group (A) in compounds of the type DCH(R1)CHR2A (R1= R2= H or alkyl) is reviewed.

Conformational Analysis of N-Methylpyrrolidine Betaine Hydrochloride by X-Ray Diffraction and Ab Initio Calculations

The structure of the title compound in the solid state and its five most stable conformers in the gas phase have been analysed by X-ray diffraction, and by MP2/6-31G(d,p) and BLYP/6-31G(d,p) calculations, respectively.

Crystal and molecular structure of anhydroerythromycinA cyclic carbonateN-methyl iodide

The crystal and molecular structure of C39H66INO13 · CH3OH has been determined by single-crystal x-ray diffraction analysis. The compound crystallizes in the monoclinic space, groupP21, witha =14.35(1),b=14.38(1),c =10.91(1) Å, β = 96.10(5) °, andZ = 2. Three-dimensional intensity data were collected on a four-circle fully automated diffractometer. The structure was solved by the heavy-atom method. The positions of all atoms have been refined by block-diagonal and full-matrix least squares, using anisotropic temperature factors. The finalR value was 0.109 for 2194 independent reflections. The analysis does not confirm the hypothetical structure proposed by the Eli Lilly group, as far as a position of a cyclic carbonate moiety is concerned. They postulated that the cyclic carbonate moiety was attached to C(9) and C(11) of the erythronolide. The results obtained by us show that the cyclic carbonate moiety is attached to C(11) and C(12). The absolute configuration of the asymmetric centers agrees fully with that established for erythromycinA.