Luigi R. Nassimbeni

A study of adduct formation between bis(acetylacetonato)oxovanadium(IV) and substituted pyridines

Abstract The reaction of several variously substituted pyridines with bis(acetylacetonato)oxovanadium(IV), VO(ACA)2, has been studied. The complexes were isolated in the solid form, and it appears from their i.r. spectra that, depending on the pyridine substituent, the complexes exist as either cis- or trans-isomers (with reference to the acetylacetone rings). This structural isomerism has been confirmed by an X-ray crystallographic study.

Packing patterns in lanthanide–edta complexes: crystal and molecular structures of sodium triaqua(ethylenediaminetetraacetato)dysprosate(III) pentahydrate and caesium diaqua(ethylenediaminetetraacetato)ytterbate(III) trihydrate

Na+[Dy(CIoHI2N2Oa)(H20)3]-.5H2 O, Na + C1oH18 DyN20~-~.5H20, crystallizes in space group Fdd2 with a = 19.34 (1), b = 35.40 (2), c = 12.116 (6) A, Z = 16. Cs+[Yb(C~oH~2N2Os)(H20)2] . 3H20, Cs + C~0H~6N2OIoYb-.3H20 crystallizes in space group P2,/c with a = 12.935 (6), b = 8.997 (5), c = 17.22 (1) A, fl = 106.7 (2) °, Z = 4. The structures were refined to a final R of 0.045 and 0.050 respectively. The decrease in ionic radius from Dy 3+ to Yb 3+ results in a change in coordination number of the Ln 3+ ion from nine to eight with concomitant loss of a water molecule.

Unusual 1C4 conformation of a methylglucose residue in crystalline permethyl-β-cyclodextrin monohydrate

The severely distorted conformation adopted by the uncomplexed TRIMEB molecule in the solid state is attended by ring-inversion of one of the seven methylglucose residues.

Selective formation of hydrogen bonded cocrystals between a sulfonamide and aromatic carboxylic acids in the solid state

Co-grinding sulfadimidine [4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide] with several aromatic carboxylic acids in the solid state produces 1 : 1 hydrogen bonded cocrystals which are identical to those obtained from reaction between the components in solution. The kinetics of solid state formation of selected cocrystals have been measured using X-ray powder diffraction. Sulfadimidine selectively cocrystallizes with 2-aminobenzoic acid when the latter is present in binary mixtures of acids. Solid state reaction of the cocrystal sulfadimidine·2-hydroxybenzoic acid with 2-aminobenzoic acid results in elimination of 2-hydroxybenzoic acid and formation of the cocrystal sulfadimidine·2-aminobenzoic acid.

Complexation with diol host compounds. Part 6. Structure and dynamics of enclathration by 1,1,6,6-tetraphenyl-hexa-2,4-diyne-1,6-diol

Abstract The host compound 1,1,6,6-tetraphenyl-hexa-2,4-diyne-1,6-diol forms inclusion compounds with acetone(Pbca) and benzophenone( P2 1 c ). The structures of the nonporous α-phase of the host (P1bar), as well as those of the host-guest compounds, have been elucidated. The kinetics of the reaction of the host with both these guest molecules have been analyzed.

Inclusion and separation of picoline isomers by a diol host compound

Structures of the inclusion compounds formed between the host compound 1,1-bis(4-hydroxyphenyl)cyclohexane and the isomers of picoline have been elucidated. The activation energies and the kinetics of desolvation for the complexes have been determined. Competition experiments have been performed to investigate which isomer is preferentially enclathrated by the host. Lattice energy calculations explain the results of the competition experiments.

X-ray structure and thermal analysis of a 1∶1 complex between (S)-naproxen and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin

An inclusion complex between TRIMEB and (S)-naproxen has been crystallised and characterised by physicochemical methods including X-ray analysis. The complex crystallises in the orthorhombic crystal system, space groupP212121, witha=15.179(4),b=21.407(5),c=27.67(1) Å andZ=4. The structure was solved using published coordinates for the skeleton atoms of TRIMEB in an isomorphous complex. Refinement by full-matrix least-squares analysis yieldedR=0.0571 for 6573 unique observed reflections. Hydrophobic forces are responsible for the inclusion of the drug, which has its methoxy group buried in the cavity of the host and its propionic acid moiety protruding from the O(2), O(3) side of the TRIMEB molecule. Both host and guest undergo conformational changes on complexation relative to their conformations observed in the TRIMEB monohydrate and naproxen crystal structures respectively. Complex units pack in a screw-channel mode in a head-to-tail fashion with their axes almost parallel to theb-axis.

The chemistry of uranium. Part 23. Isomorphous tetrachlorobis(hexamethylphosphoramide)uranium(IV) and tetrabromobis(hexamethylphosphoramide)uranium(IV)

The structures of UCl 4 ·2hmpa and UBr 4 ·2hmpa have been determined by Fourier methods from single-crystal X-ray diffraction data Full-matrix least-squares refinement yielded final conventional R factors of 0.062 and 0.059 respectively. The complexes are isomorphout and crystallise in the space group P2 1 /n with a = 14.141(5), b = 10.530(5), c = 9.076(5) A , β = 93.33° and a = 14.348(5), b = 10.698 (5), c = 9.304(5), β = 91.95 respectively. The hmpa moieties are in trans-octahedral arrangement about the uranium atom. The principal bond lengths are U—X (X = Cl, Br) = 2.615, 2.78; U—O = 2.23, 2.18; O—P = 1.50, 1.53 A respectively.

Synthesis and X-ray crystal structure of β-cyclodextrin diclofenac sodiu undecahydrate, a β-CD complex with a unique crystal packing arrangement

The title complex crystallizes in the hexagonal system forming infinite helical host channels residing on crystallographic screw hexads.

Irregular three-coordination in mercury: structures of phenyl- and methylmercury(II) dithizonate

[Hg(C6Hs)(CI3HIlN4S)] crystallizes in the monoclinic space group P2Jc with a = 5.991 (3), b = 20.68 (1), c = 17.129 (9) A,/~= 99.40 (5) °, Z = 4. [Hg(CH3)(CI3HIIN4S)] crystallizes in the triclinic space group Pl with a = 14.866 (7), b = 11.194 (6), c = 4.557 (3) A, a = 89.30 (5),/~= 95.85 (5), y= 97.62 (5) °, Z = 2. Final R = 0.058 and 0.061 respectively. In both structures the Hg atom exhibits planar, irregular three-coordination, the geometry at the Hg atom being approximately T-shaped, with the dithizone residue (C 13HllN4S-) acting as a bidentate ligand coordinating through S and N. The imino proton participates in a weak intramolecular hydrogen bond which stabilizes the N-N-C-N-N chain in an anti,s-trans configuration relative to the formal C=N double and C-N single bonds.