Band 229, Heft 1

The structural characterization of Al 2 (PO 4 )(OH) 3 augelite, a natural orthophosphate coming from Rapid Creek, Yukon, Canada, was carried out by means of a multi-methodological approach based on WDS-EMPA chemical analysis, single crystal X-ray diffraction, and infrared spectroscopy. The structure was solved in the C 2 /m monoclinic space group, with the following unit cell constants: a = 13.0740(10), b = 7.9690(7), c = 5.0910(7) Å, β = 112.282(5)°, V = 490.81(9) Å 3 . Phosphorus atoms display tetrahedral (PO 4 ) coordination, while aluminum cations display octahedral and unusual five-fold coordination. The framework of the mineral can be viewed as the repetition of cationic arrays made up by AlO 6 /AlO 5 polyhedra, bridged by PO 4 groups, and further joined by O–H···O hydrogen bonds: such interactions were also correlated to IR spectroscopy analysis, by means of Libo­witzky formula applied on OH stretching vibrations.

For two different polyhedra, the cube and the rhombic dodecahedron, there are an infinite number of closely related polyhedra. We find the same for the icosahedron and dodecahedron. We show with direct mathematical methods how an unlimited number of different structures can be derived from the smallest up to any size.

Three new organotin(IV) structures of general formula RSn(S 2 CN R ′ R ″) 2 Cl, where R ′ ≠ R ″, namely MeSn · [S 2 CN(Me)(Cy)] 2 Cl ( 1 ), MeSn[S 2 CN( i -Pr)(CH 2 Ph)] 2 Cl ( 2 ) and PhSn[S 2 CN(Et)( i -Pr)] 2 Cl ( 3 ) are described. Each structure features tin in a distorted octahedral geometry defined by a C Cl S 4 donor set as a result of two chelating dithiocarbamate ligands. In all cases the tin-bound carbon and chloride atoms are cis . The shorter Sn–S bond lengths in 3 are correlated with the presence of the relatively more electronegative Sn-bound phenyl substituent. The new structures conform to the structural motif adopted by all other compounds with the formula RSn(S 2 CN R ′ R ″) 2 Cl, where R ′ = R ″, suggesting the unsymmetrical substitution pattern of the dithiocarbamate ligands in the present study does not influence the adoption of this structural motif. The homogeneity in the structural motif notwithstanding, non-systematic variations in geometric parameters are found in these structures indicating an overall influence of crystal packing upon molecular geometry.

The complex, [Cu(dmap)(OAc)(H 2 O)] 2 · 2H 2 O (dmap = N,N -dimethylaminopropanolato, OAc = acetato) was synthesized by drop-by-drop addition of N,N -dimethylaminopropanol to copper(II) acetate dihydrate suspended in toluene. The blue crystalline product was characterized by its melting point, elemental analysis, infrared spectral study, mass analysis, thermal analysis and by the single-crystal X-ray structure analysis. Compound ( 1 ) crystalizes in triclinic space group, P ̄1, a = 6.3716(9) Å, b = 8.2719(12) Å, c = 10.9254(16) Å, α = 79.918(2)°, β = 81.812(2)°, γ = 77.171(2)° and Z = 1. The complex ( 1 ) is binuclear. The copper s’ environment is square pyramidal with chelating dimethylaminopropanol rings being in the equatorial and water molecules in axial positions. Acetate ligands are attached to Cu via oxygen, in a monodentate mode while the C=O oxygen is involved in O···H–O H-bonds with water molecules. Dimethylaminopropanol serves as a chelating as well as bridging ligand.