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  • Author: G. P. Voutsas x
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Abstract

The title compound, [Ni(acac) (ΦenΦ)(O2NO)] C19H23N3NiO5, is monoclinic, space group P21/a, Z = 4. Cell dimensions are a = 13.659(7) Å, b = 12.746(6) Å, c = 13.707(7) Å and β = 117.71(3)°. A total of 3498 reflections were measured with a PC-computer controlled PHILIPS PW1100 automatic diffractometer using MoKα radiation. The structure was refined by full-matrix least squares to a conventional R = 0.038 for 2623 observed reflections with I > 2σ(I). The coordination around the central nickel atom is a distorted octahedron with the apices of the octahedron occupied by the oxygen atoms of the acetylacetonato (2,4-pentanedionato) moiety, the nitrogen atoms of the N,N′-diphenyl-1,2-diaminoethane (ΦenΦ) ligand, and two of the oxygens on the nitrato group, [NO3]. As a result of this coordination a resonance-stabilised six-membered β-dionato chelate ring, a five-membered chelate ring with the 1,2-diamine ligand in the gauche conformation, and a four-membered chelate ring are formed, with the NO3 acting as an O,O′ chelating ligand. As expected, the bite angle becomes more acute as the ring size diminishes, the actual values being 95.43°, 81.83°, and 59.63° respectively.

Abstract

The structure of the title compound [Cu(CN-acac)H2O(Me4en)]ClO4(C12H24ClCuN3O7) was determined by X-ray diffraction studies. The structure is orthorhombic, space group Pbca, Z = 8, a = 10.302 Å, b = 15.971 Å, c = 22.945 Å and ϱ x = 1.483 Mgm−3. The water molecule is covalently bonded to copper. The structure around the central copper atom is distorted square pyramidal with the apex occupied by the oxygen atom of the water molecule and the base formed by the oxygen atoms of the β-dionato (3-cyano-2,4-pentanedionato) moiety and the nitrogen atoms of the N,N,N′,N′-tetramethyl-1,2-diaminoethane, Me4en. As a result of this coordination a resonance-stabilised, planar, six-membered β-dionato chelate ring and a five-membered chelate ring with the 1,2-diamine ligand in the gauche conformation are formed. The Perchlorate ion, ClO4 interacts electrostatically with the [Cu(CN-acac)H2O(Me4en)] entity and forms hydrogen bonds with a hydrogen atom of the water molecule.

Abstract

The crystal structure of SbSeI has been determined with the intensities of 821 independent reflections, measured on a computer-controlled Philips PW 1100 single-crystal diffractometer. The cell constants, obtained by least-squares calculations from direct -value measurements on the diffractometer, are: a = 8.6862(9), b = 10.3927(9), c = 4.1452(3) Å, Z = 4; space group Pnam. The positional and thermal parameters, with anisotropic temperature factors, were refined by full-matrix, least-squares calculations to a final R = 0.054.

The compound is isotypic with BiSCl (Voutsas and Rentzeperis, 1980). Each Sb atom is seven-coordinated by three Se atoms at distances 2.601 to 2.796 Å and four iodine atoms at distances 3.150 to 3.822 Å. The four I atoms form a square parallel to c, while the three Se atoms form an isosceles triangle perpendicular to (001), with its base parallel to c. The I atoms and two of the Se atoms are at the vertices of a triangular prism parallel to c and of height equal to c. The third Se atom is at the apex of a pyramid whose base is one of the Se2I2 faces of the triangular prism. The composite coordination polyhedron (prism + pyramid) is linked to a symmetry-equivalent polyhedron by a common Se, Se edge of the corresponding pyramids. This characteristic double-polyhedron system is repeated along the c axis, thus forming an infinite double chain of composition {Sb2Se4I8}n. The chain is further linked to each of four similar chains by a common (I,I)n row parallel to c. This system of chains explains very well the needle-like growth of the crystals along c.

Abstract

The crystal structure of BiOCl has been redetermined with 3570 observed reflections of which 174 were unique measured on a computer controlled Philips PW 1100 single crystal diffractometer. The structure belongs to the tetragonal space group P4/nmm and the cell constants, obtained by a least-squares calculation from direct θ-value measurements on the diffractometer, are a = 3.8870(5) and c = 7.3540(5) Å.

The positional and thermal parameters, with anisotropic temperature factors, were refined by full-matrix least-squares calculations to a final R = 9.17%.

Each Bi atom is eight-coordinated by 4 O and 4 Cl atoms at distances of 2.316 Å and 3.059 Å respectively thus forming a decahedron. The faces of the decahedron are 2 rectangles (O–O–O–O and Cl–Cl–Cl–Cl) with sides 3.487 Å and 8 isosceles triangles (four O–Cl–O and four Cl–O–Cl) with sides O–Cl 3.249 Å and O–O or Cl–Cl 3.487 Å.

The decahedra are linked to each other by a common O–Cl edge along the a and b axes in infinite layers.