Pongthipun Phuengphai

Drastic steric effects from, respectively, a hydrogen, a methyl and an ethyl group on the coordination network of a zinc(II)–4,4′-bipyridine–carboxylato ternary system

The combination of a [zinc(II)–4,4′-bpy] coordination moiety with, respectively, formato, acetato and propionato ligands leads to the formation of the compounds {[Zn3(4,4′-bpy)3.5(µ-O2CH)4 (H2O)2](ClO4)2(H2O)2}n (1), {[Zn3(4,4′-bpy)3(µ-O2CCH3)4(H2O)2](PF6)2(H2O)2}n (2) and {[Zn3(4,4′-bpy)4(µ-O2CCH2CH3)4](ClO4)2(4,4′-bpy)2(H2O)4}n (3). The molecular structures determined by single-crystal X-ray diffraction data reveal significant changes, which are apparently due to the sole different steric hindrance between a H atom (formato, compound 1), a methyl group (acetato, compound 2) and an ethyl group (propionato, compound 3). The three coordination materials have been fully characterized and their thermal decomposition behavior has been investigated. The 3D (1), 1D (2) and 2D (3) networks exhibit voids that contain the counter-ions and guest molecules as well, namely water for compounds 1 and 2, and water/4,4′-bpy for compound 3.

Crystal structures and electronic properties of three fluxional [Cu(di-2-pyridylamine)2(OXO)]Y complexes

The crystal structures of three bis(dpyam)copper(II) complexes, [Cu(dpyam)2(ONO)](SO4)0.5(H2O) (I), [Cu(dpyam)2(O2CCH3)](ClO4) (II) and [Cu(dpyam)2(O2CCH2CH3)](ClO4) (III) (dpyam = di-2-pyridylamine) have been determined at room temperature by single-crystal X-ray methods. The complexes involve a CuN4O2 chromophore with a symmetric cis-distorted octahedral stereochemistry for I, and an asymmetric cis-distorted octahedral stereochemistry for II and III. In I the copper atom and the oxygen donor atoms of the symmetrically bonded nitrito group lie on a crystallographic C 2 axis. This is the first reported example in the literature of such a complex with this type of stereochemistry, involving the [Cu(dpyam)2(OXO)][Y] series as a whole, where (OXO)− involves an oxoanion. In contrast, complexes II and III involve a distortion of the CuN4O2 chromophore towards a square pyramidal (4 + 1 + 1) stereochemistry. Here, the stereochemistries of I, II and III are compared with other closely related complexes. The highly asymmetric geometry of the CuN4O2 chromophores of II and III suggests that both complexes appear to be static in nature. Electronic spectra of the three complexes involve two bands of similar intensity corresponding to cis-distorted octahedral copper(II) stereochemistry.

Poly[tris­(μ-4,4′-bi­pyridine-κ2N:N′)bis(dimethyl sulfoxide-κO)tetra­kis­(thiocyanato-κN)dicobalt(II)]

The asymmetric unit of the title compound, [Co2(NCS)4(C10H8N2)3(C2H6OS)2]n, consists of one CoII atom, two thiocyanate anions, one dimethyl sulfoxide molecule and one and a half 4,4′-bipyridine molecules. The half-molecule is completed by inversion symmetry. The CoII atom is coordinated in a distorted octahedral geometry by two N atoms from two thiocyanate anions, one O atom from dimethyl sulfoxide as a terminal ligand and three N atoms from three 4,4′-bipyridine molecules as bridging ligands linking the cations, with a Co⋯Co separation of 11.5964 (5) Å. This generates a two-dimensional structure parallel to (-103). A C—H⋯S hydrogen bond links the layers into a three-dimensional supramolecular framework. The layers are stacked in an ABC fashion preventing the occurrence of interlayer void space and hence leading to the absence of lattice solvent and/or organic guest molecules in the structure.