Dimethyl 3,3'-di-meth-oxy-biphenyl-4,4'-di-carboxyl-ate.

In the title compound, C18H18O6, the biphenyl moiety is twisted with a dihedral angle of 29.11 (10)°. The carbometh-oxy groups form C-C-C-O torsion angles of -18.3 (3) and -27.7 (3)° with the attached rings, as a result of steric hindrances from the nearby meth-oxy groups. In the absence of stacking inter-actions and with no H⋯O contacts shorter than 2.7 Å, the packing is dominated by weaker van der Waals inter-actions.

Methyl 5-iodo-2-meth-oxy-benzoate.

In the title compound, C9H9IO3, the mol-ecules are close to planar [maximum deviation from benzene ring plane = 0.229 (5) Šfor the methyl carboxylate C atom] with the methyl groups oriented away from each other. In the crystal, mol-ecules form stacked layers parallel to the ab plane, where every layer has either the iodine or meth-oxy/methyl carboxyl-ate substituents pointing towards each other in an alternating fashion.

4,4'-Dimeth-oxybi-phenyl-3,3'-di-car-box-ylic acid.

The title compound, C16H14O6, was recrystallized under solvothermal conditions. The mol-ecules are located on inversion centres, with one complete mol-ecule generated from the asymmetric unit by inversion. There are intra-molecular O-H⋯O hydrogen bonds involving the carb-oxy-lic acid group and the O atom of the adjacent meth-oxy group. In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds, forming chains propagating along [100]. The chains are linked via C-H⋯O hydrogen bonds, forming sheets parallel to (001).

Poly[bis-(1,3-dimethyl-imidazolidin-2-one)(µ2-2,5-dioxidoterephthalato)zirconium(IV)].

In the title coordination polymer, [Zr(C8H2O6)(C5H10N2O)2] n , the Zr(IV) atom (site symmetry 2) is coordinated by two O,O'-bidentate 2,5-dioxidoterephthalate (DHTP(4-)) ligands and two O-bonded 1,3-dimethyl-2-imidazolidinone (DMI) ligands (the latter in a cis orientation) in a distorted ZrO6 octa-hedral geometry. The deprotonated hy-droxy and carb-oxy O atoms of the DHTP(4-) ligand chelate the Zr(IV) ion via a six-membered ring; the dihedral angle between the carboxyl-ate group and the aromatic ring is 14.46 (11)°. The DHTP(4-) ligand is completed by crystallographic inversion symmetry and coordinates to two Zr(IV) atoms, thereby forming polymeric zigzag chains propagating in [001].

Poly[bis-(1,3-dimethyl-1,3-diazinan-2-one)(2,5-dioxidoterephthalato)zirconium(IV)].

In the title coordination polymer, [Zr(C8H2O6)(C6H12N2O)2] n , the Zr(IV) atom, which lies on a crystallographic twofold rotation axis, is coordinated by two O,O'-bidentate 2,5-dioxidoterephthalate (DHTP(4-)) ligands and two O-bonded 1,3-dimethyl-1,3-diazinan-2-one (DMPU) ligands (the latter in a cis orientation) in a distorted ZrO6 octa-hedral geometry. The deprotonated hy-droxy and carb-oxy O atoms of the DHTP(4-) ligand chelate the Zr(IV) ion via a six-membered ring; the dihedral angle between the carboxyl-ate group and the aromatic ring is 19.94 (11)°. The DHTP(4-) ligand is completed by crystallographic inversion symmetry and coordinates to two Zr(IV) atoms, thereby forming polymeric zigzag chains propagating in the c-axis direction.

Di-µ-chlorido-bis-[(2,2'-bipyridine-5,5'-dicarb-oxy-lic acid-κ(2)N,N')chloridocopper(II)] dimethyl-formamide tetra-solvate.

In the title compound, [Cu(2)Cl(4)(C(12)H(8)N(2)O(4))(2)]·4C(3)H(7)NO, which contains a chloride-bridged centrosymmetric Cu(II) dimer, the Cu(II) atom is in a distorted square-pyramidal 4 + 1 coordination geometry defined by the N atoms of the chelating 2,2'-bipyridine ligand, a terminal chloride and two bridging chloride ligands. Of the two independent dimethyl-formamide mol-ecules, one is hydrogen bonded to a single -COOH group, while one links two adjacent -COOH groups via a strong accepted O-H⋯O and a weak donated C(O)-H⋯O hydrogen bond. Two of these last mol-ecules and the two -COOH groups form a centrosymmetric hydrogen-bonded ring in which the CH=O and the -COOH groups by disorder adopt two alternate orientations in a 0.44:0.56 ratio. These hydrogen bonds link the Cu(II) complex mol-ecules and the dimethyl-formamide solvent mol-ecules into infinite chains along [-111]. Slipped π-π stacking inter-actions between two centrosymmetric pyridine rings (centroid-centroid distance = 3.63 Å) contribute to the coherence of the structure along [0-11].

(5,5'-Dimethyl-2,2'-bipyridine)-iodido-trimethyl-platinum(IV).

In the title compound, [Pt(CH(3))(3)I(C(12)H(12)N(2))], the Pt(IV) atom is six-coordinated in a slightly distorted octa-hedral configuration with one CH(3) group and the I atom forming a near perpendicular axis relative to the square plane formed by the bipyridine ligand and the two remaining CH(3) groups. The CH(3) group trans to the I atom has a slightly elongated bond to Pt compared to the other CH(3) groups, indicating a difference in trans influence between iodine and the bipyridine ligand.

Biphenyl-4,4'-dicarb-oxy-lic acid N,N-dimethyl-formamide monosolvate.

Biphenyl-4,4'-dicarb-oxy-lic acid was recrystallized from N,N-dimethyl-formamide (DMF) yielding the title compound, C(14)H(10)O(4)·2C(3)H(7)NO. The acid mol-ecules are located on crystallographic centres of inversion and are hydrogen bonded to DMF mol-ecules. These hydrogen-bonded units form infinite chains although there is no inter-action between the methyl groups of neighboring DMF mol-ecules.

Poly[tris-(µ-2-amino-benzene-1,4-dicarboxyl-ato)tetra-kis-(N,N-dimethyl-formamide)-diyttrium(III)].

The asymmetric unit of the title coordination polymer, [Y(2)(C(8)H(5)NO(4))(3)(C(3)H(7)NO)(4)](n), contains one Y(3+) ion, three half-mol-ecules of the 2-amino-benzene-1,4-dicarboxyl-ate (abz) dianion and two O-bonded N,N-dimethyl-formamide (DMF) mol-ecules. Each abz half-mol-ecule is completed by crystallographic inversion symmetry and its -NH(2) group is disordered in each case [relative occupancies within the asymmetric unit = 0.462 (18):0.538 (18), 0.93 (2):0.07 (2) and 0.828 (16):0.172 (16)]. The combination of disorder and crystal symmetry means that each of the four C-H atoms of the benzene ring of each of the dianions bears a statistical fraction of an -NH(2) group. The coordination geometry of the yttrium ion is a fairly regular YO(8) square anti-prism arising from its coordination by two DMF mol-ecules, four monodentate abz dianions and one O,O-bidentate abz dianion. The polymeric building unit is a dimeric paddle-wheel with two metal ions linked by four bridging abz dianions. Further bridging linkages connect the dimers into a three-dimensional framework containing voids in which highly disordered DMF mol-ecules are presumed to reside.