Copper(II) Coordination Compounds with Methanoato and Pyridine Ligands: Conversion from Mononuclear to Polynuclear in the Presence of Moisture.

Blue prismatic crystals of mononuclear [CuII(O2CH)2(Py)3] (Py = pyridine, C5H5N), 1, were prepared from reaction solution containing dry pyridine and dinuclear [Cu2II(O2CH)4(Py)2]. When a portion of solution together with crystals was exposed to air moisture, crystals of 1 dissolved in mother liquid. Simultaneously, blue needles of 2, i.e. covalently linked one-dimensional chain structure with formula [Cu(O2CH)2(Py)2]n·nH2O, grew out of the solution. The process lasted few minutes and was observed under optical microscope. The conversion from 1 to 2 takes place also outside of solution in the solid state. Single crystal X-ray diffraction data were collected at 150 K for 1 and after that for 2, originating from the same reaction solution. This paper reports the structures of both compounds. Alternative synthesis method of 2 arising from a mixture of copper methanoate and pyridine is also reported.

Dichloridotetra-kis-(1H-1,2,4-triazole-κN(4))copper(II).

The central Cu(II) atom of the molecular title complex, [CuCl(2)(C(2)H(3)N(3))(4)], is situated on a site with symmetry 2.22. It is six-coordinated in an elongated octa-hedral geometry, with the equatorial plane defined by four N atoms of four 1,2,4-triazole ligands and the axial positions occupied by two Cl atoms situated on a twofold axis. The mol-ecules are connected via N-H⋯Cl hydrogen bonds and the crystal consists of two inter-penetrating three-dimensional hydrogen-bonded frameworks.

Preparation, Characterization and Crystal Structure of [Cu2(O2CH)4(nicotinamide)2].

The novel copper(II) coordination compound, [Cu2(O2CH)4(nia)2] (nia = nicotinamide), was isolated from the reaction mixture containing Cu2(OH)2CO3, nicotinamide, methanoic acid and ethanol. The new complex was characterized by X-ray single crystal diffraction and other standard physico-chemical methods. The structure contains binuclear centrosymmetric molecules in which two central atoms are bridged by four methanoate bridges forming a paddle-wheel structure type. The fifth coordination site completing the distorted square pyramid around copper is occupied by aromatic nitrogen of nicotinamide. The molecules pack together via hydrogen bonds resulting in a formation of extended supramolecular sheets. The results of other physical measurements are also in a complete agreement with the obtained structure.

catena-Poly[disodium [[diformatotricopper(II)]-di-mu3-formato-tetra-mu2-formato]]: a new mode of bridging between binuclear and mononuclear formate-copper(II) units.

The novel title polymeric copper(II) complex, {Na2[Cu3-(CHO2)8]}n, consists of sodium cations and infinite anionic chains, in which neutral dinuclear [Cu2(O2CH)4] moieties alternate with dianionic [Cu(O2CH)4]2- units. Both metal-containing moieties are located on crystallographic inversion centers. The syn-syn bridging configuration between the mononuclear and dinuclear components yields a structure that is significantly more dense than the structures previously reported for mononuclear-dinuclear copper(II) carboxylates with syn-anti or anti-anti bridging modes.

Di-mu-formato-1kappa2O:2kappa2O'-di-mu-pyridin-2-olato-1kappaO:2kappaN;1kappaN:2kappaO-bis[(2-pyridone-kappaO)copper(II)] acetonitrile 1.02-solvate.

In the title compound, [Cu2(CHO2)2(C5H4NO)2(C5H5NO)2].1.02CH3CN, the dimeric unit is centrosymmetric, with two bidentate pyridin-2-olate and two bidentate formate syn-syn bridges, and two apical 2-pyridone ligands coordinated through the O atoms. The N atom from the apical 2-pyridone ligand is a donor of a hydrogen bond to the O atom of the bridging pyridinolate ligand of the same complex. The coordination polyhedron of the Cu atom is a distorted square pyramid.