Synthesis of nanoscale CuO via precursor method and its application in the catalytic epoxidation of styrene.

Nanoscale CuO with diameters in the range of 7-8 nm has been synthesized via a two-step precipitation-calcination method using copper(ii) isonicotinate tetrahydrate as the precursor. The first step involves the room temperature stirring of an alkaline ethanolic solution of the precursor which gives a non-crystalline CuO species, while the second step involves the calcination of the product of the first step at 180 °C to form nanocrystalline CuO which has been characterized by PXRD, TEM, SEM, H2-TPR and Raman spectroscopy, etc. The CuO material has shown excellent catalytic activity in the oxidation of styrene using TBHP as the oxidizing agent leading to complete styrene conversion with more than 95% styrene oxide selectivity at the end of 6 h. The oxide catalyst can be reused for at least 6 successive runs without significant loss in activity.

Tetra-aqua-bis-(pyridine-3-carbo-nitrile-κN 1)nickel(II) benzene-1,4-di-carboxyl-ate tetra-hydrate.

A nickel(II) terephthalate complex, viz. [Ni(C6H4N2)2(H2O)4](O2CC6H4CO2)·4H2O, has been synthesized and studied by single-crystal X-ray diffraction. It crystallizes in the triclinic space group P . The crystal structure shows an approximately octa-hedral coordination environment of the complex with the [Ni(H2O)4(3-NCpy)2]2+ (3-NCpy is pyridine-3-carbo-nitrile) cation associated with four free water mol-ecules and hydrogen bonded to a terephthalate dianion [graph set R 2 2(8)]. The supra-molecular structure of the compound is stabilized by a three-dimensional array of O-H⋯O and O-H⋯N hydrogen bonds, along with π-π stacked pyridine-3-carbo-nitrile rings and C-H⋯O inter-actions.

Structure of tetra-kis-(µ-deca-noato-κ2 O:O')bis-[(4-methyl-pyridine-κN)copper(II)], a dimeric copper(II) complex.

The 4-methyl-pyridine (4-Mepy) based dimeric copper(II) carboxyl-ate complex [Cu2(C10H19O2)4(C6H7N)2] or [Cu2(µ-O2CC9H19)4(4-Mepy)2] crystallizes with triclinic (P ) symmetry. The two CuII ions exhibit a distorted square-pyramidal environment and are connected into a centrosymmetric paddle-wheel dinuclear cluster [Cu⋯Cu = 2.6472 (8) Å] via four bridging carboxyl-ate ligands arranged in the syn-syn coordination mode. The apical positions around the paddle-wheel copper centers are occupied by the N atoms of the 4-methyl-pyridine ligands. The structure exhibits disorder of the terminal alkyl carbon atoms in the deca-noate chains.

Crystal structure of tetra-kis-(µ-caproato-κ(2) O:O')bis-[(4-cyano-pyridine-κN (1))copper(II)].

The title dinuclear complex, [Cu2(C6H11O2)4(C6H4N2)2], has a paddle-wheel structure. The two crystallographically independent Cu(II) atoms are each in a distorted square-pyramidal environment, in which four O atoms from the four bridging caproate ligands form the basal plane and the pyridine N atom of the 4-cyano-pyridine ligand occupies the apical position. The Cu⋯Cu distance is 2.6055 (9) Å. One of the alkyl chains of the caproate ligands is disordered over two sets of sites, with occupancies of 0.725 (5) and 0.275 (5). In the crystal, two pairs of C-H⋯N hydrogen bonds connect the mol-ecules into chains along [11-1] and C-H⋯O hydrogen bonds link the chains into a three-dimensional network.