A New Dimeric Copper(II) Complex of Hexyl Bis(pyrazolyl)acetate Ligand as an Efficient Catalyst for Allylic Oxidations

A new dimeric copper(II) bromide complex, [Cu(LOHex)Br(μ-Br)]2 (1), was prepared by a reaction of CuBr2 with the hexyl bis(pyrazol-1-yl)acetate ligand (LOHex) in acetonitrile solution and fully characterized in the solid state and in solution. The crystal structure of 1 was also determined: the complex is interlinked by two bridging bromide ligands and possesses terminal bromide ligands on each copper atom. The two pyrazolyl ligands in 1 coordinate with the nitrogen atoms to complete the Cu coordination sphere, resulting in a five-coordinated geometry—away from idealized trigonal bipyramidal and square pyramidal geometries—which can better be described as distorted square pyramidal, as measured by the τ and χ structural parameters. The pendant hexyloxy chain is disordered over two arrangements, with final site occupancies refined to 0.705 and 0.295. The newly synthesized complex was evaluated as a catalyst in copper-catalyzed C–H oxidation for allylic functionalization through a Kharasch–Sosnovsky reaction without any external reducing agent. Using 0.5 mol% of this catalyst, and tert-butyl peroxybenzoate (Luperox) as an oxidant, allylic benzoates were obtained with up to 90% yield. The general reaction time was only slightly decreased to 24 h but a very significant decrease in the alkene:Luperox ratio to 3:1 was achieved. These factors show relevant improvements with respect to classical Kharasch–Sosnovsky reactions in terms of rate and amount of reagents. The present study highlights the potential of copper(II) complexes containing functionalized bis(pyrazol-1-yl)acetate ligands as efficient catalysts for allylic oxidations.

The Mechanism of Adsorption of Rh(III) Bromide Complex Ions on Activated Carbon

In the paper, the mechanism of the process of the Rh(III) ions adsorption on activated carbon ORGANOSORB 10—AA was investigated. It was shown, that the process is reversible, i.e., stripping of Rh(III) ions from activated carbon to the solution is also possible. This opens the possibility of industrial recovery of Rh (III) ions from highly dilute aqueous solutions. The activation energies for the forward and backward reaction were determined These are equal to c.a. 7 and 0 kJ/mol. respectively. Unfortunately, the efficiency of this process was low. Obtained maximum load of Rh(III) was equal to 1.13 mg per 1 g of activated carbon.

Hydrogenation reactions catalyzed by HN(CH2CH2PR2)2-ligated copper complexes

Hydrogenation of aldehydes and ketones can be catalyzed by a PNP-ligated copper hydride that is accessible from the copper borohydride or bromide complex or the copper hydride cluster.

SPECTROPHOTOMETRIC INVESTIGATION OF COBALT BROMIDE COMPLEX FORMATION IN AQUEOUS CALCIUM NITRATE– AMMONIUM NITRATE MELTS AT T = 328.15 K. INFLUENCE OF WATER CONTENT

In this work, the absorption spectra of cobalt(II) nitrate and bromide complexes in the composition 0.3Ca(NO3)2 – 0.7NH4NO3 – H2O have been investigated in the 400-800 nm range of wavelength at T = 328.15 K and atmospheric pressure P = 101.3 kPa. Spectra were recorded in solutions with variable water content (R = H2O/salt mole ratio; R = 1.0, 1.2 and 1.6). The blue shift of the absorption maximum with the water content increase (R) suggest simultaneous coordination by water molecules and nitrate ions. From an analysis of the spectra, it can be concluded that the following: [Co(NO3)4(H2O)2]2−, [Co(NO3)2Br2]2− and [CoBr4]2− complexes were formed. The overall stability constants of these complexes species spectra were calculated at T = 328.15 K.

One-dimensional chains based on linear tetranuclear copper(i) units: reversible structural transformation and luminescence change

Two extended metal chains based on linear tetracopper units are reported, in which the bromide complex undergoes reversible structural transformation and luminescence change.

Tunable luminescent lead bromide complexes

Efficient emission from lead bromide in polyethylene glycol is tuned from orange to green by alkylammonium salts, which influence the particular lead bromide complex formation.

A copper(i) bromide organic–inorganic zwitterionic coordination compound with a new type of core: structure, luminescence properties, and DFT calculations

A new organic–inorganic Cu(i) bromide complex based on protonated tris(2-pyridyl)phosphine, [(HPy)3PCu2Br5], has been synthesized by a straightforward reaction in solution or by modification of the [Cu2Br2(Py3P)2] complex using hydrobromic acid.