Copper chloride catalysis is a well-established field in organic and inorganic chemistry. However, in most cases a detailed mechanistic understanding of the individual reaction steps and identification of reactive intermediates are still missing. The present study reports the results of spectroscopic and spectrometric measurements that support formation of copper agglomerates during catalytic processes. The composition of CuCl2·2H2O in several coordinating solvents and the influence of basic coreagents such as NaO(t)Bu and K2CO3 on the structure in the solid state as well as in solution were investigated. Several experiments involving crystal structure determination, IR spectroscopy, and ultra-high-resolution cryospray-ionization mass spectrometry were performed. The crystal structures of [CuCl2(H2O)]·0.5(CH3)2CO (1), [Cu2(CH3CN)2Cl4] (2), [Cu3(CH3CN)3Cl6] (3), [Cu3Cl6(THF)4] (4), [Cu(DMSO)2Cl2] (5), (H2N(CH3)2)2[CuCl3] (6), and [Cu4OCl6(THF)(urea)3]·3THF·urea (8) are reported herein. It can be clearly demonstrated that μ4-oxido copper clusters of the formula [Cu4OCl6(solvent)4] are the main product from the reactions of CuCl2·2H2O and basic coreagents. As a final result of these experiments, it can be stated that μ4-oxido copper clusters most likely play an important role in the mechanism of copper chloride-catalyzed reactions.

The production of nylon‐6.6 is one of the largest scale syntheses in industrial chemistry. The standard procedure is based on an energy consuming low‐level conversion of cyclohexane to yield adipic acid in two steps that is converted to nylon‐6.6 in a separate step. Therefore, there is a strong intent to optimize the synthetic route in an economic and ecologic matter. In this work, we present a one‐pot oxygenation of cyclohexane with hydrogen peroxide and a µ4‐oxido‐copper cluster catalyst to yield dicarboxylic acids with adipic acid as the main product.

A new tripodal imine ligand tris(2-(propan-2ylideneamino)ethyl)amine (imine 3 tren) was prepared in order to stabilize high valent iron-oxido complexes. Iron complexes were synthesized in template reactions from iron(II) salts, tris(2-aminoethyl)amine (tren) and acetone. Due to the reversibility of the imine formation, complexes with different ligands were obtained depending on the reaction conditions. Three complexes, [Fe(imine 3 tren)(OAc) 2 ] (1), [Fe(imine 3 tren) (OAc)]OTf (2) and [(imine 3 tren) 2 Fe 2 (F) 2 ](SbF 6) 2 (3), could be synthesized and structurally characterized. However, reactions with hydrogen peroxide, iodosobenzene or ozone did not lead to any kind of "oxygen adduct" complex that could be spectroscopically observed.

Due to the increasing pharmaceutical interest of oligonucleotides, for example in antisense therapy and vaccines, their analytical characterization is of fundamental importance due to their complex structure. For this purpose, mass spectrometry is a viable tool for structural studies of nucleic acids. Structural information regarding the primary sequence of a nucleic acid can reliably be gained via tandem mass spectrometry (MSMS) fragmentation. In this work, we present the characteristic fragmentation behavior of short-chain oligonucleotides (15–35 nucleotides) with respect to the collision-induced dissociation (CID) voltage used. The relationship and influence of the length of the oligonucleotide and its charge state is also discussed. The results presented here can be helpful for estimating the required fragmentation energies of short-chain oligonucleotides and their sequencing.

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The tripodal ligand (2-aminoethyl)bis(2-pyridylmethyl)amine (uns-penp), known for its Cu/O 2 intermediates, was modified at one side arm by a selection of amino acids. With L-Tyrosine (Tyr), L-Histidine (His) and L-Lysine (Lys) it was possible to introduce chirality into the tripodal ligand system and to investigate the corresponding copper(I) complexes [Cu{L-His (BPh 3 )uns-penp}], [Cu(L-Lys)uns-penp]OTf and [Cu(L-Tyr)uns-penp]OTf. [Cu{L-His(BPh 3 )uns-penp}] could be structurally characterized and represents the first example of a copper(I) complex with a coordinated imidazole ring of the histidine ligand. Furthermore, these complexes demonstrated catalytic activity for the oxygenation of thioanisole with hydrogen peroxide as an oxidant.

Invited for the cover of this issue are the groups of Sabine Becker, Technische Universität Kaiserslautern, and Siegfried Schindler, Justus‐Liebig‐Universität Gießen, Germany. The cover image shows the one‐pot oxygenation of cyclohexane to yield adipic and glutaric acid under mild conditions with a µ4‐oxido copper cluster and H2O2 as catalyst and oxidant, respectively.