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1,2-Bis(2'-nitrophenoxy)-3-R-benzenes {R = H (1), CH3 (2) and OCH3 (3)} have been prepared from the S-N-Ar reaction between 1-fluoro-2-nitrobenzene and 3-R-catechol (aromatic diol), and are then reduced to the corresponding diamines 1,2-bis(2'-aminophenoxy)-3-R-benzene {R = H (4), CH3 (5) and OCH3 (6)}, respectively. Reaction of these diamines with 2-hydroxy-1-naphthaldehyde gives tetradentate Schiff base ligands {H2L: R = H (H2L1), CH3 (H2L2) and OCH3 (H2L3)}, respectively. The Schiff base ligands coordinate to metal(II) ions to provide the complexes ML1, ML2 and ML3 (M = Cu and Zn), respectively. X-ray molecular structure determinations were performed to explore stereochemical rigidity as the origin of chirality induction in the dinitro (2), diamine (5) and Schiff base ligands (H2L1 and H2L2) as well as in the complexes (ZnL2, ZnL3 and CuL3), respectively. The structures feature an N2O2-chromophore from bis(2-oxo-1-naphthaldiminate) moieties with one additional weak Cu/Zn center dot center dot center dot O (ether) contact to give a 4 + 1 coordination with a distorted square-pyramidal geometry for ZnL2, ZnL3 and CuL3, respectively. Without considering this additional contact, the structures are distorted tetrahedral or distorted square-planar for the Zn or Cu complexes, such that a chiral Lambda- and Delta-configuration at the metal atom is induced. All three metal complexes crystallize as a crystalline racemate or racemic mixture of Lambda/Delta-ML. The supramolecular packing in the structures is organized by inter-/intra-molecular pi-pi and C-H center dot center dot center dot pi interactions, respectively. The optimized structures and excited state properties from DFT/TDDFT calculations support the experimental results.

The journal of chemical physics 152(16), 164303 (2020). doi:10.1063/5.0004465, The site-specific first microsolvation step of furan and some of its derivatives with methanol is explored to benchmark the ability of quantum-chemical methods to describe the structure, energetics, and vibrational spectrum at low temperature. Infrared and microwave spectra in supersonic jet expansions are used to quantify the docking preference and some relevant quantum states of the model complexes. Microwave spectroscopy strictly rules out in-plane docking of methanol as opposed to the top coordination of the aromatic ring. Contrasting comparison strategies, which emphasize either the experimental or the theoretical input, are explored. Within the harmonic approximation, only a few composite computational approaches are able to achieve a satisfactory performance. Deuteration experiments suggest that the harmonic treatment itself is largely justified for the zero-point energy, likely and by design due to the systematic cancellation of important anharmonic contributions between the docking variants. Therefore, discrepancies between experiment and theory for the isomer abundance are tentatively assigned to electronic structure deficiencies, but uncertainties remain on the nuclear dynamics side. Attempts to include anharmonic contributions indicate that for systems of this size, a uniform treatment of anharmonicity with systematically improved performance is not yet in sight., Published by American Institute of Physics, Melville, NY

Self-assembly of the selenium-bridged novel metallacyclophanes [{(CO)(3)Re(mu-SeR)(2)Re(CO)(3)}(2)(mu-L)(2)] (1-3) has been accomplished by treating diaryl diselenide with low-valent transition-metal carbonyl and rigid bidentate azine ligands under one-pot reaction conditions. The oxidative addition of diphenyl/dibenzyl diselenides to S Re-2(CO)(10) with 4,4'-bipyridine, trans-1,2-bis(4-pyridyl)ethylene, and 1,4-bis[2-(4-pyridyl)ethenyl]benzene afforded tetranuclear metallacyclophanes. These compounds have been characterized by elemental analysis and IR, NMR, and UV-vis absorption spectroscopic techniques. The molecular structures of metallacylophanes 1a,b and 2 were determined by single-crystal X-ray diffraction methods, and the crystal structures showed that two selenium-bridged dirhenium metallacycles were linked by two bipyridyl spacers and attained a framework of molecular rectangles. In addition, the molecular recognition capabilities of the molecular rectangles la,b and 2 with aromatic compounds such as pyrene and triphenylene have been investigated by studying their binding properties, using UV-visible absorption and fluorescence emission spectrophotometric methods. The nature of the binding interactions were further supported by single-crystal X-ray diffraction methods, and the crystal structures of 1b center dot(pyrene) and 1b center dot(triphenylene) revealed that CH center dot center dot center dot pi interactions are mainly responsible for the binding of 1b with pyrene and triphenylene.

Oxidative addition of diaryl disulphides RSSR to low-valent transition metal carbonyl Re(2)(CO)(10) with monodendate pyridine ligands bring forth novel sulphur bridged neutral dinuclear rhenium metallacycles [L(CO)(3)Re(mu-SR)(2)Re(CO)(3)L] (1-9) (L = pyridine ligand, R = aryl group) under one pot reaction conditions. The Metallacycles 1-9 have been characterised by elemental analysis, NMR and IR and absorption spectral analysis. Molecular structures of 4, 8 and 9 were determined by crystallographic analysis and the structural studies reveal that pyridyl groups attached to metal centres exhibit cis conformation. (C) 2010 Elsevier B. V. .