From Mononuclear to Tetranuclear Oxalate- or Chloranilate-Based Complexes of Copper(II) with Halogen Atoms and N-donor Ligands

Four novel copper(II) complexes were prepared and characterised by single-crystal X-ray diffraction and IR spectroscopy: [Cu(bpy)(H2O)(C6O4Cl2)] · H2O (1), [Cu2(phen)2(C2O4)I2] (2), [Cu2(bpy)2(C2O4)Br2] (3), and [Cu4(bpy)4(C2O4)3(I3)2] (4). Three types of ligands were varied to assess their effects on the structure, nuclearity and topology: the bridging O-donor ligand (oxalate and chloranilate), the terminal N-donor ligand (2,2\u27-bipyridine and 1,10-phenanthroline) and the halogen anion present in the solution (Cl, Br, I). Compound 4 is a rare example of a triiodide anion coordinated to a copper(II) metal centre

Stereokemija na drugi način: puževi, zrcala, koordinatni sustavi

U ovome se članku prikazuje sustavan pristup stereokemiji te tumačenju njezina središnjeg pojma, kiralnosti, jednostavnijim načinom koji se može prilagoditi nastavi kroz eksperimente. Polazeći od predmetâ iz svakodnevne uporabe (cipele, zrcala, puževi, itd.), dolazi se do općeg opisa kiralnosti, iz kojega se onda izvodi molekulska kiralnost. Tetraedarski se ugljikov atom može smatrati specijalnim slučajem, koji se može izvesti naknadno

Chemistry in Teaching: 90 Minutes of (Free) Radical Chemistry

Radikale, kemijske vrste s nesparenim elektronima, obično se smatra vrlo nestablinima, tako da ih se može pripraviti samo pod posebnim uvjetima i proučavati samo pomoću posebnih, vrlo skupih, instrumenata. Također ih se smatra štetnima te neprimjerenima za pokuse u školi. Ipak, radikali imaju ključnu ulogu u biološkim sustavima. Zahvaljujući nesparenim elektronima, obično su živo obojani, tako da se njihovo nastajanje često može opaziti golim okom. Ovdje je opisano nekoliko jednostavnih reakcijâ s biološki najvažnijim radikalom, semikinonom. Lako ih je izvesti u školskom laboratoriju uporabom male količine jeftinih i bezopasnih tvari. Jednostavnim promatranjem tih reakcijâ dade se naučiti mnogo toga o kemiji (slobodnih) radikala. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Radicals, chemical species with unpaired electrons, are usually believed to be very unstable; they can be prepared only under special conditions, and can be studied using only special, very expensive, instruments. They are also believed to be harmful, and that they should be kept away from school laboratories. However, radicals have a crucial role in biological reactions. Due to their unpaired electron(s), radicals have a distinct colour, so their appearance may be easily detected. Several simple reactions involving the biologically most relevant radical, semiquinone, are described. They can be easily performed in a school laboratory, using small quantities of cheap, harmless substances. A great deal of radical chemistry can be learned by simple observation of these reactions. This work is licensed under a Creative Commons Attribution 4.0 International License

A Strong Link Between Organic Chemistry and Chemical Crystallography Started a Century Ago

The article sheds light on some historical crossings of organic chemistry and chemical crystallography. It connects past and present bringing into the focus Prof. Kata Mlinarić-Majerski’s research. An impact of structural chemistry on organic synthesis and reactivity is shown. X-ray structure analysis was established as a unique method to determine the composition and architecture of synthetic and natural organic molecules, already in the second decade of the last century; some of historical and scientific milestones are shown. Numerous controversies were solved, when intriguing molecular structures had been determined and the nature of chemical bond was clarified. An absolute structure (chirality) determination using an anomalous dispersion of X-rays was an important step forward, particularly in pharmaceutical industry. Structural data provided by X-ray crystallography, stored by Cambridge Structural Data Centre have been of great impact on many areas of science. They are closely related to intra- and intermolecular forces and structure/function correlations directing us to synthesis of compounds with designed properties. The developments of supramolecular chemistry, crystal engineering, materials science, and most of all of molecular machines have been assisted by chemical crystallography. The essay does not aim to review the complete scientific opus of Prof. K. Mlinarić-Majerski but it is focused on some of the highlights of her research. The interdisciplinary approach in her research is related to the use of X-ray structural analysis to define molecular architecture, conformational chirality, conformational isomerism, and get insight into reaction paths, interactions governing molecular assembling, and to recognise chemical properties of new compounds. In these researches the X-ray crystallographers were involved. This work is licensed under a Creative Commons Attribution 4.0 International License

Tetra­kis(2-amino-4-methyl­pyridinium) cyclo-tetra-μ2-oxido-tetra­kis­[dioxido­vanadate(V)] tetra­hydrate

The asymmetric unit of the title compound, (C6H9N2)4[V4O12]·4H2O, contains half of a [V4O12]4− anion, two 2-amino-4-methyl­pyridinium, (2a4mpH)+, cations and two water mol­ecules. One water mol­ecule is disordered over two sets of sites with equal occupancies and the H atoms for this mol­ecule were not included in the refinement. The cation lies on an inversion center with four tetra­hedral VO4 units each sharing two vertices, forming an eight-membered ring. In the crystal, the components are linked by inter­molecular N—H⋯O hydrogen bonds, forming a one-dimensional network along [100]. Further stabilization is provided by weak inter­molecular C—H⋯O hydrogen bonds. In addition, π–π stacking inter­actions with centroid–centroid distances of 3.5420 (18), 3.7577 (18) and 3.6311 (19) Å are observed

Study on the Lewis Acid-promoted Aza-Diels - Alder Reaction of Azetidin-2-one-tethered Imines with Siloxydienes in the Asymmetric Synthesis of 2-Aryl(alkyl)-2,3-dihydro-4-pyridones

trans-3-Amino-b-lactams were evaluated as the chiral building blocks in the aza-Diels – Alder reaction of azetidin-2-one-tethered imines with siloxydienes under Lewis acid catalysis, as a route for the asymmetric synthesis of 2-aryl(alkyl)-2,3-dihydro-4-pyridones

Alkali salts of nitranilic and cyanochloranilic acids

Series of novel alkali salts of nitranilic acid (3, 6-dinitro-2, 5-dihydroxyquinone) and cyanochloranilic acid (3-cyano-6-chloro-2, 5-dihydroxyquinone), and also of neutral cyanochloranilic acid dihydrate, were prepared and their structures were studied. The nitranilate dianion revealed a considerable conformational flexibility of nitro groups. Steric and inductive effects exerted by different substituents (nitro, cyano and chloro) and their influence on molecular geometry and crystal packing are discussed