Spectroscopic characterization of the oxo-transfer reaction from a bis(µ-oxo)dicopper(III) complex to triphenylphosphine

The oxygen-atom transfer reaction from the bis(µ-oxo)dicopper(III) complex [CuIII2(µ-O)2(L)2]2+1, where L =N,N,N,N -tetraethylethylenediamine, to PPh3 has been studied by UV-vis, EPR, 1H NMR and Cu K-edge X-ray absorption spectroscopy in parallel at low temperatures (193 K) and above. Under aerobic conditions (excess dioxygen), 1 reacted with PPh3, giving OPPh3 and a diamagnetic species that has been assigned to an oxo-bridged dicopper(II) complex on the basis of EPR and Cu K-edge X-ray absorption spectroscopic data. Isotope-labeling experiments (18O2) established that the oxygen atom incorporated into the triphenylphosphine oxide came from both complex 1 and exogenous dioxygen. Detailed kinetic studies revealed that the process is a third-order reaction; the rate law is first order in both complex 1 and triphenylphosphine, as well as in dioxygen. At temperatures above 233 K, reaction of 1 with PPh3 was accompanied by ligand degradation, leading to oxidative N-dealkylation of one of the ethyl groups. By contrast, when the reaction was performed in the absence of excess dioxygen, negligible substrate (PPh3) oxidation was observed. Instead, highly symmetrical copper complexes with a characteristic isotropic EPR signal at g= 2.11 were formed. These results are discussed in terms of parallel reaction channels that are activated under various conditions of temperature and dioxygen

ROLE OF INFORMAL ASSESSMENT IN IMPROVING STUDENTS` REFLECTION

Purpose. The article is devoted to various methods of informal assessment and their potential for developing students’ reflective skills. The authors analyze different theories and approaches to reflective learning in order to design tools for enhancing students’ reflective abilities. Methodology. The data obtained through the research are evaluated and interpreted on the basis of the descriptive approach. The authors also adopt the reflective-activity approach for designing a set of reflective statements. Results. The authors study the main features of informal assessment, compare and contrast them with the forms of formal assessment pointing out that new approaches to assessment such as Learning Oriented Assessment (LOA) should be adopted in order to promote learning, motivate students and encourage their autonomy. Special attention is given to feedback as an LOA component, which correlates with the concept of reflective learning. The authors analyze various theories of reflective learning and design a system of reflective statement, which could be used as a means of practical development of students’ reflective abilities. Practical implications. The results of the research can be applied in teaching practice of various disciplines at higher educational establishments

2-Hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazide

The title compound, C10H12N4O2, features an intra­molecular N—H⋯N hydrogen bond formed between the imine NH and oxime N atoms. The oxime group and the amide C=O bond are anti to each other. In the crystal, mol­ecules are connected by O—H⋯O hydrogen bonds into supra­molecular zigzag chains along the c axis

(2E)-2-Hydroxy­imino-N′-[(E)-2-pyridyl­methyl­ene]propanohydrazide

In the title compound, C9H10N4O2, the pyridine ring is twisted by 16.5 (1)° from the mean plane defined by the remaining non-H atoms. An intra­molecular N—H⋯N inter­action is present. In the crystal, inter­molecular O—H⋯N and N—H⋯O hydrogen bonds link mol­ecules into layers parallel to the bc plane. The crystal packing exhibits π–π inter­actions indicated by the short distance of 3.649 (1) Å between the centroids of the pyridine rings of neighbouring mol­ecules

μ-Oxalato-bis­[(2,2′-bipyridyl)­copper(II)] bis(perchlorate) dimethyl­formamide disolvate monohydrate

The title compound, [Cu2(C2O4)(C10H8N2)4](ClO4)2·2C3H7NO·H2O, contains doubly charged centrosymmetric dinuclear oxalato-bridged copper(II) complex cations, perchlorate anions, and DMF and water solvate mol­ecules. In the complex cation, the oxalate ligand is coordinated in a bis-bidentate bridging mode to the Cu atoms. Each Cu atom has a distorted tetra­gonal-bipyramidal environment, being coordinated by two N atoms of the two chelating bipy ligands and two O atoms of the doubly deprotonated oxalate anion. Pairs of perchlorate anions and water mol­ecules are linked into recta­ngles by O—H⋯O bonds in which the perchlorate O atoms act as acceptors and the water mol­ecules as donors. Methyl groups of the DMF solvent molecule are disordered over two sites with occupancies of 0.453 (7):0.547 (7), and the water molecule is half-occupied

μ-Peroxido-bis­[acetonitrile­bis­(ethyl­enediamine)­cobalt(III)] tetrakis(per­chlorate)

The title compound, [Co2(O2)(CH3CN)2(C2H8N2)4](ClO4)4, consists of centrosymmetric binuclear cations and perchlorate anions. Two CoIII atoms, which have a slightly distorted octa­hedral coordination, are connected through a peroxido bridge; the O—O distance is 1.476 (3) Å. Both acetonitrile ligands are situated in a trans position with respect to the O—O bridge. In the crystal, the complex cations are connected by N—H⋯O hydrogen bonds between ethyl­endiamine NH groups and O atoms from the perchlorate anions and peroxide O atoms

2-Hydroxy­amino-2-oxoacetohydrazide

In the title compound, C2H5N3O3, the hydroxamic group adopts an anti orientation with respect to the hydrazide group. In the crystal, mol­ecules are connected by N—H⋯O and O—H⋯N hydrogen bonds into zigzag chains along the c axis

Synthesis, structure and dioxygen reactivity of a bis(µ-iodo)dicopper(I) complex supported by the [N-(3,5-di-tert-butyl-2-hydroxybenzyl)-N,N-di-(2-pyridylmethyl)]amine ligand

The air-sensitive bis(µ-iodo)dicopper(I) complex 1 supported by [N-(3,5-di-tert-butyl-2-hydroxybenzyl)-N,N-di-(2-pyridylmethyl)]amine (L) has been prepared by treating copper(I) iodide with L in anhydrous THF. Compound 1 crystallizes as a dimer in space group C2/c. Each copper(I) center has distorted tetrahedral N2I2 coordination geometry with Cu–N(pyridyl) distances 2.061(3) and 2.063(3) Å, Cu–I distances 2.6162(5) and 2.7817(5) and a CuCu distance of 2.9086(8) Å. Complex 1 is rapidly oxidized by dioxygen in CH2Cl2 with a 1 : 1 stoichiometry giving the bis(µ-iodo)peroxodicopper(II) complex [Cu(L)(µ-I)]2O2 (2). The reaction of 1 with dioxygen has been characterized by UV-vis, mass spectrometry, EPR and Cu K-edge X-ray absorption spectroscopy at low temperature (193 K) and above. The mass spectrometry and low temperature EPR measurements suggested an equilibrium between the bis(µ-iodo)peroxodicopper(II) complex 2 and its dimer, namely, the tetranuclear (peroxodicopper(II))2 complex [Cu(L)(µ-I)]4O4 (2). Complex 2 undergoes an effective oxo-transfer reaction converting PPh3 into OPPh3 under anaerobic conditions. At sufficiently high concentration of PPh3, the oxygen atom transfer from 2 to PPh3 was followed by the formation of [Cu(PPh3)3I]. The dioxygen reactivity of 1 was compared with that known for other halo(amine)copper(I) dimers

Who are you, Griselda? A replacement name for a new genus of the Asiatic short-tailed shrews (Mammalia, Eulipotyphla, Soricidae): molecular and morphological analyses with the discussion of tribal affinities

The first genetic study of the holotype of the Gansu short-tailed shrew, Blarinella griselda Thomas, 1912, is presented. The mitochondrial analysis demonstrated that the type specimen of B. griselda is close to several recently collected specimens from southern Gansu, northern Sichuan and Shaanxi, which are highly distinct from the two species of Asiatic short-tailed shrews of southern Sichuan, Yunnan, and Vietnam, >B. quadraticauda and B. wardi. Our analysis of four nuclear genes supported the placement of B. griselda as sister to B. quadraticauda / B. wardi, with the level of divergence between these two clades corresponding to that among genera of Soricinae. A new generic name, Parablarinella, is proposed for the Gansu short-tailed shrew. Karyotypes of Parablarinella griselda(2n = 49, NFa = 50) and B. quadraticauda (2n = 49, NFa = 62) from southern Gansu are described. The tribal affinities of Blarinellini and Blarinini are discussed.Copyright Anna A. Bannikova et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article