Synthesis and Crystal Structure of a Bixbyite‐Type Solid Solution Zr0.43Er0.57O1.07N0.43

A powder of the composition 40 mol‐% Er₂O₃ and 60 mol‐% ZrO₂ has been prepared. The anion deficient fluorite related compound Zr₃Er₄O₁₂ [R\bar{3} : a = 971.79(7) pm and c = 907.976(0) pm] was produced. This precursor was treated with gaseous ammonia at temperatures between 25 and 1200 °C. The reaction was followed in situ by X‐ray diffraction in a high temperature reaction chamber under a constant flow of ammonia. The nitridation of Zr₃Er₄O₁₂ led to a nitride oxide of the solid‐solution‐type with an apparent composition Zr_0.43Er_0.57O_1.07N_0.43 The compound crystallizes isostructural to bixbyite due to vacancy ordering [Ia\bar{3} : a = 1036.37(4) pm]. The reoxidation of the nitride oxide was monitored in DTA/TG experiments exhibiting an almost complete reoxidation to the starting composition except for some inclusions of dinitrogen.     

Cycloaddition routes to polycyclic quinones: part 1 boron triacetate as a regiochemical directing agent

9-Hydroxy-1,4-anthraquinone, a benzannelated juglone derivative, undergoes regiospecific cycloaddition with isoprene when conducted in the presence of boron triacetate. The structure of this regiomer has been determined by X-ray crystallography.     

Behind the Masks: Identifying Students' Competencies for Learning Mathematics and Science in Urban Settings

Three mathematics and science educators reexamine and reflect on their teaching within the context of the American Association for the Advancement of Sciences (AAAS) and National Council of Mathematics' call to make math and science education accessible to all. The paper highlights the importance of teachers reflecting on their teaching practices in order to create opportunities for their students especially those in the urban setting. The educators argue that teachers' reflection on their teaching can cause them to recognize and validate their students' ways of knowing as they identify the students' hidden/concealed abilities that are often masked by their behaviors. The educators discuss their experiences and highlight the lessons that they learned about ways to prepare teachers to successfully teach math and science students in urban settings. Culturally responsive pedagogy and cultural competency are critical skills that teachers need to develop in order to teach all children, especially those in the math and science classroom in the urban setting.     

The x-ray crystal structure,resolution and absolute configuration of thecis-α-dichloro(1, 8-diamino-3, 6-diazaoctane)-ruthenium(III) cation

Summary Acis- configuration for the [RuCl₂(trien)]Cl·2H₂O (trien=1, 8-diamino-3, 6-diazaoctane) complex has been confirmed by an x-ray crystal structure determination. Crystals are monoclinic, space group P2₁/c witha=7.336 (1),b=8.477 (2),c=23.181 (4) Å, =103.3 (1)°, U=1403 (1) Å.³ Z=4 and M=389.7, D_c=1.84 g cm^–3. The structure was refined by full matrix least squares methods to final residual values of R=0.025 and R_w=0.033 on the basis of 3882 unique reflections. The complex has been resolved into its optical isomers using the (+)1, 2-diaminoethanebis(oxalato)cobaltate(III) anion and the absolute configuration assigned.     

Crystal structure of di-μ-methoxo-bis(chloro-2-methylpyridine copper(II))

The crystal structure of di--methoxo-bis(chloro-2-methylpyridine copper(II)), [CuCl(OCH₃)-(2-mepy)]₂, has been determined from three-dimensional, photographically recorded X-ray data. The unit cell is monoclinic, space groupP2₁/c, with dimensionsa = 8·79,b = 6·01,c = 17·59 Å, = 104·4° and contains two centrosymmetric dimeric units [CuCl(OCH₃). (2-mepy)]₂, in which the copper atoms are linked by methoxide oxygen bridges, the dimers being joined into infinite chains through long copper-chlorine bonds. The environment of each copper atom may be described as a distorted tetragonal pyramid with one chlorine, one nitrogen and two oxygen atoms in the base and a chlorine atom from an adjacent dimer at the apex.