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The rigorous analysis of crystallographic models, refined through the use of least‐squares minimization, is founded on the expectation that the data provided have a normal distribution of residuals. Processed single‐crystal diffraction data rarely exhibit this feature without a weighting scheme being applied. These schemes are designed to reflect the precision and accuracy of the measurement of observed reflection intensities. While many programs have the ability to calculate optimal parameters for applied weighting schemes, there are still programs that do not contain this functionality, particularly when moving beyond the spherical atom model. For this purpose, CAPOW (calculation and plotting of optimal weights), a new program for the calculation of optimal weighting parameters for a SHELXL weighting scheme, is presented and an example of its application in a multipole refinement is given. [ABSTRACT FROM AUTHOR]

Since the inception of the use of synchrotron radiation in the structural characterisation of crystalline materials by single-crystal diffraction in the late 20th century, the field has undergone an explosion of technological developments. These cover all aspects of the experiments performed, from the construction of the storage rings and insertion devices, to the end user functionalities in the experimental hutches. Developments in automation have most frequently been driven by the macromolecular crystallography community. The drive towards greater access to ever-brighter X-ray sources has benefited the entire field. Herein, we detail the revolution that is now occurring within the chemical crystallography community, utilising many of the tools developed by their more biologically oriented colleagues, along with specialised functionalities that are tailored to the small-molecule world. We discuss the benefits of utilising the advanced features of Diamond Light Source beamline I19 in the newly developed remote access mode and the step-change in productivity that can be established as a result. [ABSTRACT FROM AUTHOR]

The crystal structure and magnetic properties of the compound Na5[Mn(l-tart)2]·12H2O (1, l-tart = l-tartrate) have been investigated over the pressure range 0.34–3.49 GPa. The bulk modulus of 1 has been determined as 23.9(6) GPa, with a compression of the coordination spheres around the Na+ ions observed. 1 is therefore relatively incompressible, helping it to retain its magnetic anisotropy under pressure. [ABSTRACT FROM AUTHOR]

The complexes [Ni(S2CR)(triphos)]BPh4 (R = Me, Et, Bun or Ph; triphos = PhP{CH2CH2PPh2}2) have been prepared and characterised. X-ray crystallography (for R = Et, Ph, C6H4Me-4, C6H4OMe-4 and C6H4Cl-4) shows that the geometry of the five-coordinate nickel in the cation is best described as distorted trigonal bipyramidal, containing a bidentate carboxydithioate ligand with the two sulfur atoms spanning axial and equatorial sites, the other axial site being occupied by the central phosphorus of triphos. The reactions of [Ni(S2CR)(triphos)]+ with mixtures of HCl and Cl− in MeCN to form equilibrium solutions containing [Ni(SH(S)CR)(triphos)]2+ have been studied using stopped-flow spectrophotometry. The kinetics show that proton transfer is slower than the diffusion-controlled limit and involves at least two coupled equilibria. The first step involves the rapid association between [Ni(S2CR)(triphos)]+ and HCl to form the hydrogen-bonded precursor, {[Ni(S2CR)(triphos)]+…HCl} (KSTACKABOVER/ABOVEBELOW1/BELOW/STACK) and this is followed by the intramolecular proton transfer (kSTACKABOVER/ABOVEBELOW2/BELOW/STACK) to produce [Ni(SH(S)CR)(triphos)]2+. In the reaction of [Ni(S2CMe)(triphos)]+ the rate law is consistent with the carboxydithioate ligand undergoing chelate ring-opening after protonation. It seems likely that chelate ring-opening occurs for all [Ni(S2CR)(triphos)]+, but only with [Ni(S2CMe)(triphos)]+ is the protonation step sufficiently fast that chelate ring-opening is rate-limiting. With all other systems, proton transfer is rate-limiting. DFT calculations indicate that protonation can occur at either sulfur atom, but only protonation at the equatorial sulfur results in chelate ring-opening. The ways in which protonation of either sulfur atom complicates the analyses and interpretation of the kinetics are discussed. [ABSTRACT FROM AUTHOR]

The reaction between iPr2 PCl and one equivalent of MeMgBr, followed by one equivalent of BH3·SMe2, gives the phosphine-borane iPr2 P(BH3)Me ( 4). Treatment of 4 with nBuLi, followed by Me3 SiCl, gives the sterically demanding phosphine-borane { iPr2 P(BH3)}(Me3 Si)CH2 ( 5) in good yield. Metalation of 5 with nBuLi yields { iPr2 P(BH3)}(Me3 Si)CHLi ( 6), which was crystallised as the TMEDA adduct [{ iPr2 P(BH3)}(Me3 Si)CH]Li(TMEDA) ( 6a) and characterised by X-ray crystallography [TMEDA = N,N,N′,N′-tetramethylethylenediamine]. The reaction between two equivalents of in situ-generated 6 and Cp2 Sn in toluene gives the dialkylstannylene [{ iPr2 P(BH3)}(Me3 Si)CH]2 Sn ( 7), which was crystallised from methylcyclohexane/THF as the rac diastereomer. X-ray crystallography reveals that stabilisation of the Sn centre in 7 is afforded by two agostic-type B-H...Sn interactions, one from each BH3 group. [ABSTRACT FROM AUTHOR]

The article focuses on the compound cis-dichloridobis(triethylphosphane)-platinum(II) chloroform monosolvate obtained from ligand scrambling in the complex cis-[PtCl2(Cyp2PCl)(PEt3)] where Cyp is cyclopentyl when chloroform is added. The compound exhibits a reversible temperature-dependent structural phase transition and a reduced antisotropic displacement and crystallographic symmetry on cooling. The compound was made from the study on hydrolysis/hydroxylation of chlorophosphane ligands in situ on platinum(II) centers.

The article describes the development of the XIPHOS single-crystal X-ray diffraction facility designed for the study of laboratory samples under extreme conditions. Main components of XIPHOS include a direct-drive rotating-anode generator, a cantilevered generator and a four-circle Huber goniometer. The normal mode of operation of XIPHOs is also described.

At temperatures below 5 K the field dependence of the magnetization of the π-stacked bis-dithiazolyl radical 1(R1= Me, R2= H) is consistent with metamagnetic behavior. [ABSTRACT FROM AUTHOR]

The relative configuration of the quaternary C atom in the title bromide, C9H13BrO5, prepared by bromination of the parent ester, has been determined by X-ray crystallographic analysis; the absolute configuration is known from the synthesis. [ABSTRACT FROM AUTHOR]

The title compound, C17H20NO4P, contains pyramidal N atoms and adopts similar conformations in its three independent mol­ecules ( A, B and C). Mol­ecules A and B form a dimer in the crystal structure by way of a pair of N—H⋯O hydrogen bonds, as does C with its inversion-generated partner. [ABSTRACT FROM AUTHOR]

Review: current state of the art in low temperature and high pressure crystallography of molecular organic and coordination compounds; 50 refs. [ABSTRACT FROM AUTHOR]

Abstract: Directed ortho-metallation is used to introduce a boron function into N,N-diisopropylbenzamide, resulting in the formation of both borinate and boronate derivatives. N,N-Diisopropylbenzamide ortho-boronate pinacol ester can be reduced with sodium borohydride–TMSCl resulting in N,N-diisopropylbenzylamino ortho-boronic acid. X-ray crystallography and 11B NMR of this compound clearly shows that the hindered isopropylamino groups are sufficient to prevent B–N intramolecular coordination, which contrasts with N,N-dimethylbenzylamino ortho-boronic acid. [Copyright &y& Elsevier]