A comparison of a microfocus X-ray source and a conventional sealed tube for crystal structure determination

Abstract

Experiments are described in which a direct comparison was made between a conventional 2 kW water‐cooled sealed‐tube X‐ray source and a 30 W air‐cooled microfocus source with focusing multilayer optics, using the same goniometer, detector, radiation (Mo Kα), crystals and software. The beam characteristics of the two sources were analyzed and the quality of the resulting data sets compared. The Incoatec Microfocus Source (IµS) gave a narrow approximately Gaussian‐shaped primary beam profile, whereas the Bruker AXS sealed‐tube source, equipped with a graphite monochromator and a monocapillary collimator, had a broader beam with an approximate intensity plateau. Both sources were mounted on the same Bruker D8 goniometer with a SMART APEX II CCD detector and Bruker Kryoflex low‐temperature device. Switching between sources simply required changing the software zero setting of the 2θ circle and could be performed in a few minutes, so it was possible to use the same crystal for both sources without changing its temperature or orientation. A representative cross section of compounds (organic, organometallic and salt) with and without heavy atoms was investigated. For each compound, two data sets, one from a small and one from a large crystal, were collected using each source. In another experiment, the data quality was compared for crystals of the same compound that had been chosen so that they had dimensions similar to the width of the beam. The data were processed and the structures refined using standard Bruker and SHELX software. The experiments show that the IµS gives superior data for small crystals whereas the diffracted intensities were comparable for the large crystals. Appropriate scaling is particularly important for the IµS data.

Preparation of RSn(I)–Sn(I)R with Two Unsymmetrically Coordinated Sn(I) Atoms and Subsequent Gentle Activation of P4

“…The data of 2 and 3 were measured on an INCOATEC Mo Microsource with Quazar mirror optics and a Smart APEX II Ultra detector on a D8 goniometer and are summarized in Table 1. 30 The diffractometers were equipped with a low temperature device and used Mo Kα radiation, λ = 0.71073 Å. The data sets were integrated with SAINT, 31 and an empirical absorption (SADABS) was applied.…”

From the Lithium‐2‐anilide‐2‐fluoro‐1,3‐diaza‐2‐sila‐cyclopentene‐GaCl3 Adduct to 1,4,6‐Triaza‐5‐gallium‐7‐sila‐cyclo‐3‐heptene ‐ Experimental and Quantum‐chemical Results

“…Appropriate crystals were selected using a polarizing microscope, mounted on the tip of a glass fibre, fixed to a goniometer head and shock cooled by the crystal cooling device. For 1 data were collected on a Bruker APEXII Quazar diffractometer with D8 goniometer at 100 K (Mo Kα radiation, λ = 71.073 pm; INCOATEC Quazar mirror optics) [23 ] For 2 data was collected on a Bruker Smart 6000 CCD diffractometer (Cu Kα radiation, λ = 154.178 pm, graphitemonochromator). Data reduction and processing, carried out with SAINT (1) or SAINT+ [24 ] (2) was followed by semi-empirical absorption correction with SADABS (1) or TWINABS [25] (2).…”

π-Spacer-coupled Diimidosulfinates

“…For 1 -3 a Bruker TXS-Mo rotating anode was used as X-ray source, for 4 an Incoatec microfocus source was utilized [40]. All diffractometers were equipped with a low-temperature device and used monochromated MoK α Unauthenticated Download Date | 5/8/18 6:19 AM radiation, λ = 0.71073Å, with mirror optics as monochromator.…”