Chemists of all fields currently publish about 50 000 crystal structures per year, the vast majority of which are X‐ray structures. We determined two molecular structures by employing electron rather than X‐ray diffraction. For this purpose, an EIGER hybrid pixel detector was fitted to a transmission electron microscope, yielding an electron diffractometer. The structure of a new methylene blue derivative was determined at 0.9 Å resolution from a crystal smaller than 1×2 μm 2 . Several thousand active pharmaceutical ingredients (APIs) are only available as submicrocrystalline powders. To illustrate the potential of electron crystallography for the pharmaceutical industry, we also determined the structure of an API from its pill. We demonstrate that electron crystallography complements X‐ray crystallography and is the technique of choice for all unsolved cases in which submicrometer‐sized crystals were the limiting factor.

aThe simple perrhenate salt [NIJhexyl) 4 ]ij(ReO 4 )] acts as a catalyst for the reduction of organic carbonyls and carbon dioxide by primary and secondary hydrosilanes. In the case of CO 2 , this results in the formation of methanol equivalents via silylformate and silylacetal intermediates. Furthermore, the addition of alkylamines to the reaction mixture favours catalytic amine N-methylation over methanol production under certain conditions. DFT analysis of the mechanism of CO 2 reduction shows that the perrhenate anion activates the silylhydride forming a hypervalent silicate transition state such that the CO 2 can directly cleave a Si-H bond. IntroductionThe hydrosilylation of CO 2 to silylformates and silylethers is an attractive route for CO 2 utilisation as, unlike hydrogenation, this reaction is exergonic due to the comparative ease of Si-H bond activation and the strength of the Si-O bond, and the availability of relatively inexpensive and environmentally benign hydrosilanes. 66 Important to this chemistry is the formation of a lipophilic ion pair in which electrostatic and hydrogen-bonding interactions are enhanced in the hydrophobic phase. This catalyst has the advantages of ease of synthesis and manipulation and lack of air-sensitivity, and the recovery of the precious metal is driven by straightforward reverse phase-transfer. Given the efficacy of this new catalyst system and the use of high oxidation state rhenium oxo complexes in reduction catalysis, it is shown here that perrhenate can act as a catalyst for the reduction of carbon dioxide to methanol equivalents by hydrosilanes, that the methylation of alkylamines using CO 2 as the C 1 source occurs under similar catalytic conditions, and that this method can be used to reduce aldehydes and ketones to silylalcohols. Results and discussion Reduction of carbon dioxideInitially, the reaction between CO 2 (2.5 bar), PhSiH 3 (2.0 mmol), and pyridinium perrhenate 1 (2.0 mol%) at 80°C in C 6 D 6 in a Teflon-tapped NMR tube was monitored by 1 H NMR spectroscopy. However, only 15% consumption of hydrosilane is seen under these conditions after 16 h ( Fig. S2 and S3, ESI †). In contrast, when the reaction is carried out using the simple lipophilic quaternary ammonium salt [NIJhexyl) 4 ]ijReO 4 ] 2 (2.5 mol%) with PhSiH 3 in C 6 D 6 at 1 bar of

Derzeit publizieren Chemiker aller Fachrichtungen ca. 50 000 Kristallstrukturen pro Jahr,von denen es sich bei der überwältigenden Mehrheit um Rçntgenstrukturen handelt. Wir setzen Elektronen-statt Rçntgenbeugung ein, um die Struktur zweier molekularer Verbindungen zu bestimmen. Zu diesem Zweckw urde ein EIGER-Hybridpixeldetektor an ein Transmissionselektronenmikroskop angebaut und so ein Elektronendiffraktometer konstruiert. Die Struktur eines neuen Methylenblauderivates wurde aus einem Kristall kleiner als 1 2 mm 2 mit einer Auflçsung von 0.9 bestimmt. Mehrere tausend Wirkstoffe sind nur als submikrokristallines Pulver verfügbar.Umdas Potenzial fürdie pharmazeutische Industrie zu verdeutlichen,h aben wir die Struktur eines Wirkstoffs direkt aus einer Tablette bestimmt. Wird emonstrieren, dass Elektronenkristallographie die Rçntgenkristallographie ergänzt und die Methode der Wahl ist füra lle ungelçsten Strukturen von submikrometergroßen Kristallen. Die Grçße der Kristalle ist uns hier wichtig als Kriterium fürd ie Elektronenbeugung.