polymorphism; chemical bonding; high pressure; X-ray diffraction; solid state chemistry; crystallography; density functional theory
Machat Martin R., Fischer Andreas, Schmitz Dominik, Vöst Marcel, Drees Markus, Jandl Christian, Pöthig Alexander, Casati Nicola P. M., Scherer Wolfgang, Rieger Bernhard (2018), Behind the Scenes of Group 4 Metallocene Catalysis: Examination of the Metal–Carbon Bond, in Organometallics
, 37(16), 2690-2705.
Wehinger Björn, Fiolka Christoph, Lanza Arianna, Scatena Rebecca, Kubus Marius, Grockowiak A, Coniglio W A, Graf D, Skulatos M, Chen J H, Gukelberger J, Casati Nicola, Zaharko Oksana, Macchi Piero, Krämer Karl, Tozer S, Mudry C, Normand B, Rüegg Christian (2018), Giant pressure dependence and dimensionality switching in a metal-organic quantum antiferromagnet, in Physical Review Letters
, 121, 117201.
Casati Nicola, Genoni Alessandro, Meyer Benjamin, Krawczuk Anna, Macchi Piero (2017), Exploring charge density analysis in crystals at high pressure. Data collection, data analysis and advanced modelling, in Acta Crystallographica Sect. B
, 73, 584.
Gauthier N., Wermeille D., Casati N., Sakai H., Baumbach R.E., Bauer E.D., White J.S. (2017), Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt2In7 using magnetic resonant x-ray diffraction, in Phys. Rev. B
, 96, 064414.
Meixner Petra, Batke Kilian, Fischer Andreas, Schmitz Dominik, Eickerling Georg, Kalter Marcel, Ruhland Klaus, Montisci Fabio, Barquera-Lozada José E., Casati Nicola, Montisci Fabio, Macchi Piero, Scherer Wolfgang (2017), J(Si,H) Coupling Constants of Activated Si–H Bonds, in Journal of Physical Chmistry, A
Andrzejewski M., Casati N., Katrusiak A. (2017), Reversible pressure pre-amorphization of a piezochromic metal–organic framework, in Dalton Transactions
, 46(43), 14795-14803.
Casati Nicola, Kleppe Annette, Jephcoat Andrew, Macchi Piero (2016), Putting pressure on aromaticity along with in situ experimental electron density of a molecular crystal, in Nature Communications
, 7, 10901.
In the last decade, high-pressure crystallography made enormous progresses, especially in the previously unexplored field of organic and organo-metallic crystals. The techniques to apply pressure to materials and to investigate the structural changes have been further developed and standardized, which enabled more systematic studies and a broader spectrum of observations. The data, that can nowadays be collected, allow to speculate not only on the softer intermolecular interactions, heavily affected by compression, but also on the finer changes of a molecular geometry, that better reveal the mechanisms of molecular activation.Our previous research has contributed to foster this rapidly growing field, thanks especially to investigations of soft interactions (metal-metal and metal-ligand bonds in metal complexes and coordination polymers) and on the reactivity of organic molecules. In addition, we have recently started exploring transformations, which are kinetically controlled.The possibility to step-wise investigate the mechanism of a chemical reaction in the solid state is one of the most appealing outcomes of high-pressure crystallography, on which we plan to dedicate further efforts during this research project. In particular, we will focus on:a) nucleophilic/electrophilic interactions in the solid state, that may give rise to predictable reaction paths. This is a way to put into practice the concepts of crystal engineering, using pressure to obtain the reaction products.b) pre-reactive states of molecules, that anticipate the occurrence of a chemical reaction. Although small, changes of molecular structures are observable, especially with single crystal X-ray diffraction and provide enormous information on the reactivity of functional groups in molecules. c) non-equilibrium processes, that enrich the diversity of transformations. So far, we have applied this concept to simple phase transformations involving the rupture and the formation of intermolecular hydrogen bonds, but it could be as well adopted for pressure induced chemical reactions occurring in molecular crystals.d) pressure transmission media, which are fundamental in order to preserve good crystallinity of the samples. Because most of the fluids typically employed are hydrostatic only below 10 GPa, accurate structural investigations are not accessible for many reaction products, that require higher pressure to occur. Finding fluids that remain hydrostatic (or quasi-hydrostatic) above this limit would enable significant extension of the pressure range that can be investigated, without resorting on more expensive and difficult techniques (like He-loading).The outcome of this research project will further enrich the current knowledge of pressure induced solid-state transformations in molecular crystals, providing more insight into the reactivity of species and the products of chemical reactions.