The solid form screening of galunisertib produced many solvates, prompting an extensive investigation into possible risks to the development of the favored monohydrate form. Inspired by crystal structure prediction, the search for neat polymorphs was expanded to an unusual range of experiments, including melt crystallization under pressure, to work around solvate formation and the thermal instability of the molecule. Ten polymorphs of galunisertib were found; however, the structure predicted to be the most stable has yet to be obtained. We present the crystal structures of all ten unsolvated polymorphs of galunisertib, showing how state-of-the-art characterization methods can be combined with emerging computational modeling techniques to produce a complete structure landscape and assess the risk of lateappearing, more stable polymorphs. The exceptional conformational polymorphism of this prolific solvate former invites further development of methods, computational and experimental, that are applicable to larger, flexible molecules with complex solid form landscapes.

Mechanochemical methods offer unprecedented academic and industrial opportunities for solvent‐free synthesis of novel materials. The need to study mechanochemical mechanisms is growing, and has led to the development of real‐time in situ X‐ray powder diffraction techniques (RI‐XRPD). However, despite the power of RI‐XRPD methods, there remain immense challenges. In the present contribution, many of these challenges are highlighted, and their effect on the interpretation of RI‐XRPD data considered. A novel data processing technique is introduced for RI‐XRPD, through which the solvent‐free mechanochemical synthesis of an organic salt is followed as a case study. These are compared to ex situ studies, where notable differences are observed. The process is monitored over a range of milling frequencies, and a nonlinear correlation between milling parameters and reaction rate is observed. Kinetic analysis of RI‐XRPD allows, for the first time, observation of a mechanistic shift over the course of mechanical treatment, resulting from time evolving conditions within the mechanoreactor.

The intercalation of lithium into graphite was studied at temperatures between 400 and 550 °C by heating mixtures of LiH and graphite powders with molar ratios 4:1, 1:1, and 1:6 under dynamic vacuum for periods between 1 and 72 h. These conditions probe the formation and thermal stability of metastable staged Li–graphite intercalation compounds (Li-GICs) close to the competing formation of the thermodynamically stable carbide Li2C2. Li-GICs of stages I (LiC6, Aα), IIa (Li0.5C6, AαA), IIb (Li∼0.33C6, AαABβB), III (Li∼0.22C6, AαAB), IV (Li∼0.167C6), and dilute stage lithium Id have been identified and characterized by powder X-ray diffraction and Raman spectroscopy. The rate and extent of intercalation (i.e., the achieved stage of Li-GIC) depends on LiH activity and temperature. Stage I was only observed for temperatures above 500 °C. At 400 °C, the highest intercalation corresponded to stage IIb, which was obtained after 2 and 24 h for 4:1 and 1:1 reaction mixtures, respectively. Lower-staged Li-GICs attained at temperatures below 500 °C deintercalate upon prolonged dwelling with the exception of stage IIa, which can be maintained for very long periods (several days) in the presence of LiH. At temperatures above 500 °C, the kinetically controlled formation of Li-GICs is followed by Li2C2 carbide formation. It is shown that the Li-GIC Id coexists with Li2C2 at temperatures up to 800 °C and that the Li content of Id (solubility of Li in graphite) increases between 550 and 800 °C. Consequently, Id with a temperature-dependent homogeneity range should be added as a stable phase in the Li–C phase diagram. A sketch of a revised Li–C phase diagram is provided.

High‐pressure conditions afford unique all‐hydrido hypervalent complexes [SiH6]2− in the crystalline hydridosilicates A2SiH6 (A=K, Rb). Compared to normal‐valent silanes the SiH bond appears considerably enlarged, by about 0.15 Å. Accordingly, SiH stretching frequencies are drastically reduced, by about 400–500 cm−1, thus reflecting the weakness of a hypervalent SiH bond.

The effects of high pressure (up to 30 GPa) on the structural properties of lithium and calcium carbide, Li(2)C(2) and CaC(2), were studied at room temperature by Raman spectroscopy in a diamond anvil cell. Both carbides consist of C(2) dumbbells which are coordinated by metal atoms. At standard pressure and temperature two forms of CaC(2) co-exist. Monoclinic CaC(2)-II is not stable at pressures above 2 GPa and tetragonal CaC(2)-I possibly undergoes a minor structural change between 10 and 12 GPa. Orthorhombic Li(2)C(2) transforms to a new structure type at around 15 GPa. At pressures above 18 GPa (CaC(2)) and 25 GPa (Li(2)C(2)) Raman spectra become featureless, and remain featureless upon decompression which suggests an irreversible amorphization of the acetylide carbides. First principles calculations were used to analyze the pressure dependence of Raman mode frequencies and structural stability of Li(2)C(2) and CaC(2). A structure model for the high pressure phase of Li(2)C(2) was searched by applying an evolutionary algorithm.