Experimental charge density of grossular under pressure – a feasibility study

Gajda, Roman; Stachowicz, Marcin; Makal, Anna; Sutuła, Szymon; Parafiniuk, Jan; Fertey, Pierre; Woźniak, Krzysztof

doi:10.1107/s2052252520001955

Cited by 17 publications

(17 citation statements)

References 55 publications

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“…A previous paper on DMACB (the 1,2 substituted isomer of SQ) summarises the EDD topological analysis [34], originally devised for theoretical charge densities, but then widely applied to experimental electron distributions [37] (for very recent applications see refs. [38,39]). Selected values of ρ(r) and its Laplacian ∇ 2 ρ(r) at the (3, −1) bond critical points (bcps) of the squaraine molecules are listed in Table 6.…”

Section: The Electron Density Distribution (Edd)mentioning

confidence: 99%

Experimental Charge Density Analysis and Electrostatic Properties of Crystalline 1,3-Bis(Dimethylamino)Squaraine and Its Dihydrate from Low Temperature (T = 18 and 20 K) XRD Data

Destro

Roversi

Soave³

et al. 2020

Crystals

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Multipolar refinements of structural models fitting extensive sets of X‐ray diffraction(XRD) data from single crystals of 1,3‐bis(dimethylamino)squaraine [SQ, C8H12N2O2] and itsdihydrate [SQDH, C8H12N2O2∙2H2O], collected at very low T (18 ± 1 K for SQ, 20 ± 1 K for SQDH),led to an accurate description of their crystal electron density distributions. Atomic volumes andcharges have been estimated from the experimental charge densities using the Quantum Theory ofAtoms in Molecules (QTAIM) formalism. Our analysis confirms the common representation (in theliterature and textbooks) of the squaraine central, four‐membered squarylium ring as carrying twopositive charges, a representation that has been recently questioned by some theoreticalcalculations: the integrated total charge on the C4 fragment is estimated as ca. +2.4e in SQ and +2.2ein SQDH. The topology of the experimental electron density for the SQ squaraine molecule ismodified in the dihydrated crystal by interactions between the methyl groups and the H2Omolecules in the crystal. Maps of the molecular electrostatic potential in the main molecular planesin both crystals clearly reveal the quadrupolar charge distribution of the squaraine molecules.Molecular quadrupole tensors, as calculated with the PAMoC package using both Stewart andQTAIM distributed multipole analysis (DMA), are the same within experimental error.

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Section: The Electron Density Distribution (Edd)mentioning

confidence: 99%

Experimental Charge Density Analysis and Electrostatic Properties of Crystalline 1,3-Bis(Dimethylamino)Squaraine and Its Dihydrate from Low Temperature (T = 18 and 20 K) XRD Data

Destro

Roversi

Soave³

et al. 2020

Crystals

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“…This unfortunately leaves many interesting chemical phenomena out of reach of experimental charge density studies. Up to date experimental charge densities under high pressure were recently obtained using synchrotron radiation for only two compounds, syn-1,6:8,13-biscarbonyl [14]annulene (Casati et al, 2017a,b) and grossular Ca 3 Al 2 (SiO 4 ) 3 (Gajda et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Charge density studies of multicentre two-electron bonding of an anion radical at non-ambient temperature and pressure

Milašinović

Molčanov

Krawczuk

et al. 2021

IUCrJ

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The variation of charge density of two-electron multicentre bonding (pancake bonding) between semiquinone radicals with pressure and temperature was studied on a salt of 5,6-dichloro-2,3-dicyanosemiquinone radical anion (DDQ) with 4-cyano-N-methylpyridinium cation (4-CN) using the Transferable Aspheric Atom Model (TAAM) refinement. The pancake-bonded radical dimers are stacked by non-bonding π-interactions. With rising pressure, the covalent character of interactions between radicals increases, and above 2.55 GPa, the electron density indicates multicentric covalent interactions throughout the stack. The experimental charge densities were verified and corroborated by periodic DFT computations. The TAAM approach has been tested and validated for atomic resolution data measured at ambient pressure; this work shows this approach can also be applied to diffraction data obtained at pressures up to several gigapascals.

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“…Using high-pressure technnologies, structural parameters of molecules [6][7][8] and crystals [9][10][11][12] have been found to change under pressure and the accompanying changes in charge density have been discussed. 13,14 As a result, many pressure-initiated chemical reactions are known. 3,15 However, progress in experimental high-pressure chemistry would have been significantly slower if it were not for computational methods that allow the modeling of atoms, molecules and crystals under pressure.…”

Section: Introductionmentioning

confidence: 99%

Modeling Molecules under Pressure with Gaussian Potentials

Scheurer

Dreuw

Epifanovsky

et al. 2020

J. Chem. Theory Comput.

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The computational modeling of molecules under high pressure is a growing research area that augments experimental high-pressure chemistry. Here, a new electronic struc-1 ture method for modeling atoms and molecules under pressure, the Gaussians On Surface Tesserae Simulate HYdrostatic Pressure (GOSTSHYP) approach, is introduced. In this method, a set of Gaussian potentials is distributed evenly on the van der Waals surface of the investigated chemical system, leading to a compression of the electron density and the atomic scaffold. Since no parameters other than the pressure need to be specified, GOSTSHYP allows straightforward geometry optimizations and ab initio Molecular Dynamics simulations of chemical systems under pressure for non-expert users.Calculated energies, bond lengths and dipole moments under pressure fall within the range of established computational methods for high-pressure chemistry. A Diels-Alder reaction and the cyclotrimerization of acetylene showcase the ability of GOSTSHYP to model pressure-induced chemical reactions. The connection to mechanochemistry is pointed out.

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Experimental charge density of grossular under pressure – a feasibility study

Cited by 17 publications

References 55 publications

Experimental Charge Density Analysis and Electrostatic Properties of Crystalline 1,3-Bis(Dimethylamino)Squaraine and Its Dihydrate from Low Temperature (T = 18 and 20 K) XRD Data

Experimental Charge Density Analysis and Electrostatic Properties of Crystalline 1,3-Bis(Dimethylamino)Squaraine and Its Dihydrate from Low Temperature (T = 18 and 20 K) XRD Data

Charge density studies of multicentre two-electron bonding of an anion radical at non-ambient temperature and pressure

Modeling Molecules under Pressure with Gaussian Potentials

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