Band 240, Heft 9-10

The metal-rich antimonide Gd 5 Rh 19 Sb 12 was synthesized by induction-melting of the elements in a sealed tantalum ampoule. The Gd 5 Rh 19 Sb 12 structure was refined from single crystal X-ray diffractometer data of a twinned crystal: P 31 m , a = 1,349.3(3), c = 417.99(12) pm, w R 2 = 0.0682, 1545 F 2 values and 67 variables. Gd 5 Rh 19 Sb 12 is closely related to the Sc 5 Co 19 P 12 -type. A split position of Rh5 is avoided by a translationengleiche symmetry reduction of index 2 from P 6 ‾ $\overline{6}$ 2 m to P 31 m , leading to a fully ordered model. The crucial difference between Sc 5 Co 19 P 12 and Gd 5 Rh 19 Sb 12 concerns the position of the transition metal atoms on the c axis. The Co4 atoms show a split position around the origin in Sc 5 Co 19 P 12 (Co4@Sc 6 trigonal prisms) while the Rh5 atoms in Gd 5 Rh 19 Sb 12 are shifted by c /2 and then form Rh5@Sb 6 trigonal prisms. The remaining substructures of Sc 5 Co 19 P 12 and Gd 5 Rh 19 Sb 12 are comparable. The Rh–Sb and Rh–Rh distances within the [Rh 19 Sb 12 ] substructure range from 255–290 and 292–336 pm, respectively.

In the mineral schafarzikite (FeSb 2 O 4 ) the stereochemical active 5 s 2 lone electron pairs (LEPs) play pivotal roles to diverse crystal-physico-chemical properties. The complete substitution of Sb(III) with an equivalent amount of Pb(II) and Bi(III) leads to higher oxidation state of the transition element (e.g., Fe 3+ ) and offers a mixed stereochemical activity of the 6 s 2 LEPs. Here we report the synthesis and characterization of a solid solution (PbBi)(Fe 1− x Mn x )O 4 ( x  = 0–1.0; Δ x  = 0.1). The polycrystalline samples are synthesized in sealed quartz tubes at 923 K and a pressure of about 1.0 Pa. The crystal structure of each member of the solid solution has been analyzed by X-ray power diffraction data Rietveld refinements. The metric and the geometric parameters (bond lengths, angles, distortion of the polyhedra) have been followed with respect to the chemical composition. The Wang-Liebau eccentricity (WLE) parameter, which measures the strength of the stereochemical activity, has been found to be associated with the over-bonding nature of the LEP cations. The vibrational properties are characterized using Raman and infrared spectroscopy, supporting the structural features. The optical band gap is evaluated from the UV/Vis diffuse reflectance spectra using both conventional Tauc’s and derivation of absorption spectrum fitting (DASF) methods. This study particularly highlights the miscibility between Fe(III) and Mn(III) cations on a single Wyckoff site within the schafarzikite-type structures, where the LEP driven void channels seem to be more suitable for a small cation (e.g., Li + ) insertion than the mineral schafarzikite.

Crystallographically well-documented examples of “Racemic Mimic” pairs remain scarce. We describe two new species belonging to this rare class of pseudo-symmetric crystals, which we term “Racemic Mimics.” The Mn(III) and Co(III) compounds – azido-methanol-((R,R)-N,N′-bis(salicylidene)-1,2-diaminocyclohexane)manganese(III) and (1-cyanoethyl)-pyridine-bis(dimethylglyoximato)cobalt(III) – have been studied in two distinct crystalline forms: (1) a centrosymmetric form [ P 2 1 / n , Z ′ = 1.0] and (2) a Sohncke form [ P 2 1 , Z ′ = 2.0]. In each case, the structures are related by their nearly identical cell constants, with the latter form exhibiting a doubled Z ′ due to the loss of the n-glide plane. Our findings expand the scope of racemic mimicry beyond previously recognized purely organic systems, demonstrating that this phenomenon is more widespread than previously appreciated. Additionally, we highlight the overlooked chirality of the tri-bonded oxygen in the Mn(III) compound, a feature typically disregarded in the Cambridge Structural Database. This work adds another chapter to the intriguing study of racemic mimicry in crystallography.

The equiatomic plumbides SrPdPb and SrPtPb were synthesized by induction-melting of the elements in sealed tantalum ampoules followed by annealing in muffle furnaces. Both crystal structures were refined from single crystal X-ray diffractometer data: TiNiSi type, Pnma , a = 764.58(4), b = 478.23(7), c = 832.20(7) pm, wR 2 = 0.0432, 643 F 2 values, 20 variables for SrPdPb and a = 765.05(2), b = 476.31(3), c = 825.25(4), wR 2 = 0.0691, 642 F 2 values, 20 variables for SrPtPb. The palladium (platinum) and lead atoms built orthorhombically distorted and strongly puckered Pd 3 Pb 3 (283–290 pm Pd–Pb) respectively Pt 3 Pb 3 (281–291 pm Pt–Pb) hexagons that coordinate the strontium atoms.

The tetra-hydrate of pentafluorobenzene sulfonic acid has been crystallized using an in situ technique on a single crystal diffractometer ( P 1 ‾ $P\overline{1}$ , Z  = 2, a  = 705.65(3) pm, b  = 761.62(3) pm, c  = 1,132.34(4) pm, α  = 91.492(2)°, β  = 102.974(2)°, γ  = 90.718(2)°). It turns out that the compound has to be described according to (H 9 O 4 )[C 6 F 5 SO 3 ]. It contains the so-called Eigen ion which is a combination of a central H 3 O + and three H 2 O molecules attached by hydrogen bonds.

Under solvothermal conditions, the reaction of 3-carboxy-1-carboxymethyl-2-oxidopyridinium (H 2 L), and N-donor ligands (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine) with copper(II) ions, two new complexes biaqua-bis[( μ 2 - 3-carboxylato-1-carboxylatomethyl-2-oxidopyridinium-κ 3 O,O′:O″)-(2,2′-bipyridine-κ 2 N,N′) copper(II)] tetrahydrate (1) and poly{aqua-( μ 2 - 3-carboxylato-1-carboxylatomethyl-2-oxidopyridinium-κ 3 O,O′:O″)-hemi( μ 2 -4,4′-bipyridine-κ 2 N:N′) copper(II)] bihydrate} (2) have been successfully synthesized and structurally confirmed by single-crystal X-ray diffraction analysis techniques and elemental analysis. In complex (1) , the anionic H 2 L ligand connects Cu(II) ions in a μ 2 -η 1 :η 1 :η 1 :η 0 :η 0 mode to form a [Cu(L)] 2 unit, which is further extended into chains via π-π stacking between 2,2′-bipy ligands. Adjacent chains interconnect to form supramolecular layers through additional π-π stacking. Complex (2) was shown to have a chains structure in which the binuclear [Cu(L)] 2 moieties are linked into chains due to the bridging function of the 4,4′-bipy ligand, and further connected by hydrogen bond interactions to form a layered structure. Additionally, the properties of (1) and (2) were characterized by FT-IR, UV–vis, PL, TG and Hirshfeld surfaces analyses.

Two regioisomers obtained from the same reaction and differing in the position of an n-butyl substituent, i.e. on either an imidazoyl-N ( 2 ) or a pyridyl-N ( 3 ), have been characterised. Different electronic structures are evident, especially in key bond lengths and angles in the imidazoyl and pyridyl rings, as discerned by X-ray crystallography, and by geometry-optimisation, natural bonding orbital and electrostatic potential charge calculations. The distinctive molecular packing in their crystals has been confirmed by Hirshfeld surface analysis as well as by interaction energy and energy framework calculations. These differences notwithstanding, the calculated lattice energies indicate very similar stabilisation between the molecules in their crystals, i.e. −101.3 and −103.5 kJ/mol for 2 and 3 , respectively, consistent with their similar calculated molecular volumes (376.8 cf. 374.1 Å 3 ), packing coefficients (69.0 cf. 69.5 %) and crystal densities (1.575 cf. 1.586 g/cm 3 ).

The present study, an ultrashort hybrid peptide, namely, Boc-L-Pro-5-AIA(OMe) 2 was synthesized, where 5-amino isophthalic acid (5-AIA) was employed as a rigid non-coded aromatic γ-amino acid. The single crystal X-ray diffraction analysis revealed that L-Pro created a turn with ϕ, Ψ values around −65°, 150° for which a bend was generated in the molecular conformation. In the solid state, two hybrid peptide molecules are assembled in antiparallel fashion and interlocked by using two N–H⋯O hydrogen bonding interactions, resulting in a robust dimer. Interestingly, the dimers are self-assembled via N–H⋯O, O–H ⋯ O, C–H⋯O, π⋯π, and C–H⋯π interactions to fabricate a unique water-mediated sheet network. The classical and non-classical interactions play a crucial role in the stability of the crystal packing, which are supported by Hirshfeld surface and 2D fingerprint analysis.