Volume 239, Issue 7-8

New triazole-based tridentate ligands were synthesized, and their crystal structures determined. Through comparison with the crystal structures of the starting materials and related published ligands, dependencies of intermolecular interactions based on the substitution patterns of the triazole motif were identified. In addition to π-stacking interactions, hydrogen bonding, and C–H···π interactions emerged as key players in intermolecular interactions. The observed variations in these interactions will aid in the design of platinum(II) complexes with specific properties.

A series of ternary rare earth – transition metal – tetrelides RET 2 Tt 2 ( RE = Sc, Y, La, Lu; T = Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au; Tt = Si, Ge) was synthesized by arc melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction and in addition, the structures of RE Os 2 Si 2 ( RE = Y, La, Lu), LaAu 2 Si 2 , LaAg 2 Ge 2 and LaAu 2 Ge 2 were refined from single crystal X-ray diffractometer data. The tetrelides crystallize with the ThCr 2 Si 2 type ( I 4/ mmm ) except the platinum compounds which adopt the klassengleiche superstructure of the CaBe 2 Ge 2 type ( P 4/ nmm ). The transition metal atoms have tetrahedral tetrel coordination and the tetrahedra condense to layers via common edges. The stacking of these layers leads to Tt − Tt bonds in the ThCr 2 Si 2 type phases and heteroatomic T − Tt bonds in the CaBe 2 Ge 2 type phases. The rare earth atoms fill larger cages within these three-dimensional networks (coordination number 16 with RE @ T 8 Tt 8 ) with site symmetries 4/ mmm (ThCr 2 Si 2 type) and 4 mm (CaBe 2 Ge 2 type). Systematic multinuclear solid state NMR spectroscopic investigations allowed observing the effect of the involved rare-earth metal, transition metal and tetrel group element, respectively. In particular, 29 Si isotropic resonance shifts can be predicted from element-specific increments and interatomic Si–Si bonding interactions manifest themselves in axially symmetric magnetic shielding anisotropies.

A first cadmium copper selenite–bromide Cd 7 Cu 2 (SeO 3 ) 8 Br 2 ( 1 ) was obtained via chemical vapor transport reactions. The new compound is triclinic, P 1 ‾ $P\overline{1}$ , a  = 5.3280(5) Å, b  = 10.6190(12) Å, c  = 11.4380(13) Å, α  = 100.856(4)°, β  = 93.321(4)°, γ  = 91.021(4)°, V  = 634.22(12) Å 3 , R 1  = 0.027. 1 has no structural analogs and belongs to a new structure type. The structure of 1 can be described as a host-guest architecture. The host is the [Cd 7 (SeO 3 ) 8 ] 2− interrupted framework, which consists of zigzag layers with a large aperture. The guests are copper bromide species. Thus, the formula can be written as [Cd 7 (SeO 3 ) 8 ]{Cu 2 Br 2 }.

To fabricate metals from the base materials for future Mars exploration, synthesis of representative olivine phases and their structural and spectroscopic characterizations are of crucial importance. Using mechanochemical technique that mimics the mechanical weathering, a complete solid solution of (Mg 1− x Fe x ) 2 SiO 4 has been synthesized to investigate the associated crystal chemical properties. X-ray powder diffraction data Rietveld analysis confirms that each polycrystalline sample crystallizes in space group Pbnm . The average crystallite size ranges between 80(1) nm and 223(4) nm. Each lattice parameter increases with increasing Fe-content due to the larger Fe 2+ radius than that of Mg 2+ , following Vegard’s rule. For a given nominal chemical composition, substitution of Mg with Fe at the M 1-site (4 a : 0,0,0) is preferred to the M 2-site (4 c : x , y ,¼). As a consequence, the average Fe-content lies slightly below the equivalence line for x  = 0.2–0.8, indicating that the Fe/Mg ratio in the amorphous scattering content is most likely greater than unity. Characteristic Raman spectral features of the olivines have been explained in terms of the chemical composition ( x ). Simple regression models are demonstrated based on both X-ray diffraction and Raman spectroscopic data for the calculation of Mg/Fe in olivines. Diffuse reflectance UV/Vis spectra RATD analysis shows each olivine phase possesses direct band-gap between 3.38(3) eV and 4.90(3) eV. This study could keep valuable information to relevant databases for future human missions on Mars, in particular, for precise estimation of the representative olivines from the remote X-ray diffraction and spectroscopic data.

The zinc-rich intermetallic phases CaRu 2 Zn 10 , SrRu 2 Zn 10 and EuRu 2 Zn 10 were synthesized by induction-melting of the elements in sealed tantalum ampoules followed by annealing to increase the crystallinity. The samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data: new type, P 4 2 / nnm , a  = 894.68(14), c  = 518.44(9) pm, w R 2 = 0.0830, 432 F 2 values, 22 variables for CaRu 2 Zn 10 , a  = 907.01(10), c  = 516.35(6), w R 2 = 0.0469, 445 F 2 values, 22 variables for SrRu 2 Zn 10 and a  = 902.84(9), c  = 515.91(5) pm, w R 2 = 0.0469, 434 F 2 values, 22 variables for EuRu 2 Zn 10 . The three structures are new ordering variants of the aristotype ThMn 12 . They are discussed on the basis of a group-subgroup scheme and compared to the known superstructures CaCr 2 Al 10 , ErNi 10 Si 2 and ScFe 6 Ga 6 . The calcium atoms within the Ca@Ru 4 Zn 16 polyhedra have flattened tetrahedral ruthenium coordination, reducing the calcium site symmetry to 4 ‾ $\overline{4}$ 2 m (instead of 4/ mmm in the aristotype). Electronic structure calculations show a substantial charge transfer from calcium to ruthenium and an almost neutral zinc substructure.

Pigment Red 48:2 is an industrially important hydrazone pigment, used for the colouration of plastics and printing inks. The crystal structure of the commercial phase was solved and refined from X-ray powder diffraction data. The phase (P.R.48:2, α-phase) was found to be a monohydrate with a chemical composition of Ca[C 18 H 11 ClN 2 O 6 S]·H 2 O. Its tautomeric state was investigated by multinuclear solid-state NMR. The 15 N CPMAS unambiguously revealed the compound to adopt the hydrazone tautomeric form in the solid state. In an unrestrained Rietveld refinement, the crystal structure did not significantly change. The crystal structure was confirmed by dispersion-corrected DFT optimisation, which also included the calculation of solid-state NMR chemical shifts. Heating the monohydrate to about 200 °C results in an anhydrate (P.R.48:2, β-phase), which has not been described before. Its crystal structure was determined by X-ray powder diffraction, and confirmed by DFT-D, too. Solid-state NMR spectra confirmed that the crystal structure of P.R.48:2 remains mostly unchanged upon dehydration and that also the hydrazone tautomeric form is maintained. Both crystal structures are similar and present a double-layer structure. The non-polar layer contains the phenyl and naphthalene moieties, whereas the polar/ionic layer comprehends the calcium ions, carboxylate, sulfonate, carbonyl groups and water molecules. The calcium ions have a coordination number of 8 and 7 in the monohydrate and anhydrate phases, respectively. For the corresponding Mn salt (Pigment Red 48:4), at least two phases were found, but the quality of the powder patterns did not allow determining their crystal structures.