Volume 231, Issue 7

A new fluorine-dominant titanium calcium amphibole (FTCA) was found in alkali basalts of the Rothenberg volcano situated in the Eifel paleovolcanic region, Rhineland-Palatinate (Rheinland-Pfalz), Germany. The empirical formula based on 24 (O+F) atoms is (Na 0.65 K 0.30 )(Ca 1.95 Na 0.05 )(Mg 3.36 Fe 3+ 0.87 Fe 2+ 0.13 Ti 0.60 )(Si 5.92 Al 2.08 )O 22 (F 1.11 O 0.89 ). The crystal structure has been studied based on single-crystal X-ray diffraction data. The monoclinic unit-cell parameters are: a =9.8684(2) Å, b =18.0457(3) Å, c =5.3113(1) Å, β =105.543(3)°; space group C 2/ m . The structure was refined to R =3.39% in anisotropic approximation using 3661 F >4σ F . The studied mineral is the first representative of F-dominant amphiboles with C Ti>0.5. It is considered as a F-dominant analogue of ferri-kaersutite NaCa 2 [Mg 3 Fe 3+ Ti](Si 6 Al 2 O 22 )O 2 .

The rare earth-based zinc compounds RE 13 Pd 25+ x Zn 28– x ( RE = Y, Ho–Lu) were synthesized from the elements in sealed niobium ampoules with a maximum reaction temperature of 1470 K followed by different annealing sequences. The structures of all compounds were refined from single crystal X-ray diffraction data, indicating substantial Zn/Pd mixing on one 8 c and one 24 g zinc site. Exemplarily, the homogeneity range of the solid solution Yb 13 Pd 25+ x Zn 28– x was manifested from samples of different starting compositions and five single crystal data sets. The RE 13 Pd 25+ x Zn 28– x structures are cubic, space group I 4̅3 m with lattice parameters ranging from 1295 to 1307 pm, as a function of the rare earth element and the Zn/Pd mixing. Hierarchically, one can derive the RE 13 Pd 25+ x Zn 28– x structures from the simple bcc packing. A group–subgroup scheme was developed for this new 4 × 4 × 4 tungsten superstructure which shows vacancy ordering and dumbbell formation. Temperature dependent magnetic susceptibility measurements show diamagnetism for a Lu 13 Pd 29 Zn 24 sample and Curie–Weiss paramagnetism for Tm 13 Pd 29 Zn 24 down to 3 K.

The presence of both κ 2 -chelating and μ 2 ,κ 2 -tridentate bridging dithiocarbamate ligands in centrosymmetric {Hg[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 ( 1 ) leads to globular aggregates that are linked into a three-dimensional architecture via hydroxyl-O–H···O(hydroxy) hydrogen bonding. The structure contrasts that of Hg[S 2 CN(CH 2 CH 2 OH) 2 ] 2 ( 2 ; this is a literature structure) in which square planar units are connected into supramolecular chains via Hg···S secondary bonding; chains are connected in the crystal structure by hydroxyl-O–H···O(hydroxy) hydrogen bonding. A Hirshfeld surface analysis on 1 and 2 reveal the influence of O–H···O and Hg···S interactions on the molecular packing as well as the distinctive interactions, such as C–H···S interactions in 1 and C–H···π (HgS 2 C) contacts in 2 . A bibliographic survey shows the different structural motifs observed for 1 and 2 are complimented by an additional five motifs for binary mercury(II) dithiocarbamates revealing a fascinating structural diversity for this class of compound.

The common feature of two conformational polymorphs of N,N ′-bis(pyridin-3-ylmethyl)oxalamide is their crystallisation in the monoclinic space group P 2 1 / c with Z =4. In low symmetry form 1 , the central core is effectively planar and the terminal pyridyl rings adopt a syn-periplanar conformation. In the high symmetry form, 2 , there are two independent molecules in the asymmetric unit but each is located about a centre of inversion. The rings again are almost perpendicular to the central plane but, from symmetry are anti-periplanar. Computational chemistry shows that symmetric molecules with syn (two-fold) and anti (centrosymmetric) conformations have nearly identical energies. In the molecular packing of each of 1 and 2 , supramolecular tapes based on amide-N–H···O(amide) hydrogen bonding are found. In 1 , these are connected into layers by C–H···N(pyridyl) interactions, while in 2 , the chains are linked into a three-dimensional architecture by C–H···N(pyridyl) interactions. The importance of hydrogen bonding is emphasised in the analysis of the Hirshfeld surfaces.

At low temperatures the metalorganic compound trimethyltin hydroxide, (CH 3 ) 3 SnOH, possesses a commensurately modulated crystal structure, the modulation wave vector can be described as q = 12c∗.${\bf{q}}\; = \;{1 \over 2}{{\bf{c}}^ * }.$ The crystal structure is studied by analysing single-crystal X-ray diffraction data within the (3+1)-dimensional superspace approach and superspace group P 2 1 2 1 2(00 γ )00 s . The corresponding twofold superstructure has space group symmetry P 2 1 2 1 2 1 . The structure is characterised by polymeric chains running along c -axis, generated by Sn–O–Sn bridges between neighbouring Sn atoms and packed in a distorted hexagonal pattern and linked via C–H···O interstrand hydrogen bonds along the (orthorhombic) directions [110] and [11̅0], but not along [100].

The weak intermolecular noncovalent interactions in the solvate cis- [PtCl 2 (C 2 H 5 CN) 2 ]·CHCl 3 were studied by XRD and DFT methods. Special attention was paid to a chloroform molecule as a potential donor of both hydrogen and halogen bonds. On the one hand, the H atom of chloroform links two Cl atoms of cis- [PtCl 2 (C 2 H 5 CN) 2 ] (H chloroform –Cl complex (2.660 Å, 2.811 Å)), and on the other side, the weak Cl chloroform –Cl complex (3.247 and 3.497 Å) interactions were found. According to DFT calculation, only the H chloroform –Cl complex (2.660 and 2.811 Å) and Cl chloroform –Cl complex (3.247 Å) interactions can be classified as weak noncovalent bonds, whereas the contacts Cl chloroform –C nitrile (3.391 Å) and Cl chloroform –Cl complex (3.497 Å) are due to the crystal packing effect.

A new magnesium antimony tartrate perchlorate [Mg 2 Sb 2 (C 4 H 2 O 6 ) 2 (H 2 O) 8 ](ClO 4 ) 2 ·5H 2 O, 1 , was synthesized in single crystal form by slowly evaporating an aqueous solution of potassium antimony tartrate and magnesium perchlorate. In the temperature interval 298 K–123 K, the compound undergoes two reversible structural phase transitions. The transition from phase I to phase II at ca. 236 K is second order and the transition from phase II to phase III at ca. 144 K is first order. Phase I has an orthorhombic structure, P 2 1 2 1 2, a=11.8658(4) Å, b=16.464(1) Å, c=8.3895(4) Å at 298 K, containing infinite chains of antimony tartrate dimeric clusters bridged by MgO 2 (H 2 O) 4 octahedra. The ClO 4 − anions occupying the interchain space show pronounced dynamic disorder. Phase II is monoclinic, P 2 1 , a=8.3813(8) Å, b=11.760(1) Å, c=16.289(2) Å, β=92.442(2)° at 153 K. Phase III has an orthorhombic unit cell with quadrupled cell volume, P 2 1 2 1 2 1 , a=11.6914(8) Å, b=16.176(1) Å, c=33.426(2) Å at 123 K. While the infinite chains in phases II and III are closely similar to those in phase I, the ClO 4 − anions show different orientations and gradual disappearance of dynamic disorder as the temperature is lowered.