A unique lead perrhenate crown ether complex, [Pb(12-crown-4)(H2O)(ReO4)2], exhibits an incommensurately modulated crystal structure at 101 K. In this (3 + 1)D superspace description, the ReO4- tetrahedra undergo continuous rotation. Describing their continuous rotation required introducing several constraints into the Legendre polynomials describing the displacive modulation of these atoms. At 296 K, the rotation of these tetrahedra is characterized by jumps between certain "stationary" positions. The average structure is monoclinic, P21/c with Z = 4, and can be described as comprising [Pb(C8H16O4)(ReO4)2(H2O)] ribbons. One half of the Pb2+ coordination sphere is occupied by the crown ether ligand, while the other is occupied by the oxygen atoms of water molecules and the perrhenate groups. The latter play two crystallographic roles: one bridging the PbO8 polyhedra and the other acting as a terminal ligand with a very rare monodentate (kappa 1) coordination. This is probably the reason for the nearly free rotation of these terminal ReO4 groups along the Pb-O-Re axis. The structural chemistry of lead crown ether complexes, even those with relatively simple counteranions, is expected to yield a wide variety of unique and complex structures.

The rapid development of the chemistry of fluorooxoborates is associated with their important role as valuable optical materials. In this work, we report the first two silver representatives of the family, Ag2B5O8F (1) and Ag3B5O8F2 (2). Both structures are based on pentaborate groups with different degrees of "fluorination": 1 contains interpenetrating frameworks composed of [B5O10F] fundamental building units, while 2 consists of layers of [B5O10F2].

We report the first two silver fluorooxoborates, which extend the fluorooxoborate family to the silver system for the first time.

Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates.

Single crystals of a novel silver borate nitrate, Ag-12(B9O18)(NO3)(3) (1), were produced as a byproduct upon preparation of Ag3B6O10(NO3). 1 is hexagonal, (P6(3)/m, a = 11.2896(3) & Aring;, c = 11.6693(3) & Aring;); its structure exhibits just a second example of unique [B9O18](9-) nonaborate anions [9B:6 Delta 3 square:3(<2 Delta square>-)<3 square>] which can be described as three triborate groups linked in a large cycle. As commonly observed among silver borates, the Ag+ cations exhibit strongly anharmonic vibrations which were described using Gram-Chariler series up to 4th order. 1 is characterized by single-crystal X-ray diffraction, variable-temperature powder X-ray diffraction, IR, Raman, and UV-vis-NIR spectroscopy, complex thermal analysis, and DFT calculations. The thermal expansion of 1 is slightly anisotropic (alpha(a) = 15.0, alpha(c) = 17.7 x 10(-6) degrees C-1 at 200 degrees C). Upon heating, the compound decomposes with formation of metallic silver and another borate, AgBO2, which could be earlier prepared only at high oxygen pressure.

Belomarinaite KNaSO4 (space group P3m1, a = 5.6072(3), c = 7.1781(4) Å and Z = 2) has been studied by high-temperature single crystal X-ray diffraction. The K and Na atoms are disordered, and M1(1c) and M2(1b) sites merge into an M1(2d)(K50%/Na50%) site with increasing temperature, and novel translationsgleiche phase transition of belomarinaite KNaSO4 (P3m1 → P-3m1) was revealed at 123 °C. Then, the temperature increase leads to phase transition of P3¯m1-polymorph of KNaSO4 to α-KNaSO4 (P63/mmc) at 446 °C, and sodium and potassium atoms in K1(1a) and Na1(1b) sites merged into an M4(2a)(K50%/Na50%) site. Crystal structures of KNaSO4 were refined at 300, 500 and 750 °C to R1 = 0.057, 0.056 and 0.048, respectively. The BVS maps and bond-valence energy landscape (BVEL) have been calculated, and the probability of the Na+ migration has been predicted using structural data for belomarinaite at 25 °C. The Na+ ion migration can occur at 2.14 eV in the ab plane and 2.80 eV along the c axis at 25 °C.

New silver-based representatives of the larderellite and veatchite families, Ag2B10O14(OH)4 center dot H2O (1) and Ag2B5O8(OH)center dot H2O (2) respectively, have been prepared using a soft hydrothermal synthetic approach inside a sealed silica tube. Both structures are built of the pentaborate groups yet exhibit various dimensionality: 2D for 1 and 1D for 2. The silver atoms in 1 exhibit noticeable anharmonicity approximated using Gram-Charlie approach. 1 was additionally characterized by thermal analysis, high-temperature X-ray powder diffraction and IR spectroscopy. Thermal expansion of 1 is strongly anisotropic (alpha 11 = 38, alpha 22 = -13, alpha 33 = 14 x 10-6 degrees C- 1) which is related with the hinge mechanism of the larderellite chains from corner-sharing pentaborate groups. Topology and complexity analysis of these compounds within the larderellite and veatchite families is presented.

Two mineral species of the labuntsovite group from Khibiny (sample 1) and Lovozero (sample 2) alkaline massifs are analyzed by single crystal X-ray diffraction and Raman spectroscopy. They are intermediate members of the tsepinite-Na–“tsepinite-Ba”–tsepinite-K solid solution, which are characterized by a high degree of hydration and a low concentration of extra-frame cations. Parameters of monoclinic cells are: a = 14.5086(6) Å, b = 14.2174(6) Å, c = 7.8712(3) Å, β = 117.119(4)°, V = 1444.09(11) Å3 (sample 1) and a = 14.2582(4) Å, b = 13.7541(6) Å, c = 7.7770(2) Å, β = 116.893(4)°, V = 1360.20(9) Å3 (sample 2). Crystal chemical formulas (Z = 2) are: |A[Na0.84K0.6[(H2O)4]5.2]BK0.2CBa0.25D[Ca0.35Na0.15Fe0.025(H2O)]| M1(Ti1.2Nb0.8)M2(Ti1.1Nb0.9)(O,OH)4(Si4O12)2 for sample 1 and |A[Na1.6(H2O,H3O)0.4]BK2C(Ba0.51Sr0.21)D [Mn0.3Ca0.2(H2O)](H2O)4|M1(Ti1.94Nb0.06)M2(Ti1.88Nb0.12)(O,OH)4(Si4O12)2 for sample 2. The high degree of hydration of sample 1 is expressed in the presence of proton hydrate complexes and tetrahedral [H2O]4-associates. Labuntsovite group minerals (LGMs) are characterized by so-called block isomorphism due to different distributions of D cations. Our analysis of heteropolyhedral MT-frameworks in LGMs allows us to determine the topological features of cation networks.

Solvothermal reaction of magnesium nitrate and boron oxide in N , N -dimethylformamide produced a number of particularly complex supramolecular magnesium borates.

Single crystals of two new quaternary bismuth oxychlorides, Bi18O22Cl8.5(BO3)0.5 (1) and Bi18O22Cl8Se (2), have been serendipitously produced in syntheses starting from bismuth borate or oxyselenide and oxychloride. The crystal structure of 1 represents a high symmetry analog of the PbBi17O22Cl9 type structure, formed by double aliovalent (Pb2+ -> Bi3+, 0.5Cl- -> 0.5BO33-) substitution at the two respective cationic and anionic sites, while 2 is a full structural analog of PbBi17O22Cl9. Overall, their structures can be described as sequences of thick (16 & Aring;) slabs (2D "host" structure) comprised of litharge-like layers and ribbons formed by edge-sharing oxocentered OBin, polyhedra (n = 4 and 5). The chloride anions fill the 7.6 & Aring; channels with the triangular cross-section inside the slabs as well as the interlayer space wherein they are partially substituted by disordered BO33- groups or Se2- anions. Compound 1 is just the second example of a mixed halide-borate occupancy among bismuth compounds while 2 illustrates much broader perspectives of mixed oxyhalide-oxychalcogenide approach to construction of novel complex bismuth compounds. Both compounds make new contributions to the family of tunnel structures of anion-centered tetrahedra featuring wide trigonal channels filled by halide anions or more complex metal- -halide "salt inclusions".

On March 26, 2024, the Center for the Study of the Russian-African Relations and African States’ Foreign Policy, Institute for African Studies of the Russian Academy of Sciences, held an all-Russian scientific conference on the topic “Africa in contemporary system of international relations”. The conference was attended by scientists, teachers, postgraduates, applicants, and students from a number of scientific and educational institutions, namely: Institute for African Studies of the Russian Academy of Science, the Russian Institute for Strategic Studies, Lomonosov Moscow State University, Patrice Lumumba Peoples’ Friendship University, Lobachevsky National Research Nizhny Novgorod State University and the Institute of Social Sciences of the I.M.Sechenov First Moscow State Medical University. In two sections of the conference, 22 scientific reports were heard and discussed, which reflected the results of the implementation of the first 10-year plan of Agenda 2063, the activities of leading international players on the continent, as well as Russian-African cooperation after the second Russia - Africa summit.

Extensive searches for new monovalent metal borates as promising nonlinear optical materials continuously provide new exciting results. Attempts to add the iodine end-member of the acentric Na3B4O7X family resulted in a compound with a complex twofold monoclinic superstructure, Na17B24O42I5. As for the lighter-halide analogies, its crystal structure is formed by a 12B:infinity(3)[3(4:2 Delta + 2T)] framework of B4O9 tetraborate groups, 4B:2 Delta 2 square:=, yet the guest metal- halide sublattice is less dense and contains 5 NaI per 6 Na2B4O7 formula units, most likely due to the large size of the iodide ion. Upon heating in the presence of excess NaI, Na17B24O42I5 converts into a simple hexagonal Na3B4O7I structure, completely analogous to Na3B4O7Br, which exists above 444 degrees C.

It is generally accepted that aragonite crystals of biogenic origin are characterized by significantly higher twin densities compared to samples formed during geological processes. Based on our single crystal X-ray diffraction (SCXRD) and transmission electron microscopy (TEM) study of aragonite crystals from various localities, we show that in geological aragonites, the twin densities are comparable to those of the samples from crossed lamellar zones of molluscs shells. The high twin density is consistent with performed calculations, according to which the Gibbs free energy of twin-free aragonite is close to that of periodically twinned aragonite structure. In some cases, high twin densities result in the appearance of diffuse scattering in SCXRD patterns. The obtained TEM and optical micrographs show that besides the twin boundaries (TBs) of growth origin, there are also TBs and especially stacking faults that were likely formed as the result of local strain compensation. SCXRD patterns of the samples from Tazouta, in addition to diffuse scattering lines, show Debye arcs in the a ∗ b ∗ plane. These Debye arcs are present only on one side of the Bragg reflections and have an azimuthal extent of nearly 30°, making the whole symmetry of the diffraction pattern distinctly chiral, which has not yet been reported for aragonite. By analogy with biogenic calcite crystals, we associate these arcs with the presence of misoriented subgrains formed as a result of crystal twisting during growth.

The crystal structure of a new polymorph of metaboric acid, delta-HBO2 (s.g. Pnma, a = 14.7578(9), b = 9.3973(5), c = 3.6352(2) & Aring;) is described. The structure consists of flat six-membered B3O3(OH)3 rings forming chains linked to each other by hydrogen bonds. Also, the stability of delta-HBO2 phase was investigated.

Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates. Five topologically different types of negatively charged {Mg@[B18φ34-35]}-clusters, φ = O, OH, were observed with the magnesium cation as a core and octadecaborate anions as shells. The clusters assemble via common borate polyhedra forming 1D chains, a 2D mesoporous layer, and 3D mesoporous frameworks with an effective channel width of up to 16 Å. Topological analysis of the clusters in combination with the modular crystallography approach indicates that numerous new functional materials can be obtained by varying their assembly mode. At least one compound containing such clusters exhibits a very strong luminescence.

Первый водный борат-нитрат серебра Ag3B4O6(OH)2(NO3) обладает нецентросимметричной кристаллической структурой (P43212, a = 10.0196(3) Å, c = 9.2594(2) Å). Соединение получено методом мягкого гидротермального синтеза внутри вакуумированной кварцевой ампулы. Структура полученного соединения 1D-5B-бората образована цепочками [B4O6(OH)2]2-, состоящими из двух триборатных колец с обобществленным тетраэдром, (2∆3□:(<∆2□>–<∆2□>–)∞, между которыми находятся треугольники NO3 и атомы серебра. Обсуждается соотношение между структурой Ag3B4O6(OH)2(NO3), Tl2B4O6(OH)2⸱2H2O и структурой кернита (Na2B4O6(OH)2⸱3H2O), также образованными цепочками [B4O6(OH)2]2-.

Методами рентгеноструктурного анализа и КР-спектроскопии были изучены два образца минералов группы лабунцовита из Хибинского (образец 1) и Ловозерского (образец 2) щелочных массивов – промежуточных членов твердого раствора цепинит-Na–«цепинит-Ba»–цепинит-K, которые характеризуются высокой степенью гидратации и низким содержанием внекаркасных катионов. Параметры моноклинных ячеек: a = 14.5086(6), b = 14.2174(6), c = 7.8712(3) Å, β = 117.119(4)°, V = 1444.09(11) Å3 (образец 1) и a = 14.2582(4), b = 13.7541(6), c = 7.7770(2) Å, β = 116.893(4)°, V = 1360.20(9) Å3 (образец 2). Кристаллохимические формулы (Z = 2): |A[Na0.84K0.6[(H2O)4]5.2]BK0.2CBa0.25D[Ca0.35Na0.15Fe0.025(H2O)]|{M1(Ti1.2Nb0.8)M2(Ti1.1Nb0.9)(O,OH)4(Si4O12)2} для образца 1 и |A[Na1.6(H2O,H3O)0.4]BK2C(Ba0.51Sr0.21)D[Mn0.3Ca0.2(H2O)](H2O)4|{M1(Ti1.94Nb0.06)M2(Ti1.88Nb0.12)(O,OH)4(Si4O12)2} для образца 2. Высокая степень гидратации образца 1 выражается в присутствии гидратных комплексов протона, а также тетраэдрических [H2O]4-ассоциатов. Для минералов группы лабунцовита характерен так называемый «блочный изоморфизм» связанные с различным распределением D-катионов. Проведенный нами анализ гетерополиэдрических МТ-каркасов в МГЛ позволил установить топологические особенности катионных сеток.