The structure of Na 3 [UO 2 F 5 ] (I) and CaRb 4 [UO 2 F 4 ] 3 ⋅3H 2 O (II) crystals was studied using X-ray diffraction analysis. The uranium-containing structural units are pentagonal bipyramids [UO 2 F 5 ] 3− , which are isolated from each other in I and linked by bridging fluorine atoms into trinuclear complexes of the composition [(UO 2 ) 3 F 12 ] 6− in II. The latter one fills the existing gap in the crystal chemistry of uranyl fluorides and oxofluorides by representing the first example of a trinuclear complex, while di-, tetra- and pentanuclear complexes have been observed before. The first compound has been known for more than half a century, although here we present the first report on its crystal structure. The crystal chemical formulae of the uranium-containing complexes in I and II are AM 1 5 and A 3 M 2 3 M 1 9 , where A = UO 2 2+ , М 2 and М 1 = F − . In both structures, the uranyl-containing complexes are linked into 3D frameworks by R –F and R –O coordination bonds with outer-sphere R cations ( R = Na, Rb or Ca). As both compounds I and II turned out to be non-centrosymmetric their ability to generate the second harmonic was theoretically predicted based on parameters of Voronoi–Dirichlet polyhedra. Experimental verification of the obtained values is of undoubted interest.

The structure of Na3[UO2F5] (I) and CaRb4[UO2F4]3 & sdot;3H2O (II) crystals was studied using X-ray diffraction analysis. The uranium-containing structural units are pentagonal bipyramids [UO2F5]3-, which are isolated from each other in I and linked by bridging fluorine atoms into trinuclear complexes of the composition [(UO2)3F12]6- in II. The latter one fills the existing gap in the crystal chemistry of uranyl fluorides and oxofluorides by representing the first example of a trinuclear complex, while di-, tetra- and pentanuclear complexes have been observed before. The first compound has been known for more than half a century, although here we present the first report on its crystal structure. The crystal chemical formulae of the uranium-containing complexes in I and II are AM 1 5 and A3M 2 3M 1 9, where A = UO22+, & Mcy;2 and & Mcy;1 = F-. In both structures, the uranyl-containing complexes are linked into 3D frameworks by R-F and R-O coordination bonds with outer-sphere R cations (R = Na, Rb or Ca). As both compounds I and II turned out to be non-centrosymmetric their ability to generate the second harmonic was theoretically predicted based on parameters of Voronoi-Dirichlet polyhedra. Experimental verification of the obtained values is of undoubted interest.

New iodoacetate complexes of uranyl with imidazoles have been synthesized: (C3H5N2)[UO2(mia)3] (I) and (C4H7N2)[UO2(mia)3] (II), where mia is the iodoacetate ion CH2ICOOˉ, C3H5N _2^ + is the imidazolium cation, and C4H7N _2^ + is the 2-methylimidazolium cation. The complexes were studied by IR spectroscopy, thermography, and X-ray diffractometry. In crystals I and II, each uranium(VI) atom coordinates three cyclic bidentate mia anions, forming a hexagonal bipyramidal complex [UO2(mia)3]ˉ with the crystal chemical formula A(B01)3, where A = UO _2^2 + and B01 = mia. The nonvalence interactions in the structures of crystals I and II were analyzed by the Voronoi–Dirichlet polyhedra method. It was established that, in addition to hydrogen bonds, the U=O⋅⋅⋅I−C halogen bonds also contribute to the formation of the supramolecular structure of crystals II.

NaUO2(mia)3 (I) crystals (mia: monoiodacetate ion CH2ICOO−) were synthesized and studied by X-ray diffraction and IR spectroscopic analyses. Uranyl-containing complexes [UO2(mia)3]– in the structure correspond to the crystal chemical formula A(B01)3, where A = UO22+, B01 = mia. Using coordination sequences, we analyzed the features of the 3D framework, which is realized in the structure of crystals of I and contains 8 crystallographically nonequivalent U or Na atoms. A semiempirical calculation and comparison of the calculated and experimental vibration frequencies in the IR spectrum of I were performed.

Проведены синтез, ИК-спектроскопическое, термографическое и рентгеноструктурное исследование новых иодоацетатных комплексов уранила с имидазолами: (C3H5N2)[UO2(mia)3] (I) и (C4H7N2)[UO2(mia)3] (II), где mia — иодоацетат-ион CH2ICOOˉ, C3H5N2+ – катион имидазолия, C4H7N2+ – катион 2-метилимидазолия. В кристаллах I и II каждый атом урана(VI) координирует три бидентатно-циклических аниона mia, образуя гексагонально-бипирамидальный комплекс [UO2(mia)3]ˉ с кристаллохимической формулой А(В01)3, где A = UO22+, B01 = mia. С помощью метода молекулярных полиэдров Вороного-Дирихле проведен анализ невалентных взаимодействий в структурах кристаллов I и II. Установлено, что в формирование супрамолекулярной структуры кристаллов II, помимо водородных связей, вносят вклад галогенные связи U = O∙∙∙I−C.

Crystal structure Na3[UO2(C2O4)F3] · 4H2O (I), K3[UO2(C2O4)F3] (II), K3[UO2(C2O4)2F] · 3H2O (III) and Cs[UO2(C2O4)F] · H2O (IV) first studied by X-ray diffraction. Uranium–containing structural units are complexes [UO2(C2O4)F3]3ˉ (for I and II), [UO2(C2O4)2F]3- (III) and [UO2(C2O4)F]- (IV), accordingly with crystal chemical formulas А(В01)M13, А(В01)2M1 and А(Q02)M1, where A = UO22+, B01 or Q02 = C2O42-, and M1 = F- . In all compounds U(VI) atoms implement pentagonal-bipyramidal coordination, at that in I—III uranyl complexes have single–core structure, and in IV crystals–chain structure which is similar for the well — known for [UO2(C2O4)(H2O)] · 2H2O. The obtained results suggest that a sharp increase in the solubility of uranyl oxalate trihydrate in aqueous solutions with the addition of fluorides is due to the well-known effect of structural depolymerization of coordination polymers of d- or f-metals in the presence of fluoride ions. Semi-empirical calculation and comparison of calculated and experimental oscillation frequencies in IR spectra II and IV are carried out.

Synthesis, IR spectroscopic, and X-ray diffraction studies of R[UO2(mia)(3)](2)2Hmia4H(2)O crystals, where R = Sr2+ (I) or Ba2+ (II), and mia is the monoiodacetate ion CH2ICOO-, have been carried out. The [UO2(mia)(3)](-) complexes correspond to the crystal chemical formula A(B-01)(3), where A = UO22+, B-01 = mia. It has been established that a common feature of I and II is the presence of trinuclear electrically neutral clusters {R[UO2(mia)(3)](2)(Hmia)(2)(H2O)(2)}. At the centers of the clusters there are trigonal RO8 dodecahedra; half of their oxygen atoms belong to four different mia anions of two [UO2(mia)(3)](-) complexes. In addition, each R atom coordinates the oxygen atoms of two water molecules and the carbonyl oxygen atoms of two Hmia molecules. Using the method of molecular Voronoi-Dirichlet polyhedra, an analysis of noncovalent interactions in the structure of I was carried out.

Using X-ray diffraction analysis, the structure of the crystals of Li(UO2)2(C5H6O4)2F⋅6H2O (I), NaUO2(C5H6O4)F⋅4H2O (II) and Sr(UO2)2(C5H6O4)2F2⋅8H2O (III) was studied for the first time. The uranium-containing structural units in crystals of I are 1D complexes [UO2(C5H6O4)F0.5(H2O)]0.5– with the crystal chemical formula AQ02M20.5M1, where A = UO22+, Q02 = C5H6O42–, M2= F–, M1 = H2O, and in II and III, 1D complexes of the same composition and structure [UO2(C5H6O4)F]– with the crystal chemical formula AQ02M2. In all compounds, the U(VI) atoms implement hexagonal-bipyramidal coordination, forming coordination polyhedra UO2FO5 (I) and UO2F2O4 (II and III). It was found that the long-characterized uranyl fluoroglutarate {UJUBEG}, for which the composition [UO2(С5H6O4)F]⋅2H2O was erroneously indicated, contradicting the principle of electrical neutrality, should be considered as (Н3O)[UO2(С5H6O4)F]⋅H2O.

Syntheses, IR spectroscopic and X-ray diffraction studies of new uranyl iodoacetate complexes with divalent metals were carried out: R [UO 2 (CH 2 ICOO) 3 ] 2 & sdot; 6H 2 O ( R = Mg 2+ ( I ), Mn 2+ ( II ), Ni 2+ ( III )). It was established that isostructural I - III crystallize in the cubic crystal system and contain octahedral aqua complexes [ R (H 2 O) 6 ] 2+ , which connect hexagonal-bipyramidal complexes [UO 2 (CH 2 ICOO) 3 ] - into a three-dimensional framework by hydrogen bonds. Using molecular Voronoi - Dirichlet polyhedra, it was found that bifurcate halogen bonds O & sdot;& sdot;& sdot; I- C are also involved in the interconnection of anionic complexes. On the example of two series of stoichiometrically similar compounds dependence of the ratio of sizes of carboxylate ligands and counter cations on crystal system was observed and crystal systems for the compounds that have not yet been structurally characterized were assumed.

The structures of crystals Na3[UO2(C2O4)F3]⋅4H2O (I), K3[UO2(C2O4)F3] (II), K3[UO2(C2O4)2F]⋅3H2O (III), and Cs[UO2(C2O4)F]⋅H2O (IV) were studied for the first time using X-ray diffraction. The uranium-containing structural units are complexes [UO2(C2O4)F3]3– (for I and II), [UO2(C2O4)2F]3– (III), and [UO2(C2O4)F]– (IV) with crystal chemical formulas А(В01)M _3^1 , А(В01)2M1, and А(Q02)M1 (A = UO_2^2 + ; B01 or Q02 = C_2O_4^2 - ; M1 = F–), respectively. In all compounds, the U(VI) atoms implement a pentagonal-bipyramidal coordination; in I–II the uranyl complexes have a mononuclear structure, and in crystals IV they have a chain structure similar to that known for [UO2(C2O4)(H2O)]⋅2H2O. The results obtained suggest that the sharp increase in the solubility of uranyl oxalate trihydrate in aqueous solutions with the addition of fluorides is due to the effect of structural depolymerization of coordination polymers in the presence of fluoride ions. A semi-empirical calculation was performed and the calculated and experimental vibration frequencies in the IR spectra of II and IV were compared.

Synthesis, IR spectroscopic, and X-ray diffraction studies of R[UO2(mia)3]2·2Hmia·4H2O crystals, where R = Sr2+ (I) or Ba2+ (II), and mia is the monoiodacetate ion CH2ICOO−, have been carried out. The [UO2(mia)3]– complexes correspond to the crystal chemical formula A(B01)3, where A = UO22+, B01 = mia. It has been established that a common feature of I and II is the presence of trinuclear electrically neutral clusters R[UO2(mia)3]2(Hmia)2(H2O)2. At the centers of the clusters there are trigonal RO8 dodecahedra; half of their oxygen atoms belong to four different mia anions of two [UO2(mia)3]– complexes. In addition, each R atom coordinates the oxygen atoms of two water molecules and the carbonyl oxygen atoms of two Hmia molecules. Using the method of molecular Voronoi–Dirichlet polyhedra, an analysis of noncovalent interactions in the structure of I was carried out.

Two new disulfatouranylates, Rb 2 [UO 2 (SO 4 ) 2 (H 2 O)]⋅1.75H 2 O ( I ) and (N 2 H 5 ) 2 [UO 2 (SO 4 ) 2 (H 2 O)] ( II ), were synthesized and their structures were determined by single-crystal X-ray diffraction. In structures I and II , each uranyl ion is coordinated in the equatorial plane by four bidentate-bridging sulfate groups and one water molecule to form pentagonal-bipyramidal complexes with the crystal-chemical formula АВ _2^2 М 1 ( A = UO_2^2 + , B 2 = SO_4^2 - , M 1 = H 2 O). It was found that, while having the same composition [UO 2 (SO 4 ) 2 (H 2 O)] 2– , the uranium-containing structural units are geometric isomers, which have a chain and layered structure in I and II , respectively.

The crystals of (CN3H6)3[UO2(mia)3]2(NO3) (I) and (CN3H6)3[UO2(mia)3]2(OH) (II), where mia is the monoiodoacetate ion CH2ICOO–, were synthesized and studied by IR spectroscopy, thermogravimetric analysis, and X-ray diffraction. The uranyl-containing [UO2(mia)3]– complexes in the structures of I and II are described by the crystal chemical formula A(B01)3, where A = UO_2^2 + , B01 = mia. The non-covalent interactions in the crystals of I were analyzed by the method of molecular Voronoi–Dirichlet polyhedra. Considering the available published data, it was found that the nature of the iodine-containing carboxylate ions (aliphatic or aromatic) does not affect the geometric characteristics (d(I⋅⋅⋅O) and ∠C–I⋅⋅⋅O) of the non-covalent interactions involving iodine atoms.

Two new coordination polymers: Ba2[(UO2)3(suc)3F4]⋅5H2O (I) and Ba[(UO2)2(glt)2(Hglt)F]⋅8H2O (II), where suc is C4H4O _4^2 - (succinate ion) and glt is C5H6O _4^2 - (glutarate ion), were synthesized, and their structure was studied. The uranium-containing structural units of crystals I are the [(UO2)3(C4H4O4)3F4]4– layers belonging to the crystal-chemical group A3(Q02)3 M_2^2 M_2^1 of uranyl complexes, where A = UO_2^2 + , Q02 = C4H4O _4^2 - , М1 and М2 = F–. Structure II contains the uranium-containing 3D complex [(UO2)2(C5H6O4)2(C5H7O4)F]2–, which corresponds to the crystal-chemical formula A2(Q02)2B01M2, where A = UO_2^2 + , Q02 = C5H6O _4^2 - , B01 = C5H7O _4^ - , and М2 = F–.

Two uranyl succinate polymers, NH4[UO2(Suc)(HSuc)]∙H2O (I) and [UO2(Suc)(H2O)2] (II), where Suc = succinate ion ( C_4H_4O_4^2- ), were synthesized and studied by X-ray diffraction, IR spectroscopy, and thermography (CCDC nos. 2202634 and 2202635, respectively). The main structural units in the crystals of I are infinite zigzag chains [UO2(Suc)(HSuc)]–, corresponding to the AQ02B01 crystal chemical formula (A = UO_2^2 + , Q02 = C_4H_4O_4^2-, B01 = C_4H_5O_4^ - ). It was established that in structure II, the electrically neutral [UO2(Suc)(H2O)2] chains correspond to the AQ^02M_2^1 crystal chemical formula (A = UO_2^2 + , Q02 = C_4H_4O_4^2-, M1 = H2O). The intermolecular interactions in structures I and II were analyzed using the method of molecular Voronoi–Dirichlet polyhedra.

The features of actinide contraction in isostructural crystals AnL (L = N, P, or As; An = Th, Pa, U, Np, Pu, Am, Cm, or Bk) are revealed and discussed with the help of parameters of Voronoi–Dirichlet polyhedra. It was found that in the Pa, U, Np, and Pu pnictides, the Voronoi–Dirichlet polyhedra volume of the An atoms, the length of the An–L bonds and the An–An contacts in the actinide sublattices are anomalously reduced compared to the analogous parameters for the Th, Am, Cm, and Bk pnictides, for which linear actinide contraction occurred in all cases. It was shown that the revealed anomalies can be considered as a consequence of 5 f binding interactions, which are typical of Pa, U, Np, and Pu, but absent in the case of Th and transplutonium actinides.

Crystals UO 2 (mac) 2 ⋅L, where mac is the methacrylate ion C 3 H 5 COO – and L is diethylacetamide (DEA) or dimethylformamide (DMF), are synthesized and studied via IR spectroscopy and X-ray diffraction. It is established that the crystal structure of the resulting adducts has the same structure and contains dimers [UO 2 (mac) 2 ⋅L] 2 belonging to the crystal chemical group AВ 2 B 01 М 1 (А = UO_2^2 + , B 2 and B 01 = mac – , М 1 = DEA or DMF) of uranyl complexes. The effect the nature of amides has on the composition and structure of adducts that form in the UO 2 (mac) 2 /L/H 2 O systems is discussed.

Crystal chemical analysis was carried out of compounds containing UO22+ ions in the structure, which coordinate fluorine and oxygen atoms. It was found that in 193 complexes of the composition UObFc at b ≥ 2 and c ≠ 0, the U(VI) atoms exhibit coordination numbers of 7 and 8. The volume of the Voronoi–Dirichlet polyhedra of U(VI) atoms in the UObFc complexes was found to regularly reduce with increasing parameter λ = c/(b + c). The data on the most important topological features of structural groups arising from the mutual binding of UObFc complexes are systematized. It was established that formed by UO2F5 pentagonal bipyramids, which are connected to each other only by common equatorial vertices or edges, can have an identical topology even at different F : U ratios.

Two new uranyl complexes are synthesized: [Co(H2O)6][UO2(Mac)3]2·8H2O (I) and {Ca(H2O)2[UO2(Mac)3]2} (II) (Mac is methacrylate ion CH2C(CH3)COO–). The crystals of complexes I and II are studied by the X-ray diffraction method (CIF files CCDC nos. 2124087 (I) and 2124088 (II)) and IR spectroscopy. The uranyl-containing structural units of the crystals of compounds I and II are mononuclear complexes [UO2(Mac)3]– with the crystal chemical formula $${\text{AB}}_{3}^{{01}}$$ (A = $${\text{UO}}_{2}^{{2 + }},$$ B01 = Mac). In the crystals of complex I, the [UO2(Mac)3]– complexes coexist with octahedral aqua complexes [Co(H2O)6]2+ and outer-sphere water molecules. In the crystals of complex II, each calcium ion binds two water molecules and two [UO2(Mac)3]– anions to form trinuclear electroneutral complexes {Ca(H2O)2(UO2)2(Mac)6} with the crystal chemical formula $${\text{A}}{\kern 1pt}' {\text{M}}_{2}^{1}{{{\text{A}}}_{{\text{2}}}}{\text{B}}_{2}^{{01}}{\text{B}}_{4}^{{11}}$$ (A' = Ca2+, A = $${\text{UO}}_{2}^{{2 + }}{\text{,}}$$ B01 and B11 = Mac, M1 = H2O). In compound II, the uranium-containing complexes are joined into a 3D framework through intermolecular contacts, which are characterized using the method of molecular Voronoi–Dirichlet polyhedra.

Synthesis, IR spectroscopic and X-ray structural studies of crystals [UO 2 (C 4 H 4 O 4 )(C 6 H 5 NO 2 ) 2 ] ( I ) and a new modification [UO 2 (C 4 H 4 O 4 )(H 2 O)] ( II ), where C 4 H 4 O 4 2– are succinate ions, and C 6 H 5 NO 2 is isonicotinic acid. Structure I is formed by chains in which succinate ions play the role of bridging ligands Q 02 and B 2 , and isonicotinic acid molecules in the form of a zwitterion are monodentate ligands M 1 . Chains I correspond to the crystal chemical formula АQ 02 0.5 B 2 0.5 M 1 2 , where = UO 2 2+ , Q 02 and B 2 = C 4 H 4 O 4 2– , and M 1 = C 6 H 5 NO 2 . The reasons of the change in the coordination type of half of the succinate ions in I from characteristic Q 02 to rare B 2 are explained from the standpoint of the 18-electron rule in uranyl compounds. Structure II , like the two already known modifications, corresponds to the crystal chemical formula АQ 4 M 1 , where A = UO 2 2+ , Q 4 = C 4 H 4 O 4 2– , and M 1 = H 2 O. By the example of uranyl succinate monohydrate polymorphs, it was found that, like silica polymorphs, chemically identical 3D uranyl-containing frameworks can differ both in topology (reconstructive isomers) and in the symmetry of the framework (deformation isomers). It was found that the new γ-form of II in the region of ≈180 K reversibly transforms into the already known low-temperature β-modification. It was shown using the Voronoi–Dirichlet polyhedra, that the available data for the fourth polymorph [UO 2 (C 4 H 4 O 4 )(H 2 O)] registered in the CSD as {SUCCUR02}, are erroneous.