G. Bombieri

Structural studies on actinides carboxylates—III Preparation, properties and crystal structure of lithium glutarate hydrogenglutarate dioxouranate(VI)tetrahydrate UO2(C5H6O4)Li(C5H7O4)·4H2O

The synthesis, thermal behaviour and crystal structure of lithium glutaratehydrogenglutaratedioxouranate(VI) tetrahydrate is described. The compound crystallizes in the monoclinic system, space group P21/n with a = 9.143(3), b = 26.825(11), c = 7.776(2) A, β = 101.2°(2) and Z = 4. The two glutarato ligands behave differently; one is bridging the uranyl groups in infinite chains running approximately in the a axis direction, the second is bridging the uranyl and the lithium ions. The carboxylic groups are chelated on the uranium and monodentate on the lithium. The structure is linked through a network of hydrogen bonding involving water molecules and oxygen atoms from the carboxylato groups. The geometry around the uranium is approximately hexagonal bipyramidal while the lithium is tetrahedrally coordinated with one glutarate oxygen and 3 water oxygens.

Crown ether complexes of actinide elements an X-ray study of the conformational change of the crown ether within the UO2(NO3)2(H2O)2(18-crown-6) molecule

Abstract Uranyl nitrate dihydrate-18-crown-6 crystallizes in the triclinic system with a = 9.072(3), b = 9.144(3), c = 8.323(3) A; α = 64.53(10)°, β = 104.23(10)°, γ = 110.72(10)°, space group P 1 . Its structure has been determined from three dimensional X-ray data collected with an automatic diffractometer at room temperature and refined with full matrix methods to the final conventional R value = 0.038. The uranyl group does not enter into the 18-crown-6 cavity, but presents the usual hexacoordination in the equatorial plane where two water molecules and the bidentate nitrato groups are coordinated trans to each other. The whole structure is constituted by neutral UO2(NO3)2(H2O)2 units alternated with 18-crown-6 molecules and linked together in infinite chains developping along [001] through a hydrogen bonding system. The cyclic ether assumes two statistically non-equivalent sites in the crystal (occupancy factor 0.7 and 0.3, respectively) related to each other by a 180° rotation about 0(7) …0(7′) axis.

Structural studies on the actinide carboxylates—IV The crystal and molecular structure of succinate dioxouranium(VI) monohydrate

Abstract The structure of the title compound, UO2(CH2COO)2·H2O, has been determined from three-dimensional X-ray data. The crystals are orthorhombic, space group Pbcn with four formula units in a cell of dimensions a = 7.583(2), b = 9.491(3) and c = 10.890(3) A . Least-squares refinement has led to a value of the conventional R index of 0.039 for the 418 unique reflections having I⩾3σ(I). The coordination geometry about the uranium atom is pentagonal bipyramidal. The uranyl ions are equatorially surrounded by one water oxygen and by four carboxylate oxygen atoms of different succinic ligands. Each ligand is shared by four uranyl units giving rise to a polymeric-like structure.

Crown ether complexes of lanthanoid and actinoid elements. Crystal and molecular structure of Nd(NO3)3 (18-crown-6)

Abstract Nd(NO3)3. 18-Crown-6 crystallizes in the orthorhombic system, space group Pbca with eight molecules in a cell of dimensions a = 15.512(9), b = 21.662(1), c = 12.141(6) A. The structure has been determined by Patterson heavy -atom methods and refined by full-matrix least squares to R = 0.038. The neodymium atom is coordinated by 6 oxygen atoms of the 18-crown-6 unit and by three bidentate nitrate groups; one of the more hindered side of the ring and two on the opposite side.

A new uranium(IV) organometallic tetrahydroborate complex. The preparation and characterization of the bis(cyclopentadienyl)uranium (iv) bis(tetrahydroborate):(η5c5h5)2u(bh4)2 ☆

The synthesis and characterization of (η 5 -C 5 H 5 ) 2 U(BH 4 ) 2 are reported. I.r. and room temperature Hnmr data support a tridentate ligation and themagnetic equivalence of the bridge and terminal BH − 4 hydrogen atoms. Preliminary X-ray analysis results suggest a structure consisting of the uranium atom in an approximately tetrahedral configuration surrounded by two pentahaptocyc o pentadienyl rings and two tetrahydroborate groups.

Preparation, crystal and molecular structure of GdCl3(18-crown-6)·EtOH

Abstract The structure of the title compound has been determined from single-crystal X-ray analysis. The triclinic cell has dimensions a = 13.225(3), b = 10.246(2), c = 8.283(2) A, α = 112.1(1), β = 101.9(1) and γ = 85.0(1)°, space group P 1 , Z = 2. The structure was refined by least square methods to the conventional R value 0.032 for 2791 observed reflections. The molecule is formed by [GdCl 2 EtOH(18-crown-6)] + cations and Cl − anions. In the cation the crown ether ligand, which includes the Gd ion, is folded away from the side where a chlorine and the ethanolic oxygen are coordinated to the metal ion; a second chloride ion is coordinated on the opposite side.

Structural studies on actinides carboxylates—V[1]: Crystal and molecular structure of ammonium uranyldimalonate monohydrate (NH4)2[UO2(C3H2O4)2]·H2O

Abstract The crystal structure of the title compound has been determined from single crystal diffractometer data. The crystals are monoclinic, space group P21/c, a = 12.112(3), b = 7.217(2), c = 16.359(4), β = 111.96(10), Z = 4.1845 reflections were refined to a final R = 4.7%. The crystals contain water, NH4+ and [UO2(C3H2O4)2]n2n−1 ions. In the latter, one malonate group is bidentate and the second terdentate, giving chains parallel to b. Both ligands form six-membered rings with uranium. The uranyl Uue5f8O distance (mean value) is 1.76 A and the geometry around the uranium is approximately pentagonal bipyramidal.

Structural studies on actinides carboxylates—VI [1]: Crystal structures of strontium uranyldimalonate trihydrate and barium uranyldimalonate trihydrate

Abstract SrUO2(C3H2O4)2 · 3H2O and BaUO2 (C3H2O4) · 3H2O are isostructural. They crystallize in the orthorhombic system space group Pbca with eight molecules in cells of dimensions a = 16.729 (8), b = 23.247 (11) and c = 6.848 (5) A and a = 17.063 (9), b = 23.604 (12) and c = 6.885 (5) A, respectively. The structures were solved by the heavy-atom technique and refined with full-matrix least-squares to the R values of 0.043 and 0.046, respectively. The coordination geometry around the uranium atom is a pentagonal bipyramid with the malonates behaving as bidentate or terdentate ligands to the uranium atoms forming polymeric chains [UO2(C3H2O4)2]n2n− parallel to c. The space between the uranyl dimalonate chains is occupied by the oxygen atoms belonging either to the water molecules or to the carboxylic groups. Each polyhedron shares two edges forming columns running in the same direction as the uranyl chains and connecting them four by four.

Crystal and molecular structure of trans-PtCl(CH2CN)(PPh3)2

The structure of trans -ptCl(CH 2 CN)(PPh 3 ) 2 has been determined from three dimensional X-ray data. The complex crystallizes in the monoclinic system, space group C 5 2h -P2 1 /n with four molecules in a unit cell of dimension, a = 12.366(5), b = 23.019(8), c = 12.303(4) A , β = 110.7(1)°. Least-squares refinement of 137 variables has led to a value of the conventional R index (on F) of 0.038 for the 4313 independent reflections having I ⩾ 3σ(1). The complex is a typical square-planar Pt(II) complex; structural parameters: Ptue5f8P, 2.308(3) and 2.310(3), Ptue5f8Cl, 2.390(3), Ptue5f8C(1), 2.08(1), C(1)ue5f8C(2), C(2)ue5f8N(1), 1.15(2) A ; Ptue5f8C(1)ue5f8C(2), 111.1(8)° andC(1)ue5f8C(2)ue5f8N(1), 180.0(8)°. The crystal packing is determined only by van der Waals interaction and all intermolecular contacts agree with those predicted from radiisum rules.

The crystal and molecular structure of an isomer of chloro [1,9-bis(2-pyridyl)-2,5,8-triazanonane] cobalt(III), tetrachlorozincate(II), [Co(picdien)Cl]ZnCl4

Abstract The structure of the title compound has been determined by counter data. The crystals are orthorhombic, space group P bca , with a = 16.363(7), b = 18.382(8), c = 14.940(6) A, Z = 8. The structure has been defined by full-matrix least-squares to a final conventional R value of 0.092 ( R w = 0.081 ). The coordination geometry of the complex cation is near regular octahedral, with the pentadentate picdien ligand present in the α,β configuration and with a Cl trans to an ‘angular’ secondary nitrogen. Only two, i.e. , one ‘angular’ and the ‘flat’ of the three secondary nitrogen atoms of the picdien ligand exhibit chirality and it is opposite. The absolute configuration of the complex can be designed as Δ-α, β-R (or Λ-α, β-S). The ZnCl 4 anion assumes a distorted tetrahedral configuration.