M. Biagini Cingi

Spectral Properties and Crystal Structure of Bis(μ-thiocyanato-N,S)bis(thiocyanato-N)-tetrakis(5,7-dimethyl[1,2,4]triazolo[1,5-α]pyrimidine-N3)dicopper(II) and of Tetrakis(5,7-dimethyl[1,2,4]triazolo[1,5-α]pyrimidine-N3)platinum(II)hexa(thiocyanato-S)platinate(IV).

Abstract The preparation, spectroscopic studies and the crystal structure of Cu(dmtp) 2 (NCS) 2 ( I ) and Pt(dmtp) 4 Pt(SCN) 6 ( II ) (dmtp stands for the 5,7-dimethyl[1,2,4]triazolo[1,5- a ] pyrimidine ligand) are described. Crystals of I are monoclinic, space group C 2/ c , with a = 19.088(7), b = 11.516(8), c = 20.118(7) A, β = 104.51(4)°, Z = 28; crystals of II are monoclinic, space group P 2 1 / n , with a = 16.914(8), b = 11.474(9), c = 11.893(7) A, β = 91.52(4)°, Z = 2. The structures of I and II have been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.044 for I and 0.051 for II . The structure of I consists of centrosymmetric dimers [Cu(dmtp) 2 (NCS) 2 ] 2 , in which the copper atoms, bridged by two thiocyanate groups, are in a square pyramidal arrangement involving two isothiocyanate nitrogen atoms and two triazole nitrogen atoms from two dmtp ligands in the basal plane and a thiocyanate sulphur atom from the centrosymmetric complex in the apical position. The structure of II consists of square planar [Pt(dmtp) 2 ] 2+ cations, in which the platinum atom is bound to four triazole nitrogen atoms from dmtp ligands and of octahedral [Pt(SCN) 6 ] 2− anions with the metal bound to sulphur atoms of thiocyanate anions.

Polymeric chains of tetranuclear hydroxo-o-phthalatocuprate(II) units and silver(I)–aromatic interactions in the crystal structure of Ag[Cu2(C8H4O4)2(OH)].5H2O

The crystal structure of Ag[Cu2(C~H404)~(OH)I.5H20, CI6H9AgCu209.5H20, has been determined from diffractometer data by Patterson and Fourier methods and refined to R = 0.079 for 2359 counter reflections: a = 11.388 (11), b = 11.772 (12), c = 7.875 (9) A, ,~ = 100.3 (1), fl = 80.2 (1), y = 102.2 (1) °, space group P i , Z = 2. The structure consists of centrosymmetric tetranuclear [ C u 2 ( C s H 4 0 4 ) 2 ( O H ) ] 2 2 anions (linked in polymeric chains by bridging ophthalate anions), Ag ~ cations and water molecules. The tetranuclear hydroxo-o-phthalatocuprate(II) anions contain two independent Cu atoms linked by triplybridging hydroxo O atoms and by carboxylate bridges from o-phthalate anions. The coordination polyhedron of Cu(1) is a trigonal bipyramid whose equatorial plane is tbrmed by three O atoms from three bridging carboxylates [ C u O = 2.049 (10), 2.101 (10), 2.233 (12) A], the axial positions being occupied by an O atom from an OHion [ C u O = 1.911 (11) A] and by an O atom from a monodentate carboxylate group [ C u O = 1.923 (11) AI. The coordination of Cu(2) is square pyramidal, the basal plane comprising two O atoms from OHions [ C u O = 1.955 (9), 1-949 (9) /k] and two O atoms from two bridging carboxylates [ C u O = 1-924(10), 1.928(10) AI. Another O atom from a bridging carboxylate is at the apex of the pyramid [ C u O = 2.352 (13) /k]. The Ag I ion is linked to this last O atom [ A g O = 2.264 (12) ,~,1 and to two water molecules [ A g O w = 2.328 (25), 2.536 (26) AI, and interacts with a benzene C C bond [ A g (midpoint of C C ) = 2.431 (16) ,~1, so that Ag-aromatic complexes, in a distorted tetrahedral configuration, are present.

Interaction of metal ions with humic-like models. Part 5. The crystal and molecular structure of diaquabis(2,6-dihydroxybenzoato)-dioxouranium(VI) octahydrate ☆

Abstract The crystal and molecular structure of the complex [UO 2 (DHB) 2 (H 2 O) 2 ]·8H 2 O (DHB = 2,6-di- hydroxybenzoato) has been determined from single- crystal X-ray analysis and refined to a final R value of 0.033 for 3620 observed reflections. The complex crystallizes in the monoclinic system, space group C 2/ m , with a = 6.704(3), b = 20.171(6), c = 9.454(4) A and Z = 2. The coordination about the uranyl group, which is linear, involves two bidentate carboxylate groups and two water molecules in trans positions giving rise to an irregular hexagonal bipyramid. Intra- molecular hydrogen bonds between phenolic and carboxylate groups forming six-membered rings allow the molecule to be nearly planar. Spectroscopic (IR, NMR and electronic absorption) data and thermal properties of the compound are also reported.

The structure of (o‐phthalato)bis(pyridine)copper(II) with bridging and chelating o‐phthalate anions

[Cu(C5HsN)2(CaH404)] , M r = 385.9, is monoclinic, space group P21/c, with a = 18.199(6), b = 11.991 ( 1 4 ) , c = 1 7 . 9 2 3 ( 8 ) , ~ , f l = 119.98(2) ° , V = 3388 (4)/~ 3, Z = 8, D x = 1.51, D m = 1 . 5 1 M g m -3, F(000) = 1576, 2(Cu Ks) = 1.54178 ,A, #(Cu Ks) = 1.999 mm -~. R = 0.055 for 5425 observed reflections. 0567-7408/81/122159-05501.00 The structure consists of two crystallographically independent square-pyramidal [Cu(C 5HsN) 2 (C8H404)] complexes linked in polymeric chains by bridging phthalate anions which also act as chelating ligands through two O atoms from one carboxylate group. Pentacoordination of Cu involves two N atoms (one at the apex of the pyramid) from two pyridine molecules, one O atom from the monodentate carboxylate of an

The crystal and molecular structure of barium diaquadi(o-phthalato)cuprate(II) dihydrate. An example of the chelating behaviour of the o-phthalate anion

The crystal structure of barium diaquadi(o-phthalato)cuprate(II) dihydrate has been determined from diffractometer data by Patterson and Fourier methods and refined by block-diagonal least squares to R = 0.032 for 1749 observed reflections. Unit-cell constants are: a = 9. 155 (9), b = 7.831 (8), c = 13.498 (14) ,~, fl = 95. I (1) °. The space group is P2~ with Z = 2. In the structure, discrete [Cu(H20)2(CsH404)212complex anions are present, containing two non-equivalent o-phthalate anions: one acting as a monodentate ligand, the other as a bidentate chelating ligand. The Cu complexes are held together by interactions with Ba 2+ ions and by hydrogen bonds with water molecules. The coordination polyhedron of Cu is a square pyramid whose base is formed by one water molecule [Cu-Ow = 1.971 (10) ~], one O atom [Cu-O = 1-946 (8) AI from the monodentate o-phthalate ligand and two O atoms [Cu-O = 1-907 (7), 1.972 (9) fi,] from the chelating ophthalate ligand. Another water molecule is at the apex of the pyramid [Cu-O w = 2.289 (9) A I. Ba 2~ cations are surrounded by nine O atoms (three from the water molecules): the coordination polyhedron is a distorted trigonal prism with lateral centred faces. The Ba-O bond distances are in the range 2-670-3-055/k.

Electronic structure of diatomic metals Cu2, Cu2 + and Ag2, Ag2 +

The electronic structure of the dimers Cu2 and Ag2 and of their positive ions Cu2 + and Ag2 + is investigated by ab initio LACO-MO-SCF calculations; to perform these computations the gaussian basis sets for transition metals recently proposed by Hyla-Krypsin et al., first contracted as suggested by the authors, then with other segmentation schemes, are used. A good description of molecular orbitals and other molecular properties is achieved. The results indicate also that medium-size basis sets can be successfully used in molecular computations, provided that the optimization is properly performed.

Preparation, crystal and molecular structure of ∥UO2(o-OC6H4CHN(CH2)2N(CH3)2∥·CH2Cl2

Abstract The crystal and molecular structure of ∥UO2(o-OC6H4CHN(CH2)2NH(CH2)2N(CH3)2)NO3∥· 2Cl2 has been determined from 3-dimensional X-ray data collected by counter methods. The structure has been refined by least-squares techniques to a final conventional R factor of 8·2 per cent. The material crystallizes in space group Pbc21 of the orthorhombic system, with four molecules in a cell of dimensions a = 9·298(6), b = 20·541(9) and c = 10·925(8) A . The crystal consists of discrete monomeric molecules interspersed with CH2Cl2 molecules which do not interact with the “inner core” of the complex. The coordination around uranium is approximately pentagonal bipyramidal with uranyl oxygens in axial positions; four equatorial sites are occupied by the tetradentate Schiff base, nitrate group occupying the fifth site. The bond distances and angles reveal no surprises when compared with other analogous uranyl-Schiff bases complexes.

The polarized absorption spectra of the pentacoordinated complex [Cu(OH2)3NO3(C8H10N4O2)]NO3

Abstract Single crystal polarized absorption spectra of penta-coordinated triaquanitratocaffeinecopper(II) nitrate have been measured. An interpretation of the spectra is given on the basis of the data from the crystallographic and molecular structure which gives complete explanation of the change of the intensity with different polarizations.

Preparation and molecular structure of diaquabis(2,6-dihydroxybenzoato)dioxouranium(VI) octahydrate

Metal complexes formed by dihydroxybenzoic acids could be of help in elucidating the metal binding properties of humic-like substances, which are of major importance in the environmental behavior of metals. In this connection, compounds obtained by reaction of 2,6-dihydroxybenzoic acid with some divalent metal ions have isolated and fully characterised [1, 2]. Interestingly, the role of hydrogen bonding in favouring the formation of outer-sphere arrangements in the solid state has been show by X-ray analysis. Here we report preliminary structural data for the title compound which was obtained by reaction of 2,6-dihydroxybenzoic acid with uranyl acetate in aqueous solution. Crystal data: monoclinic, space group C2/m, a = 6.704(3), b = 20.171(6), c = 9.454(4) A, β = 99.57(3)°, V = 1260.6 A3, Dc = 1.99 g cm−3, Dm = 2.03 g cm−3, Z = 2,MoKα radiation, λ = 0.7107 A. 1627 independent reflections were used for the structure determination and refinement (usual R = 0.033). A views of the complex is reported in Fig. 1, together with the more significant bond distances and angels. The molecule consists of uranyl groups equatorially surrounded by two trans bidentate carboxylate groups and two oxygen atoms from water molecules. The remaining eight water molecules are hydrogen bonded to the structure to give intermolecular contacts between neighbouring units. Also in this case, hydrogen bonding appears to be responsible for uncommon structural features of the complex. In fact, coordination of dioxouranium(VI) by only two carboxylate groups is rather unusual [3] and is probably accounted for by the favourable involvement of an extended network of hydrogen bonds.

Nuclear recoil synthesis of metallorganic compounds and crystal structure of Co3(CO)9(C6H7)

Abstract The formation of the complexes Co2(CO)6(C6H8) (I) and Co3(CO)9(C6H7) (II) by nuclear recoil of 60Co and T is reported together with the crystal structure of II. The very low T activity found in II suggests that benzvalene species play an important role in the formation of II. The crystal structure of II has been determined by X-ray diffraction methods. Crystals are triclinic, space group P 1 , a = 8.593(4), b = 14.305(7), c = 8.144(5) A, α=95.28(2), β = 112.24(2), γ = 100.78(2)°. The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least-squares to R = 0.0578 for 1456 observed reflections. The structure consists of an equilateral triangular cluster of Co atoms [CoCo bond distances: 2.450(3), 2.451(3) and 2.459(3) A]. A carbon atom from the (2-cyclopenten-1-methylidine) ligand nearly symmetrically caps the metal triangle [CoC bonds: 1.883(11), 1.901(11) and 1.902(14) A].