Anna Bonamartini Corradi

Monomeric and oligomeric phosphates as deflocculants of concentrated aqueous clay suspensions

Abstract The deflocculating ability of some phosphates, with different P2O5/Na2O molar ratios, towards very concentrated aqueous suspensions (62.5 wt.%) of three clays (named Castellamonte, Samone and Debbia), widely used in the factories of Sassuolo (Italy), has been investigated by means of rheological measurements in the absence and the presence of calcium (II) ions (0–6·10−3 mol dm−3). All slips present a non-Newtonian, thixotropic behaviour. Oligomeric phosphates are very efficient deflocculants for clay suspensions, acting by an essentially electrostatic stabilization mechanism. Furthermore their strong complexing capabilities toward calcium (II) ions make them very appropriate deflocculants for industrial aqueous clay suspensions.

Imidazole-containing ternary complexes of N-benzyloxycarbonyl-aminoacids. Crystal and molecular structure of bis(N-benzyloxycarbonyl-alaninato)bis-(N-methylimidazole) copper (II) ethanol solvate

Abstract Mixed ligand complexes of the type Cu(Z-aminoacidato)2(B2) (Z = benzyloxycarbonyl group, Z-aminoacidate = Z-glycinate (Zgly), Z-alaninate (Zala); Z-valinate (Zval), Z-leucinate (Zleu) ion, B = imidazole (Im), N-methylimidazole (MeIm)) were synthesized and characterized by means of electronic, infrared and EPR spectroscopies. For one of them, bis(Z-alaninato)bis(N-methylimidazole)copper(II) ethanol solvate, the crystal and molecular structure was also determined by the single crystal X-ray diffraction method. The complex crystallizes in the monoclinic space group P21/c, with cell dimensions a = 11.1119(6), b = 18.8398(7), c = 8.9652(5) A, β = 105.380(2)° and Z = 2. The structure was solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares to an R value of 0.045. The complex has square-planar coordination via two centrosymmetric carboxylic oxygens and two N-methylimidazole nitrogens. The second carboxylate oxygen is 2.731(5) A from the copper atom in an ‘out of plane’ position. Packing is mainly determined by hydrogen bondings between amide nitrogen and amide carboxyl oxygen. Electronic, infrared and EPR spectra are consistent with this type of coordination geometry for anhydrous complexes, while for hydrate complexes are suggestive of tetragonal bipyramidal geometry.

Solution and solid state behavior of Co2+, Ni2+ and Zn2+ tosylaminoacidate systems: Crystal and molecular structure of bis(N-tosylglycinato)tetraaquocobalt(II) and bis(N-tosyl-β-alaninato)tetraaquozinc(II) complexes

The interactions between N-tosylamino acids and cobalt(II), nickel(II) and zinc(II) ions in aqueous solution and in the solid state have been investigated. From concentrated aqueous solutions, compounds of general formula [M(II)(N-tosylaminoacidato) 2 (H 2 O) 4 ](M = Co(II), Ni(II) and N-tosylaminoacidato = N-tosylglycinate (Tsgly − ), N-tosyl-α- and -β-alaninate (Ts-α- and Ts-β-ala − ); M = Zn(II) and N-tosylaminoacidate = Tsgly − , Ts-β-ala − ) and [Zn(II)(N- tosylaminoacidato) 2 (H 2 O) 2 ] were isolated and characterized by means of thermogravimetric, electronic and infrared spectra. For two of them: [Co(Tsgly) 2 (H 2 O) 4 ]( I ) and [Zn(Ts-β-ala) 2 (H 2 O) 4 ]( II ) the crystal and molecular structures were also determined. Both compounds crystallize in the monoclinic space group P 2 1 / c , with two formula units in a cell of dimensions: a = 13.007(6), b = 5.036(2), c = 18.925(7) A, β = 102.33(3)° for ( I ) and a = 14.173(6), b = 5.469(2), c = 17.701(7) A, β = 106.63(3)° for ( II ). The structures were solved by the heavy-atom method and refined by least-squares calculations to R = 0.031 and 0.064 for ( I ) and ( II ) respectively. The cobalt and zinc atoms lie in the centers of symmetry, each bonded to two amino- acid molecules through a carboxylic oxygen atom and four water molecules in a slightly tetragonally distorted octahedral geometry. The second carboxylic oxygen atom is not involved in metal coordination. Electronic and X ray-powder spectra suggest that the tetrahydrate complexes of Co 2+ , Ni 2+ and Zn 2+ ions of the same amino acids are isomorphous and isostructural. No coordinative interactions between ligand and metal ions were found in aqueous solution on varying the pH values before hydroxide precipitation.

The hydrogen bonding effect on the halobismuthate(III) geometry: thermal, spectroscopic and structural properties of halobismuthate complexes of 4,6-dimethylpyrimidine-2(1H)-thione

Abstract Reactions involving Bi(III) halides and 4,6- dimethylpyrimidine-2(1H)-thione (L) in HX solution result in the formation of [HL]3[BiX6]·2H2O (X=C1, Br) and [HL]3[Bi2I9]. These compounds together with the organic molecule in the form of the hydrochloride, (HLCl) were characterized by means of spectroscopic and thermogravimetric measurements. For HLCl·H2O (1) and [HL]3[BiCl6]·2H2O (2), X-ray structures were determined. In 1, which crystallizes in the space group Pca21, with four molecules in the cell, the structure consists of roughly planar protonated organic molecules stacked along the [100] axis and built up by hydrogen bonds involving chlorine atoms and water molecules. For 2, the space group is P21/n, Z=4, the structure contains [BiCl6]3− anions, protonated organic molecules stacked along the [010] axis and water molecules which form strong hydrogen bonds with the [BiCl6]3− anions. The final R indices are 0.0320 and 0.0465 for 1 and 2, respectively.

The crystal and molecular structure of diethylenetriammonium hexachloro-antimonate(III)

A compound of the type [DenH 3 ]SbCl 6 (DenH 3 = diethylenetriammonium cation) was prepared and characterized by means of structural and vibrational measurements. The structure consists of monomeric SbCl 6 3− anions and triprotonated diethylenetriam-monium cations. The SbCl 6 3− anion has a strongly distorted octahedral geometry, presenting three short (2.415–2.495 A) and three long (2.836–3.114 A) Sbue5f8Cl bonds. The presence of multiple hydrogen bonds, mainly involving the counterion and the three long-bonded chlorine atoms, is considered to be responsible for the octahedral distortion. Vibrational properties of the complex are discussed in the light of its known crystal structure.

Crystal and molecular structure of μ-propane-1,3-diamine Di[bis(propane1,3-diamine) copper(II)]perchlorate complex

Abstract The title compound, [Cu2(1,3-pn)5](ClO4)4, crystallizes in the orthorhombic space group Pbca with Z = 8 formula units in a cell of dimensions: a = 30.88(9), b = 14.664(6), c = 15.737(6) A. The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.082 for 3156 counter data. It consists of discrete dinuclear [Cu2(1,3-pn)5]4+ cations and ClO4− anions. In the dinuclear cation two propane diamine molecules act as chelating to each copper atom in the basal plane; the fifth amine molecule in an extended form, with its nitrogen atoms located at the apices of two square-pyramides, bridges two copper atoms. Magnetic and spectroscopic data are also discussed.

Research on titanium-cyclopentadienyl complexes with phosphines and arsines: the crystal and molecular structure of μ-1-diphenylphosphino-μ-2-diphenylarsinoethanebis[chlorodicyclopentadienyltitanium(III)]

Abstract The adduct between Cp 2 TiCl 2 (Cp = η 5 -cyclopentadienyl) and Arphos(Arphos = 1-diphenylphosphino-2-diphenylarsinoethane) was prepared by reducing Cp 2 TiCl 2 with manganese powder in presence of potassium t-butylate, using diethylenglycoldimethylether as solvent and then adding the ligand. The crystals are monoclinic ( P 2 1 / n ) with cell parameters: a = 9.581(1), b = 14.678(2), c = 14.523(2) A , β = 98.29(1)°, Z = 2. The structural analysis was carried out from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to an R value of 5.8%. The titanium atom is tetrahedrally surrounded by two cyclopentadienyl rings in a staggered configuration, one chlorine and one P or As atom (disordered distributed with population parameters 50%) from the centrosymmetrical ligand molecule which joins adjacent coordination polyhedra so that the resulting complex molecule is dimeric.

Syntheses and spectroscopic properties of halocadmates(II): crystal and molecular structure of a new tribromo[N-benzylpiperazinium]cadmium(II) compound

Abstract Compounds of formula [CdX4]·(LH2)·(H2O) (LH2 = N-benzylpiperazinium dication X = Cl, Br, I) and one of formula [CdBr3(LH)] (LH = N-benzylpiperazinium monocation) wem prepared and characterized. The crystal structure of the monoprotonated N-benzylpiperazinium tribromocadmate(II) complex was determined by means of X-ray analysis. The [CdBr3·(LH)] salt is triclinic (space group and lattice constants: P 1 , a = 9.500(3), b = 13.145(7), c = 6.801(1) A, α = 103.79(2), β = 96.24(2), γ = 96.17(5)°, Z = 2, R = 0.0392, Rw = 0.0394). Its structure consists of discrete monomeric [CdBr3(LH)] units, in which the coordination polyhedron around the cadmium ion is a distorted tetrahedron. The coordination sphere is comprised of the three anionic bromide ligands and one terminal N atom of the N-benzylpiperazinium monocation. All the compounds were also investigated by means of IR and Raman spectroscopic measurements. The Cdue5f8Br stretching vibrations of the structurally known [CdBr3·(LH)] salt were unambiguously assigned on the basis of calculations performed on its spectra and by comparison with literature data. The Cd-X stretching vibrations of the [CdX4]·(LH2)·(H2O) compounds, assigned by comparing their spectra with those of the monoprotonated N-benzylpiperazinium tribromocadmate and on the basis of literature data, strongly suggest the presence of discrete [CdX4]2− anions.

Crystal structures of inclusion compounds of 4-aminobenzenesulfamidine (sulfaguanidine) with two dicyclohexano-18-crown-6 isomers

The crystal structures of inclusion compounds of 4-aminobenzenesulfamidine (sulfaguanidine) (L) with two dicyclohexano-18-crown-6 (DCH-6) isomers A(cis-syn-cis) and B(cis-anti-cis) have been determined by X-ray methods. The complexes exhibit 1:2 host-guest ratios. In fact the complex of isomer A is formulated as [DCH-6A·[L]H2O]L (complexI), while that of isomerB is DCH-6BL2 (complex I1).In the crystals, host and guests are connected by O-H...0 and N-H...O bonds.

Crystal and molecular structure of tris(propane-1,3-diamine)nickel(II) dinitrate complex

Abstract The title compound, [Ni(1,3-pn)3](NO3)2, crystallizes in the orthorhombic space group Pbca with eight formula units in a cell of dimensions a = 17.146(8), b = 14.364(5) and c = 15.054(7). The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.053 for 1439 counter data. It consists of discrete, slightly distorted octahedral [Ni(1,3-pn)3]2+ cations and NO3− anions. One of the three six-membered chelate rings show a pronounced flattening unusual chair conformation. Magnetic and spectroscopic data agree to a lower stability of six-membered chelate rings, compared to five-membered chelate ones.