R. Graziani

Platinum(II) and palladium(II) complexes with dithiocarbamates and amines: synthesis, characterization and cell assay

The [M(ESDT)Cl]n (M = Pd or Pt; ESDT = EtO2CCH2(CH3)NCS2, methylamino-acetic acid ethyl ester-dithiocarboxylate) species have been reacted with various amines (py, pyridine; PrNH2, n-propylamine; c-BuNH2, cyclobutylamine; en, ethylenediamine) in dichloromethane or chloroform with the aim to obtain mixed ligand complexes. The neutral complexes [M(ESDT)(L)Cl] (L = py, PrNH2 or c-BuNH2) and the ionic species ([M(ESDT)(L)2]Cl and [M(ESDT)(En)]Cl) have been isolated, and characterized by IR and proton NMR spectroscopies. The crystal structure of [Pd(ESDT)(PrNH2)Cl] has been determined by X-ray crystallography. The behaviour of the complexes in various solvents was described on the basis of the proton NMR spectra. The complexes and the dithiocarbamato intermediates have been tested for in vitro cytostatic activity against human leukemic HL-60 and HeLa cells.

Lanthanide complexes with compartmental schiff bases

Abstract Lanthanide complexes have been prepared with acyclic and cyclic compartmental Schiff bases (H2L) obtained by condensation of 2,6-diformyl-4-chlorophenol and the polyamines NH2(CH2)2X(CH2)2NH2 (X = NH, S). They can be formulated as Ln(L)NO3· nH2O or Ln(H2L)(NO3)3·nH2O (Ln3+ = La, Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb; n = 0–5) and have been obtained by step-by-step reactions, which allow a more appropriate control of the reaction procedure. Template syntheses often produce not well defined complexes. The Schiff bases act as neutral of dinegative chelating ligands according to the experimental conditions employed. When they coordinate as neutral ligands, one ionic and two bidentate nitrate groups are present in the complexes. A ring contraction, through an interanl cyclization, has been observed in the macrocyclic complexes when X = NH (H2Lc). The crystal structure of [Tb(H2Lc)(NO3)2]NO3 was determined by X-ray crystallography. The compound is monoclinic, space group C2/c, with a = 23.668(5), b = 14.328(7), c = 19.482(5) A and β = 91.82(5)°; Dc = 1.70 g cm−3 for Z = 8. The structure was refined to R = 0.078. The terbium ion is nona-coordinated in the usual coordination geometry of a distorted tricapped trigonal prism. Two nitrato groups are chelate in approximately bisphenoidal position, the third nitrate being ionic. The organic macrocycle is coordinated through two oxygen and three nitrogen atoms. Selected bond distance are: TbO(nitrate) 2.46 A (mean), TbO(ligand) 2.25 A (mean), TbN(ligand) 2.54 A (mean).

A tetranuclear complex of tin: Crystal structure of {[(n-C4H9)2SnOOCCCl3]2O}2 and related properties in solution

Abstract The structure of the title compound has been determined by X-ray analysis. Tetranuclear dimers with a planar, central, four-membered Sn 2 O 2 ring are present in the solid. The compound crystallizes in space group P 1 with a 12.202(8), b 12.785(8), c 12.535(8) A, α 101.97(3), β 111.49(3), γ 108.73(3)°, and Z = 1. The structure was refined to R 6.7%. The coordination modes in the solid are discussed and related to the IR spectra in the solid and in solution.

Analysis, imitation and emulation of classical texts in the Hebrew Bible

Some uranyl complexes with triphenylphosphine and triphenylarsine oxides as ligands have been reinvestigated. The crystal structure of Dioxo-dinitratobis(triphenylarsineoxide) uranium(VI) has been determined by X-ray diffraction. The crystals are monoclinic with a = 11.09±0.04, b = 19.28±0.06, c = 10.88±0.04 A, β = 128° 10′±10′, Z = 2, space group P2 1 /c. Intensities of 921 independent reflections were obtained photographically with CuK α radiation. The structure was solved by three-dimensional Fourier syntheses and refined by was full-matrix least squares. The final R index 8.6%. The uranium atom is octacoordinated with two bidentate nitrate ions and two oxygens from ligands coordinated in the plane perpendicular to the uranyl group.

Reactivity of the [ReNR]3+ and [ReN]2+ cores toward bis(diphenylphosphino)amine and its derivatives. Synthesis and crystal structures

The complexes fac-[Re(NMe)Cl3{NH(PPh2)2-P,P′}]1, [ReNCl{NH(PPh2)2-P,P′}2]X (X = Cl 2 or BPh42a), [Re(NMe) Cl2{N(XPPh2)2-X,X′}(PPh3)](X = 0 3, S 4 or Se 8), [Re(NMe)Cl{N(XPPh2)2-X,X′}2](X = S 5 or Se 9), [ReNCl{N(SPPh2)2-S,S′}(PPh3)]6, [ReN{N(XPPh2)2-X,X′)2](X = S 7 or Se 10) and trans-[ReOCl2{N(OPPh2)2-O,O′}(AsPh3)]11 were obtained by treatment of [Re(NMe)Cl3(PPh3)2], [ReNCl2(PPh3)2] or [ReOCl3(AsPh3)2] with the appropriate ligand under different experimental conditions. The structures of complexes 1, 2a and 6 were determined by X-ray crystallography. In 1 and 2a the Re atom is six-co-ordinate in a distorted octahedral configuration, whereas in 6 the Re atom is five-co-ordinate square pyramidal with the N atom in the apical position.

Preparation, properties and crystal structure of dioxane-bis-{μ-oxobis[oxo-vanadium(V) 2-(2′-hydroxypheny)iminomethylphenato]}

Abstract The title compound has been prepared by oxydation of vanadyl(IV) 2-(2′-hydroxyphynel)liminomethylphenato. The crystal structure has been determined by X-ray analysis from diffractometer data and refined to R 0.085. The crystals are triclinic, space group P 1 , with a = 12.98(1), b = 11.99(1), c = 11.97(1) A, α=94.12(4)°, β = 97.99(4)° and γ=102.13(4)°. Two five-coordinate vanadium atoms are oxygen bridged to form the binuclear asymmetric unit of the cell. Such units are additionally bridged in pairs by a dioxane molecule which makes two weak bonds with two symmetry related vanandium atoms forming a tetramer. Axial VO distances are 1.55 and 1.56 A whereas VO distances to the terminal oxygen atoms average 1.85 A and those to the bridging oxygens average 1.78 A. The VO(dioxane) bond (2.51 A) is opposite to the axial bond.

Organotin compounds with 2,2′-biimidazole derivatives. The crystal structure of dibromo(N,N′-dimethyl-2,2′-biimidazole)dimethyltin(IV)

The compounds [SnMe2Br2(DMBIm)], [(SnMe2X2)2(DMBIm)] and (NEt4)2[(SnMe2X3)2(DMBIm)] (X  Cl or Br; DMBIm = N,N′-dimethyl-2,2′-biimidazole) have been synthesized and characterized by conductivity measurements and IR and 1H NMR spectroscopy. The structure of dibromo(N,N′-dimethyl-2,2′-biimidazole)dimethyltin(IV) was determined by X-ray diffraction. Crystals are: orthorhombic, P212121, with a 9.402(2), b 10.389(3), c 16.228(3) A, V 1585 A3, Z = 4. The structure was refined to R = 0.047 based on 1461 observed intensities. The compound consists of discrete [SnMe2Br2(DMBIm)] molecules in which the tin atom is octahedrally six-coordinate with trans methyl groups and bidentate DMBIm. IR data for [(SnMe2X2)2(DMBIm)] complexes are consistent with coordination number 5, and those for (NEt4)2[(SnMe2X3)2(DMBIm)] with coordination number 6 for the tin atom. The 1H NMR spectra show that the compounds undergo extensive dissociation in CDCl3.

Tri(η-cyclopentadienyl)uranium(IV) silyl and siloxide compounds. Crystal structure of [U(η5-C5H5)3(OSiPh3)]. Insertion of lsocyanide into a uranium–silicon bond

The complex [U(η5-C5H5)3(SiPh3)](1) has been synthesized from [U(η5-C5H5)3Cl] and Li(SiPh3) and fully characterized. The direct U–Si bond in (1) is quite reactive towards proton acidicmolecules, moreover it reacts with 2,6-dimethylphenyl isocyanide to give the insertion product [U(η5-C5H5)3{C(NC6H3Me2-2,6)SiPh3}](3), the 1H n.m.r. and i.r. data for which show that the isocyanide ligand is η2-co-ordinated to the uranium atom. The synthesis of [U(η5-C5H5)3(OSiPh3)](2) by reaction of [U(η5-C5H5)3(NEt2)] with SiPh3(OH) and its X-ray structural determination are also reported. Compound (2) crystallizes from diethyl ether in the monoclinic space group P21/n with a= 15.368(5), b= 17.333(5), c= 10.778(5)A and β= 106.27(3)° for Z= 4. The main features are the almost linear U–O–Si bond angle of 172.6(6)° and the short U–O distance of 2.135(8)A.

Heteropolymetallic complexes of 1,1′-bis(diphenylphosphino) ferrocene (dppf). II. Crystal structure of dppf and NiCl2(dppf)

The crystal structures of dppf [dppf=1,1′-bis(diphenylphoshino)ferrocene] and (dppf)NiCl2 were determined by X-ray crystallography and refined toR=0.043 (both). The molecule of dppf is centrosymmetric, with the inversion center at the Fe atom. The ferrocene rings are parallel and staggered. In (dppf)NiCl2 the coordination around nickel is tetrahedral, with a significantly large Cl-Ni-Cl angle (125°) due to repulsion of the chlorine atoms. The ferrocene ligand exhibits a slightly distorted (9°) eclipsed conformation, very similar to that observed in (dppf)NiBr2.

Preparation, characterization, thermal analysis and crystal structure of bis(tetraphenylarsonium)uranyl bis(pyridine-2,6-dicarboxylate) hexahydrate

Abstract A salt-like compound of formula (Ph 4 As) 2 [UO 2 (PDC) 2 ]. 6H 2 O (H 2 PDC = pyridine-2,6-dicarboxylic acid) has been synthesized and characterized. The crystal structure has been determined by X-ray analysis from three-dimensional counter data, and refined by least squares to R = 0·073 for 2750 reflections. The crystals are triclinic, space group P 1 with a = 15·12(1), b = 11·21(1), c = 9·35(1) A , α = 101·22(2)°, β = 100·27(2)°, γ = 100·53(2)° and Z = 1. The uranium atom is eight-coordinate, the linear uranyl group being equatorially surrounded by an irregular hexagon of four oxygen atoms and two nitrogen atoms from two pyridine-2, 6-dicarboxylate groups. The crystallographic results are related to i.r. measurements. A study of the thermal decomposition is also reported.