J. Zukerman-Schpector

Diorganotin(IV) derivatives of salicylaldehydethiosemicarbazone. The crystal structure of dimethyl- and diphenyl- (salicylaldehydethiosemicarbazonato)tin(IV)

Abstract The title compounds have been prepared by reacting the corresponding diorganotin(IV) oxide with salicylaldehyde thiosemicarbazone (H2L). [SnMe2(L)] crystallizes in the monoclinic space group P21/n with a=9.480(3), b=13.532(7), c=10.541(3) A, β=100.33(2)° and Z=4 (R=0.0230, R′=0.0258). [SnPh2(L)] crystallizes in the space group P21/a with a=13.483(8), b=10.078(1), c=15.622(4) A, β=113.66(4)° and Z=4 (R=0.030, R′=0.031). Both complexes consist of molecules in which the bisdeprotonated ligand is O,N,S-bonded and the tin atom exhibits distorted pentacoordination, with small differences between the methyl and phenyl derivatives in bond distances, bond angles and intermolecular hydrogen bonds. The spectral properties of the complexes (IR, Mossbauer and 1H, 13C and 119Sn NMR spectra) are discussed in the light of this structural information.

Copper(I) complexes with 4,6-dimethylpyrimidine-2-thione (Hdmpymt); the crystal and molecular structure of [Cu6(dmpymt)6]

The complex [Cu6(dmpymt)6]·H2O was synthesised by electrochemical oxidation of copper in an acetonitrile solution of the neutral ligand 4,6-dimethylpyrimidine-2-thione (Hdmpymt). The reaction of [Cu6(dmpymt)6] with 1,2-bis(diphenylphosphino)methane (dppm) and 1,2-bis(diphenylphosphino)ethane (dppe) yielded compounds of general formulae [Cu(dmpymt)(dppm)] and [Cu2(dmpymt)2(dppe)3]. The molecular structure of [Cu6(dmpymt)6] was determined: the crystals are triclinic, space group P1, a= 11.432(3), b= 13.395(2), c= 15.694(4)A, α= 80.28(2), β= 87.75(2), γ= 73.87(2)° and Z= 2. The six copper atoms are arranged with distorted-octahedral geometry, each copper atom being trigonally co-ordinated to one nitrogen and two sulfur atoms of three different ligands. Infrared, 1H, 13C and 31P NMR spectral data are presented for all the compounds.

CRYSTAL STRUCTURE OF TRIPHENYL(5-MERCAPTO-1-PHENYL-1,2,3,4-TETRAZOLATO)TIN(IV)

Abstract The title compound was prepared from 1-phenyl-5-thione-1,2,3,4-tetrazole and triphenyltin(IV) hydroxide and its crystal structure was determined by X-ray diffraction. The lattice is formed by discrete molecules that contain the tin atom coordinated to three phenyl groups and to the tetrazole via the deprotonated -SH group in a distorted tetrahedral coordination polyhedron. There is evidence of a very weak intramolecular interaction between N(4) of the tetrazole and the Sn atom. 13C and 15N NMR studies (CDCl3) suggest that in solution the tetrazole is also in the deprotonated thiol form, and binds to the tin via its S atom.

Biological Activity of Quinoline Alkaloids from Raulinoa echinata and X-ray Structure of Flindersiamine

Phytochemical survey of stems and leaves extracts of the South Brazilian endemic plant Raulinoa echinata Cowan, Rutaceae, led to the isolation of known furoquinoline alkaloids: the widespread skimmianine; kokusaginine, maculine, flindersiamine, and also quinolone derivatives: 1-methyl-2-n-nonyl-4-quinolone, 2-n-nonyl-4-quinolone and 1-methyl-2-phenyl-4-quinolone. These alkaloids showed antifungal activity against Leucoagaricus gongylophorus; the symbiotic fungus of leaf-cutting ants (Atta sexdens). They were inactive or displayed weak inhibitory activity when assayed in vitro against trypomastigote forms of Trypanosoma cruzi. In this paper, the isolation, structure elucidation and bioactivity results of these compounds are reported together with the X-ray structure of flindersiamine.

Electrochemical synthesis of cobalt(II) and cobalt(III) complexes of Schiff bases: The crystal structure of tris{2-[(2-methylphenyl)iminomethyl] pyrrolato}cobalt(III)

Abstract The electrochemical oxidation of anodic cobalt in an acetonitrile solution of Schiff bases (HL) derived from H-pyrrole-2-carbaldehyde and substituted anilines gives solutions from which [CoL3] complexes were obtained. When 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) was added to the electrolytic phase, [CoL2 phen] or [CoL2 bipy] are obtained. The crystal structure of tris{2-[(2-methylphenyl)iminomethyl]pyrrolato} cobalt(III) has been determined by X-ray diffraction. The crystal structure consists of monomeric molecules in which the central CoN6 unit has a slightly distorted octahedral geometry. The electronic, IR and 1H NMR spectra of the complexes are discussed and related to the structure.

Electrochemical synthesis of cadmium(II) complexes of schiff bases : the crystal structure of 2,2'-bipyridine bis {2-[(2-methoxyphenyl)-iminomethyl]pyrrolato}cadmium(II)

Abstract The electrochemical oxidation of anodic cadmium in acetonitrile containing both a Schiff base, HL (derived from H-pyrrole-2-carbaldehyde and a substituted aniline), and a nitrogen donor ligand [1,10-phenanthroline(phen) or 2,2′-bipyridine(bipyl)] yielded the mixed complexes CdL2·phen and CdL2·bipy. The crystal structure of 2,2′-bipyridine bis{2-[(2-methoxyphenyl)iminomethyl]pyrrolato}cadmium(II) was determined by X ray diffraction.

Synthesis, crystal structure and spectroscopic properties of bis(diphenyldithiophosphinato)cadmium(II)

Abstract Reacting cadmium(II) perchlorate with the ammonium salt of diphenyldithiophosphinic acid in ethanol yielded the title compound, which crystallized in the triclinic space group P 1 with a = 9.273(1), b = 10.426(1), c = 13.845(3) A, α = 94.38(1), β = 103.16(1), γ = 104.63(1)° and Z = 2. The crystal contains dimeric complexes in which two cadmium atoms and two bridging ligands form an eight-membered ring, the coordination of each metallic centre being made up to four by an additional S,S-dentate chelating diphenyldithiophosphinate ligand. Solid state vibrational spectra (IR and Raman) and multinuclear NMR spectra in DMSO solution (13C, 31P and 113Cd) are discussed and compared with those of aliphatic cadmium(II) dithiophosphinates.

Synthesis and structure of lanthanide picrates with trans-1,3-dithiane-1,3-dioxide

Abstract Compounds with the formula [Ln(pic) 3 ( trans -DTSO 2 ) 2 ] (Ln=La–Lu and Y) were obtained by reaction of hydrated lanthanide picrates with trans -1,3-dithiane-1,3-dioxide ( trans -DTSO 2 ) in absolute ethanol. Lanthanide contents were determined by titration with EDTA; CHN were determined by microanalytical procedures. Data are in good accordance with the proposed stoichiometry. IR absorption spectra were interpreted in terms of trans -DTSO 2 and picrate anions coordinated through the oxygen atoms. The parameters obtained from the absorption spectrum of the Nd(III) compound indicate weakly covalent metal–ligand bonds. The emission spectrum obtained at 77 K for the Eu(III) compound suggests a C 2v symmetry for the coordination polyhedron. X-Ray powder patterns show that the compounds are isomorphous. The structure of europium compound was determined by single crystal X-ray analysis and showed that the crystals are triclinic, space group P 1 , a =10.771(1) A, b =12.243(1) A, c =16.415(2) A, α =99.930(10)°, β =103.970(10)°, γ =106.220(10)°. The compound exhibits a polymeric structure, in which two trans -DTSO 2 are bridging the Eu(III) ions. The central ion is octacoordinated to four oxygens of trans -DTSO 2 and four oxygens of one bidentate and two monodentate picrate anions, in a bicapped trigonal prism geometry, the dihedral angle between the bases being 14.2(1) o .

Rearranged (4 → 2)-abeo-clerodane and clerodane diterpenes from Aristolochia chamissonis

Abstract From stems of Aristolochia chamissonis Duch., five new diterpenes, one rearranged (4→2)-abeo-clerodane and four ent-clerodanes, were isolated. Their structures were determined to be (+)-(4→2)-abeo-kolavelool-3-oic acid, (−)-13-epi-2-oxokolavelool, (−)-2β-hydroxykolavelool, (−)-2β-hydroperoxykolavelool and (+)-13-epi-2α-hydroxykolavelool. In addition, lignans, sesquiterpenes, steroids and two known ent-clerodane diterpenes were isolated.

Hexamethylphosphoramide complexes of neodymium and europium picrates

Abstract Isomorphous neodymium and europium picrate complexes with hexamethylphosphoramide (HMPA) were prepared and characterized. Single-crystal X-ray data of the neodymium compound indicate that the metal ion is coordinated to three HMPA groups and three bidentate picrates in a distorted tricapped-trigonal prismatic geometry. The bands of the fluorescence spectrum of the europium complex indicate a D 3h symmetry distorted to C 3v .