R. Alfredo Toscano

Synthesis, spectroscopic characterization and structural studies of dialkyl dithiophosphinate and N,N-dialkyl dithio- and monothio-carbamate derivatives of 1-iodo-1,1,2,3,4,5-hexahydrotellurophene

Abstract The synthesis of the organotellurium(IV) compounds [C4H8TeI(S2PMe2)] (2), [C4H8TeI(S2PEt2)] (3), [C4H8TeI(S2CNC4H6)] (4) and [C4H8TeI(SOCNC5H10)] (6) was achieved. All of them were characterized by IR, 1H-, 13C-, 31P- and 125Te-NMR, mass spectroscopy, elemental analyses and single-crystal X-ray diffraction. In addition, the crystal and molecular structures of the previously known 1,1-diiodotetrahydrotellurophene and [C4H8TeI(S2CNEt2)] (5) were obtained. The geometry around Te(IV) is that of a sawhorse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. All the structures exhibit different supramolecular associations. The intermolecular Te⋯S and Te⋯I interactions result in the formation of dimeric species in 4, and in 1 and 6, respectively. The intermolecular Te⋯S bonds in 2, 3 and 5 lead to formation of one-dimensional polymers.

Lanthanide(III) Complexes with 4,5-Bis(diphenylphosphinoyl)-1,2,3-triazolate and the Use of 1,10-Phenanthroline As Auxiliary Ligand

New lanthanide complexes with 4,5-bis(diphenyl)phosphoranyl-1,2,3-triazolate (L(-)), LnL(3).nH(2)O (1-8) and LnL(3)(phen).nH(2)O (9-16) (Ln = La, Ce, Nd, Sm, Eu, Gd, Tb, Er), have been prepared and spectroscopically characterized. The structures of LnL(3).nH(2)O (Ln = La, Ce, Nd, Sm and Gd) were determined by X-ray crystallography. The metal centers exhibit a distorted trigonal dodecahedron coordination environment with two symmetrically O,O-bidentate ligands and one unsymmetrically O,N- ligand attached to the metal; two oxygen atoms from neighboring dimethyl sulfoxide (DMSO) molecules complete the coordination sphere. This unsymmetrical ligand coordination behavior was also identified in solution through (31)P{(1)H} NMR studies. Photoluminescence spectroscopy experiments in CH(2)Cl(2) for both types of complexes containing Eu(III) (6, 14) and Tb(III) (7, 15) exhibit strong characteristic red and green emission bands for Eu(III) and Tb(III), respectively. Furthermore, NdL(3) (phen).5H (2)O (11) displays emission in the near-infrared spectral region ((4)F(3/2) --> (4)F(9/2) at 872 nm and (4)F(3/2) --> (4)F(11/2) at 1073 nm). The complexes containing 1,10-phenantroline exhibit higher quantum yields upon excitation at 267 nm, indicating that this auxiliary ligand promotes the luminescence of the complexes; however, luminescence lifetimes (tau) in this case are shorter than those of the LnL(3).nH(2)O series.

Synthesis, characterization and crystal structure of 1,3-dihydro-2λ4-benzotellurole-2,2-diyl bis(N-piperidine-dithiocarbamate), [1,2-C6H4(CH2)2Te(S2CNC5H10)2] (1), 1,3 dihydro-2λ4-benzotellurole-2-iodo-2-yl-diethyldithiophosphinate, [1,2-C6H4(CH2)2TeI(S2PEt2)] (2) and 1,3-dihydro-2λ4-benzotellurole-2-iodo-2-yl dimethyldithiophosphinate, [1,2-C6H4(CH2)2TeI(S2PMe2)] (3)

Abstract Three new 1,1-dithiolato organoyltellurium(IV) compounds were synthesized, [1,2-C6H4(CH2)2Te(S2CNC5H10)2] (1), [1,2-C6H4(CH2)2TeI(S2PEt2)] (2), and [1,2-C6H4(CH2)2TeI(S2PMe2)] (3). They have been characterized by means of IR, 1H, 13C, 31P NMR spectroscopy, positive-ion FAB mass spectrometry, elemental analysis and single-crystal X-ray diffractomery. The 1,1-dithiolato ligands display an anisobidentate chelating coordination mode on interacting with the tellurium centre. Two 1,1-piperidindithiocarbamates are attached to the tellurium atom in 1, while a iodine atom and only one 1,1-dialkyldithiophosphinate are bonded to Te in compounds 2 and 3. The solid state structures show that the compounds 2 and 3 exhibits important intermolecular interactions (Te⋯I(b) for 2 and Te⋯S(b) for 3). These interactions result in the formation of a dimer in 2, and of a one-dimensional polymer in 3. Compound 1 shows weaker intermolecular Te⋯S(b) interactions.

CHIRAL COMPLEXES BY DIRECT SYNTHESIS OF A BIOMOLECULE AND METAL POWDERS. CRYSTAL STRUCTURES OF THE DICHLORO[(−)-SPARTEINE-N,N′]M(II) COMPLEXES (M = Cu, Zn)

Abstract Direct synthesis of chiral complexes dichloro[(−)-sparteine-N,N′]copper(II) 2 and dichloro[(−)-sparteine-N,N′]zinc(II) 3 derived from a biomolecule-namely the natural base (−)-sparteine- and elemental metals (Cu and Zn) in a CCl4/DMSO solvent system (DMSO = dimethylsulfoxide) is reported. The complexes were partly characterized by spectroscopic methods and their structures were fully confirmed by single-crystal x-ray analysis. A comparison between the new crystal structures of 2 and 3 and that of the free ligand (−)-sparteine displayed only slight differences on the ligand framework.

Synthesis of (2R,3S)-( -)-2-phenyl-3-methylaziridine

Abstract We report the total synthesis of aziridine 3 , carried out in a two-step method involving double Walden inversion at the carbon atom bearing the hydroxy group of (1 R ,2 S )-(−)-norephedrine, 1 , which was used as starting material. Compound 3 was obtained for the first time as a solid therefore allowing its unambiguous X-ray structure determination.

Synthesis and spectroscopic characterization of new mixed ligand organotellurium(IV) compounds employing dithiocarbamates and imidotetraphenyldithiodiphosphinates. Crystal structure of [C4H8Te(S2CNEt2){(SPPh2)2N}], [C4H8Te(S2CNC5H10){(SPPh2)2N}] and [C4H8Te(S2CNC4H8S){(SPPh2)2N}]

Abstract The synthesis of new mixed ligand organotellurium(IV) compounds, [C4H8Te(S2CNEt2){(SPPh2)2N}] (1), [C4H8Te(S2CNC5H10){(SPPh2)2N}] (2), [C4H8Te(S2CNC4H8O){(SPPh2)2N}] (3) and [C4H8Te(S2CNC4H8S){(SPPh2)2N}] (4), was achieved. They were characterized by FAB+ mass spectrometry, IR, 1H-, 13C-, 31P- and 125Te-NMR spectroscopy. The crystal structures of 1, 2 and 4 were determined by X-ray diffraction. The solid state structures show that the coordination geometry can be described as the sawhorse structure typical for Te(IV) in which the lone pair is regarded as stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. Both types of ligands exhibit an anisobidentate chelating coordination mode on interaction with the tellurium center. If the aniso-bonded donor atoms are included in the coordination sphere, the coordination number increases to seven and the environment at Te can be described as the 1:2:2:2 structure. No intermolecular interaction was observed.

Synthesis and X-ray characterization of new 1-[μ-dithio-bis-(tricarbonyliron)]-2-(p-R-benzoyl)ethane complexes

Diiron nonacarbonyl reacts with the para- substituted derivatives 1a – d of 3,3-dithio-1-( p -substituted phenyl)-2-propen-1-one affording surprisingly the new dinuclear Fe(0) complexes 2a – d with a σ - S coordination instead of the attended η 2 or η 4 π -coordination upon the α , β -unsaturated system of the ligands. The complexes 2a – c were characterized by mass spectrometry, IR and 1 H- and 13 C-NMR spectroscopies and their structures were fully confirmed by single-crystal X-ray analysis. Such structural studies revealed as the main feature an ideal C 2v (mm 2 ) symmetry with the carbonyl groups in an eclipsed configuration of the Se 2 Fe 2 (CO) 6 moiety.

Reactivity of a two heteroatom stabilized anionic chromium (0) carbene complex towards a mono- and a disubstituted alkyne: New synthesis of γ-aminobutenolides and formation of a novel oligomer chromium (0) complex

Abstract The reaction of the chromium anionic carbene complex 1 towards diphenylacetylene and phenylacetylene is reported. In the former case the synthesis of γ-functionalized butenolides results after demetallation of the chromium complex 2 and the latter leads to the formation of a novel oligomer chromium complex 5. These complexes were characterized by mass spectrometry, IR and 1H and 13C NMR spectroscopies and their structures were confirmed by single-crystal X-ray analysis.

Reaction of lithium dimethyl cuprate with carbonyl iron alpha,beta-unsaturated ketone complexes: The structure of a novel eta(3),eta(3)-[(1,6-diphenyl)-3,4-(distyr-1-yl)-1,3,5-hexatriene]-Fe(CO)(2) complex

Abstract The reaction between η4-α,β-unsaturated ketene-Fe(CO)3 complexes and Me2CuLi in the absence of CO atmosphere yields the corresponding η4-vinylketene complexes 2, 4 and 6. The reaction between η2-dibenzylideneacetone-Fe(CO)4 and Me2CuLi gives a new dimeric complex 8, which was characterized by mass spectrometry, IR, 1H and 13C NMR spectroscopy and its structure confirmed by single-crystal X-ray analysis.

Synthesis of novel dinuclear complexes of Fe(O) derived from 1,2-dicarbonylic monohydrazones

Abstract Synthesis of three novel dinuclear complexes of Fe(O) are reported, la-c were prepared by-reaction of the corresponding monohydrazones with Fe2(CO)9. The structures of the complexes were determined by IR, 1H and 13C-NMR and HR-MS.