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Vito Lippolis - One of the best experts on this subject based on the ideXlab platform.
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Reaction of imidazoline-2-Selone derivatives with mesityltellurenyl iodide: a unique example of a 3c-4e Se→Te←Se three-body system embedding a tellurenyl cation
New Journal of Chemistry, 2019Co-Authors: M. Carla Aragoni, Francesco Isaia, Vito Lippolis, Massimiliano Arca, Alexander J. Blake, Enzo Cadoni, Lucian Copolovici, Sergio Murgia, Alexandra Pop, Cristian SilvestruAbstract:The reactions of 1,1′-bis(3-methyl-4-imidazolin-2-Selone)methane (L1) and 1,2-bis(3-methyl-4-imidazolin-2-Selone)ethane (L2) with mesityltellurenyl iodide (MesTeI) [Mes = 2,4,6-Me3C6H2] yielded the neutral [L1·2MesTeI]·2CH2Cl2 and the ionic [L2·MesTe]2(MesTeI2)2 compounds, respectively, which were characterized by X-ray diffraction analysis. DFT (mPW1PW//LANL08d/def2-SVP) and NBO calculations, supported by structural and FT-Raman measurements, show that the latter compound represents the first example of an authentic mesityltellurenyl cation, [MesTe]+, stabilized within a [MesTe(B)2]+ (B = Lewis base) charge transfer adduct featuring a 3c-4e Se→Te←Se three-body system.
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group 11 complexes with imidazoline 2 thione or Selone derivatives
European Journal of Inorganic Chemistry, 2011Co-Authors: Teresa M Aroz, Concepcion M Gimeno, Monika Kulcsar, Antonio Laguna, Vito LippolisAbstract:The authors thank the Ministerio de Educacion y Ciencia (MEC) (grant number CTQ2010-20500-C02-01) for financial support. M. K. thanks the MEC (CSIC JAE-Doc ¨Junta para la Ampliacion de Estudios¨).
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conductometric and spectroscopic investigations on the reactions between n methylthiazolidine 2 3h Selone 1 and n methylbenzothiazole 2 3h Selone 2 with br2
Polyhedron, 1998Co-Authors: Massimiliano Arca, Francesco A. Devillanova, Francesco Demartin, Francesco Isaia, Vito Lippolis, Alessandra Garau, Silvia Piludu, Gaetano VeraniAbstract:Abstract The formation of the compounds C 4 H 7 Br 2 NSSe (3) , (C 4 H 7 BrNS) 2 [SeBr 6 ] (4) and C 8 H 7 Br 2 NSSe (5) from the reaction of the title selenium donors (1 and 2) with molecular dibromine in CH 2 Cl 2 and MeCN solutions has been investigated by 77 Se and 13 C NMR, UV-visible spectroscopies and by conductometric measurements. In the conductometric titrations of 1 or 2 with dibromine, the very low values of conductivity recorded up to the 1 : 1 Br 2 ⧹1 (2) molar ratio indicate the formation of the non-conducting hypervalent selenium compounds 3 and 5, as confirmed by UV–visible and NMR spectroscopies. Above this ratio, 1 and 2 behave differently ; in fact, for both of them the conductivity values increase on increasing the amount of added dibromine, but the values recorded for 1, that are much higher than those for 2, are time-dependent. This indicates a kinetic transformation of 1 that has been shown to lead to the previously characterized 4.
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variety of products from the reaction between Selone donors and halogen interhalogen acceptors the case of n methylthiazolidine 2 3h Selone and n methylbenzo thiazole 2 3h Selone
Phosphorus Sulfur and Silicon and The Related Elements, 1998Co-Authors: Francesco Demartin, Francesco A. Devillanova, Francesco Isaia, Vito Lippolis, Gaetano VeraniAbstract:The great variety of products obtained from the reaction between Selone donors and halogens (I2, Br2) or interahogens (IBr, ICl) is reported for the Title compounds as starting molecules. The characterization of these products by either X-ray crystal structure or Raman spectroscopy evidentiates the latter technique to be not always sufficient in identifying the nature of the products unambiguosly.
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crystal structure and vibrational characterization of the reaction products of n methylthiazolidine 2 3h Selone 1 and n methylbenzothiazole 2 3h Selone 2 with br2
Polyhedron, 1998Co-Authors: Francesco A. Devillanova, Francesco Isaia, Vito Lippolis, Paola Deplano, Maria Laura Mercuri, Silvia Piludu, Gaetano Verano, Francesco DemartinAbstract:Abstract The products obtained by reacting the title selenium donors, 1 and 2 , with molecular dibromine, both in 1 : 1 and 1 : 2 1 ( 2 )/Br 2 molar ratios in CH 2 Cl 2 solution, are described. Depending on the molar ratio of the reagents, 1 gives two different products having stoichiometries 1 ·Br 2 ( I ) and C 8 H 14 Br 8 N 2 S 2 Se ( II ). Compound II , characterised by X-ray diffraction on a single crystal, is an ionic compound having formula (C 4 H 7 BrNS) 2 [SeBr 6 ]. Thus, the reaction occurs through CSe bond breaking and formation of the N -methyl-2-bromothiazolidinium cation and oxidation of the selenium atom to a hexabromo selenate(2-) anion. In the corresponding reaction with 2 , the same compound of stoichiometry 2 ·Br 2 ( III ) is obtained in both molar ratios. The X-ray diffractometric analysis on a single crystal of III shows that it is a hypervalent Se-compound, C 8 H 7 Br 2 NSSe, bearing the BrSeBr linear group. FT-IR and FT-Raman spectra are in accordance with structural results for II and III and help to characterise I .
Francesco Demartin - One of the best experts on this subject based on the ideXlab platform.
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conductometric and spectroscopic investigations on the reactions between n methylthiazolidine 2 3h Selone 1 and n methylbenzothiazole 2 3h Selone 2 with br2
Polyhedron, 1998Co-Authors: Massimiliano Arca, Francesco A. Devillanova, Francesco Demartin, Francesco Isaia, Vito Lippolis, Alessandra Garau, Silvia Piludu, Gaetano VeraniAbstract:Abstract The formation of the compounds C 4 H 7 Br 2 NSSe (3) , (C 4 H 7 BrNS) 2 [SeBr 6 ] (4) and C 8 H 7 Br 2 NSSe (5) from the reaction of the title selenium donors (1 and 2) with molecular dibromine in CH 2 Cl 2 and MeCN solutions has been investigated by 77 Se and 13 C NMR, UV-visible spectroscopies and by conductometric measurements. In the conductometric titrations of 1 or 2 with dibromine, the very low values of conductivity recorded up to the 1 : 1 Br 2 ⧹1 (2) molar ratio indicate the formation of the non-conducting hypervalent selenium compounds 3 and 5, as confirmed by UV–visible and NMR spectroscopies. Above this ratio, 1 and 2 behave differently ; in fact, for both of them the conductivity values increase on increasing the amount of added dibromine, but the values recorded for 1, that are much higher than those for 2, are time-dependent. This indicates a kinetic transformation of 1 that has been shown to lead to the previously characterized 4.
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variety of products from the reaction between Selone donors and halogen interhalogen acceptors the case of n methylthiazolidine 2 3h Selone and n methylbenzo thiazole 2 3h Selone
Phosphorus Sulfur and Silicon and The Related Elements, 1998Co-Authors: Francesco Demartin, Francesco A. Devillanova, Francesco Isaia, Vito Lippolis, Gaetano VeraniAbstract:The great variety of products obtained from the reaction between Selone donors and halogens (I2, Br2) or interahogens (IBr, ICl) is reported for the Title compounds as starting molecules. The characterization of these products by either X-ray crystal structure or Raman spectroscopy evidentiates the latter technique to be not always sufficient in identifying the nature of the products unambiguosly.
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crystal structure and vibrational characterization of the reaction products of n methylthiazolidine 2 3h Selone 1 and n methylbenzothiazole 2 3h Selone 2 with br2
Polyhedron, 1998Co-Authors: Francesco A. Devillanova, Francesco Isaia, Vito Lippolis, Paola Deplano, Maria Laura Mercuri, Silvia Piludu, Gaetano Verano, Francesco DemartinAbstract:Abstract The products obtained by reacting the title selenium donors, 1 and 2 , with molecular dibromine, both in 1 : 1 and 1 : 2 1 ( 2 )/Br 2 molar ratios in CH 2 Cl 2 solution, are described. Depending on the molar ratio of the reagents, 1 gives two different products having stoichiometries 1 ·Br 2 ( I ) and C 8 H 14 Br 8 N 2 S 2 Se ( II ). Compound II , characterised by X-ray diffraction on a single crystal, is an ionic compound having formula (C 4 H 7 BrNS) 2 [SeBr 6 ]. Thus, the reaction occurs through CSe bond breaking and formation of the N -methyl-2-bromothiazolidinium cation and oxidation of the selenium atom to a hexabromo selenate(2-) anion. In the corresponding reaction with 2 , the same compound of stoichiometry 2 ·Br 2 ( III ) is obtained in both molar ratios. The X-ray diffractometric analysis on a single crystal of III shows that it is a hypervalent Se-compound, C 8 H 7 Br 2 NSSe, bearing the BrSeBr linear group. FT-IR and FT-Raman spectra are in accordance with structural results for II and III and help to characterise I .
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Electrochemical synthesis of tetrakis[N-methylbenzothiazole-2(3H)-Selone]selenium(2+) tetrafluroborate: an uncommon dication containing the mixed-valence Se5 framework
Chemical Communications, 1996Co-Authors: Carlo Adamo, Francesco Demartin, Francesco Isaia, Vito Lippolis, Paola Deplano, Franceso A. Devillanova, Francesco Lelj, Peter J. Lukes, Maria Laura MercuriAbstract:The electrochemical oxidation o N-methylbenzothiazole-2(3H)-Selone leads to tetrakis[Nmethylbenzothiazole-2(3H)-Selone]selenium(2+) tetrafluoroborate showing an uncommon dication containing a non-cyclic square-planar Se5 framework; both Mulliken and NBO population analyses explain the relatively long Se–Se bond lengths between the central and the peripheral selenium atoms.
Joachim Fuchs - One of the best experts on this subject based on the ideXlab platform.
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neue selenreiche 1 3 dichalkogenol 2 Selone via 4 5 dilithio 1 3 dichalkogenol 2 Selone
Journal of Organometallic Chemistry, 1992Co-Authors: Helmut Poleschner, Reiner Radeglia, Joachim FuchsAbstract:Abstract 1,3-Dithiole-2-thione ( 1 ), 1,3-diselenole-2-Selone ( 2 ), 1,3-thiaselenole-2-thione ( 3 ), 1,3-dithiole-2-Selone ( 4 ), 1,3-diselenole-2-thione ( 5 ) and 1,3-thiaselenole-2-Selone ( 6 ) are dilithiated with lithium diisopropyl amide in the 4/5 position, followed by selenation (thiolation) and complexation of the resulting heterocyclic diselenolates (dithiolates) to the zinc bis-chelates (tetrabutylammonium or tetraphenylphosphonium salts). These zinc complexes react with benzoyl chloride to the corresponding selenole and thiole esters. It is noteworthy that the heterocyclic thiones with one or two ring selenium atoms undergo ring transformation (Dimroth rearrangement) during the lithiation chalcogenation sequence, whilst the thione sulfur and one ring selenium atom change their places: 3 → 1,3-dithiole-2-Selone-4,5-diselenolate or dithiolate structure, 5 → 1,3-thiaselenole-2-Selone-4,5-diselenolate structure. This observed rearrangement is verified by independent synthetic pathways. The corresponding identical zinc chelates 12 and complex 18 result from the precursors 3 and 4 and 5 and 6 respectively. Trapping experiments support the conclusion that this rearrangement takes place already during lithiation. The zinc chelates and thiole and selenole esters are characterized in detail by IR and above all by 13 C and 77 Se NMR spectroscopy, including NMR shift values of the precursor heterocycles. The X-ray crystal structure determination of bis(tetraphenylphosphonium)-bis(1,3-thiaselenole-2-Selone-4,5-diselenolato) zincate ( 18 ), obtained from 5 , shows the rearrangement of 5 to the 1,3-thiaselenole-2-Selone partial structure in 18 .
Louis A. Silks - One of the best experts on this subject based on the ideXlab platform.
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chiral n acetyl Selone promoted aldol reactions
Synthetic Communications, 2009Co-Authors: Louis A. Silks, R. Michalczyk, David B Kimball, Duane Hatch, Morgane Ollivaultshiflett, Eddie MoodyAbstract:Abstract The chiral oxazolidineSelone functionality was found to be an excellent partner in the stereospecific acetate aldol reaction with aldehydes via the titanium enolates. Good stereocontrol was obtained as determined by NMR spectroscopy. The oxazolidineSelone also provided a straightforward way to establish the stereopurity of the coupling reaction through 77Se NMR spectroscopy.
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Stereoselectivity in aldol reactions of chiral N-acyl Selones
Journal of the American Chemical Society, 2000Co-Authors: R. Michalczyk, R.b. Dunlap, Jerome D. Odom, Louis A. SilksAbstract:Aldol reactions have played a central role in many stereoselective constructions of carbon-carbon bonds. During the past several years the selenocarbonyl group has been used both as a chiral interrogation tool (using {sup 77} SeNMR spectroscopy) and as a platform for the development of new chemical methods associated with Selone based chiral derivatizing agents. During the course of these studies the authors have uncovered a new type of aldol reaction using chiral Selone reagents in which the selenocarbonyl plays a pivotal role in determining the stereoselectivity of these reactions. This report describes the results of the studies involving the use of titanium(IV) enolates of N-acyl-oxaxolidin-2-Selones with a variety of aldehydes.
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Reaction of alcohols (via the Mitsunobu reaction) and alkyl halides with chiral Selone derivatizing agents
Tetrahedron: Asymmetry, 1999Co-Authors: Jerome D. Odom, R. Bruce Dunlap, Louis A. SilksAbstract:Abstract Coupling of a Selone chiral derivatizing agent (CDA) to d , l -alkyl halides gives Se-alkylated adducts in yields ranging from 76–97%. Reaction of d , l -alcohols with the Selone CDAs via the Mitsunobu reaction has given rise to Se-alkylated adducts in yields ranging from 82–92%. Examination of the 77 Se NMR spectra of the resulting diastereomeric adducts indicates that discrimination of remotely disposed chiral centers is possible using this technique.
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Synthesis and Characterization of Acylated Chiral Oxazolidine-2-Selones: Selone Chiral Derivatizing Agents for the Detection and Quantitation of Remotely Disposed Chiral Centers
The Journal of Organic Chemistry, 1995Co-Authors: Jie Peng, Jerome D. Odom, Mary E. Barr, David A. Ashburn, Lukasz Lebioda, Albert R. Garber, Rodolfo A. Martinez, R. Bruce Dunlap, Louis A. SilksAbstract:Racemic and chiral carboxylic acids and acid chlorides are coupled cleanly to oxazolidine-2-Selone chiral derivatizing agents (CDA`s) with yields ranging from 85 to 99%. {sup 77}Se NMR spectroscopy provides a highly sensitive method for the determination of the enantiomeric excesses of these remotely disposed chiral centers. The geometrical relationship between the selenocarbonyl and the adduct carbonyl (syn or anti) appears to have a profound effect on the chemical shift difference ({Delta}{delta}{sub Se}) observed for pairs of adduct diastereomers. Crystallographic and solution state NMR studies suggest that the syn orbital overlap enhances the {Delta}{delta}{sub Se}. 12 figs., 8 tabs.
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Synthesis of (4S,5R)-(–)-4-methyl-5-phenyloxazolidine-2-Selone: a chiral auxiliary reagent capable of detecting the enantiomers of (R,S)-lipoic acid by 77Se nuclear magnetic resonance spectroscopy
J. Chem. Soc. Perkin Trans. 1, 1991Co-Authors: Louis A. Silks, Jerome D. Odom, Jie Pang, R. Bruce DunlapAbstract:(4S,5R)-(–)-4-Methyl-5-phenyloxazolidine-2-Selone was constructed in 5 steps on the 10-gram scale. 77Se NMR spectroscropic studies revealed that this Selone served as a remarkably sensitive chiral auxiliary agent which readily distinguished the Selone-coupled (R,S)-lipoic acid (Δδ 0.119 ppm), even though its chiral centre was separated by 8 bonds from the observed nucleus.
Victor N. Khrustalev - One of the best experts on this subject based on the ideXlab platform.
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1 methyl 2 3 dihydro 1h benzimidazole 2 Selone
Acta Crystallographica Section E-structure Reports Online, 2012Co-Authors: Gunay Z. Mammadova, Zhanna V. Matsulevich, Vladimir K. Osmanov, Alexander V. Borisov, Victor N. KhrustalevAbstract:The title compound C8H8N2Se, is the product of the reaction of 2-chloro-1-methylbenzimidazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.041 A) owing to the presence of the long chain of conjugated bonds (Se=C—NMe—C=C—C=C—C=C—NH). The C=Se bond length [1.838 (2) A] corresponds well to those found in the close analogs and indicates its pronounced double-bond character. In the crystal, molecules form helicoidal chains along the b axis by means of N—H⋯Se hydrogen bonds.
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1 3 benzothia zole 2 3h Selone
Acta Crystallographica Section E-structure Reports Online, 2011Co-Authors: Gunay Z. Mammadova, Zhanna V. Matsulevich, Vladimir K. Osmanov, Alexander V. Borisov, Victor N. KhrustalevAbstract:The title compound, C7H5NSSe, is the product of the reaction of 2-chlorobenzothiazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.018 A) owing to the presence of the long chain of conjugated bonds (Se=C—N—C=C—C=C—C=C). The geometrical parameters correspond well to those of the analog N-methylbenzothiazole-2(3H)-Selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the molecule. In the crystal, molecules form centrosymmetric dimers by means of intermolecular N—H⋯Se hydrogen bonds. The dimers have a nonplanar ladder-like structure. Furthermore, the dimers are linked into ribbons propagating in [010] by weak attractive Se⋯S [3.7593 (4) A] interactions.
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1,3-Benzothiazole-2(3H)-Selone
Acta Crystallographica Section E Structure Reports Online, 2011Co-Authors: Gunay Z. Mammadova, Zhanna V. Matsulevich, Vladimir K. Osmanov, Alexander V. Borisov, Victor N. KhrustalevAbstract:The title compound, C7H5NSSe, is the product of the reaction of 2-chlorobenzothiazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.018 A) owing to the presence of the long chain of conjugated bonds (Se=C—N—C=C—C=C—C=C). The geometrical parameters correspond well to those of the analog N-methylbenzothiazole-2(3H)-Selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the molecule. In the crystal, molecules form centrosymmetric dimers by means of intermolecular N—H⋯Se hydrogen bonds. The dimers have a nonplanar ladder-like structure. Furthermore, the dimers are linked into ribbons propagating in [010] by weak attractive Se⋯S [3.7593 (4) A] interactions.