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Vito Lippolis

Publications and source records attributed to Vito Lippolis.

23 records · Page 2Linked to original sources
PubMed2002

Anti-thyroid drug methimazole: X-ray characterization of two novel ionic disulfides obtained from its chemical oxidation by I(2).

Interaction of methimazole (MMI, 1-methyl-imidazole-2-thione) with I2 in solvents having different polarity gives two new stable compounds containing a dication disulfide and a monocation disulfide arranged in dimers, respectively. These two species could represent effective intermediates in the reaction of MMI with an active iodine species in the thyroid gland and therefore shed more light on the mechanism of action of MMI as an antithyroid drug.

Antithyroid Agents↗
PubMed2002

4-Methoxyphenylphosphonic acid: reactivity of Lawesson's reagent.

The title compound, C(7)H(9)O(4)P, obtained as a by-product of the reaction between Lawesson's reagent, (I), and CH(3)I, can be recognized as the final product of the S/O interchange reaction at the P atom of (I). Hydrogen bonds of type P-O-H.O=P link molecules into helical chains and form ten-membered hydrogen-bonded rings with the graph-set notation R(3)(2)(10). Weaker intermolecular contacts between P-O and a phenyl H atom link the chains into a three-dimensional lattice. The parent benzenephosphonic acid [Weakley (1976). Acta Cryst. B32, 2889-2890] does not adopt an analogous structure, but its arsenic analogue [Shimada (1960). Bull. Chem. Soc. Jpn, 33, 301-304] does and can be regarded as isostructural. We rationalize these three structures in terms of their significant intermolecular interactions.

Journal Article↗
PubMed1997

Syntheses, X-ray Crystal Structures, and Spectroscopic Properties of New Nickel Dithiolenes and Related Compounds.

The direct addition of nickel powder to the reaction mixtures of 1,3-dialkyl-4,5-dioxoimidazolidine-2-thione (1) with the thionation Lawesson reagent produces [Ni(II)(R(2)timdt(-))(2)] (R(2)timdt = 1,3-dialkylmidazolidine-2,4,5-trithione). These complexes belong to a new class of nickel-dithiolenes, showing remarkably high absorption (epsilon approximately 80 000 dm(3) mol(-)(1) cm(-)(1), lambda approximately 1000 nm) in the near-infrared region (near-IR), accompanied by high photochemical stability that makes these complexes promising near-IR dyes. In the absence of nickel the reaction yields generally the compounds 4,5,6,7-tetrathiocino[1,2-b:3,4-b']diimidazolyl-1,3,8,10-tetraalkane-2,9-dithione (2) instead of the expected 1,3-dialkylimidazolidine-2,4,5-trithione. However, with bulky substituents on the nitrogen atoms, well-characterized reaction products have not been obtained until now. Only in the R = Pr(i) case, the new tetrathiocino isomer (4,5,9,10-tetrathiocino[1,2-b:5,6-b']diimidazolyl-1,3,6,8-tetraisopropane-2,7-dithione (3) in trace amounts and the bis(1,3-diisopropyl-2-thioxoimidazolin-4-yl) disulfide (4) were isolated from the reaction with the Lawesson reagent and P(4)S(10), respectively. Reaction of 5 with different amounts of I(2) leads to a variety of products, and among them the following derivatives have been characterized: [Ni(II)(Pr(i)(2)timdt(-))(2)].2I(2) (6) a neutral adduct in which each I(2) molecule interacts with each peripheral thione sulfur atom of 5; [Ni(II)(Pr(i)(2)timdt(-))(2)].2I(2).(1)/(2)I(2) (7), which differs from 6 with the presence of half diiodine as a guest; with a larger diiodine excess (starting from a 1:10 molar ratio) a partial oxidation of 5 is achieved and [Ni(II)(Pr(i)(2)timdt(-))(2)] [Ni(II)(I)(2)(Pr(i)(2)timdt)(2)].5I(2) (8) is formed, a ligand mixed-valence compound in which the square-planar complex 5 and the octahedral complex [Ni(II)(I)(2)(Pr(i)(2)timdt)(2)] (the ligand in neutral form) are bound by diiodine molecules in such a way that a sequence of 12 iodine atoms (S.I(2).I(2).I(-).I(2).I(-).I(2).I(2).S) is formed. Spectroscopic and X-ray diffractometric studies of 3 (monoclinic, space group P2(1)/n, a = 13.104(6) Å, b = 15.091(6) Å, c = 6.067(7) Å, beta = 103.00(2) degrees, Z = 2), 4 (monoclinic, space group C2/c, a = 18.717(5) Å, b = 8.846(5) Å, c = 14.475(5) Å, beta = 97.78(2) degrees, Z = 4), 5 (orthorhombic, space group Pna2(1), a = 18.806(5) Å, b = 5.628(7) Å, c = 23.665(5) Å, Z = 4), 7 (triclinic, space group P&onemacr;, a = 9.126(7) Å, b = 9.153(7) Å, c = 12.924(6) Å, alpha = 82.11(2), beta = 70.14(2), gamma = 72.51(2) degrees, Z = 1), and 8 (monoclinic, space group C2/c, a = 21.971(6) Å, b = 28.081(5) Å, c = 12.207(8) Å, beta = 93.57(2) degrees, Z = 4) are given.

Journal Article↗
PubMed1996

Synthesis, Characterization, and Crystal Structures of New Dications Bearing the -Se-Se- Bridge.

Starting from 1,3-dimethyl-4-imidazoline-2-selone (1), 1,2-bis(2-selenoxo-3-methyl-4-imidazolinyl-2-)ethane (3) and 1,3-dimethylimidazolidine-2-selone (4), the following six compounds, [(C(5)H(8)N(2)Se-)(2)](2+).2Br(-) (I), [(C(5)H(8)N(2)Se-)(2)](2+).2I(-) (II), [(C(5)H(8)N(2)Se-)(2)](2+).Cl(-).I(3)(-) (III) [(C(5)H(10)N(2)Se-)(2)](2+).Br(-).IBr(2)(-) (IV), [(C(5)H(7)N(2)Se-)(2)](2+).I(3)(-).(1)/(2)I(4)(-) (V) and [(C(5)H(7)N(2)Se-)(2)](2+).2I(-).CH(3)CN (VI), in which the selenium compounds are oxidized to dications bearing the uncommon -Se-Se- bridge, have been prepared, and I-V crystallographically characterized. I and III were obtained by reacting 1 with IBr and ICl respectively, while II was obtained by reduction of previously described hypervalent selenium compound of 1 (5) bearing the I-Se-I group with elemental tellurium. These three compounds contain the same [(C(5)H(8)N(2)Se-)(2)](2+) dication balanced by two bromides in I, two iodides in II, and Cl(-) and I(3)(-) in III. However, on the basis of the Se-Cl bond length of 2.778(5) Å, III can also be considered as formed by the [(C(5)H(8)N(2)Se-)(2)Cl](+) cation, with I(3)(-) as counterion. Similarly to III, compound IV, which was obtained by reacting 4 with IBr, can be considered as formed by [(C(5)H(10)N(2)Se-)(2)Br](+) cations and IBr(2)(-) anions. As in II, compound V has been prepared by reduction of the hypervalent selenium compound of 3 (6) bearing two I-Se-I groups with elemental tellurium. In V, the [(C(5)H(7)N(2)Se-)(2)](2+) cation is balanced by I(3)(-) and half I(4)(2-) anions. The structural data show that all the cations are very similar, with Se-Se bond lengths ranging from 2.409(2) to 2.440(2) Å. FT-IR and FT-Raman spectra of I-VI allow one to identify two bands around 230 +/- 10 and 193 +/- 5 cm(-1) that are common to all compounds. These bands are generally strong in the FT-Raman and weak in the FT-IR spectra and should contain a contribution of the nu(Se-Se) stretching vibration. The spectra are also in good agreement with the structural features of the polyhalide anions present in the crystals. Crystallographic data are as follows: I is monoclinic, space group P2(1), with a = 9.849(6) Å, b = 11.298(5) Å, c = 7.862(6) Å, beta = 106.44(2) degrees, Z = 2, and R = 0.0362; II is monoclinic, space group P2(1), with a = 8.063(6) Å, b = 11.535(5) Å, c = 10.280(5) Å, beta = 107.13(2) degrees, Z = 2, and R = 0.0429, III is monoclinic, space group P2(1)/n, with a = 10.431(7) Å, b = 18.073(5) Å, c = 11.223(6) Å, beta = 100.76(2) degrees, Z = 4, and R = 0.0490; IV is monoclinic, space group P2(1)/n, with a = 10.298(5) Å, b = 18.428(7) Å, c = 11.475(6) Å, beta = 104.10(4) degrees, Z = 4, and R = 0.0300; V is triclinic, space group P&onemacr;, with a = 7.456(6) Å, b = 11.988(5) Å, c = 12.508(5) Å, alpha = 79.32(2) degrees, beta = 85.49(2) degrees, gamma = 80.62(2) degrees, Z = 2, and R = 0.0340.

Journal Article↗