1,720,990 research outputs found
A 1H NMR fourier transform investigation on cobalt(II) chloride complexes with imidazolidine-2-thione and its N-mono- and N,N′-dialky-substituted derivatives
No full textCharge-Transfer complexes of N-methylthiazolidine-2(3H)-selone (1) and N-methylbenzothiazole-2(3H)-selone (2) with I2 and IBr: crystal structures of 1.I2, 1.I1.25Br0.75, 2.2I2 and 2.2IBr
No full textIn CH2Cl2 solution, N-methyl-1,3-thiazolidine-2(3H)-selone (1) and N-methylbenzothiazole-2(3H)-selone (2) react with molecular diiodine to form 1:1 adducts. From solutions having 1 and diiodine in a 1:1 molar ratio, a neutral charge-transfer compound of formula 1.I-2 (C4H7I2NSSe; I) has been obtained, whereas, in the same conditions, 2 yields the previously described ionic compound [(2)(2)I]I-+(3)-, having the 2.I-2 stoichiometry. The crystals of I are monoclinic [space group Cc with a = 16.400(7) Angstrom, b = 5.976(3) Angstrom, c = 12.942(4) Angstrom, beta = 127.66(2)degrees, Z = 4, and R = 0.024] and contain units formed by one diiodine molecule bonded almost linearly [177.49(3)degrees] to the selenium atom. From solutions having a 1:2 molar ratio between the selonic compounds and diiodine, N-methyl-1,3-thiazolidine-2(3H)-selone (1) affords again the same I adduct, whereas 2 yields a crystalline compound with formula 2 .2I(2) (C8H7I4NSSe; III). The crystals of III are triclinic [space group <P(1)over bar>, with a = 11.439(4) Angstrom, b = 14.337(4) Angstrom, c = 16.479(6) Angstrom, alpha = 115.47(2)degrees, beta = 97.02(3)degrees, gamma = 97.85(3)degrees, Z = 6, and R = 0.028]. Unexpectedly, this compound is not ionic as [(2)(2)I]I-+(3)-, and contains three independent 2.2I(2) molecular adducts per asymmetric unit. In each molecular adduct, one diiodine molecule is almost linearly bonded to the selenium atom and lies essentially in the plane of the organic molecule. These units are packed in the crystal on parallel stacked planes separated by ''graphite-like'' interactions, between the organic molecules. The other weakly interacting diiodine molecules fall out of the planes and fit into the cavities left in the packing. In the same solvent and for a 1:1 molar ratio, the reaction between 1 and IBr yields 1. IBr (C4H7IBrNSSe) microcrystals, whereas for a 1:2 molar ratio, violet crystals of formula 1.I1.25Br0.75 (C4H7I1.25Br0.75NSSe; II) isotypic with those of I, have been obtained [space group Cc, with a = 16.233(8) Angstrom, b = 5.900(4) Angstrom, c = 12.793(6) Angstrom, beta = 127.43-(3)degrees, Z = 4, and R = 0.038]; here, the IBr molecule is bonded almost linearly [176.90(4)degrees] to the selenium atom through the iodine atom and about 25% of bromine is substituted by iodine thus obtaining a solid solution formed by 25% of the 1.I-2 adduct and 75% of the 1.IBr adduct. The reaction of 2 with IBr yields both 2.IBr (C8H7-IBrNSSe) microcrystals and 2.2IBr (C8H7I2Br2NSSe; IV) brown crystals using 1:1 and 1:2 molar ratios respectively. The crystals of IV are triclinic [space group <P(1)over bar>, with a = 9.078(5) Angstrom, b = 9.872(5) Angstrom, c = 9.979(3) Angstrom, alpha = 60.66(2)degrees, beta = 74.21(2)degrees, gamma = 82.09(2)degrees, Z = 2, and R = 0.027]. On the basis of the large lengthening of the I-Br bond [3.129(1) Angstrom] in the molecule coordinated to selenium, IV can be almost envisaged as an ionic [2I](+)IBr(2)(-)compound, with the ions strongly interacting with each other. FT-Raman spectra of the solid samples are discussed compared with their structural features and with the spectra of CH2Cl2 solutions containing equimolecular concentrations of 1 (or 2) and I-2 (or IBr)
Pd(II) Complexes with N(1) and N(3) Monomethylated 5,5-dimethyl-4-oxoimidazolidine-2-thione
No full textN-Coordinated Copper(II) Complexes with 2-S-Methyl-5,5-dimethylimidazolin-4-one (L). Crystal Structure of [CuL4H2O][CuCl4]
No full textThe reaction between CuX(2) (X = Cl, Br, NO3, ClO4) and 2-S-methyl-5,5-dimethylimidazolin-4-one (L) yields complexes having stoichiometry CuL(2)Cl(2) . 1/2H(2)O (1), CuL(2)Br(2) (2), CuL(4)X(2) . 2H(2)O [X = NO3 (3), ClO4 (4)]. The X-ray crystal structure solved for 1 showed that it contains discrete [CuL(4) . H2O](2+) and [CuCl4](2-) ions, separated by normal van der Waals contacts. The [CuL(4)H(2)O](2+) cation has crystallographic C-4 symmetry, with the copper atom and the oxygen of the water molecule lying on a four-fold axis of the space group P4/n and the metal atom in a square-pyramidal coordination geometry, obtained by a square basal plane defined by four N atoms and the apex occupied by the water molecule. The [CuCl4](2-) anion shows a very flattened tetrahedral geometry. FT-IR and FT-Raman spectra of 1-4 show that 2,3 and 4 also are N(3)-coordinated to copper; nitrate and perchlorate do not coordinate. The v(CuO) vibrations are present at about 380 cm(-1) for 3 and 4, while for 2 v(CuBr) are at 224 and 215 cm(-1). Esr data for 1-4 recorded on solid samples highlight a d(x)(2) - y(2) ground state for the cation of 1, 3, and 4 which is typical for tetragonally elongated monomeric copper(II) complexes. Compound 2 exhibits two couples of g values characteristic of two independent copper centres both with compressed tetrahedral geometry. The deconvoluted reflectance spectra of 1-4 substantially confirm the presence of CuN4 and CuBr4 chromophores in 2 and a trans-CuN4O2 chromophore in 3 and 4. For the latter complexes an orbital sequence d(x2-y2)&gt;d(xy)&gt;d(z2)&gt;d(xy), d(yz) is also suggested on the basis of the similarity between L and imidazole type ligands
LSb(m-I)2(m-S)SbL:a neutral triply bridged complex obtained from Sb powder and diiodine activated by tetraphenyldithioimidodiphosphine (HL)
No full textThe synthesis of the complex LSb(μ-I)2(μ-S)SbL (1) was accomplished by reacting antimony powder with diiodine activated by tetraphenyldithioimidodiphosphine (SPPh2NHPPh2S) (HL). X-ray diffraction (tetragonal, M = 1426.30, space group I 41/a (No. 88), Z = 8, a = 18.020(2) Å, c = 33.037(4) Å) shows that (1) is a dinuclear SbIII complex, in which the two metal ions are bridged by one sulphide and two iodide anions. An anionic bidentate L ligand completes the coordination sphere of each metal with its two sulphur atoms, leading to a slightly distorted pyramidal coordination geometry, since each metal ion shows the presence of a sterically active lone-pair in trans position to the bridging sulphide. 31P CP-MAS NMR and IR spectroscopies are in accordance with the structural features of the complex
Reaction of Imidazole-2-selone derivatives with diiodine: synthesis, structural and spectroscopic cheracterization of the adduct 1,1\'-bis(3-methyl-4-imidazolil-2-selone)methane bis(diiodine) and the first examples of I-Se-I hypervalent selenium compounds: 1,3-dimethyl-4-imidazolium-2-ylium diiodo selenanide and 1,2-bis(3-methyl-4-imidazolin-2-ylium diiodo selenanide)ethane bis(dichloromethane)
No full textCharge transfer complexes between some S-Methylated derivatives of 5,5-dimethyl-2,4-dithiohydantoin and molecular diiodine. A Uv-Visible, IR, FT-Raman, and 13C NMR study
No full textEquilibrium constants (K) and thermodynamic parameters for the charge-transfer complexes between diiodine and Delta(3)-4-S-methyl-5,5-dimethylimidazolidine-2-thione (1), 2-S-methyl-5,5-dimethylimidazolidine-4-thione (2), and Delta(1)-Delta(3)-2S-methyl-4-S-methyl-5,5- dimethylimidazolidine (3) have been determined in CH2Cl2 by UV-Visible spectroscopy. Depending on the solvent polarity, compound 2 exists as a Delta(1) or Delta(2) tautomer; both the tautomers are present in CH2Cl2. Compounds 1 and 2 act as good donors (K = 11,000 +/- 800 and 640 +/- 21 dm(3) mol(-1), 25 degrees C, respectively) owing to the presence of a thioamidic group in the molecule, whereas in compound 3, the N-coordination causes a strong reduction of the formation constant (K = 14.6 +/- 0.8 dm(3) mol(-1), 25 degrees C). The high difference between the stability constants of 1 and 2 has been ascribed to an intramolecular hydrogen bonding between NH and the bonded iodine, which can be possible only for 1. Additional spectroscopic data (FT-Raman, NMR) enables a deeper understanding of the mutual interaction between donors and diiodine
On the use of Raman spectroscopy in the characterisation of iodine in charge-transfer complexes
No full textFT-Raman spectra of some polyiodides and of a series of D.I2 charge-transfer complexes (where D is a molecule containing the thione or selone groups as donors), all characterized by x-ray diffraction, are reported. For the adducts with the thione compounds, which can be considered weak or medium-weak complexes, an empirical linear correlation between the frequency of the nu(I-I) stretching vibrations and the d(I-I) bond distances has been found. Some polyiodides show FT-Raman spectra that are indistinguishable with respect to those displayed by the neutral complexes of weak or medium-weak strength; in such cases, the polyiodide can be regarded as a diiodine molecule, perturbed by an I(n)- (n = 1,3....) donor. Polyiodides of this type show Raman absorptions falling in the linear correlation
Polyiodides and polytellurides: Analogies and differencies
No full textAnalogies and differences between polytellurides and polyiodides are discussed with
the help of quantum chemical DFT calculation
A new class of mixed az-thioether crown containing the 1,10-phenanthroline sub-unit
No full textThe new aza-thioether crowns [15]ane(phen N-2)S-3 and [19]ane(phen N-2)S-4 have been synthesised. Their complexation with nickel(II) salts afforded a range of octahedral complexes. The single crystal structures of [Ni{[15]ane(phen N-5)S-3)}(NCMe)][BF4](2), [NiCl{[15]ane(phen N-2)S-3}]BF4 . dmf(dmf = dimethylformamide) and [Nil{[15]ane(phen N-2)S-3}][I-3] have been determined and confirm N2S3 donation of the aza-thioether crown in a folded conformation to Ni-II with the sixth co-ordination site taken up by MeCN, Cl- and I- respectively. The complex [Ni2Cl2{[19]ane(phen N-2)S-4}(2)][BF4](2) . 3MeNO(2) shows a dichloro-bridged binuclear structure with the aza-thioether crown bound via only two S- and two N-donors, with two thioether S-donors unbound. A dichloro-bridged binuclear structure was found also for [Ni2Cl2{[12]ane-(py N)S-3}(2)][BF4](2) . 1.5MeNO(2). The redox properties of [Ni{[15]ane(phen N-2)S-3}(NCMe)][BF4](2) in MeCN have been examined
- …
