584-10-1Relevant articles and documents
Carbonates, thiocarbonates, and the corresponding monoalkyl derivatives. 1. Their preparation and isotropic 13C NMR chemical shifts
Stueber,Patterson,Mayne,Orendt,Grant,Parry
, p. 1902 - 1911 (2001)
Three series of potassium carbonate and thiocarbonate salts were synthesized, and the corresponding 13C isotropic solid-state NMR and the aqueous solution 13C and 1H NMR data were collected. The series of compounds that were studied consists of (1) the parent compounds, i.e., potassium carbonate, K2CO3, potassium hydrogen carbonate, KHCO3, potassium monothiocarbonate, K2CO2S, potassium dithiocarbonate, K2COS2, and potassium trithio-carbonate, K2CS3, (2) the oxygen monoalkyl substituted derivatives of the parent compounds (OR series), i.e., three potassium O-alkylcarbonates, KO2COR, three potassium O-alkylmonothiocarbonates, KOSCOR, and three potassium O-alkyldithiocarbonates, KS2COR, all with R = CH3, CH2CH3, CH(CH3)2, and (3) the sulfur monoalkyl substituted derivatives of the parent compounds (SR series), i.e., two potassium S-alkylmonothiocarbonates, KO2-CSR; two potassium S-alkyldithiocarbonates, KOSCSR, and two potassium S-alkyltrithiocarbonates, KS2CSR, all with R = CH3 or CH2CH3. The preparation and proper characterization of KO2CSR and KOSCSR with R = CH3 and CH2CH3 along with new IR and X-ray powder diffraction data for several other compounds in the series are reported for the first time in this study. Solution NMR data for KO2CSR (R = CH3, CH2CH3) and KOSCSR (R = CH3) and solid-state NMR data for K2CO2S and K2COS2 could not be obtained because they are unstable under the corresponding measurement conditions. The isotropic chemical shift values of the central carbon atoms obtained from solid-state MAS (magic angle spinning) NMR experiments deviate at most by 3 ppm from the corresponding solution values. Two major trends in the 13C chemical shift values of the central carbon atoms were found. First, if an oxygen atom in a parent compound or in an alkyl-substituted derivative is replaced by a sulfur atom, a significantly higher chemical shift value is observed. This trend is discussed in terms of the paramagnetic contribution to the chemical shielding constant. Second, the size of the alkyl group in the monoalkyl derivatives has a very small effect on the chemical shift values of the central carbon atoms. This observation is explained using the concept of varying inductive effects produced by alkyl groups. The trends observed for the 13C and 1H chemical shift values of the alkyl groups follow common concepts on the structure dependency of chemical shifts.
Rosenbladt
, p. 15 - 18 (1887)
Extended TTF-type donors fused with pyrazine units; Synthesis and characterization
Raba?a, Sandra,Oliveira, Sandrina,Santos, Isabel C.,Almeida, Manuel
, p. 6635 - 6639 (2013/11/19)
Pyrazinedicyanoethylthiotetrathiafulvalene, (pzdc-TTF) (1a), an extended TTF fused with a pyrazine moiety and also a dithiolene ligand precursor, was synthesized through a cross-coupling with triethyl phosphite between pyrazine-1,3-dithiole-2-thione (I) and 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2- one (III). This reaction also yields to dipyrazine TTF derivative (1b) and 2,3,6,7-Tetrakis(2-cyanoethylthio)TTF (1c), resulting from the self-coupling reactions of the thione (I) and ketone (III). The crystal structure of 1a is composed by pairs of head to head donor stacks of pzdc-TTF molecules along b in opposite orientations. Single crystals of 1b revealed a new polymorph with a face-to-face π-stacking motif. The electrochemical properties of 1a studied by cyclic voltammetry (CV) in DMF, shows two single electron oxidation processes typical of TTF-based donors; one pair of asymmetric redox waves centered at 627 mV versus Ag/Ag+ is ascribed to the couple [pzdc-TTF] +/[pzdc-TTF]2+, and one pair of quasi-reversible redox waves centered at 430 mV is ascribed to the couple [pzdc-TTF] 0/[pzdc-TTF]+.
Synthesis, structure and physical properties of transition metal bis 4-cyanobenzene-1,2-dithiolate complexes [M(cbdt)2]z - (M = Zn, Co, Cu, Au, Ni, Pd, z = 0, 1, 2)
Cerdeira, Ana C.,Afonso, Mónica L.,Santos, Isabel C.,Pereira, Laura C.J.,Coutinho, Joana T.,Raba?a, Sandra,Sim?o, Dulce,Henriques, Rui T.,Almeida, Manuel
, p. 228 - 237 (2013/01/13)
A series of new [M(cbdt)2]z- complexes of the 4-cyanobenzene-1,2-dithiolate (cbdt) ligand with a range of transition metals M (M = Zn, Co, Cu, Au, Ni, Pd) were prepared in different oxidation states (z = 0, 1, 2) as salts with several cations and characterised by X-ray diffraction, cyclic voltammetry, EPR and static magnetic susceptibility. Their properties are discussed in comparison either with the Fe analogue or corresponding complexes based on the dicyano substituted ligand (dcbdt) previously described by us. These complexes can be prepared either from the ligand dithiol as previously described for the Fe analogue, or in a more convenient way to obtain the more reduced forms, from the 4-cyanobenzene-1,3- dithiole-2-thione (1) which is described here for the first time. The structure of these complexes presents square planar coordination geometry, and belong to four distinct groups: (i) the Au monoanionic compound 4a is monoclinic, C 2/c, where the complex presents a cis-trans disorder; (ii) the compounds 10b, 7b of the dianionic Pd and Ni complexes, are isostructural, monoclinic, P21/c, with the metal in an inversion centre, a perfect square-planar coordination geometry and a ligand trans configuration; (iii) the compounds (8a and 9a) of the Co and Cu dianionic complexes, which are monoclinic P21, with the metal located in a general position with square planar coordination and ligand trans configuration; and (iv) the monoanionic Cu compound 12 is triclinic, P1?, with the metal in a general position with almost ideal square-planar coordination and ligand trans configuration. These complexes present redox properties intermediate between those based on dcdbt and unsubstituted benzenedithiolate ligand (bdt), and the gold complex can be obtained in the neutral state. The EPR and static magnetic susceptibility measurements show that the dianionic cobalt and copper complexes (8a and 9a) the monoanionic nickel (3), and the neutral gold (11) complexes are paramagnetic corresponding to an S = state. The powder EPR spectrum of the dianionic Co complex 8a presents a hyperfine structure typical of I = 7/2 59Co with a component a0x = 8.6 mT.
