TY - JOUR A1 - Rudershausen, S. A1 - Drexler, Hans-Joachim A1 - Banße, Wolfgang A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Joachim T1 - Three polymorphs of bis(5-methylthio-1,2-dithiole-3-thione)-disulfide N2 - The title compound, bis(5-methylthio-1,2-dithiole-3-thione)-disulfide, was yielded for the first time as by- product of the reaction of nickel(II) and cobalt(II) ions with 5-methylthio-1,2-dithiole-3-thione-4-thiolate. The compound can be obtained directly by oxidation of the ammonium salt of the ligand. C8H6S10 forms three polymorphs: (I), which crystallizes in the orthorhombic space group P212121, (II) and (III), which crystallize in the monoclinic space groups P21/c and P21/n, respectively. The crystal and molecular structures are presented here. The determination of the absolute configuration of (I) indicated the P-helical enantiomer. In contrast to this, the crystals of (II) und (III) are racemic, containing P- and M-helical enantiomers. The polymorphs differ in the kind of skewing around the disulfide bond and of the positions of the both dithiole rings to the S-S-moiety Y1 - 2007 UR - http://onlinelibrary.wiley.com/doi/10.1002/crat.200610776/pdf U6 - https://doi.org/10.1002/crat.200610776 ER - TY - JOUR A1 - Laschewsky, André A1 - Pound, Gwenaelle A1 - Skrabania, Katja A1 - Holdt, Hans-Joachim A1 - Teller, Joachim T1 - Unsymmetrical bifunctional trithiocarbonate as unexpected by-product in the synthesis of a dithioester RAFT agent N2 - The trithiocarbonate 2-(benzylsulfanylthiocarbonylsulfanyl) propanoic acid is formed as minor by-product in the synthesis of the dithioester 2-((2-phenylthioacetyl)sulfanyl) propanoic acid via the Grignard route. The mechanism for this side reaction is not clear. The isolated trithiocarbonate may act as unsymmetrical but bifunctional RAFT agent in the aqueous polymerization of N,N-dimethyl acrylamide. Therefore, it is important to separate it completely from the dithioester before engaging the latter in controlled free radical polymerization to guarantee a maximum control. Y1 - 2007 UR - http://www.springerlink.com/content/101551 U6 - https://doi.org/10.1007/s.00396-007-1653-5 SN - 0303-402X ER - TY - JOUR A1 - Holdt, Hans-Jürgen A1 - Müller, Holger A1 - Kelling, Alexandra A1 - Drexler, Hans-Joachim A1 - Müller, Thomas A1 - Schwarze, Thomas A1 - Schilde, Uwe A1 - Starke, Ines T1 - Mercury(II) chloride and iodide complexes of dithia- and tetrathiacrown ethers N2 - The complexes [(HgCl2)(2)((ch)(2)30S(4)O(6))] (1), [HgCl,(mn21S(2)O(5))] (2), [HgCl2(ch18S(2)O(4))] (3) and [HgI(meb12S(2)O(2))](2)[Hg2I6] (4) have been synthesized, characterized and their crystal structures were determined. In [(HgCl2)(2)((ch)(2)3OS(4)O(6))] two HgCl2 units are discretely bonded within the ligand cavity of the 30-membered dichinoxaline-tetrathia-30-crown-10 ((ch)(2)30S(4)O(6)) forming a binuclear complex. HgCl2 forms I : I "in-cavity" complexes with the 21-membered maleonitrile-dithia-21-crown-7(mn21S(2)O(5)) ligand and the 18-membered chinoxaline- dithia-18-crown-6 (ch18S(2)O(4)) ligand, respectively. The 12-membered 4-methyl-benzo-dithia-12-crown-4 (meb12S(2)O(2)) ligand gave with two equivalents HgI2 the compound [HgI(meb12S(2)O(2))](2)[Hg2I6]. In the cation [HgI(meb12S(2)O(2))](+) meb12S(2)O(2) forms with the cation HgI+ a half-sandwich complex Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/10005159 U6 - https://doi.org/10.1002/zaac.200500281 SN - 0044-2313 ER - TY - JOUR A1 - Jansen, K. A1 - Buschmann, Hans-Jürgen A1 - Wego, A. A1 - Dopp, D. A1 - Mayer, C. A1 - Holdt, Hans-Joachim A1 - Schollmeyer, E. T1 - Curcubit[5]uril, decamethylcururbit[5]uril and curcurbit[6]uril : synthesis, solubility and amin complex formation N2 - A simple way to prepare cucurbit[5]uril is described. The macrocycles of the cucurbituril type are nearly insoluble in water. The solubilities of cucurbit[5]uril, decamethylcucurbit[5]uril and cucurbit[6]uril in hydrochloric acid, formic acid and acetic acid of different concentrations have been investigated. Due to the formation of complexes between cucurbit[n]urils and protons the solubility increases in aqueous acids. The macrocyclic ligands are able to form complexes with several organic compounds. Thus, the complex formation of the cucurbituril macrocycles with different amines has beenstudied by means of calorimetric titrations. The reaction enthalpy gives noevidence of the formation of inclusion or exclusion complexes. 1H-NMR measurements show that in the case of cucurbit[5]uril and cucurbit[6]uril the organic guest compound is included within the hydrophobic cavity. Decamethylcucurbit[5]uril forms only exclusion complexes with organicamines. This was confirmed by the crystal structure of the decamethylcucurbit[5]uril-1,6- diaminohexane complex. complex formation - cucurbit[5]uril - cucurbit[6]uril - decamethylcucurbit[5]uril - solubility - synthesis Y1 - 2001 ER - TY - JOUR A1 - Spannenberg, A. A1 - Buschmann, Hans-Jürgen A1 - Holdt, Hans-Joachim A1 - Schollmeyer, E. T1 - Complex formation of noncyclic, monocyclic and bicyclic ligands with nickel(II) and cobalt(II) in acetonitrile N2 - Equilibrium constants and thermodynamic parameters for the complexation of nickel(II) and cobalt(II) by noncyclic, monocyclic and bicyclic ligands in acetonitrile have been determined by calorimetric titrations. The donor atoms and the ring size of the ligands play an important role for the stabilities of the complexes formed. An increasing number of nitrogen atoms in the crown ether favours complex formation. The number of nitrogen donor atoms of the macro- cyclic ligands examined has a direct influence on the values of the reaction enthalpies. Keywords: Complex formation; crown ethers; azacrown ethers; thiacrown ethers; cryptands; acetonitrile Y1 - 1999 SN - 0095-8972 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Grotjahn, Manuela A1 - Klinka, Karel D. A1 - Drexler, Hans-Joachim A1 - Holdt, Hans-Jürgen T1 - Conformational and complexational study of some maleonitrile mixed oxadithia crown ethers by NMR spectroscopy and molecular modelling N2 - The macrocyclic ring interconversion of four maleonitrile mixed oxadithia crown ethers of variable ring size, mn-12-S2O2, mn-15-S2O3, mn-18-S2O4 and fn-12-S2O2, were studied by 1H and 13C NMR spectroscopy and by molecular modelling. The barriers to ring interconversion were estimated using variable temperature NMR spectroscopy and from the calculated activation energies, together with the spin-lattice relaxation times of the CH2 carbon atoms, conclusions were drawn regarding the intramolecular flexibility of the crown ethers in both the free state as well as the complexed state incorporating either AgI, BiIII, SbIII, PdII or PtII metal cations. Furthermore, both the stoichiometry of the complexes and the coordination sites of the crown ethers to the various cations were also clearly implicated. Molecular modelling was also utilised to ascertain the preferred conformers of the four compounds and their corresponding complexes, the results of which corroborated the experimental NMR results to a high degree. Y1 - 2001 ER - TY - JOUR A1 - Grotjahn, Manuela A1 - Lehmann, S. A1 - Aurich, Ines A1 - Holdt, Hans-Joachim A1 - Kleinpeter, Erich T1 - NMR spectroscopic and molecular modelling studies of the solution structure and complexational behaviour of some bis(benzocrown ether)s N2 - Structural information about the bis(benzo crown ether)s I-VI and their complexes with alkali metal cations was deduced from the 13C NMR chemical shifts, the salt-induced 1H and 13C chemical shifts and the vicinal 1H,1H coupling constants. Especially the isomerism with respect to the amide O=C - NH bonds and imine fragments were assigned by various useful NMR parameters ( C=O, 1JN,H, 1JC,H) and proved to be E,E-anti,anti. Furthermore, stereochemical information about preferred conformations about flexible bonds was obtained from 2D ROESY NMR experiments. The complex formation (2:1 complexes and sandwich-like 1:1 complexes, respectively) were determined also by 23Na NMR spectroscopy. The conformational study of the crown ethers was accompanied and corroborated by molecular dynamics and quantum chemical calculations. Y1 - 2001 ER - TY - JOUR A1 - Holdt, Hans-Jürgen A1 - Drexler, Hans-Joachim A1 - Starke, Ines A1 - Grotjahn, Manuela A1 - Kleinpeter, Erich T1 - Homologous series of the PdCl2 and PtCl2 complexes of maleonitrile-dithiacrown ethers : synthesis, crystal structures, NMR spectroscopy and mass spectrometry Y1 - 2001 ER - TY - JOUR A1 - Drexler, Hans-Joachim A1 - Grotjahn, Manuela A1 - Kleinpeter, Erich A1 - Holdt, Hans-Jürgen T1 - A novel polymeric disilver(I) complex containing both macrocyclic- and linear-coordinate silver(I) centres : [Ag-2(mn-15S(2)O(3))](infinity)(ClO4)(2 infinity) (mn-15S(2)O(3) = maleonitrile-dithia[15]crown-5) Y1 - 1999 ER - TY - JOUR A1 - Drexler, Hans-Joachim A1 - Starke, Ines A1 - Grojahn, Manuela A1 - Reinke, H. A1 - Kleinpeter, Erich A1 - Holdt, Hans-Jürgen T1 - SbCl3, BiCl3 and Na+ Complexes of maleonitrile-dithiacrown ethers: synthesis, crystal structures and DEP-MS experiments Y1 - 1999 ER - TY - JOUR A1 - Grotjahn, Manuela A1 - Jäger, Norbert A1 - Drexler, Hans-Joachim A1 - Holdt, Hans-Jürgen A1 - Kleinpeter, Erich T1 - Molecular modeling study of the PtCl2 complexes of unsaturated S2On+1- coronands: dynamic simulations and investigation of the ring interconversion Y1 - 1999 ER - TY - JOUR A1 - Grotjahn, Manuela A1 - Drexler, Hans-Joachim A1 - Jäger, Norbert A1 - Kleinpeter, Erich A1 - Holdt, Hans-Jürgen T1 - Molecular dynamic and conformational study of an unsaturated 12-crown-S202 ether and its AgI complexes Y1 - 1997 ER -