title: Optically active zwitterionic lambda(5)Si,lambda(5)Si'-disilicates: syntheses, crystal structures, and behavior in aqueous solution.
abstract: The zwitterionic lambda(5)Si,lambda(5)Si'-disilicates 1-8 were synthesized and characterized by solid-state and solution NMR spectroscopy. In addition, compounds 26 H(2)O, 32 CH(3)CN, 45/2 CH(3)CN, 6CH(3)OH, 7, and 8CH(3)OHCH(3)CN were studied by single-crystal X-ray diffraction. The optically active (Delta,Delta,R,R,R,R)-configured compounds 1-8 contain two pentacoordinate (formally negatively charged) silicon atoms and two tetracoordinate (formally positively charged) nitrogen atoms. One (ammonio)alkyl group is bound to each of the two silicon centers, and two tetradentate (R,R)-tartrato(4-) ligands bridge the silicon atoms. Although these lambda(5)Si,lambda(5)Si'-disilicates contain SiO(4)C skeletons, some of them display a remarkable stability in aqueous solution as shown by NMR spectroscopy and ESI mass spectrometry.
authors.affiliation: Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, Würzburg, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Theis
authors.forename: Christian
authors.initials: C
authors.lastname: Burschka
authors.forename: Reinhold
authors.initials: R
authors.lastname: Tacke
mesh_terms: D020650:Combinatorial Chemistry Techniques; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008958:Models, Molecular; D015394:Molecular Structure; D012015:Reference Standards; D017640:Silicates / Q000138:chemical synthesis* / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013237:Stereoisomerism; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D017640:Silicates; D012996:Solutions; D014867:Water