title: Zwitterionic dithiocarboxylates derived from N-heterocyclic carbenes: coordination to gold surfaces.
abstract: The zwitterionic dithiocarboxylates 1(+)-CS(2)(-)-4(+)-CS(2)(-) were prepared by reacting the corresponding N-heterocyclic carbenes 1,3-bis(2,6-diisoproylphenyl)imidazol-2-ylidene (1), 1,3-diisopropylimidazol-2-ylidene (2), 1,3-dibenzylimidazol-2-ylidene (3) and 1,3-diethylbenzimidazol-2-ylidene (4) with CS(2). In the latter two cases, the corresponding N-heterocylic carbene was generated in situ. Compounds 2(+)-CS(2)(-)-4(+)-CS(2)(-) were structurally characterised by single-crystal X-ray diffraction studies. The chemisorption of these zwitterionic dithiocarboxylates on solid gold substrates was investigated in situ and in real time by optical second harmonic generation (SHG). The resulting thin films were exemplarily characterised by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) in the case of 1(+)-CS(2)(-) and 2(+)-CS(2)(-), revealing the formation of almost contamination-free self-assembled monolayers, which exhibit a remarkable degree of orientational order.
authors.affiliation: Institute of Chemistry, University of Kassel, Kassel, Germany. siemeling@uni-kassel.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Siemeling
authors.forename: Henry
authors.initials: H
authors.lastname: Memczak
authors.forename: Clemens
authors.initials: C
authors.lastname: Bruhn
authors.forename: Florian
authors.initials: F
authors.lastname: Vogel
authors.forename: Frank
authors.initials: F
authors.lastname: Träger
authors.forename: Joe E
authors.initials: JE
authors.lastname: Baio
authors.forename: Tobias
authors.initials: T
authors.lastname: Weidner
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006046:Gold / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D055620:Optical Phenomena; D010084:Oxidation-Reduction; D013499:Surface Properties
chemical_list: D002264:Carboxylic Acids; D006571:Heterocyclic Compounds; D008024:Ligands; C030011:carbene; D006046:Gold; D008697:Methane