title: First π-linker featuring mercapto and isocyano anchoring groups within the same molecule: Synthesis, heterobimetallic complexation and self-assembly on Au(111).
abstract: Mercapto (-SH) and isocyano (-N≡C) terminated conducting π-linkers are often employed in the ever-growing quest for organoelectronic materials. While such systems typically involve symmetric dimercapto or diisocyano anchoring of the organic bridge, this article introduces the chemistry of a linear azulenic π-linker equipped with one mercapto and one isocyano terminus. The 2-isocyano-6-mercaptoazulene platform was efficiently accessed from 2-amino-6-bromo-1,3-diethoxycarbonylazulene in four steps. The 2-N≡C end of this 2,6-azulenic motif was anchrored to the [Cr(CO)5] fragment prior to formation of its 6-SH terminus. Metalation of the 6-SH end of [(OC)5Cr(η1-2-isocyano-1,3-diethoxycarbonyl-6-mercaptoazulene)] (7) with Ph3PAuCl, under basic conditions, afforded X-ray structurally characterized heterobimetallic Cr0/AuIensemble [(OC)5Cr(μ-η1:η1-2-isocyano-1,3-diethoxycarbonyl-6-azulenylthiolate)AuPPh3] (8). Analysis of the13C NMR chemical shifts for the [(NC)Cr(CO)5] core in a series of the related complexes [(OC)5Cr(2-isocyano-6-X-1,3-diethoxy-carbonylazulene)] (X = -N≡C, Br,H, SH, SCH2CH2CO2CH2CH3, SAuPPh3) unveiled remarkably consistent inverse-linear correlations δ(13COtrans) vs. δ(13CN) and δ(13COcis) vs. δ(13CN) that appear to hold well beyond the above 2-isocyanoazulenic series to include complexes [(OC)5Cr(CNR)] containing strongly electron-withdrawing substituents R, such as CF3, CFClCF2Cl, C2F3, and C6F5. In addition to functioning as asensitive13C NMR handle, the essentially C4v-symmetric [(-NC)Cr(CO)5] moiety proved to be an informative, remote, νN≡C/νC≡Oinfrared reporter in probing chemisorption of7on the Au(111) surface.
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Applegate
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Monisola K
authors.initials: MK
authors.lastname: Okeowo
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Erickson
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Brad M
authors.initials: BM
authors.lastname: Neal
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Berrie
authors.affiliation: Department of Chemistry, Missouri State University, 901 S. National Ave., Springfield, MO 65897, USA.
authors.forename: Nikolay N
authors.initials: NN
authors.lastname: Gerasimchukand
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Barybin