First π-linker featuring mercapto and isocyano anchoring groups within the same molecule: Synthesis, heterobimetallic complexation and self-assembly on Au(111).

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)] fragment prior to formation of its 6-SH terminus. Metalation of the 6-SH end of [(OC)Cr(η-2-isocyano-1,3-diethoxycarbonyl-6-mercaptoazulene)] () with PhPAuCl, under basic conditions, afforded X-ray structurally characterized heterobimetallic Cr/Au ensemble [(OC)Cr(μ-η:η-2-isocyano-1,3-diethoxycarbonyl-6-azulenylthiolate)AuPPh] (). Analysis of the C NMR chemical shifts for the [(NC)Cr(CO)] core in a series of the related complexes [(OC)Cr(2-isocyano-6-X-1,3-diethoxy-carbonylazulene)] (X = -N≡C, Br,H, SH, SCHCHCOCHCH, SAuPPh) unveiled remarkably consistent inverse-linear correlations δ( O) vs. δ( N) and δ( O) vs. δ( N) that appear to hold well beyond the above 2-isocyanoazulenic series to include complexes [(OC)Cr(CNR)] containing strongly electron-withdrawing substituents R, such as CF, CFClCFCl, CF, and CF. In addition to functioning as asensitive C NMR handle, the essentially C-symmetric [(-NC)Cr(CO)] moiety proved to be an informative, remote, ν/ν infrared reporter in probing chemisorption of on the Au(111) surface.