Rigid-Rod Polymers and Model Compounds with Gold(I) Centers Bridged by Diisocyanides and Diacetylides

Abstract

Binuclear alkynyl(isocyanide)gold(I) complexes have been prepared by reaction of oligomeric precursors [(AuC⋮CRC⋮CAu)n] (R = C6H4, C6H4C6H4, 2,5-C6H2Me2, CH2OC6H4C(Me)2-C6H4OCH2) with 2,6-dimethylphenyl isocyanide (XyN⋮C) to give [XyN⋮CAuC⋮CRC⋮CAuC⋮NXy] or by reaction of [(R‘C⋮CAu)n] with a diisocyanide CNRNC to give [R‘C⋮CAuCNRCAuCNC⋮CR‘] (R = C6H4, 2-MeC6H3, C6Me4, 2,5-Me2C6H2-2,5−Me2C6H2, 2,5-C6H2(t-Bu)2; R‘ = t-Bu or Ph). The products were characterized spectroscopically and, for R = 2,5-C6H2(t-Bu)2; and R‘ = Ph, by an X-ray structure determination. The molecule has a rodlike structure, and there is a bowing of the isocyanide ligand, angle CN⋮C = 168(2)°, which allows the molecules to pack in zigzag chains with short intermolecular Au··Au contacts of 3.174(1) Å to give a loosely held polymeric structure. Analogous σ-bonded, conjugated rigid-rod polymeric complexes are prepared by reactions of the linear digold complexes [(AuC⋮CRC⋮CAu)n] (R = C6H4, C6H4C6H4, C6H2Me2 and CH2OC6H4C(Me)2C6H4OCH2) with appropriate diisocyanoarenes C⋮NR‘N⋮C (R‘ = C6H4, C6H3Me, C6Me4, C6H2Me2C6H2Me2, C6H2-t-Bu2) to give [(AuC⋮CRC⋮CAuC⋮NR‘N⋮C)x]. These polymers are insoluble and are characterized by elemental analysis, IR and XPS methods; the IR, and XPS data indicate that the polymers contain the same functional groups as the binuclear model complexes. It is argued that the low solubility results in part from crosslinking due to interchain Au··Au contacts of the kind established crystallographically in the model binuclear complex.