Effect of the organic fragment on the mesogenic properties of a series of organogold(I) isocyanide complexes. X-ray crystal structure of [Au(Ctriple bond; length of mdashCC5H4N)(CNC6H4O(O)CC6H4OC10H21)]

Rod-like organogold(I) complexes [AuR(CNC6H4O(O)CC6H4OC10H21-p)] were prepared and their liquid crystal behaviour was studied. Depending on the nature of R, the synthetic methodology was different. Thus, for R = substituted alkynyl ligands, the new compounds were prepared in two steps:(i) reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with R′Ctriple bond; length of mdashCH(R′ = C5H4N, C6H4Ctriple bond; length of mdashN, C6H4Ctriple bond; length of mdashCC5H4N) in the presence of NaOAc to give insoluble [Au(Ctriple bond; length of mdashCR′)]n; (ii) reaction of the latter polymers with the isonitrile CNC6H4O(O)CC6H4OC10H21-p.For R = fluorinated aryls, the complexes were prepared by displacement of tht from the compounds [AuR(tht)] (R = C5F4N, C6F4C5H4N, C6F5) with isonitrile.In addition, an unexpected ionic derivative [Au(Ctriple bond; length of mdashCC5H4NC10H21)2][Au(Ctriple bond; length of mdashCC5H4N)2] was formed in the reaction between [PPh4][Au(Ctriple bond; length of mdashCC5H4N)2] and C10H21I. All these compounds have been characterized by IR and NMR spectroscopy and mass spectrometry. The X-ray crystal structure of the compound with R = Ctriple bond; length of mdashCC5H4N shows a linear molecule in which the gold atom is surrounded by the pyridine-containing acetylene and the isonitrile ligand, and no direct gold–gold interaction occurs. Six of the neutral compounds are liquid crystals and their optical, thermal and thermodynamic data were analyzed and compared in terms of molecular polarizability.