Effect of the organic fragment on the mesogenic properties of a series of organogold(I) isocyanide complexes.: X-ray crystal structure of [Au(C≡CC5H4N)(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'C equivalent to CH(R' = C5H4N, C6H4C equivalent to N, C6H4C equivalent to CC5H4N) in the presence of NaOAc to give insoluble [Au(C equivalent to CR')](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, C6F) with isonitrile. In addition, an unexpected ionic derivative [AU(C equivalent to CC5H4NC10H21)(2)][Au(C equivalent to CC5H4N)(2)] was formed in the reaction between [PPh4][Au(C equivalent to CC5H4N)(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 = C equivalent to CC5H4N 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. (c) 2005 Elsevier B.V. All rights reserved.