Synthesis and phase behaviour of mesomorphic transition-metal complexes of alkoxydithiobenzoates

Abstract

Reaction of 4-alkoxydithiobenzoates (n-odtb, where n refers to the number of carbon atoms in the alkoxy chain) with divalent salts of nickel, palladium and zinc leads to complexes of the formula [M(n-odtb)2] where M = Ni, Pd and [Zn2(n-odtb)4] which are mesomorphic. The shortest-chain homologues of the Ni and Pd complexes show a nematic phase while at longer chain lengths, an SC phase is observed. Most homologues of the zinc complexes show a nematic phase with an SC phase appearing only for the longest homologues. The gold(III) complexes [AuX2(n-odtb)] are also mesomorphic and show the SA phase. Single-crystal X-ray structure determinations have been carried out for [Pd(8-odtb)2], [Zn2(4-odtb)4] and [Zn2(8-odtb)4], showing the first to be planar and the last two dinuclear with pseudo five-co-ordinate zinc atoms.