Liquid crystals based on palladium orthometallated complexes with amido or dialkyldithiocarbamato ligands †

Abstract

The dinuclear cyclopalladated compounds [Pd2(μ-OAc)2(Ln)2] 2 derived from imines HLn = p-CnH2n + 1OC6H4CH NC6H4OCnH2n + 1-p1 (n = 2, 6 or 10) react with NaOH to give dinuclear derivatives [Pd2(μ-OH)2(Ln)2] 3. The reaction of 3 with amines (1 ∶ 1 molar ratio) yields the corresponding hydroxo–amido complexes [Pd2(μ-NHR)(μ-OH)(Ln)2] (R = CmH2m + 1 (m = 1, 6, 10, 14 or 18) 4 or C6H4C14H29-p5). With excess of amine [Pd2(μ-NHR)2(Ln)2] 6 (R = CmH2m + 1) are formed. Complexes 4 react with thiols or decanoic acid in 1 ∶ 1 mole ratio to give the corresponding amido–thiolato or amido–carboxylato complexes [Pd2(μ-SCjH2j + 1)(μ-NHR)(Ln)2] 7 ( j = 4, 10 or 18) or [Pd2(μ-O2CC9H19)(μ-NHR)(Ln)2] 8. The mononuclear complexes [Pd(S2CNR′2)(Ln)] (R′ = C2H59a or C8H179b) are prepared when complexes 3 are treated with dialkylamines in the presence of carbon disulfide. Most of the complexes show liquid crystal behaviour and nematic, smectic A and smectic C phases are found.