PLATINUM ORTHOMETALATED LIQUID-CRYSTALS COMPARED WITH THEIR PALLADIUMANALOGS - FIRST OPTICAL STORAGE EFFECT IN AN ORGANOMETALLIC LIQUID-CRYSTAL

Di-mu-chlorobis(eta(3)-2-methylallylplatinium) reacts with imines HL(n ) = p-CnH2n+1O-C6H4CH=N-C6H4-OCnH2n+1-p (n = 6, 1a; n = 2, 1b) to yiel d the C,N-cyclometalated platinum(II) compounds [Pt-2(mu-Cl)(2)(L(n))( 2)] (2a, 2b). From 2, other types of dinuclear complexes [Pt-2(mu-X)(2 )(L(n))(2)] with X = OAc, (R)-2-chloropropionato, SCnH2n+1), mixed bri dged complexes [Pt-2(mu-X)(mu-Y)(L(n))(2)] (X = Cl, OAc, (R)-2-chlorop ropionato; Y = SCnH2n+1), and mononuclear complexes [Pt(acac)(L(n))] h ave been prepared, and their mesogenic properties are compared with th ose of their palladium analogues reported previously. The Pt compounds exhibit higher temperature transitions, unless a different compositio n hides this effect when the material is a mixture of isomers. One of the compounds, cis-[Pt-2(mu-X)(mu-Y)(L(n))(2)] (X = (R)-2-chloropropio nato; Y = SC16H33), forms a glasslike state on cooling from the choles teric phase and shows absorption of light in the visible wavelength ra nge. As a consequence, it is suitable for optooptical storage effects, which have been realized on the complex without the addition of dye.