Calamitic liquid crystals containing metal–metal bonds : design of mesomorphic materials based on the Ru₂(CO)₄(µ-^η2-O₂CR)₂L₂ sawhorse unit

A series of complexes based on the stable [Ru₂(CO)₄(µ-^η2-O₂CR)₂L₂] sawhorse unit has been prepared and characterized. The derivatives [Ru₂(CO)₄(µ-^η2-O₂CR)₂{NC₅H₄(CO₂C₆H₄OC_<i>n</i>H_2<i>n</i>+1-<i>p</i>)-<i>p</i>}₂] (R = H, <i>n</i> = 10; R = C₆H₅, <i>n</i> = 6, 10, 12, 14 or 16; R = C₆H₄CH₃-<i>p</i>, <i>n</i> = 10; R = C₆H₄OCH₃-<i>p</i>, <i>n</i> = 6, 10 or 16) proved to be mesomorphic, giving rise to nematic phases.