Magnetic and liquid-crystalline properties of chlorido- and cyanato-bridged chain complexes of mixed-valent dinuclear ruthenium(ii,iii) 3,4,5-trialkoxybenzoates

Abstract

A series of cyanato-bridged chain complexes of mixed-valent dinuclear ruthenium(II,III) 3,4,5-trialkoxybenzoates, [Ru₂{3,4,5-(n-C_mH_2m+1O)₃C₆H₂CO₂}₄(OCN)]_n (mOCN) (m = 2–7, 9–18), were synthesized. IR spectra of mOCN showed that the cyanato ligands adopt a μ_1,1-O mode to form zigzag chains. Temperature dependence of magnetic susceptibilities of mOCN showed that the antiferromagnetic interaction between the dinuclear units is strong compared with that of the chlorido-bridged derivatives [Ru₂{3,4,5-(n-C_mH_2m+1O)₃C₆H₂CO₂}₄Cl]_n (mCl). The liquid-crystalline behaviors for mCl with m = 5–18 and mOCN with m = 6–18 were confirmed by polarized-microscopy, X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC) measurements. The XRPD data confirmed a zigzag form for all samples of mCl. Furthermore, single-crystal X-ray diffraction analyses revealed a chain structure of pentyloxy derivative 5Cl·2nH₂O and a pseudo chain structure of hexyloxy derivative [Ru₂{3,4,5-(n-C₆H₁₃O)₃C₆H₂CO₂}₄(C₂H₅OH)₂][Ru₂{3,4,5-(n-C₆H₁₃O)₃C₆H₂CO₂}₄Cl₂]·2C₂H₅OH (6Cl′·2C₂H₅OH); the XRPD data indicated that the structural change occurs in ambient atmosphere.