Structure Dynamics and Isomerism of Bis[μ-(2-methylphenolato)]bis[(η2:η2-cycloocta-1,5-diene)rhodium(I)] Complex

Dinuclear rhodium(I) complex [{Rh I (cod)} 2 (μ-OC 6 H 4 -2-Me) 2 ] ( 1 ), exhibits the syn - anti isomerism consisting in the orientation of methyl groups of the bridge ligands with respect to the plane or distorted plane involving Rh and O atoms. The syn isomer predominates in CDCl 3 solution (above 90%) at room temperature. EXSY 1 H NMR measurements showed that, in CDCl 3 solution, complex 1 undergoes at least two independent dynamic processes differing substantially in values of activation parameters: (i) rotation of 2-methylphenyl rings in bridge ligands along the O-C axis, and (ii) formal rotation of cod ligands along the Rh-cod axes, which proves fluxional behavior of cod ligand in Rh I (cod) complexes.