Kinetics and crystallographic studies of the ligand monomerization of a dithiolato(methyl)(oxo)rhenium(V) dimer

The dimeric rhenium(V) chelate [CH3Re(O)-(SC6H4CH2S)](2) (D) is readily monomerized with neutral and anionic ligands (L = 1,1,3,3-tetramethyl thiourea, pyridine, 4-methylpyridine and chloride ion) in reactions that feature rapid equilibration of I:1 and a 1:2 adducts, the dissociation of which leads to a mononuclear product, [CH3Re(O)(SC6H4CH2S)L]. The mononuclear product was characterized crystallographically for L=Me(4)tu and py. Experiments with chloride ion at excess D showed the formation of a new product that conceivably features a symmetric structure with a bridging chloride ion. Kinetic modeling was used to describe the kinetics of the reaction with chloride ion at dimer excess.