KINETIC-STUDIES ON STERICALLY HINDERED PENTAAMINECOBALT(III) COMPLEXES - SYNTHESIS, ANATION REACTIONS AND CRYSTAL-STRUCTURE OF [CO(ETNH2)5H2O](CLO4)3.2H2O

The sterically hindered pentakis(ethylamine)aquacobalt(III) complex has been prepared and its perchlorate dihydrate salt characterized by X-ray spectroscopy. Anation reactions of this complex with Cl-, Br-, CF3COO-, H2PO4- and H3PO4 have been studied as a function of temperature, and the results compared with those previously obtained for other [Co(RNH2)5H2O]3+ (R = H, Me) systems. Comparison of the bond distances of the title compound with those of the corresponding pentaammine complex leads to the conclusion that the increasing steric demands of the am(m)ine ligands are responsible for the clear rate acceleration observed in the dissociative activation anation process.