KINETICS OF BASE HYDROLYSIS OF [CO(TETREN)DMF](3-DIAMINO-3,6,9-TRIAZAUNDECANE)() AND [CO(TETREN)DMSO](3+) (TETREN = 1,11)

The complexes [Co(tetren)dmf](ClO4)(3) and [Co(tetren)dmso](ClO4)(3) h ave been prepared from alpha alpha-[Co(tetren)Cl](ClO4)Cl (tetren = 1, 11-diamino-3,6,9-triazaundecane). H-1-n.m.r. and i.r. measurements con firm that the complexes contain O-bonded dmf and dmso. A biphasic reac tion is observed in the base hydrolysis of the dmf derivative, monitor ed by the pH-stat method, with the fast reaction having k(OH) = 1.2 x 10(4) dm(3) mol(-1) s(-1) and the slower reaction k(OH) = 1.9 x 10(2) dm(3) mol(-1) s(-1) at 25 degrees C and I = 0.1 mol dm(3). The fast re action is assigned to the hydrolysis of the alpha beta(R)-[Co(tetren)d mf](3+) and the slower reaction to that of the alpha alpha-isomer. The reaction appears to proceed predominantly by a D-CB pathway without p arallel hydrolysis of coordinated dmf, which has been observed in the hydrolysis of [Co(NH3)(5)dmf](3+). Base hydrolysis of [Co(tetren)dmso] (3+) was monitored spectrophotometrically over the pH range 4.2 to 5.0 . A single reaction was observed with k(OH) = 1.9 x 10(6) dm(3) mol(-1 ) s(-1) at 25 degrees C and I = 0.1 mol dm(-3). The rapid base hydroly sis is attributed to hydrolysis of the or the alpha alpha(R)- or the a lpha beta(S)-[Co(tetren)dmso](3+) isomer rather than the alpha alpha-i somer.