Jackson, William GregoryDickie, Alistair JBhula, RajumatiMcKeon, Josephine ASpiccia, LeoneBrudenell, SuzanneHockless, DavidWillis, Anthony2015-12-130020-1669http://hdl.handle.net/1885/87000The [Co(dmptacn)Cl]2+ (dmptacn = 1,4-bis(pyridylmethyl)-1,4,7- triazacyclononane) complex has been shown to be the asym isomer through 1D and 2D NMR studies, its optical resolution, and the single-crystal X-ray structure of its perchlorate salt. The kinetics of base-catalyzed hydrolysis establishes the usual [OH-] dependence (KOH = 0.040 M-1 s-1, 25 °C, / = 1.0 M, NaCl), but D-exchange experiments reveal that substantial if not complete reaction proceeds via the new pseudoaminate mechanism, i.e., via deprotonation at an α-CH2 center rather than the NH. The significant kinetic isotope effect (kH/kD = 2.1) is interpreted in terms of rate-limiting deprotonation followed by reprotonation of the conjugate base at a rate competitive with loss of Cl -. NMR and polarimetric studies establish geometric and optical retention for the hydrolysis reaction and exclude even the transient formation of a sym isomer intermediate.Keywords: [1,4 bis(pyridylmethyl) 1,4,7 triazacyclononane]cobalt complex; cobalt complex; ligand; perchlorate; pyridine derivative; unclassified drug; article; carbon nuclear magnetic resonance; hydrolysis; isomer; kinetic isotope effect; kinetics; nuclear magnetic200410.1021/ic040041m2016-02-24