THE PREPARATION, STEREOCHEMISTRY AND REACTIONS OF SOME [CO(CYCLEN)(NH3)X](3+ 2+) COMPLESES (X = OH2, CL, N-3, OH)/

A number of new [Co(cyclen)(NH3)X](3+/2+) complexes have been prepared (X = OH2, Cl, N-3, OH), and their stereochemistries, interconversions , and substitution reactions have been explored. All have the syn,anti configuration about the two meridional amine centers of the cis-coord inated cyclen ligand (syn(NH3),anti(X)and syn(X),anti(NH3)-isomers for X = OH2, Cl, N-3, OH; designated as l-X and 2-X respectively) but a s yn,syn intermediate is proposed for a number of the reactions. OH--cat alyzed hydrolysis (base hydrolysis) dominates the substitution chemist ry in aqueous solution (k(OH)/M-1 s(-1) values reported) and results f rom deprotonation at one of the relatively very acidic meridional NH c enters (k(H)/M-1 s(-1) values reported). A syn orientation of the NH p roton in the reactant is considered important in these reactions, with the resulting lone pair assisting in the displacement of X, and with this proton being transferred to X = OH to facilitate an unusually fas t and spontaneous solvent replacement reaction (k(ex) = 8 +/- 2 s(-1), I = 1.0 M (NaClO4), 25 degrees C). Anation by N-3(-) has been studied , and this proceeds largely via 2-OH for both isomers. A crystal struc ture of nti(N-3)-[Co(cyclen)(NH3)-N-3]Cl-0.5(ClO4)(1).(5). H2O is repo rted; monoclinic, P2(1)/n (No. 14), a = 9.008(6) Angstrom, b = 28.690( 15) Angstrom, c = 14.528(7) Angstrom, a = 90 degrees, beta = 104.12(7) degrees, gamma = 90 degrees, Z = 8, R = 0.0695.