Sulfur- and Carbon-Bonded Forms of the Cobalt(III) Complex With the Ligands 2-Aminoethyl 3-Aminopropyl Sulfide and 1,1,1-Tris(aminomethyl)ethane

Abstract

The new sulfur-bonded compound [Co(tame)( aeaps )] Cl3.H2O has been synthesized by the reaction of aeaps with Co(tame)Cl3 [tame = 1,1,1-tris( aminomethyl )ethane, and aeaps = 2- aminoethyl 3-aminopropyl sulfide or 3-thiahexane-1,6-diamine]. The Co(tame)( aeaps )3+ ion equilibrates in basic solution with the corresponding carbon-bonded species: Co(tame)( aeaps )3++HO-↔ Co(tame)(C-aeaps )2++H2O A salt of the carbon-bonded species, [Co(tame)(C- aeaps )](S2O6), has been isolated and its structure solved by X-ray diffraction analysis ( C- aeaps = 1,6-diamino-3-thiahexan-4-ide). The crystals are orthorhombic, Pna21, with cell dimensions a 20.455(10), b 9.960(10), c 8.982(10) Ǻ at 122(2) K. Preliminary thermodynamic and kinetic data are similar to the recently reported values for the corresponding coordination ion Co( tacn )( aeaps )3+ ( tacn = 1,4,7-triazacyclononane). In basic solution the Co(tame)( aeaps )3+ species exchanges one of its methylene protons orders of magnitude faster than any other methylene protons and also much faster than it forms the alkyl complex as shown by 13C n.m.r. measurements.