A proton magnetic resonance and preparative study of trimethylenediamine complexes of cobalt(III)

Abstract

The preparation of trans-[Co(tn)2Cl2]Cl,3.5H2O and [Co(tn)3]Cl3,H2O (1,3-diaminopropane = tn) is shown to proceed more readily and with greater yields when methanol solvent is employed instead of water. The preparation of the new species [Co(tn)2PO4]4H2O, [Co(tn)2(ox)]Cl,H2O, trans-[Co(tn)2(OH)H2O]-(ClO4)2,2H2O, and trans-[Co(tn)2(NH3)2]AsO4,3H2O is reported together with a modified preparation of [Co(tn)2CO3]ClO4. These preparations are discussed in terms of reaction mechanism. The p.m.r, spectra of the above species, trans-[Co(tn)2(NO2)2]NO2, cis-[Co(tn)2(H2O)HPO4]+, and cis-[Co(tn)2(H2O)2]3+ are reported in a range of solvents. The nature of the solvent markedly influences the observed chemical shifts and fine structure. The spectra are interpreted in terms of varying rates of conformational interchange of the tn ligands, and variation of solvent-solute interactions.