The preparation and characterization of mer-Bis[di(3-aminopropyl)amine]cobalt(III) perchlorate, and the crystal structure of its hydrolysis product Bis[di(3-aminopropyl)amine]tri-μ-hydroxo-dicobat(III) perchlorate

Abstract

mer-[Co(dpt)₂] Cl₃ [dpt = di(3-aminopropyl)amine] has been obtained from substitution or oxidation reactions in non-aqueous solvents, and transformed to the perchlorate salt. The different form of the ¹³C n.m.r. spectrum to that of mer-[Co(dien)₂]³⁺ (dien = diethylenetriamine), and variation of the spectrum with basicity, is taken to indicate high conformational mobility of the coupled six-membered chelate rings of the mer structure. Slow hydrolysis occurs in neutral water (but is prevented by acid), and the hydrolysis product has been isolated. The s-fac and u-fac [Co(dpt)₂]³⁺ isomers have not been detected chromatographically in the preparations, and any isomerization of the mer isomer is masked by the hydrolysis. X-ray crystallographic analysis shows that the isolated hydrolysis product is the racemic geometric isomer (C₂ symmetry) of [(dpt)Co(OH)₃Co(dpt)] (ClO₄)³. Each facially coordinated dpt adopts the ring conformations chair, irregular-boat. The crystals are monoclinic, space group P2₁/n, with a 15.053(5), b 13.964(2), c 14.010(3) Å, β 109.90(2)º. The structure was refined by blocked-matrix least-squares techniques to an R factor (3190F) of 0.032.