Preparation and NMR Spectra of Hexacoordinate Metal Complexes of Mono(N-ethylethanediamine) and Mono(N-benzylethanediamine) and Crystal Structure of [Co(NH3)4(N-benzylethanediamine)] (NO3)3·1.5H2O

Abstract

Abstract Mono N-ethylethanediamine and N-benzylethanediamine complexes of Co(III), Fe(II), and Fe(III) with four cyano or ammine groups were prepared. Their 1H NMR spectra were measured to determine the conformation of N-ethyl and N-benzyl groups. These N-alkyl groups take pseudo-equatorial orientation at the coordinated secondary amine. The most preferred conformation is that the methyl and phenyl groups are anti with respect to the central metal ions. The crystal structure parameters of [Co(NH3)4(N-benzylethanediamine)](NO3)3·1.5H2O were determined: P21, Z = 2, a = 8.639(3), b = 21.240(3), c = 10.897(2) Å, β = 94.11(1)°. The crystallographically independent Co complex cations had opposite absolute configuration around coordinated secondary amine sites and the benzyl groups are anti to the cobalt atom.