Nickel complexes with tris(2-aminoethyl)amine (tren): (Ni_3(tren)_4(H_2O)_2)(Cr(ox)_3)_2 centre dot 6H_2O (ox=oxalate), {(Ni_2(tren)_3)(ClO_4)_4 centre dot H_2O}_n, and (Ni_2(tren)_2(aepd)) (ClO_4)_4 centre dot 2H_2O (aepd=N-(2-aminoethyl)pyrrolidine

摘要

Reaction of K_3[Cr(ox)_3] (ox=oxalate) with nickel (II) and tris (2-aminoethyl)amine (tren) in aqueous solution resulted in isolation of the bimetallic assembly [Ni_3(tren)_4(H_2O)_2][Cr(ox)_3]_2 centre dot 6H_2O. The polymeric complex {[Ni_2(tren)_3][ClO_4]_4 centre dot H_2O}_n has been prepared by reaction of nickel (II) perchlorate and tern in aqueous solution. From the same reaction mixture the complex [Ni_2(tren)_2(aepd)][ClO_4]_4 centre dot 2H_2O (aepd = N-(2-aminoethyl)pyrrolidine-3, 4-diamine), in which a bridging tern ligand contains a carbon-carbon bond between two arms forming a substituted pyrrolidine, has been isolated. The complexes have been characterized by X-ray crystallography. The magnetic susceptibility (300-4.2 K) and magnetization data (2, 4 K, H = 0-5 T) for {[Ni_2(tren)_3][ClO_4]_4 centre dot H_2O}_n (300 K, 4.23 #mu#_B) exhibit evidence of weak antiferromagnetic coupling and zero field splitting (2J = -1.8 cm~(-1); |D| = 2 cm~(-1)) at low temperature. For [Ni_3(tren)_4(H_2O)_2][Cr(ox)_3]_2 centre dot 6H_2O the susceptibility data at 300 K are indicative of uncoupled nickel (II) and chromium (III) sites with zero-field splitting and intramolecular antiferromagnetic coupling predicted at low temperature.