Chemical assembly of an antiferromagnetic macrocyclic molecule containing two inner Co^II centers from polymeric cobalt pivalate

Abstract The reaction of the polymer {Co(Piv)2}n (Piv is the pivalic acid anion) with triethylenetetramine (L1) (M:L1 = 2:1) in MeCN affords the polymeric compound [Co2L1(η2-Piv)2(μ-Piv)2]n (1) containing asymmetric dicobalt units coordinated by one chelate ligand L1. The reaction of 1 with an additional amount of L1 (M:L1 = 1:1) in MeCN gives rise to the binuclear molecule Co2 L 1 2 (Piv)4 (2), where L1 acts as a chelate-bridging ligand. Compounds analogous to 2 with M = Fe (3) were prepared by the reaction of the polymer {Fe(Piv)2}n with L1 in MeCN using the reagent ratio M:L1 = 1:1. The reaction of the compound Co L 1 2 (Piv)4 (2) with isophthalaldehyde (L2) produces the binuclear complex Co2L3(Piv)4 (4) containing the new [2 + 2] macrocyclic ligand L3 as a result of condensation of L1 with L2. All newly synthesized compounds were characterized by X-ray diffraction and magnetic measurements.