Structurally different nickel(II) hexaaza macrocyclic complexes with the same btc~(2-) anions (btc~(2-) = 1,2,4,5-benzenetetracarboxylic acid dianion)

摘要

Two novel complexes with the composition {[Ni(L)](centre dot)(btc~(2-))_n (1) {L = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane; btc~(2-) = 1,2,4,5-benzenetetracarboxylic acid dianion} and [Ni(L)] (centre dot) (btc~(2-)) (centre dot) (btc) (2) were obtained from the reaction between [Ni(L)Cl_2] and btc (btc = ,4,5-benzenetetracarboxylic acid ), and their structures were determined by analytical, spectroscopic, and x-ray diffraction methods. The orange complex 1 contains a 1 hydrogen bonded polymeric chain with nickel(II) macrocycles and bridging btc~(2-) ligands. The nickel(II) coordination geometry in 1 is best described as square-plane with four Ni-N bonds. The weak interactions between the nickel(II) ions and the oxygen atoms of the btc~(2-) ligands are also found. The yellow complex 2 has a monomeric structure which is composed of a nickel(II) marocycle, a counter anion btc~(2-), and a free acid btc (btc = 1,2,4,5-benzenetetracarboxylic acid). The nickel(II) coordination geometry in 2 is square-planar, where the tetra-valent nickel(II) ion is completed with four nitrogen atoms from the macrocycle. In addition to the presence of counter anion btc~(2-), the free acid btc is also found in 2, which participates in abundant hydrogen-bond interactions.