Crystal structure of [{Cu(tren))(2)(cytosinato)]center dot(ClO4)(3)center dot 0.5H(2)O (tren = tris(2-aminoethyl)amine) and an overview on intra-molecular interligand interactions affecting metal binding sites of cytosine

摘要

Treatment of cytosine with tris(2-aminoethyl)amine (tren) and Cu(ClO4)(2)center dot 6H(2)O under alkaline conditions gave a ternary tren-Cu2+-cytosine complex, [{Cu(tren)}(2)(cytosinato)]center dot(ClO4)(3)center dot 0.5H(2)O, whose crystal structure was determined by X-ray diffraction. In the structure of the RCu(tren)}(2)(cytosinato)](3+) cation, two tren-capped square-pyramidal Cu2+ ions bind to a cytosinate anion, one through the deprotonated N (1) of cytosine with the formation of an intra-molecular interligand hydrogen bond between the keto substituent O(2) of the base and the amino group of tren and the other through both the ring nitrogen N(3) and the exocyclic O(2) of the base, forming a four-membered chelate-ring. An overview on metal bonding properties of N(1)-unsubstituted cytosine observed in so far reported crystal structures is given, emphasizing the significance of intra-molecular interligand interaction as a factor that affects metal binding sites of cytosine. (C) 2016 Elsevier B.V. All rights reserved.