Crystal structure of [{Cu(tren)} 2 (cytosinato)]·(ClO 4 ) 3 ·0.5H 2 O (tren=tris(2-aminoethyl)amine) and an overview on intra-molecular interligand interactions affecting metal binding sites of cytosine

Two sterically crowded, tren-capped Cu2+ ions bind to a cytosinato ligand, one through the deprotonated N(1) with the formation of an N–H(tren)⋯O(2) hydrogen bond and the other through the N(3)–Cu2+–O(2) chelation. An overview on metal bonding properties of N(1)-unsubstituted cytosine in so far reported crystal structures is given.