The enamine (HEAID) obtained from aniline and 2-acetyl-1,3-indandione (2AID) behaves as a bidentate ligand in coordination with copper (II) ion. Two types of crystals, apparently different in shape, were isolated and studied by single-crystal X-ray diffraction. The X-ray data for the brown rhombic crystals of compound 1 shows a mononuclear complex of Cu(II) coordinated with two EAID-anions, Cu(EAID)2. The X-ray data for the green crystals of compound 2 shows a dinuclear Cu(II) complex with two OH− groups acting as bridging ligands, [Cu2(μ-OH)2(EAID)2]. In both cases the ligand coordinates after deprotonation of the amine group.
 V. Enchev, G. Ivanova, G. Pavlovié, M. Rogojerov, A. Ahmedova and M. Mitewa: “Reaction of 2-acetyl-indane-1,3-dione with aniline-Schiff base or enamine?”, Journal of Molecular Structure, Vol. 654, (2003), pp. 11–20. http://dx.doi.org/10.1016/S0022-2860(03)00175-3
 A. Brbot-Ŝaranović, G. Pavlović, V. Vrdoljak and M. Cindrić: “Synthesis and strucutre of two isomeric enaminoes”, Croatica Chemica Acta, Vol. 74, (2001), pp. 441–454.
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