Copper(II)-Mediated Iodination of 1-Nitroso-2-naphthol

The 3-Iodo-1-nitrosonaphthalene-2-ol (I-NON) was obtained by the copper(II)-mediated iodination of 1-nitroso-2-naphthol (NON). The suitable reactants and optimized reaction conditions, providing 94% NMR yield of I-NON, included the usage of Cu(OAc)(2)center dot H2O and 1:2:8 Cu-II/NON/I-2 molar ratio between the reactants. The obtained I-NON was characterized by elemental analyses (C, H, N), high-resolution ESI+-MS, H-1 and C-13{H-1} NMR, FTIR, UV-vis spectroscopy, TGA, and X-ray crystallography (XRD). The copper(II) complexes bearing deprotonated I-NON were prepared as follows: cis-[Cu(I-NON-H)(I-NON)](I-3) (1) was obtained by the reaction between Cu(NON-H)(2) and I-2 in CHCl3/MeOH, while trans-[Cu(I-NON-H)(2)] (2) was synthesized from I-NON and Cu(OAc)(2) in MeOH. Crystals of trans-[Cu(I-NON-H)(2)(THF)(2)] (3) and trans-[Cu(I-NON-H)(2)(Py)(2)] (4) were precipitated from solutions of 2 in CHCl3/THF and Py/CHCl3/MeOH mixtures, respectively. The structures of 1 and 3-4 were additionally verified by X-ray crystallography. The characteristic feature of the structures of 1 and 3 is the presence of intermolecular halogen bonds with the involvement of the iodine center of the metal-bound deprotonated I-NON. The nature of the I center dot center dot center dot I and I center dot center dot center dot O contacts in the structures of 1 and 3, correspondingly, were studied theoretically at the DFT (PBE0-D3BJ) level using the QTAIM, ESP, ELF, NBO, and IGM methods.