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·H2O and 1:2:8 CuII/NON/I2 molar ratio between the reactants. The obtained I-NON was characterized by elemental analyses (C, H, N), high-resolution ESI+-MS, 1H and 13C{1H} 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)](I3) (1) was obtained by the reaction between Cu(NON-H)2 and I2 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···I and I···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.

The (Dioximate)NiII/I2 System: Ligand Oxidation and Binding Modes of Triiodide Species.

Reinvestigation of (o-benzoquinonedioximate)2Ni/I2 systems demonstrated that the reaction itself and also the crystallization conditions dramatically affect the identity of generated species. Crystallization (CHCl3, 20-25 °C) of the nickel(II) dioximate complex [Ni(bqoxH)2] (bqoxH2 = o-benzoquinonedioxime) with I2 in the 1:(1-10) molar ratios of the reactants led to several (o-benzoquinonedioximate)2Ni derivatives and/or iodine adducts [Ni(I)(bqoxH)(bqoxH2)]·3/2I2, [Ni(I3)(bqoxH)(bqoxH2)]·[Ni(bqoxH)2], and [Ni(I3)(bqox•-)(bqoxH2)]·I2; the latter one, featuring the anion-radical bqox•- ligand, is derived from the formal (-2H+/1e-)-oxidation of bqoxH2. In these three adducts, various types of noncovalent interactions were identified experimentally and their existence was supported theoretically. The [Ni(I3)(bqox•-)(bqoxH2)]·I2 adduct exhibits simultaneous semicoordination and coordination patterns of the triiodide ligand; this is the first recognition of the semicoordination of any polyiodide ligand to a metal center. The semicoordination noncovalent contact Ni···I3 (3.7011(10) Å) is substantially longer that the Ni-I3 coordination bond (2.8476(9) Å), and the difference in energies between these two types of linkages is 8-12 kcal/mol.