Jean-Claude Bunzli - Cobalt(II), Nickel(II), Copper(II), and Zinc(II) complexes with a p-tert-butylcalix[4]arene fitted with phosphinoyl pendant arms

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      Videva,V., Chauvin,A.S., Varbanov,S., Baux,C., Scopelliti,R.,   Mitewa,M., Bunzli,J.C.G. European Journal of Inorganic   Chemistry 2004 (10) 2173-2179

      Abstract: A series of complexes of (MX2)-X-II   transition metal salts (X = ClO4, M = Co, Ni, Cu, Zn; X = Cl, M =   Cu, Zn) with a calix[4]arene substituted at the lower rim {L =   5,11,17,23-tetratert-butyl-25,26,27,28-tetrakis[(dimethylphosphinoyl)-   methoxy]calix[4]arene} are isolated and characterized. Two   different stoichiometries are evidenced, 1:1 for the Co-II,   Ni-II, and Cull complexes, independently of the anion (Cl- or   ClO4-), as well as for the Zn(ClO4)(2) complex, while a 2:1   metal/ligand ratio is found for the complex with ZnCl2. The   coordination mode and structure of the complexes are investigated   by several spectroscopic and magnetochemical methods, both in the   solid state and in solution. Coordination through the phosphoryl   groups of the ligand is ascertained by X-ray diffraction and IR   and NMR spectroscopic data. The crystal structure of the 2:1 Zn   compound (triclinic, P (1) over bar, Z = 2) shows the presence of   the tetrametallic species Zn4L2 with three different tetrahedral   Zn environments, ZnCl2O2, ZnCl3O, and ZnClO3, the latter bridging   two ligand molecules. Magnetic susceptibility, EPR data, and   electronic spectra are indicative of a tetrahedral arrangement of   the ligands in the Co-II (high-spin d(7)) 1:1 complex, which is   also most probably the ligand geometry in the Ni-II and Cu-II 1:1   complexes. In solution, the extent of the interaction between L   and the M-II ions has been determined by UV/Vis   spectrophotometric titrations. The resulting stability constants   for 1:1 complexes are in the range log K-1 = 4.8-5.4. (C)   Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany,   2004

      Address (URL): J INORG CHEM