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Cobalt( II ), Nickel( II ), Copper( II ), and Zinc( II ) Complexes with a p ‐ tert ‐Butylcalix[4]arene Fitted with Phosphinoyl Pendant Arms
Author(s) -
Videva Vladimira,
Chauvin AnneSophie,
Varbanov Sabi,
Baux Christophe,
Scopelliti Rosario,
Mitewa Mariana,
Bünzli JeanClaude G.
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300858
Subject(s) - chemistry , ligand (biochemistry) , crystallography , electron paramagnetic resonance , square pyramidal molecular geometry , stereochemistry , nickel , triclinic crystal system , zinc , metal , crystal structure , cobalt , medicinal chemistry , inorganic chemistry , receptor , organic chemistry , nuclear magnetic resonance , biochemistry , physics
A series of complexes of M II X 2 transition metal salts (X = ClO 4 , 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‐tetra‐ tert ‐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 Cu II complexes, independently of the anion (Cl − or ClO 4 − ), as well as for the Zn(ClO 4 ) 2 complex, while a 2:1 metal/ligand ratio is found for the complex with ZnCl 2 . 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 $\bar 1$ , Z = 2) shows the presence of the tetrametallic species Zn 4 L 2 with three different tetrahedral Zn environments, ZnCl 2 O 2 , ZnCl 3 O, and ZnClO 3 , 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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)