title: Interaction of d(10) metal ions with thioether ligands: a thermodynamic and theoretical study.
abstract: Thermodynamic parameters of complex formation between d(10) metal ions, such as Zn(2+), Cd(2+), Hg(2+) and Ag(+), and the macrocyclic thioether 1,4,7-trithiacyclononane ([9]AneS3) or the monodentate diethylsulfide (Et(2)S), in acetonitrile (AN) at 298.15 K, were studied by a systematic methodology including potentiometry, calorimetry and polarography. [9]AneS3 is able to form complexes with all the target cations, Et(2)S only reacts with Hg(2+) and Ag(+). Mononuclear ML(j) (j = 1, 2) complexes are formed with all the metal ions investigated, where the affinity order is Hg(2+) > Ag(+) > Cd(2+) ≈ Zn(2+) when L = [9]AneS3 and Hg(2+) > Ag(+) when L = Et(2)S. Enthalpy and entropy values are generally negative, as a consequence of both metal ion interactions with neutral ligands, the reagents' loss of degrees of freedom and the release of solvating molecules. DFT calculations on the complexes formed with [9]AneS3 in vacuum and in AN are also carried out, to correlate experimental and theoretical thermodynamic values and to highlight the interplay between the direct metal-thioether interaction and the solvation effects. Trends obtained for the stability constants and enthalpies of the 1 : 1 and 1 : 2 complexes in solvent well reproduce the experimental ones for all the divalent metal ion complexes with [9]AneS3 and indicate the release of 3 AN molecules in the formation of each consecutive octahedral complex. In addition, calculated and experimental values for Ag(+) complex formation in solution suggest that in AgL(2) species [9]AneS3 ligands are not both tridentate.
authors: Dipartimento di Chimica Fisica e Ambiente, Università di Udine, Via del Cotonificio 108, 33100 Udine, Italy. andrea.melchior@uniud.it
authors: Andrea
authors: A
authors: Melchior
authors: Elena
authors: E
authors: Peralta
authors: Manuel
authors: M
authors: Valiente
authors: Claudio
authors: C
authors: Tavagnacco
authors: Francesco
authors: F
authors: Endrizzi
authors: Marilena
authors: M
authors: Tolazzi
mesh_terms: D007477:Ions / Q000737:chemistry; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D013440:Sulfides / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D007477:Ions; D008024:Ligands; D008670:Metals; D013440:Sulfides