Synthesis and Characterization of Zwitterionic Metallates and Molecular Clusters

Abstract

This thesis reports the synthesis and characterization of novel zwitterionic metallates of Rh and Pd with the ligand EtNHC(S)PPh2=NPPh2C(S)NEt (HEtSNS). This ligand is an amphoteric zwitterion, which forms the H2EtSNS+ cation upon protonation and the EtSNS- dianion–cation upon deprotonation. Determination of absolute pKa in CH2Cl2 by a spectrophotometric titration and kinetic/thermodynamic studies of the oxidative addition of methyl iodide to the zwitterionic metallate complex [Rh(CO)EtSNS] and its derivatives obtained by protonation: [Rh(CO)EtSNS]·HA and [Rh(CO)EtSNS]·2HA, where A = PF6, OTf, NO3 by 1H NMR spectroscopy are discussed. The reaction of the zwitterionic ligand with [Ru3(CO)12] affords an unprecedented methideylamide –N(Et)CH(R)– μ3-bridging moiety. Finally, enchainment cooperativity effects in neutrally charged bimetallic Nickel (II) phenoxyiminato polymerization catalysts and enhanced selectivity for polar comonomer are reported.