Metal–Thiobenzoato Complexes: Synthesis, Structure, and Processing as Carbon‐Supported Nanoparticles

Abstract

Six new compounds of formula [M(TBn) 2 L] [TBn: thiobenzoato; M: Pd II , Zn II , Cd II ; L: 2,2′-bipyridine (bpy), 1,10phenanthroline (phen), 1,2-di-(4-pyridil)-ethylene (bpe), neocuproine (neo), adenine (ade)] are obtained by the reaction of M(CH 3 COO) 2 ·2H 2 O with thiobenzoic acid and N-heterocyclic ligands. The use of chelating ligands and adenine leads to monomeric compounds: [Pd(TBn) 2 (bpy)] (PdBPY), [Pd(TBn) 2 (phen)] (PdPHEN), [Zn(TBn) 2 (neo)] (ZnNEO), [Cd(TBn) 2 (neo)] (CdNEO), and [Cd(TBn) 2 (ade)(CH 3 OH)] (CdADE). In these compounds, the metal is bonded to the sulfur atoms of two TBn anions, while the remaining coordination positions are completed by the donor atoms of the ancillary ligands. The bridging capability of the bpe ligand gives rise to the polymeric [Cd(TBn) 2 (μ-bpe)] n [a]This section first describes the crystal structures of the metalorganic precursors, as these data will support the discussion regarding the formation of carbonaceous composites of metal and metal-sulfide nanoparticles (M/C and MS/C, respectively). Prior to the dry thermolysis experiments, a subsection devoted to preliminary thermogravimetric analyses is presented, in which the decomposition mechanism and optimum treatment temperature ranges will be set. Thereafter, results on the dry thermolysis experiments are thoroughly discussed, detailing the microstructures and particle sizes obtained in each case, to end up with the influence of the thermal treatment parameters. Crystal Structure of PrecursorsAt first glance, the coordination sphere of these complexes (Figures 1 and 2) involves two sulfur-bonded thiobenzoate ligands, with the remaining coordination positions being occupied by two nitrogen donor atoms from a chelating N,N′-heterocyclic Eur.