Search

A family of ionic ferric catecholate complexes 1–4 bearing a disubstituted 3,6-di-tert-butyl-catecholate ligand (3,6-DBCatH2) and tetradentate tris(2-pyridylmethyl)amine (TPA) was prepared and its spin transitions were investigated. Variation of the outer-sphere counteranions (PF6, BPh4, ClO4, BF4) is accompanied by changes in the magnetic behavior of the compounds under consideration. The crystal structures of complexes 1, 3 and 4 were determined by single crystal X-ray diffraction analysis at 100 K and 293 K. The complexes were characterized by the occurrence of a thermally induced spin-crossover process in the solid state with different degrees of completeness, which was confirmed by the comprehensive spectroscopic investigation (EPR, magnetic susceptibility, Mössbauer, and XAS) of the isolated compounds. Complex 4 containing BF4 anions was found to demonstrate valence tautomeric transition along with spin-crossover. This finding makes compound 4 the first salt-like mononuclear ferric catecholate complex exhibiting valence tautomerism. [ABSTRACT FROM AUTHOR]

Synchrotron-based X-ray absorption spectroscopy and scattering are known in situ probes of metal nanoparticles (NPs). A limited number of laboratory techniques allow post-synthesis diagnostics of the active metal surface area. This work demonstrates the high potential of infrared spectroscopy as an in situ laboratory probe for the growth of metal NPs on a substrate. We introduce a small fraction of CO molecules into the reaction mixture as a probe to monitor the reduction kinetics of the Pd2+ precursor on ceria in hydrogen. [ABSTRACT FROM AUTHOR]