Chemical recycling of polyethylene terephthalate, known as PET, has been the subject of increased interest as a valuable feedstock for different chemical processes. In this work, glycolysis of PET waste granules was carried out using excess ethylene glycol in the presence of different simple chemicals acting as catalysts, which are, namely, categorized in ionic liquids, metal salts, hydrotalcites, and enzymes. From every category, some materials as a sample were used, and the one which is going to bring the best result is noted. The effect of some parameters such as temperature, pressure, amount of sample, material ratio, and stirring rate was investigated. As a result we compared the best of each category with the others and final result is shown.

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The Ru complex [Ru (bda-κ-N O )(N-NH ) ] (1; bda =2,2'-bipyridine-6,6'-dicarboxylate, N-NH =4-(pyridin-4-yl)aniline) was used as a synthetic intermediate to prepare new Ru and Ru bda complexes that contain NO , MeCN, or H O ligands. In acidic solution complex 1 reacts with an excess of NO (generated in situ from sodium nitrite) to form a new Ru complex in which the aryl amine ligand N-NH is transformed into a diazonium salt [N-N =4-(pyridin-4-yl)benzenediazonium)] together with the formation of a new Ru(NO) moiety in the equatorial zone, to generate [Ru (bda-κ-N O)(NO)(N-N ) ] (2 ). Here the bda ligand binds in a κ-N O tridentate manner with a dangling carboxylate group. Similarly, complex 1 can also react with a coordinating solvent, such as MeCN, at room temperature to give [Ru (bda-κ-N O)(MeCN)(N-NH ) ] (3). In acidic aqueous solutions, a related reaction occurs in which solvent water coordinates to the Ru center to form {[Ru {bda-κ-(NO) }(H O)(N-NH ) ](H O) } (4 ) and is strongly hydrogen-bonded with additional water molecules in the second coordination sphere. Furthermore, under acidic conditions the aniline ligands are also protonated to form the corresponding anilinium cationic ligands N-NH . Additionally, the one-electron oxidized complex {[Ru {bda-κ-(NO) }(H O)(N-NH ) ](H O) } (5 ) was characterized, in which the fractional value in the κ notation indicates the presence of an additional contact to the pseudo-octahedral geometry of the Ru center. The coordination modes of the complexes were studied in the solid state and in solution through single-crystal XRD, X-ray absorption spectroscopy, variable-temperature NMR spectroscopy, and DFT calculations. While κ-N O is the main coordination mode for 2 and 3, an equilibrium that involves isomers with κ-N O and κ-NO coordination modes and neighboring hydrogen-bonded water molecules is observed for 4 and 5 .