Preparation, characterization, crystal structures and catalytic oxidation activities of two transition metal complexes of an N-heterocyclic pincer ligand

Abstract

The complexes [Co(bdpdt)(dipic)]Á3H 2 O (1) and [Ni(bdpdt)(dipic)]Á3H 2 O (2) (bdpdt: 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine, H 2 dipic: 2,6-pyridinedicarboxylic acid) were synthesized by the reactions of CoCl 2 or NiCl 2 with bdpdt and H 2 dipic in mixed water-ethanol solution at 120°C. The complexes were characterized by elemental analysis, IR spectroscopy, UV-Vis spectroscopy and single-crystal X-ray diffraction. Thermogravimetric analysis showed that both complexes are stable up to 300°C. Structural analysis reveals that the Co(II) and Ni(II) atoms both have distorted octahedral geometries. The catalytic performances of both complexes for the oxidation by H 2 O 2 were studied at room temperature. Graphical Abstract Two complexes containing pincer N-heterocyclic ligand and H 2 dipic were synthesized. All the complexes were characterized by elemental analysis, IR spectroscopy, UV-Vis spectroscopy and single-crystal X-ray diffraction. In addition, the catalytic performances of complexes 1 and 2 were also studied on the oxidation reaction of cyclohexane at room temperature.

s‐Triazine pincer ligands: Synthesis of their metal complexes, coordination behavior, and applications

“…When the HCl was used instead of HNO 3 mixture of ketone and alcohol were obtained and the catalyst activity dramatically decreased. [188] S Cu(II) leads to thixotropic gels were explored [161] (Scheme 107). The ability of the metal to bind with the pyrazolyl and triazinyl groups and the exogenous silver ions chelation provided a gelator with a unique property. )…”

“…When the HCl was used instead of HNO 3 mixture of ketone and alcohol were obtained and the catalyst activity dramatically decreased. [188] S C H E M E 8 3 Synthesis of Co(II) complexes 213 and 214 with 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenyl-s-triazin-2-amine pincer ligand 212…”

Development of catalyst complexes for upgrading biomass into ester-based biolubricants for automotive applications: a review

“…Biolubricants are generally obtained from biomass or naturally occurring sources like soybean, palm, sunflower, coconut, and rapeseed oils. 16 A biolubricant is an ester of glycerides, which is still limited for application as a lubricant as their freezing point is quite high, and they are easily oxidised. Biolubricants can be prepared using long-chain alcohols/polyols with fatty acids that fulfil the toxicity and biodegradability criteria (refer to Table 4 ).…”

“…13,14 Nevertheless, to the best of our knowledge, there is a lack of comprehensive study on the usage of homogeneous transition complex catalysts in biolubricant synthesis. 15,16 As derived from the literature, a homogeneous-type transition metal complex catalyst is a potential catalyst for ester production, mainly due to its simple preparation step, large surface area, good molecular dispersion between reactants, and sufficient pore volume. 17 In contrast, the heterogeneous-type metal complex catalyst is scarce in the catalytic synthesis of biolubricants when long-chain/polyhydric alcohols are employed in the reaction due to the occurrence of undesirable side products, low selectivity and soap formation in the process.…”