Sandwich structured aryl-diimine Pd (II)/Co (II) monolayer—Fabrication, catalytic performance, synergistic effect and mechanism investigation

Catalytic Properties of Two Complexes of chromium(III) and cobalt(II) with Nitrilotriacetate, Dipicolinate, and 4-Acetylpyridine

In this paper, a synthesis of two innovative coordination compounds, based on chromium(III) and cobalt(II) ions with N,O-donor ligands (nitrilotriacetate, dipicolinate) and 4-acetylpyridine, is reported. The obtained metal-organic compounds were structurally characterized using the single-crystal X-ray diffraction (XRD) method. The well-defined chromium(III) and cobalt(II) complexes were used as precatalysts in the oligomerization reaction of 2-chloro-2-propen-1-ol and 2-propen-1-ol with methylaluminoxane (MMAO) as an activator. The products of the oligomerization reaction were subjected to full physicochemical characteristics, i.e., time-of-flight mass spectrometry (MALDI-TOF-MS), TGA, and differential scanning calorimetry (DSC) methods. The catalytic activity of the precatalysts in both reactions was calculated and compared with other catalysts known in the literature.

Pd-Pd/PdO as active sites on intercalated graphene oxide modified by diaminobenzene: fabrication, catalysis properties, synergistic effects, and catalytic mechanism

Pd–Pd/PdO nanoclusters well dispersed on intercalated graphene oxide (GO) (denoted as GO@PPD–Pd) were prepared and characterized. GO@PPD–Pd exhibited high catalytic activity (a TOF value of 60 705 h⁻¹) during the Suzuki coupling reaction, and it could be reused at least 6 times. The real active centre was Pd(200)–Pd(200)/PdO(110, 102). A change in the Pd facets on the surface of PdO was a key factor leading to deactivation, and the aggregation and loss of active centres was also another important reason. The catalytic mechanism involved heterogeneous catalysis, showing that the catalytic processes occurred at the interface, including substrate adsorption, intermediate formation, and product desorption. The real active centres showed enhanced negative charge due to the transfer of electrons from the carrier and ligands, which could effectively promote the oxidative addition reaction, and Pd(200) and the heteroconjugated Pd/PdO interface generated in situ also participated in the coupling process, synergistically boosting activity. Developed GO@PPD–Pd was a viable heterogeneous catalyst that may have practical applications owing to its easy synthesis and stability, and this synergistic approach can be utilized to develop other transition-metal catalysts.

Pd(200) and the Pd(200)/PdO(102, 110) interface generated in situ participated in coupling reactions via a synergistic effect, boosting the catalytic activity to a high level.

Dipicolinate Complexes of Oxovanadium(IV) and Dioxovanadium(V) with 2-Phenylpyridine and 4,4′-Dimethoxy-2,2′-bipyridyl as New Precatalysts for Olefin Oligomerization

Polyolefins are used in everyday life, including in the production of many types of plastic. In addition, polyolefins account for over 50% of the polymers produced in the world. After conducting the oligomerization reactions of 2-propen-1-ol, 2-chloro-2-propen-1-ol, and norborene, polyolefins are obtained. In this report, two complexes of oxovanadium(IV) and dioxovanadium(V) with dipicolinate, 2-phenylyridine, and 4,4′-dimethoxy-2,2′-bipyridyl as precatalysts for 2-propen-1-ol, 2-chloro-2-propen-1-ol, and norborene oligomerizations are prepared. We present for the first time the new dipicolinate complex compound of oxovanadium(IV) with 4,4′-dimetoxy-2,2′-bipyridyl. Both complexes were tested for catalytic activity in the oligomerization reactions of 2-propen-1-ol, 2-chloro-2-propen-1-ol, and norbornene. Both synthesized complexes showed high catalytic activity in these oligomerization reactions, except for the oligomerization of norbornene.