Zhang, Xin published the artcileN-Bridged Pincer Iridium Complexes for Highly Efficient Alkane Dehydrogenation and the Relevant Linker Effects, Quality Control of 14703-69-6, the publication is ACS Catalysis (2020), 10(11), 6475-6487, database is CAplus.
Ir complexes (RPOCR’NP)-HCl (4-HCl) and (RPSCR’NP)Ir-HCl (5-HCl) (R = substituent on P; R’ = substituent on N) supported by N-linked pincer ligands, with the other linker of being O- or S-atom, were synthesized. Among them, complexes with phosphino-iPr substituents (iPrPOCR’NP)Ir (4b, 4e, 4g) exhibit very high catalytic activity for transfer dehydrogenation (TD) of both cyclic and linear alkanes. In the prototypical TD reaction of cyclooctane (COA) with tert-butylethylene (TBE), for example, 4g affords 14720 turnovers at 200°, which are >2-fold of that obtained by the most efficient catalyst reported so far. Also, these complexes are highly effective for acceptorless dehydrogenation of 1,2,3,4-tetrahydronaphthalene, giving a turnover frequency of 8.8 min-1 for H2 production within the 1st 4 h. The effects of the linkers at the positions ortho to the Ir center were elucidated by a systematic comparison of electronic and steric properties of these O/N- and S/N-linked pincer systems to those of C/C-linked iPrPCP, O/O-linked iPrPOCOP, and S/O-linked iPrPSCOP systems. Examination of the structure-activity relations reveals that alkane C-H bond addition to the 14e (pincer)Ir fragment (the rate-determining step in the TD reaction) is more favored by iPrPOCR’NP relative to other pincers, largely due to strong N-linker C(aryl) -donation. Compared to the parent iPrPOCOP complex with similarly -donating O-linkers, the energy of the alkene-bound out-of-cycle resting state is raised by iPrPOCR’NP primarily due to steric factors. Consequently, the incorporation of N-linker exerts an overall favorable effect on the catalytic rates. The authors found the thermal stability of these catalysts with different linker-combinations differs significantly.
ACS Catalysis published new progress about 14703-69-6. 14703-69-6 belongs to alcohols-buliding-blocks, auxiliary class Amine,Benzene,Phenol, name is 3-(Methylamino)phenol, and the molecular formula is C11H23NO3, Quality Control of 14703-69-6.
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