Pincer-Supported Perfluororhodacyclopentanes: High Nucleophilicity of the M-CF Bond

Perfluororhodacyclopentane supported by PBP pincer ligand PBP-Rh-III(CF2)(4) (2) was prepared from PBP-Rh-I-PPh3 (1) and tetrafluoroethylene (TFE). By scXRD analysis, it was revealed that the Rh-C-F bond trans to the boryl ligand was largely elongated compared to the one in the apical position. Although M-C-F bonds of perfluorometallacyclopentanes are known to be very stable, 2 shows high reactivity toward hydrogenolysis, iodinolysis and protonolysis, thanks to the strong trans-effect of the highly sigma-donating boryl ligand. Analogous PCP pincer complex PCP-Rh-III(CF2)(4) (4) showed slower reaction rate both in oxidative cyclization with TFE and hydrogenolysis of Rh-C-F bond. Catalytic production of 1,1,2,2,3,3,4,4-octafluorobutane from two TFE and hydrogen in one pot was achieved via repetitive oxidative cyclization of TFE and Rh followed by the hydrogenolysis of Rh-C-F bonds. This report demonstrates the possible application of PBP-pincer skeleton to the preparation of fluorinated compounds from TFE.

Automated summary

In this study, perfluororhodacyclopentane was successfully prepared using a PBP pincer ligand. The perfluororhodacyclopentane showed high reactivity towards hydrogenolysis, iodinolysis, and protonolysis due to the strong trans-effect of the boryl ligand. This study also demonstrated the potential application of the PBP pincer skeleton in the preparation of fluorinated compounds from TFE.