Experimental and Theoretical Investigation of an SN2-type Pathway for Borate-Fluorine Bond Cleavage by Electron-Rich Late-Transition Metal Complexes

Hajime Kameo; Yuki Baba; Shigeyoshi Sakaki; Yudai Tanaka; Hiroyuki Matsuzaka

doi:10.1021/acs.inorgchem.9b03053

Experimental and Theoretical Investigation of an S_N2-type Pathway for Borate-Fluorine Bond Cleavage by Electron-Rich Late-Transition Metal Complexes

Inorg Chem. 2020 Apr 6;59(7):4282-4291. doi: 10.1021/acs.inorgchem.9b03053. Epub 2020 Feb 12.

Authors

Hajime Kameo¹, Yuki Baba¹, Shigeyoshi Sakaki², Yudai Tanaka¹, Hiroyuki Matsuzaka¹

Affiliations

¹ Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka 599-8531, Japan.
² Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-nishihiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, Japan.

PMID: 32049496
DOI: 10.1021/acs.inorgchem.9b03053

Abstract

B-F σ-bond activation of a fluoroborate has been experimentally achieved through reactions with electron-rich iridium(I) and palladium(0) complexes. The selectivity of B-F σ-bond cleavage by iridium complexes was improved through the high nucleophilicity of the iridium center, implying that a different pathway from that of well-accepted F^- abstraction was in effect. The palladium(0) complex was found to promote exclusive B-F σ-bond cleavage even at ambient temperature. Density functional theory (DFT) calculations suggested that B-F σ-bond activation occurred through an S_N2-type pathway, which is, to our knowledge, the first proposal of S_N2-type borate-fluorine σ-bond cleavage mediated by a transition metal complex. The high feasibility of the S_N2-type pathway appears to be attributed to the relatively low deformation energy of the transition state. It was also found that countercation Cs⁺ effectively stabilized the transition state and product by serving as a F^- acceptor.