C−F Bond Cleavage and Unexpected C−CN Activation by Cobalt Compounds Supported with Phosphine Ligands

Abstract

A cyclometalation reaction inVolVing C-F bond actiVation at a cobalt(I) center with an aldazine-N atom as an anchoring group, for the first time, affords an ortho-chelated cobalt(III) complex, 1, containing a [C-Co-F] fragment. Under otherwise similar conditions, the first example of an organo cobalt(II) cyanide, 2, formed through Ar-CN bond actiVation could be obtained using the reaction of 2,6difluorobenzonitrile with a cobalt(0) complex without C-F bond actiVation. Both 1 and 2 were characterized through X-ray diffraction.

Effect of anchoring group and valent of cobalt center on the competitive cleavage of C–F or C–H bond activation

“…(3)) through CeF bond activation. To the best of our knowledge, after the report of the preparation of the first example of organo cobalt(III) complex containing a [CeCoeF] fragment [24], complex 3 is the second example of organo cobalt(III) complex with a [CeCoeF] fragment.…”

“…Both CeF and CeH bond activations are favored by an increase of the degree of fluorination of the substrates [23]. We obtained the first organo cobalt(III) complex containing a [CeCoeF] fragment through a cyclometalation reaction involving CeF bond activation at a cobalt(I) center with an aldazine-N atom as an anchoring group [24]. In this paper we present competitive cleavage of CeF versus CeH bond in the cyclometalation reaction at electron-rich cobalt center with ketone and imine as anchoring group.…”

Imine-assisted C–F bond activation using low-valent cobalt compounds supported by trimethylphosphine ligands and formation of novel organic fluorides

“…5 We reported a cyclometalation reaction involving carbon-fluorine bond activation at a cobalt(I) center with an azine donor as anchoring group which, for the first time, afforded an ortho-chelated cobalt(III) complex containing a [C-Co-F] fragment (eqn (1)). 6 (1) Herein we report on progress in the research of cyclometalation reactions involving C-F bond activation at electron-rich low valent cobalt centers with imine as pre-chelate ligands. The novel cobalt complexes 5-8 containing the [C-Co-F] fragment formed by oxidative addition of an aromatic C-F bond to cobalt(I) centers were isolated and characterized.…”

Cyanidophenyltris(trimethylphosphine)cobalt(II)

“…The distortion from ideal geometry of the angles around Co1 is most likely due to the steric effects of the bulky P(Me) 3 groups. The Co1-C2 bond is relatively short, while the Co-C1 bond is relatively long compared to related distances in a complex reported by Li et al (2006).…”