Issue 4, 2021

Dissecting transmetalation reactions at the molecular level: C–B versus F–B bond activation in phenyltrifluoroborate silver complexes

Abstract

The gas-phase unimolecular reactions of the silver(I) complex [Ag(PhBF3)2], formed via electrospray ionisation mass spectrometry of solutions containing the phenyltrifluoroborate salt and AgNO3, are examined. Upon collision induced dissociation (CID) three major reaction channels were observed for [Ag(PhBF3)2]: Ph group transfer via a transmetalation reaction to yield [PhAg(PhBF3)]; F transfer to produce [FAg(PhBF3)]; and release of PhBF3. The anionic silver product complexes of these reactions, [LAg(PhBF3)] (where L = Ph and F), were then mass-selected and subjected to a further stage of CID. [PhAg(PhBF3)] undergoes a Ph group transfer via transmetalation to yield [Ph2Ag] with loss of BF3. [FAg(PhBF3)] solely fragments via loss of BF4, a reaction that involves Ph group transfer from B to Ag in conjunction with F transfer from Ag to B. Density functional theory (DFT) calculations on the various competing pathways reveal that: (i) the overall endothermicities govern the experimentally observed product ion abundances; (ii) the Ph group and F transfer reactions proceed via late transition states; and (iii) formation of BF4 from [FAg(PhBF3)] is a multistep reaction in which Ph group transfer from B to Ag proceeds first to produce a [FAgPh(BF3)] complex in which the BF3 moiety is initially weakly bound to the ipso-carbon of the phenyl group and then migrates across the linear [FAgPh] moiety from C to Ag to F yielding [PhAg(BF4)], which can then dissociate via loss of PhAg.

Graphical abstract: Dissecting transmetalation reactions at the molecular level: C–B versus F–B bond activation in phenyltrifluoroborate silver complexes

Supplementary files

Article information

Article type
Paper
Submitted
23 Sep 2020
Accepted
05 Jan 2021
First published
13 Jan 2021

Dalton Trans., 2021,50, 1496-1506

Dissecting transmetalation reactions at the molecular level: C–B versus F–B bond activation in phenyltrifluoroborate silver complexes

F. Bathie, A. W. E. Stewart, A. J. Canty and R. A. J. O'Hair, Dalton Trans., 2021, 50, 1496 DOI: 10.1039/D0DT03309J

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