Single Electron Transfer to Diazomethane-Borane Adducts Prompts C-H Bond Activations.

Levy L Cao,Zheng‐Wang Qu,Jiliang Zhou,Douglas W Stephan

doi:10.1002/anie.201912338

Levy L Cao, Zheng‐Wang Qu + Show 2 more

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https://doi.org/10.1002/anie.201912338

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Abstract

While (Ph2CN2)B(C6F5)3 is unstable, single electron transfer from Cp*2Co affords the isolation of stable products [Cp*2Co][Ph2CNNHB(C6F5)3] 1 and [Cp*Co(C5Me4CH2B(C6F5)3)] 2. The analogous combination of Ph2CN2 and BPh3 showed no evidence of adduct formation and yet single electron transfer from Cp*2Cr affords the species [Cp*2Cr][PhC(C6H4)NNBPh3] 3 and [Cp*2Cr][Ph2CNNHBPh3] 4. Computations showed both reactions proceed via transient radical anions of the diphenyldiazomethane–borane adducts to effect C−H bond activations.

Highlights

While (Ph2CN2)B(C6F5)3 is unstable, single electron transfer from Cp*2Co affords the isolation of stable products [Cp*2Co][Ph2CNNHB(C6F5)3] 1 and [Cp*Co(C5Me4CH2B(C6F5)3)] 2
The activation of small molecules has been a major driver of organometallic chemistry over the last 60 years
One avenue of main group chemistry exploited for the activation of small molecules has been frustrated Lewis pair (FLP) chemistry.[1]

Summary

Introduction

While (Ph2CN2)B(C6F5)3 is unstable, single electron transfer from Cp*2Co affords the isolation of stable products [Cp*2Co][Ph2CNNHB(C6F5)3] 1 and [Cp*Co(C5Me4CH2B(C6F5)3)] 2. Over the past 50 years numerous advances have emerged from the luminaries of organometallic chemistry including Schrock,[5] Cummins,[6] Peters,[7] Fryzuk,[8] Evans,[9] Gambarotta,[10] Nishibiashi,[11] Holland,[12] Chatt,[13] and Liddle[14] among others.[15] Avenues to metal-mediated N2 chemistry have typically involved stoichiometric reductants.[8d] More recently, in 2017 the Szymczak[16] and Simonneau[17] groups demonstrated the utility of a Lewis acidic borane in promoting reactivity of

Results

Conclusion