On thio‐substituted N‐heterocyclic arsines

Johannes Bender,Martin Nieger,Dietrich Gudat,Anna Dołęga,Agnieszka Skowrońska

doi:10.1002/zaac.202100006

Johannes Bender, Martin Nieger + Show 3 more

Open Access

https://doi.org/10.1002/zaac.202100006

Copy DOI

Abstract

Metathesis of N-heterocyclic chloroarsines with sulfur-based nucleophiles furnished thio-substituted 1,3,2-diazarsolidines and 1,3,2-diazarsolenes. Crystallographic and NMR spectroscopic studies revealed that a thiocyanato-diazarsolene exhibits a salt-like structure composed of weakly interacting thiocyanate and arsenium ions, while the remaining products formed neutral molecules. The structural data indicate that the heterocyclic framework induces an elongation of exocyclic As−S bonds that is more prominent in diazarsolenes than in diazarsolidines and parallels the bond polarisation effect established for N-heterocyclic phosphines. The NMR data suggest that diazarsolenes undergo facile inversion of the pyramidal configuration at arsenic, which was successfully modelled by DFT studies.

Highlights

Metathesis of N-heterocyclic chloroarsines with sulfur-based nucleophiles furnished thio-substituted 1,3,2-diazarsolidines and 1,3,2-diazarsolenes
The specific reactivity arising from this effect propelled unusual stoichiometric reactions, involving e. g. the activation of P C or P H bonds, but was decisive for the discovery of novel catalytic transformations that are currently emerging into interesting synthetic tools in organic synthesis.[2]
In the wake of these developments, homologous 1,3,2-diazarsolenes II[3] have moved into focus and were, like their phosphorus congeners, shown to be capable of mediating catalytic hydroboration.[2a,4] The catalytically active species – a benzannulated analogue of a secondary diazarsolene (II, X = H) – being unstable, chloro- or alkoxysubstituted derivatives were employed as pre-catalysts.[4]

Summary

Introduction

Metathesis of N-heterocyclic chloroarsines with sulfur-based nucleophiles furnished thio-substituted 1,3,2-diazarsolidines and 1,3,2-diazarsolenes. The structural data indicate that the heterocyclic framework induces an elongation of exocyclic As S bonds that is more prominent in diazarsolenes than in diazarsolidines and parallels the bond polarisation effect established for N-heterocyclic phosphines. Pounds whose superior resilience toward hydrolysis should grant easy handling and might make these species likewise potentially interesting pre-catalysts. In this context, it was of interest whether a similar hyperconjugation mechanism as in I[1]

Methods

Results

Conclusion