The structures and reactivity of NHC-supported copper() triphenylgermyls

Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh 3 complexes. Of these, (IPr)CuGePh 3 (IPr = :C{N(2,6-iPr 2 C 6 H 3 )CH} 2 ) was selected for further investigation. Analysis by EDA-NOCV indicates it to be a germyl nucleophile and its σ-bond metat...

Full description

Saved in:
Bibliographic Details
Published in:Chemical science (Cambridge) 2024-01, Vol.15 (2), p.584-593
Main Authors: Charman, Rex S. C, Evans, Nick J, English, Laura E, Neale, Samuel E, Vasko, Petra, Mahon, Mary F, Liptrot, David J
Format: Article
Language:English
Subjects:
Acetylene
Alkoxides
Chemistry
Copper
Cross coupling
Germanium
Halides
Metathesis
Nucleophiles
Substrates
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh 3 complexes. Of these, (IPr)CuGePh 3 (IPr = :C{N(2,6-iPr 2 C 6 H 3 )CH} 2 ) was selected for further investigation. Analysis by EDA-NOCV indicates it to be a germyl nucleophile and its σ-bond metathesis reaction with a range of p-block halides confirmed it to be a convenient source of [Ph 3 Ge] − . The Cu-Ge bond of (IPr)CuGePh 3 underwent π-bond insertions with t BuNCS, CS 2 , and PhNCO to furnish a series of germyl substituted carboxylate derivatives, (IPr)CuXC(Y)GePh 3 (X = S, NPh; Y = S, N t Bu, O), which were structurally characterised. (IPr)CuGePh 3 inserted phenyl acetylene, providing both the Markovnikov and anti-Markovnikov products. The (NHC)CuGePh 3 compounds were validated as catalytic intermediates; addition of 10 mol% of NHC-copper( i ) alkoxide to a mixture of triphenyl germane and a tin( iv ) alkoxide resulted in a tin/germanium cross coupling with concomitant formation of alcohol. Moreover, a catalytic hydrogermylation of Michael acceptors was developed with Ph 3 GeH adding to 7 activated alkenes in good conversions and yields in the presence of 10 mol% of NHC-copper( i ) alkoxide. In all cases, this reaction provided the β-germylated substrate implicating nucleophilicity at germanium. Four N-heterocyclic carbene (NHC) supported copper( i ) germyls have been synthesised containing both normal- and ring-expanded NHCs. Their π-insertion and σ-bond metathesis chemistry has been explored in stoichiometric and catalytic regimes.
ISSN:2041-6520
2041-6539
DOI:10.1039/d3sc05862j