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

Rex S.C. Charman; Nick J. Evans; Laura E. English; Samuel E. Neale; Petra Vasko; Mary F. Mahon; David J. Liptrot

doi:10.1039/D3SC05862J

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

Rex S.C. Charman, Nick J. Evans, Laura E. English, Samuel E. Neale, Petra Vasko, Mary F. Mahon, David J. Liptrot

Research output: Contribution to journal › Article › peer-review

8 Citations (SciVal)

Abstract

Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh₃ complexes. Of these, (IPr)CuGePh₃ (IPr = :C{N(2,6-iPr₂C₆H₃)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 [Ph₃Ge]⁻. The Cu-Ge bond of (IPr)CuGePh₃ underwent π-bond insertions with tBuNCS, CS₂, and PhNCO to furnish a series of germyl substituted carboxylate derivatives, (IPr)CuXC(Y)GePh₃ (X = S, NPh; Y = S, NtBu, O), which were structurally characterised. (IPr)CuGePh₃ inserted phenyl acetylene, providing both the Markovnikov and anti-Markovnikov products. The (NHC)CuGePh₃ 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 Ph₃GeH 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.

Original language	English
Pages (from-to)	584-593
Number of pages	10
Journal	Chemical Science
Volume	15
Issue number	2
Early online date	1 Dec 2023
DOIs	https://doi.org/10.1039/D3SC05862J https://doi.org/10.1039/d3sc05862j
Publication status	Published - 14 Jan 2024

Data Availability Statement

Full synthetic and characterisation data (NMR, MS, CHN, SCXRD) and full details of computational analysis available in ESI.† Crystallographic data for all compounds have been deposited with the Cambridge Crystallographic Data Centre as the following supplementary CCDC publications: 2221285–2221292 for compound 1 (2221285), compound 2 (2221286), compound 3 (2221288), compound 4 (2221287), compound 5 (2221289), compound 6 (2221290), compound 7 (2221291), compound 8 (2249130), compound 9 (2221292), compound 10 (2249131) and (SIMes)CuN(Ph)C(O)N(Ph)C(O)GePh3 (2249132).

Funding

DJL thanks the Royal Society for the support of a University Research Fellowship. LEE thanks the EPSRC for funding (EP/L016354/1) for a PhD studentship. PV would like to thank the Academy of Finland (grant numbers 346565 and 338271) and Jenny and Antti Wihuri Foundation for funding and the CSC – IT Center for Science, Finland, for computational resources.

Funders	Funder number
Engineering and Physical Sciences Research Council	EP/L016354/1
Royal Society
Commonwealth Scholarship Commission
Academy of Finland	346565, 338271
Jenny ja Antti Wihurin Rahasto

ASJC Scopus subject areas

General Chemistry

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10.1039/d3sc05862j

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Cite this

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title = "The structures and reactivity of NHC-supported copper(i) triphenylgermyls",

abstract = "Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh3 complexes. Of these, (IPr)CuGePh3 (IPr = :C{N(2,6-iPr2C6H3)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 [Ph3Ge]−. The Cu-Ge bond of (IPr)CuGePh3 underwent π-bond insertions with tBuNCS, CS2, and PhNCO to furnish a series of germyl substituted carboxylate derivatives, (IPr)CuXC(Y)GePh3 (X = S, NPh; Y = S, NtBu, O), which were structurally characterised. (IPr)CuGePh3 inserted phenyl acetylene, providing both the Markovnikov and anti-Markovnikov products. The (NHC)CuGePh3 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 Ph3GeH 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.",

author = "Charman, {Rex S.C.} and Evans, {Nick J.} and English, {Laura E.} and Neale, {Samuel E.} and Petra Vasko and Mahon, {Mary F.} and Liptrot, {David J.}",

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AU - Charman, Rex S.C.

AU - Evans, Nick J.

AU - English, Laura E.

AU - Neale, Samuel E.

AU - Vasko, Petra

AU - Mahon, Mary F.

AU - Liptrot, David J.

PY - 2024/1/14

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N2 - Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh3 complexes. Of these, (IPr)CuGePh3 (IPr = :C{N(2,6-iPr2C6H3)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 [Ph3Ge]−. The Cu-Ge bond of (IPr)CuGePh3 underwent π-bond insertions with tBuNCS, CS2, and PhNCO to furnish a series of germyl substituted carboxylate derivatives, (IPr)CuXC(Y)GePh3 (X = S, NPh; Y = S, NtBu, O), which were structurally characterised. (IPr)CuGePh3 inserted phenyl acetylene, providing both the Markovnikov and anti-Markovnikov products. The (NHC)CuGePh3 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 Ph3GeH 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.

AB - Deprotonation of triphenyl germane with NHC-supported copper alkoxides afforded four novel (NHC)CuGePh3 complexes. Of these, (IPr)CuGePh3 (IPr = :C{N(2,6-iPr2C6H3)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 [Ph3Ge]−. The Cu-Ge bond of (IPr)CuGePh3 underwent π-bond insertions with tBuNCS, CS2, and PhNCO to furnish a series of germyl substituted carboxylate derivatives, (IPr)CuXC(Y)GePh3 (X = S, NPh; Y = S, NtBu, O), which were structurally characterised. (IPr)CuGePh3 inserted phenyl acetylene, providing both the Markovnikov and anti-Markovnikov products. The (NHC)CuGePh3 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 Ph3GeH 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.

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U2 - 10.1039/D3SC05862J

DO - 10.1039/D3SC05862J

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VL - 15

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JO - Chemical Science

JF - Chemical Science

IS - 2

ER -

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

Abstract

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Funding

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