Formation of a hydride containing amido-zincate using pinacolborane

Marina Uzelac, Kang Yuan, Gary S. Nichol, Michael J. Ingleson

Research output: Contribution to journalArticlepeer-review

3 Citations (SciVal)

Abstract

Amido-zincates containing hydrides are underexplored yet potentially useful complexes. Attempts to access this type of zincate through combining amido-organo zincates and pinacolborane (HBPin)viaZn-C/H-BPin exchange led instead to preferential formation of amide-BPin and/or [amide-BPin(Y)](Y = Ph, amide, H), when the amide is hexamethyldisilazide or 2,2,6,6-tetramethylpiperidide and the hydrocarbyl group was phenyl or ethyl. In contrast, the use of a dipyridylamide (dpa) based arylzinc complex led to Zn-C/H-BPin metathesis being the major outcome. Independent synthesis and full characterisation of two LnLi[(dpa)ZnPh2] (L = THF,n= 3; L = PMDETA,n= 1) complexes,1and3, respectively, enabled reactivity studies that demonstrated that these species display zincate type reactivity (by comparison to the lower reactivity of the neutral complex (Me-dpa)ZnPh2,4, Me-dpa = 2,2′-dipyridyl-N-methylamine). This included1performing the rapid deprotonation of 4-ethynyltoluene and also phenyl transfer to α,α,α-trifluoroacetophenone in contrast to neutral complex4. Complex1reacted with one equivalent of HBPin to give predominantly PhBPin (ca.90%) and a lithium amidophenylzincate containing a hydride unit, complex7-A, as the major zinc containing product. Complex7-Atransfers hydride to an electrophile preferentially over phenyl, indicating it reacts as a hydridozincate. Attempts to react1with >1 equivalent of HBPin or with catecholborane led to more complex outcomes, which included significant borane and dpaZn substituent scrambling, two examples of which were crystallographically characterised. While this work provides proof of principle for Zn-C/H-BPin exchange as a route to form an amido-zincate containing a hydride, amido-organozincates that undergo more selective Zn-C/H-BPin exchange still are required.

Original languageEnglish
Pages (from-to)14018-14026
Number of pages9
JournalDalton Transactions
Volume50
Issue number39
DOIs
Publication statusPublished - 21 Oct 2021

Bibliographical note

Funding Information:
This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 769599). Crystallographic data for8measured remotely 26 at beam line I-19 of Diamond Light Source (award CY22240). We thank Mr Juraj Bella for help with multi-dimensional NMR experiments. We thank Dr Faye Cruickshank at the Mass Spectrometry facility at the University of Edinburgh for carrying out air-sensitive HRMS analysis.

ASJC Scopus subject areas

  • Inorganic Chemistry

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