Carbon–chalcogen bond formation initiated by [Al(NONDipp)(E)]– anions containing Al–E{16} (E{16} = S, Se) multiple bonds

Matthew Evans, Mathew Anker, Claire McMullin, Sam Neale, Nasir Rajabi, Martyn Coles

Research output: Contribution to journalArticlepeer-review

Abstract

Multiply-bonded main group metal compounds are of interest as a new class of reactive species able to activate and functionalize a wide range of substrates. The aluminium sulfido compound K[Al(NON Dipp)(S)] (NON Dipp = [O(SiMe 2NDipp) 2] 2−, Dipp = 2,6- iPr 2C 6H 3), completing the series of [Al(NON Dipp)(E)] anions containing Al-E{16} multiple bonds (E{16} = O, S, Se, Te), was accessed via desulfurisation of K[Al(NON Dipp)(S 4)] using triphenylphosphane. The crystal structure showed a tetrameric aggregate joined by multiple K⋯S and K⋯π(arene) interactions that were disrupted by the addition of 2.2.2-cryptand to form the separated ion pair, [K(2.2.2-crypt)][Al(NON Dipp)(S)]. Analysis of the anion using density functional theory (DFT) confirmed multiple-bond character in the Al-S group. The reaction of the sulfido and selenido anions K[Al(NON Dipp)(E)] (E = S, Se) with CO 2 afforded K[Al(NON Dipp)(κ 2E,O-EC{O}O)] containing the thio- and seleno-carbonate groups respectively, consistent with a [2 + 2]-cycloaddition reaction and C-E bond formation. An analogous cycloaddition reaction took place with benzophenone affording compounds containing the diphenylsulfido- and diphenylselenido-methanolate ligands, [κ 2E,O-EC{O}Ph 2] 2−. In contrast, when K[Al(NON Dipp)(E)] (E = S, Se) was reacted with benzaldehyde, two equivalents of substrate were incorporated into the product accompanied by formation of a second C-E bond and complete cleavage of the Al-E{16} bonds. The products contained the hitherto unknown κ 2O,O-thio- and κ 2O,O-seleno-bis(phenylmethanolate) ligands, which were exclusively isolated as the cis-stereoisomers. The mechanisms of these cycloaddition reactions were investigated using DFT methods.

Original languageEnglish
Pages (from-to)4635-4646
JournalChemical Science
Volume13
Issue number16
Early online date31 Mar 2022
DOIs
Publication statusPublished - 31 Mar 2022

ASJC Scopus subject areas

  • Chemistry(all)

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