The ‘Hidden’ Reductive [2 + 2 + 1]-Cycloaddition Chemistry of 2- Phosphaethynolate Revealed by Reduction of a Th-OCP Linkage

Jingzhen Du, Gábor Balázs, Ashley Wooles, Manfred Scheer, Stephen Liddle

Research output: Contribution to journalArticlepeer-review

Abstract

The reduction chemistry of the newly emerging 2-phosphaethynolate (OCP) − is not well explored, and there remains many unanswered questions about this ligand in this context. Here, we report that reduction of [Th(TrenTIPS)(OCP)] (2, TrenTIPS =[N(CH2CH2NSiPri 3)]3−) with RbC8 produces via [2 + 2 + 1] cycloaddition an unprecedented hexathorium complex [{Th(TrenTIPS)}6(µOC2P3)2(µ-OC2P3H)2Rb4] (5) featuring four five-membered [C2P3] phosphorus-heterocycles, which can be converted to a rare oxo [{Th(TrenTIPS)(μ-ORb)}2] (6) and the known cyclometallated complex [Th{N(CH2CH2NSiPri 3)2(CH2CH2SiPri 2CHMeCH2)}] (4) by thermolysis, providing an unprecedented example of reductive cycloaddition reactivity in the chemistry of 2-phosphaethynolate. This has permitted us to isolate intermediates which might normally remain unseen leading to the erroneous assumption of a concerted fragmentation process for (OCP)- and not cycloaddition products that then decompose with [Th(TrenTIPS)O]− essentially acting as a protecting- then leaving-group. In contrast, when KC8 or CsC8 are used, the phosphinidiide C-H bond activation product [{Th(TrenTIPS)}Th{N(CH2CH2NSiPri 3)2[CH2CH2SiPri 2CH(Me)CH2C(O)µ-P]}] (3) and the oxo complex [{Th(TrenTIPS)(μ-OCs)}2] (7) were isolated.
Original languageEnglish
JournalAngewandte Chemie International Edition
Publication statusAccepted/In press - 12 Oct 2020

Fingerprint

Dive into the research topics of 'The ‘Hidden’ Reductive [2 + 2 + 1]-Cycloaddition Chemistry of 2- Phosphaethynolate Revealed by Reduction of a Th-OCP Linkage'. Together they form a unique fingerprint.

Cite this