Issue 14, 2016

Synthetic and reactivity studies of hetero-tri-anionic sodium zincates

Abstract

The synthesis and characterisation of several sodium zincate complexes are reported. The all-alkyl monomeric sodium zincate, (PMEDTA)·Na(μ-CH2SiMe3)ZntBu22, is prepared by combining equimolar quantities of tBu2Zn, nBuNa and PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine)]. A similar approach was used to prepare and isolate the unusual dimeric zincate [(PMEDTA)·Na(μ-nBu)ZntBu2]23. When an equimolar mixture of nBuNa, tBu2Zn and TMP(H) (2,2,6,6-tetramethylpiperidine) is combined in hexane, the hetero-tri-leptic TMP(H)-solvated zincate (TMPH)Na(μ-TMP)(μ-nBu)ZntBu 4 results. Complex 4 can also be prepared using a rational approach [i.e., utilising two molar equivalents of TMP(H)]. When TMEDA is reacted with an equimolar mixture of nBuNa, tBu2Zn and TMP(H), the monomeric sodium zincate (TMEDA)Na(μ-TMP)(μ-nBu)ZntBu 5 was obtained – this complex is structurally similar to the synthetically useful relation (TMEDA)·Na(μ-TMP)(μ-tBu)Zn(tBu) 1. By changing the sodium reagent used in the synthesis of 5, it was possible to prepare (TMEDA)Na(μ-TMP)(μ-Me3SiCH2)ZntBu 6. By reacting 5 with cis-DMP(H) (cis-2,6-dimethylpiperidine), the zincate could thermodynamically function as an amide base, to give the transamination product (TMEDA)Na(μ-cis-DMP)(μ-nBu)ZntBu 7, although no crystals could be grown. However, when HMDS(H) (1,1,1,3,3,3-hexamethyldisilazane) or PEA(H) [(+)-bis[(R)-1-phenylethyl]amine] is reacted with 5, crystalline (TMEDA)Na(μ-HMDS)(μ-nBu)ZntBu 8 or (TMEDA)Na(μ-PEA)(μ-nBu)ZntBu 9 is isolated respectively. With PNA(H) (N-phenylnaphthalen-1-amine) the reaction took a different course and resulted in the formation of the dimeric sodium amide complex [(TMEDA)Na(PNA)]210. When reacted with benzene, it appears that a TMEDA-free variant of 5 functions thermodynamically as an nBu base to yield the previously reported (TMEDA)Na(μ-TMP)(tBu)Zn(μ-C6H4)Zn(tBu)(μ-TMP)Na(TMEDA) 11. Finally when reacted with TEMPO (2,2,6,6-tetramethylpiperidinyloxy), 5 undergoes a single electron transfer reaction to form (TMEDA)Na(μ-TMP)(μ-TEMPO)ZnnBu 12.

Graphical abstract: Synthetic and reactivity studies of hetero-tri-anionic sodium zincates

Supplementary files

Article information

Article type
Paper
Submitted
03 nov 2015
Accepted
27 nov 2015
First published
02 dec 2015

Dalton Trans., 2016,45, 6222-6233

Author version available

Synthetic and reactivity studies of hetero-tri-anionic sodium zincates

J. Francos, A. R. Kennedy and C. T. O'Hara, Dalton Trans., 2016, 45, 6222 DOI: 10.1039/C5DT04329H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements