Synthesis of Unsymmetrical Bis(phosphine) Oxides and Their Phosphines via Secondary Phosphine Oxide Precursors

Authors

James R. Pedroarena, University of Oregon
Bryan P. Nell, University of Minnesota - MorrisFollow
Lev N. Zakharov, University of Oregon
David R. Tyler, University of Oregon

Document Type

Article

Publication Date

8-21-2019

Embargo Period

8-21-2020

Publication Title

Journal of Inorganic and Organometallic Polymers and Materials

Abstract

The unsymmetrical bidentate phosphine ligands (Me)₂PCH₂CH₂CH₂P(Et)₂ (14), (Me)₂PCH₂CH₂CH₂P(iPr)₂ (15), (Me)₂PCH₂CH₂CH₂P(Cy)₂ (16), and (Me)₂PCH₂CH₂CH₂P(Ph)₂ (17) were synthesized using air–stable phosphine oxide intermediates. In the first step, sodium phosphinites formed by deprotonation of (Me)₂P(O)H, (Et)₂P(O)H, and (iPr)₂P(O)H were alkylated by 1-bromo-3-chloropropane. The different substitution rates of the chloride and bromide groups allowed the isolation of the intermediates (Me)₂P(O)CH₂CH₂CH₂Cl (2), (Et)₂P(O)CH₂CH₂CH₂Cl (3), and (iPr)₂P(O)CH₂CH₂CH₂Cl (4). Subsequent reaction of (Me)₂P(O)CH₂CH₂CH₂Cl (2) with the sodium phosphinites generated from (Et)₂P(O)H, (iPr)₂P(O)H, (tBu)₂P(O)H, (Cy)₂P(O)H, or (Ph)₂P(O)H gave unsymmetrical bidentate phosphine oxides; reduction of these oxides yielded the unsymmetrical phosphines. The unsymmetrical bidentate phosphines react with metal salts to form complexes. X-ray crystal structures of cis-Pt((Me)₂P(CH₂CH₂CH₂)P(iPr)₂)Cl₂ (20) and racemic [CuI((Me)₂P(CH₂CH₂CH₂)P(Ph)₂)]Cl (21) were obtained. The kinetics and scope of the synthetic route were also explored. Experiments showed that the rate of substitution of the alkyl chloride group in (R)₂P(O)CH₂CH₂CH₂Cl-type oxides increases relative to unsubstituted alkyl chlorides due to the presence of the phosphonyl group on one end of the molecule. The scope of the reaction involving 1,2-dihaloalkanes was also investigated, and it was found that the reaction mixture of sodium dimethylphosphinite and 1,2-dihaloalkanes formed tetramethylbis(phosphine) monoxide (22), which decomposes on work-up to give complex reaction mixtures.

First Page

1

Last Page

10

DOI

https://doi.org/10.1007/s10904-019-01288-9

ISSN

1574-1451

Comments

This is a post-peer-review, pre-copyedit version of an article published in Journal of Inorganic and Organometallic Polymers and Materials. The final authenticated version is available online at: https://doi.org/10.1007/s10904-019-01288-9

Rights

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Recommended Citation

Pedroarena, J.R.; Nell, B. P.; Zakharov, L. N.; Tyler, D. R. J. Synthesis of Unsymmetrical Bis(phosphine) Oxides and Their Phosphines via Secondary Phosphine Oxide Precursors. Inorg. Organomet. Polym. (2019)

Primo Type

Article