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

James R. Pedroarena, Bryan P. Nell, Lev N. Zakharov, David R. Tyler

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2 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)196-205
Number of pages10
JournalJournal of Inorganic and Organometallic Polymers and Materials
Issue number1
StatePublished - Jan 1 2020
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgment is made to the NSF (CHE-1503550) for the support of this research. The project described was supported, in part, by the Oregon State University Research Office. The content is solely the responsibility of the authors and does not necessarily represent the official views of the OSU Mass Spectrometry Center. The authors acknowledge the OSU Mass Spectrometry Center at Oregon State University and specific institutional instrument grants. Orbitrap Fusion Lumos—NIH #1S10OD020111-01, Waters Ion Mobility ToF Mass Spectrometer—NIH #1S10RR025628-01, Applied Biosystems 4000Qtrap—NIH #1S10RR022589-01, ABSciex Triple ToF 5600—NIH #1S10RR027878-01. Dillon Bryant, Daniel Berg, and Alexi Overland are acknowledged for their contributions to this project.


  • Heteroleptic phosphines
  • Phosphine ligands
  • Phosphinite anions
  • Unsymmetrical phosphine oxides
  • Unsymmetrical phosphines

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