A Masked Phosphinidene Trapped in a Fluxional NCN Pincer

Jakub Hyvl; Wesley Y Yoshida; Arnold L Rheingold; Russell P Hughes; Matthew F Cain

doi:10.1002/chem.201604415

A Masked Phosphinidene Trapped in a Fluxional NCN Pincer

Chemistry. 2016 Dec 5;22(49):17562-17565. doi: 10.1002/chem.201604415. Epub 2016 Oct 24.

Authors

Jakub Hyvl¹, Wesley Y Yoshida¹, Arnold L Rheingold², Russell P Hughes³, Matthew F Cain¹

Affiliations

¹ Department of Chemistry, University of Hawai'i at Mānoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
² Department of Chemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
³ Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, NH, 03755, USA.

PMID: 27654835
DOI: 10.1002/chem.201604415

Abstract

The trapping of a phosphinidene (R-P) in an NCN pincer is presented. Stabilized phosphinidene 1 was characterized by ³¹ P{¹ H}, ¹ H, and ¹³ C{¹ H} NMR spectroscopy, exhibiting an averaged C_2v symmetry in solution between -60 and 60 °C. In the solid state, the phosphinidene is coordinated by one adjacent N atom featuring a formal P-N bond (1.757(2) Å) to give a five-membered ring with some aromatic character, confirmed by DFT calculations (B3LYP-D3/6-311G**++) to be the ground-state structure. Equilibration of the two N ligands occurs rapidly in solution via a "bell-clapper"-type process through an associative symmetric transition state calculated to lie 4.0 kcal mol^-1 above the ground state.

Keywords: NCN ligands; VT NMR spectroscopy; azaphospholes; phosphinidenes; pincer ligands.