title: A Masked Phosphinidene Trapped in a Fluxional NCN Pincer.
abstract: The trapping of a phosphinidene (R-P) in an NCN pincer is presented. Stabilized phosphinidene 1 was characterized by31P{1H},1H, and13C{1H} NMR spectroscopy, exhibiting an averaged C2vsymmetry 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-1above the ground state.
authors.affiliation: Department of Chemistry, University of Hawai'i at Mānoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
authors.forename: Jakub
authors.initials: J
authors.lastname: Hyvl
authors.affiliation: Department of Chemistry, University of Hawai'i at Mānoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
authors.forename: Wesley Y
authors.initials: WY
authors.lastname: Yoshida
authors.affiliation: Department of Chemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Rheingold
authors.affiliation: Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, NH, 03755, USA.
authors.forename: Russell P
authors.initials: RP
authors.lastname: Hughes
authors.affiliation: Department of Chemistry, University of Hawai'i at Mānoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Cain
keywords: NCN ligands; VT NMR spectroscopy; azaphospholes; phosphinidenes; pincer ligands