Pure and Applied Chemistry

Abstract: Nitrogen-bridged bidentate phosphaalkenes reveal several exceptional properties as a new class of P=C-unsaturated diphosphinoamine (PNP) ligands: N–Si bond cleavage of the first N-silylimino-bridged bis-phosphaalkene (R₂C=P)₂NSiMe₃ (R = iPrMe₂Si) with chlorides of Ag^I, Au^I, and Rh^I leads to complexes of the 5c-6π-heteropentadienide imidobisphosphaalkene anion; double Cl^– transfer from PtCl₂ and PdCl₂ to coordinated phosphaalkene phosphorus atoms of P‑diphenylphosphanylamino phosphaalkenes R₂C=PN(R')PPh₂ (R' = Me₃Si or iPrMe₂Si; R = tBu, 1-Ada) furnishes unprecedented bis-chelate P-chloroylid complexes M[R₂CP(Cl)N(R')PPh₂]₂ (M = Pd, Pt); CO- and Rh^I-induced coupling of two P‑diphenylphosphanylamino phosphaalkenes under disilylketene elimination provides trigonal–bipyramidal Rh^III complexes with novel tetradentate dianionic “PNP–C–PNP” ligands R₂C[P^(–)N(R')PPh₂]₂.