2 research outputs found
Synthesis of a Carbene-Stabilized (Diphospha)aminyl Radical and Its One Electron Oxidation and Reduction to Nonclassical Nitrenium and Amide Species
Herein,
we report the synthesis of an acyclic carbene-stabilized
diphospha(aminyl) PNP radical CAACMePNPCAACMe 4 (CAACMe = 1-[2,6-bis(isopropyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene)
by a facile one-pot, seven-electron reduction of hexachlorophosphazene
chloride [Cl3PNPCl3][Cl]. The PNP radical 4 features a conjugated framework with spin density primarily
localized on the central nitrogen atom as well as the flanking carbenes.
Unlike other tripnictogen radicals, 4 undergoes facile
one-electron oxidation and reduction to yield nonclassical nitrenium
and amide species [5]+ and [6]−, respectively. The cation [5]+ exhibits conformational flexibility in the solution state
between the expected W-shaped geometry [5b]+ and a previously unobserved linear heteroallene-type
structure [5a]+, which
was characterized in the solid state. The equilibrium was explored
both computationally and experimentally, showing that [5a]+ is favored over [5b]+ both enthalpically (ΔH = −2.9 × 103 ± 80 J mol–1) and entropically (ΔS = 4.2
± 0.25 J mol–1 K–1). The
formal amide [6]− displays remarkable
flexibility in its coordination chemistry due to the presence of multiple
Lewis basic centers, as evidenced by the structure of its potassium
complex K262, which exhibits μ, κ-P, κ-P,
and η3-PNP coordination modes. Protonation of [6]− leads to the formation of an amine 7, which features a trigonal planar geometry around nitrogen
Synthesis of a Carbene-Stabilized (Diphospha)aminyl Radical and Its One Electron Oxidation and Reduction to Nonclassical Nitrenium and Amide Species
Herein,
we report the synthesis of an acyclic carbene-stabilized
diphospha(aminyl) PNP radical CAACMePNPCAACMe 4 (CAACMe = 1-[2,6-bis(isopropyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene)
by a facile one-pot, seven-electron reduction of hexachlorophosphazene
chloride [Cl3PNPCl3][Cl]. The PNP radical 4 features a conjugated framework with spin density primarily
localized on the central nitrogen atom as well as the flanking carbenes.
Unlike other tripnictogen radicals, 4 undergoes facile
one-electron oxidation and reduction to yield nonclassical nitrenium
and amide species [5]+ and [6]−, respectively. The cation [5]+ exhibits conformational flexibility in the solution state
between the expected W-shaped geometry [5b]+ and a previously unobserved linear heteroallene-type
structure [5a]+, which
was characterized in the solid state. The equilibrium was explored
both computationally and experimentally, showing that [5a]+ is favored over [5b]+ both enthalpically (ΔH = −2.9 × 103 ± 80 J mol–1) and entropically (ΔS = 4.2
± 0.25 J mol–1 K–1). The
formal amide [6]− displays remarkable
flexibility in its coordination chemistry due to the presence of multiple
Lewis basic centers, as evidenced by the structure of its potassium
complex K262, which exhibits μ, κ-P, κ-P,
and η3-PNP coordination modes. Protonation of [6]− leads to the formation of an amine 7, which features a trigonal planar geometry around nitrogen