Dual Supermesityl Stabilization: A Room‐Temperature‐Stable 1,2,4‐Triphosphole Radical, Sigmatropic Hydrogen Rearrangements, and Tetraphospholide Anion

Abstract

Cesium 3,5-bis(2,4,6-tri-tert-butylphenyl)-1,2,4-triphospholide (12) and cesium 5-(2,4,6-tri-tert-butylphenyl)tetraphospholide (13) were synthesized and isolated with flat fivemembered rings, which are an indication of the aromaticity in these anions. Compound 13 is the first example of a stable tetraphospholide anion, which is structurally characterized. Kinetic stabilization of the 1,2,4-triphospholide system by

Towards Spontaneous Heterolysis of the Homonuclear PP Bond in Diphosphines: The Case of Diazaphospholeniumtriphospholides

“…A J ‐resolved 2D‐NMR spectrum (see Supporting Information) discloses for the lines of a third sideband system a triplet structure that is not resolved in the 1D‐NMR spectrum. The size of this coupling (55 Hz) compares well to values of 2 J PP in known triphosphol(id)es,20–23 and the signal is readily assigned to the isolated phosphorus atom in the triphosphole ring. The lines in the last sideband pattern appear even in the J ‐resolved spectrum as singlet, and the clear assignment to the phosphorus atom in the diazaphospholene ring is supported by the similarity of the chemical shift ( δ =167 ppm) with those of known phospholyl‐1,3,2‐diazaphospholenes 5 ( δ =135–170 ppm) 8.…”

“…In contrast, the chemical shifts of all three phosphorus atoms in the P 3 C 2 ring of 8 a remain similar ( δ =202–278 ppm), and the failure to resolve a 1 J PP coupling across the PP bond between both rings indicates that the size of this coupling is distinctly smaller than the common values of 100–400 Hz in acyclic diphosphines 25 . 31 P Chemical shifts between δ =200 and 300 ppm for triphosphole derivatives are characteristic for ionic species like the alkaline and alkaline‐earth metal salts (e.g., K[P 3 (C t Bu) 2 ]: AB 2 spin system with δ A =252.8, δ B =242.8 ppm), in which the π‐electron delocalization is preserved and all phosphorus atoms remain two‐coordinate 21–23. Furthermore, we had shown that a decrease of 1 J PP in P ‐phospholyl‐1,3,2‐diazaphospholenes coincides with a lengthening of the PP bond, and had predicted that 1 J PP should vanish if the PP distance came close to a value of 2.8 Å 10.…”

Unexpected fragmentations of triphosphaferrocene – formation of supramolecular assemblies containing the (1,2,4-P3C2Mes2)− ligand

“…10 Solid-state characterization of the coordination compounds All isolated coordination compounds contain the remaining negatively charged [P 3 C 2 Mes 2 ] − unit as a building block. Surprisingly, building block 1 always underwent fragmentation.…”

Synthesis and Characterization of the Novel 1,2,4-Triphosphaferrocene [Cp*Fe(η5-P3C2Mes2)] Containing Sterically Demanding Mesityl Groups

“…These values are in good agreement with data found for K[P 3 C 2 Ph 2 ] (δ = 274.4, 253.9 ppm) 3 and Cs[P 3 C 2 Mes * 2 ] (Mes * = 2,4,6-tri-tert-butylphenyl) (δ = 287.6, 267.9 ppm). 8 The subsequent synthesis of 1 was performed by analogy with that of [Cp * Fe(η 5 -P 3 C 2 t Bu 2 )]. 4d The addition of a thf solution of K[P 3 C 2 Mes 2 ] and a thf suspension of LiCp * to a solution of [FeBr 2 (dme)] in thf leads to an immediate colour change from orange to deep red.…”

“…Solvent molecule and hydrogen atoms are omitted for clarity, thermal ellipsoids drawn at the 50% probability level. Selected bond lengths [Å]: P(1)-P(2) 2.118(1), P(2)-C(1) 1.774(3), P(3)-C(1) 1.759(3), P(3)-C(2) 1.761(3), P(1)-C(2) 1.777(3), Fe(1)-P(1) 2.2958(8), Fe(1)-P(2) 2.2969(8), Fe(1)-P(3) 2.3623(8).…”