About the Chemistry of Phosphorus Suboxides

Planar inorganic five-membered heterocycles with σ + π dual aromaticity in both S0and T1states

“…Several neutral five-membered rings containing group 15/16 elements have been theoretically predicted to be stable and aromatic in the S 0 state because they are valence isoelectronic to benzene. [60][61][62][63][64][65][66][67][68][69][70] Among them, pentagonal rings such as OP 4 , 71-73 SN 4 , 74 and SN 2 P 2 75 were successfully synthesized in the experiments, suggesting a high possibility of achieving more such simple inorganic heterocycles. Accordingly, we exhaustively constructed all the possible five-membered rings composed of one group 16 element (XQO or S) and one/two group 15 elements (Y and ZQN, P, As, Sb or Bi).…”

SN2P2: A Neutral Five‐Membered Sulfur–Pnictogen(III) Ring

“…Among these neutral planar 6 π electron ring molecules, only the C 2 v ‐symmetric five‐membered OP 4 ring (oxatetraphosphole) was tentatively identified by IR spectroscopy ( 16 O: $\tilde \nu $ =825.7 cm −1 , 18 O: $\tilde \nu $ =790.2 cm −1 ) from the productsgenerated by the photolysis of phosphorus/ozone mixtures in solid Ar or by laser ablation of P 4 O 10 11. Computationally, the C 2 v ‐symmetric ring isomer was predicted to be the global minimum on the potential energy surface (PES) of OP 4 5a. This is true also for the heavier C 2 v ‐symmetric five‐membered congener, SP 4 , which, however, remains experimentally unknown 6.…”

6 Nitrogen, phosphorus, arsenic, antimony and bismuth

“…106 Calculations on the geometries of phosphorus suboxides, P 4 O n (n = 1-5) have been undertaken, and the most stable structures for each formula have been identified and rationalised. 107 A range of tetrahalophosphonium salts containing [PBr n I 4 Ϫ n ] ϩ (n = 0-4) have been prepared and characterised spectroscopically. The nature of the counter-ion has a dramatic influence on the spectroscopic parameters of [PI 4 ] ϩ salts, as cation ؒ ؒ ؒ anion interactions serve to reduce the P-I bond order.…”