Oxidation reactions of 1,8‐bis(phosphino)naphthalenes: syntheses and molecular structures of bis(phosphine oxides) and of a bis(phosphine sulfide)

Abstract

Abstract A series of naphthalenediyl‐1,8‐bis(phosphine oxides) 1‐RR′P(:O)(C 10 H 6 )‐8‐P(:O)RR′ (R = R′ = Me ( 2a ), Et ( 2b ), iPr ( 2c ), Cy ( 2d ), Ph ( 2f ) and R = tBu, R′ = Ph ( 2e ) was prepared by oxidation of the corresponding bis(phosphines) 1a–f with molecular oxygen or H 2 O 2 ·(H 2 N) 2 C(:O) and characterized by NMR and IR spectroscopy, mass spectrometry, and elemental analysis ( 2a, 2b, 2d–f ). X‐ray crystal structure analyses were performed for 1,8‐bis(dimethylphosphinyl)naphthalene ( 2a ), (RR,SS)‐1,8‐bis(phenyl‐tert‐butylphosphinyl)naphthalene ( 2e ) and 1,8‐bis(diphenylphosphinyl)naphthalene ( 2f ). Treatment of 1,8‐bis(diphenylphosphino)naphthalene (dppn, 1f ) with an excess of sulfur in hot toluene afforded the bis(phosphine sulfide) 1‐Ph 2 P(:S)(C 10 H 6 )‐8‐P(:S)Ph 2 (dppnS 2 , 3f ) the structure of which was elucidated by X‐ray crystal structure analysis. The geometries of the compounds 2a, 2e, 2f , and 3f revealed an increase of strain from the corresponding bis(phosphines). In each case, the proximity of the P(:X)R 2 groups (X = O, S) led to distortion, the main feature of which was the out‐of‐plane displacement of the P atoms. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:102–113, 2001