BENZOPHENONE OXIDATION OF PRIMARY LITHIUM PHOSPHANIDES TO CYCLOOLIGOPHOSPHANES WITH FORMATION OF LITHIUM DIPHENYLMETHANOLATE

Abstract

The lithium phosphanides LiPHR (R = Ph, 2,4,6-Me₃C₆H₂ (Mes)) are oxidised by benzophenone in THF at room temperature to give the cyclooligophosphanes (PPh)_n (n = 4, 5, 6) and (PMes)_n (n = 3 (1), 4 (2)). Compounds 1 and 2 have been characterised by X-ray structure determination. In the solid state, the P₄ ring in 2 is puckered (torsion angle P-P-P-P 41.04(3)°). The reduction product, LiOCHPh₂ (3), was characterised by IR and NMR spectroscopy (¹H, ¹3C, ₇Li) and X-ray structure determination. LiOCHPh, is hexameric in the solid state and forms a slightly distorted hexagonal prism composed of alternating Li and O atoms.

Key Words:

• Lithium phosphanides
• cyclooligophosphanes
• lithium diphenylmethanolate
• crystal structure