Ca[(Ph 2 PO) 2 N] 2 ·nTHF,an α-hydroperoxidation promoter of coordinated THF molecules

Abstract

Ca[(Ph₂PO)₂N]₂·nTHF (2) was obtained by direct synthesis from tetraphenylimidodiphosphinic acid and Ca° in THF. X-ray quality single crystals of Ca₂[(Ph₂PO)₂N]₄·H₂O (3) and Ca[(Ph₂PO)₂N]₂·2C₄H₈O₃ (4) were obtained upon crystallization of 2 under different conditions. The solid-state structure of 3 reveals a Ca₂O₃ core in which the two hexacoordinated calcium metals are linked together by three µ-oxygen atoms from three independent tetraphenylimidodiphosphinate ligands. Compound 4 is a monomeric octahedral complex bearing two tetraphenylimidodiphosphinate ligands in the equatorial plane and two α-hydroperoxidated THF molecules, formed in situ, in the axial positions. Compound 4 represents the first example of a metal center exhibiting this type of hydroperoxidation behavior.