New phosphoranes with five- and seven-membered rings: influence of the nature of the substituents on hydrogen bonding

Abstract

Several pentacoordinated phosphoranes with a primary amino substituent have been synthesized by oxidative addition reactions on a cyclic phosphite. X-ray structures of three of these, i.e. (C₆H₁₁NH)P(2,2'-O-C₆H₄-C₆H₄-O)(1,2-O₂C₆Cl₄) (6), (C₆H₁₁NH)P(9,10-O₂C₁₄H₈)(1,2-O₂C₆H₄) (7) and (MeNH)P(2,2'-O-C₆H₄-C₆H₄-O)(1,2-O₂C₆H₄) (8) have been determined. While 6 does not show hydrogen bonding interactions involving the NH proton, compound 7 is a weak dimer with hydrogen bonding interactions between the NH proton and the apical oxygen of the catecholate ring. By contrast in 3, although hydrogen bonding again involves the NH proton and apical oxygen of the five-membered catecholate ring, a polymeric chain structure is formed.