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

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-O 2C6Cl4) (6), (C6H11NH)P(9,10-O2C14H8)(1,2-O2C6H4) (7) and (MeNH)P(2,2'-O-C6 H4-C6H4-O) (1,2-O2C6H4) (8) have been determined. While 6 does not show hyd rogen bonding interactions involving the NH proton, compound 7 is a weak di mer with hydrogen bonding interactions between the NH proton and the apical oxygen of the catecholate ring. By contrast in 3, although hydrogen bondin g again involves the NH proton and apical oxygen of the five-membered catec holate ring, a polymeric chain structure is formed. (C) 2000 Elsevier Scien ce Ltd All rights reserved.