The formation of dimeric phosph(III) azane macrocycles [{P(μ-NtBu)}2•LL]2 [LL = organic spacer]

The dimeric macrocycles [{P(mu-(NBu)-Bu-t)}(2).LL](2) [LL = OCH2C(Me)(2)CH2O (1), 2,6-(NH)(2)C5H3N (2), 1,2-(NH)(2)C6H4 (3)] have been obtained by the reactions of the appropriate diols and diamines (LLH2) with the dimeric phosph(III) azane [ClP(mu-(NBu)-Bu-t)](2). Under different conditions the reaction of 1,2-(NH2)(2)C6H4 with [ClP(mu-NtBu)](2) gives the monomer [{P(mu-(NBu)-Bu-t)} 2{1,2-(NH)(2)C6H4}] (4) (instead of the dimer 3). Contrary to the literature, the results illustrate that the formation of dimeric macrocycles is common in these reactions and dependent among other factors on the steric demands and length of the organic spacer (LL) as well as the reaction conditions.