Reactions of chalcogens and borane with phosphazane macrocycles assembled from diethanolamine and PN building blocks.

Phosphazanes of the type [ClP(μ-NR)] are excellent building blocks for the formation of a range of macrocycles. The condensation reaction of the bifunctional linkers, -substituted diethanolamine with cyclodiphosphazane, [ClP(μ-NBu)] leads to the formation of dimeric macrocycles, [{P(μ-NBu)}{O(CH)N(R)(CH)O}]; (R = Me (1), Ph (2)). Furthermore, the P centres of 1 and 2 were oxidized with chalcogens (O, S, and Se) to afford the corresponding P macrocycles - [{(O)P(μ-NBu)}{O(CH)N(R)(CH)O}] (R = Me (3), Ph (4)); [{(S)P(μ-NBu)}{O(CH)N(R)(CH)O}] (R = Me (5), Ph (6)) and [{(Se)P(μ-NBu)}{O(CH)N(R)(CH)O}] (R = Me (7), Ph (8)). An investigation of the Lewis basic behavior of the dimeric macrocycles 1 and 2 was performed by treating them with BH·SMe, which resulted in Lewis adduct formation, incorporating a total of six BH molecules in the macrocyclic skeleton of 1, [{(BH)P(μ-NBu)}{O(CH)N(BH)(Me)(CH)O}] (9) and four BH molecules in the macrocyclic skeleton of 2, [{(BH)P(μ-NBu)}{O(CH)N(Ph)(CH)O}] (10). Compounds 9 and 10 constitute the first examples of the Lewis adduct of a PN macrocycle with a main group Lewis acid. All the new compounds have been fully characterized using multinuclear NMR, HRMS, and single-crystal X-ray diffraction (compounds 1-3, 8 and 9).