Adducts of silicon tetrafluoride with aminocyclophosphazenes: synthesis and characterization

Abstract

Stable solid adducts of SiF₄ with the following aminocyclophosphazenes have been synthesized: N₃P₃(NHCH₂CH₂NH)(NMe₂)₄, (1); N₃P₃(NHCH₂CH₂NH)Cl₄, (2); N₃P₃(NMe₂)₄Cl₂, (3); N₃P₃(NHMe)₆, (4); N₃P₃(NMe₂)₆, (5); N₄P₄(NHMe)₈, (6); N₄P₄(NMe₂)₈, (7); and N₄P₄(NHBu^t)₈, (8). They have been characterized by elemental analysis, i.r., and n.m.r. (¹H, ³¹P, and ¹⁹F) spectroscopy. The composition of the adducts varies depending on the ring size and also on the nature of the substituents on the phosphorus. The number of SiF₄ molecules accommodated by the ligands is larger when the ring size is large, while it is less when the ligands contain chlorine. Except in the cases of ligands (1) and (2), bonding is through the ring nitrogens. With (1), both exocyclic nitrogen and ring nitrogen atoms, and with (2) only exocyclic nitrogen atoms, participate in co-ordination. In these two cases the silicon is six-co-ordinated, while in the other cases it is five-co-ordinated.