Skeletal Stabilization: A Basis for New Classes of Cyclophosphazanes

Abstract

Reactions involving skeletally stabilized intermediate phosphazanes yield new cyclophosphazanes. Thermolysis of C₆H₄(NH)₂PPh (9) yields (PhP)₄ and the λ⁵ phosphazane [C₆H₄(NH)₂]₂PPh (10); 10 upon cyclocondensation with PhPCl₂ yields cis,trans- and cis,cis- spiro λ³-λ⁵-λ³ phosphazanes [C₆H₄(N)₂PPh]₂PPh (12). Reaction of the bis(silyl) cyclophosphazane C₆H₄(NSiMe₃)₂PPh with PhPCl₂ yields triphosphazane C₆H₄[NP(Ph)C1]₂PPh (13); 13 with 1,2-(NH₂)₂C₆H₄ forms cyclotriphosphazane C₆H₄(N₂PPh)(PPh)₂C₆H₄(NH)₂ (14). 14 is the key intermediate in formation of several new [(C₆H₄N₂PPh)]₂-(PPh)(PR) (R = Ph, Me) cleft-containing cyclotetraphosphazanes (17). Synthesis and structural characterization of the new phosphazanes are described.

Keywords::

• phosphazanes
• cyclophosphazanes
• triphosphazanes
• tetraphosphazanes
• aminophosphines