Synthesis and structure of metallated macrocycle-bearing cyclophophazenes. - Part I : The (Li, Mg, Zn)/SPIR0(30203) derivatives

Abstract

Syntheses and molecular structures of three metallated (Li, Zn, Mg) derivatives of the macrocycle-bearing cyclophosphazene N3P3Cl4 [HN---(CH2)3---O---(CH2)2---O---(CH2)3---NH] (coded as SPIRO 30203, 1) are reported. These three molecular structures reveal three different patterns of metal coordination. In compound 2 one of the two hydrogen atoms in SPIRO 3O2O3 is substituted by lithium generating a dimeric structure with pentacoordinated lithium centers. This structure is further stabilized by N---H hydrogen bonds. In 3 both hydrogen atoms of the macrocyclic loop are replaced by two zinc atoms through a cross-link metallation leading again to a dimeric molecule. In this compound the Zn atom is found to be in a trigonal bipyramidal environment with one very long N---Zn interaction. The origin of the dimerization of the magnesium compound 4 is analogous to 3. Magnesium is in the center of a distorted octahedron, coordinated with the O- and N-donors of the macrocyclic loop and also one nitrogen atom of the N3P3 ring. 4 is the first example of a metallic center coordinated by a neutral phosphazene ligand. Typical metal-N and metal-O distances are (in Å): Li-O, 2.05—2.07; Li-N, 2.07—2.36; Zn-O, 2.08—2.14; Zn---N, 1.94—1.95 (2.49); Mg---O, 2.09—2.14; Mg---N, 2.07—2.31.