Synthesis and Structural Diversity of ZnCl₂ and Zn(C₆F₅)₂ Complexes of a Phosphinimine Ligand

Abstract

Zinc complexes of the potentially bidentate neutral monophosphinimine ligand 4‐(ArN=PPh2)dibenzofuran were prepared. Two derivatives of this framework were studied, which differ in the steric demand of the N‐aryl group (Ar = Dipp, Mes). The ligand interacts with diethylzinc in solution but does not form a tightly bound complex, whereby the degree of association is found to be dependent on temperature. However, isolable complexes are formed upon reaction with the more Lewis acidic precursors ZnCl2 and Zn(C6F5)2. In this way, the ZnCl2 complexes 1 and 2 and Zn(C6F5)2 complexes 3 and 4 were prepared and structurally characterized. The nuclearity of 1 and 2 was shown to depend on the bulk of the ligand. Furthermore, the strength of the bonding interaction between the zinc atoms and the dibenzofuran oxygen atoms in 3 and 4 also depends on the choice of ancillary ligand. Attempts to further derivatize these complexes were unsuccessful, and thus, functionalization of the complex LZnEt(OTf) was undertaken instead, resulting in formation of the novel linear trinuclear complex 5.