Zinc complexes of anionic NPPN and NP(S)PN ligands and rearrangement to the isomeric NPNP and NP(S)NP ligands in mercury complexes

Abstract

The lithium (imido)diphosphineimide Li(Et₂O)[DippNPhP–P(ⁿBu)PhNDipp] (1) (Dipp = 2,6-ⁱPr₂C₆H₃) undergoes simple metathesis reactions with equimolar amounts of zinc halides, ZnCl₂ and ^tBuZnBr, to give the respective N,N′-chelated complexes {Zn(μ-Cl)[DippNPhP–P(ⁿBu)PhNDipp]}₂ (2) and ^tBuZn[NDippPhP–P(ⁿBu)PhNDipp] (3). In contrast, the reaction of two equivalents of complex 1 with HgCl₂ affords the rearranged bis(imidodiphosphinoamine) complex, Hg[PhP(NDipp)(μ-NDipp)P(ⁿBu)Ph]₂ (4), where the ligand acts as a P-centered anion. The (imido)diphosphineimide backbone of 1 remains intact on oxidation with elemental sulfur to afford the lithium (imido)diphosphineimine sulfide complex, Li(Et₂O)[DippNPhP(S)–P(ⁿBu)PhNDipp] (6). Reactions of 6 with group 12 metal halides show similar behaviour to those of complex 1. The N,N′ chelated metathesis products RZn[DippNPhP(S)–P(ⁿBu)PhNDipp] (7, R = Cl; 8, R = ^tBu) are obtained on reaction with ZnCl₂ and ^tBuZnBr, respectively. Isomerization of the ligand backbone occurs on reaction of 6 with HgCl₂ to form the homoleptic P,S-chelated mercury complex Hg[Ph(S)P(NDipp)(μ-NDipp)P(ⁿBu)Ph]₂ (9). Complexes 2, 3, 4, 6, 8 and 9 have been characterized by X-ray crystallography.