Reactivity of Zn(II), Mg(II) and Al(III) chlorides with a phosphinimine ligand: new tetrameric inverse crown ether structures

Reaction of [Me(3)SiNPPh(2)CH(3)] 1 with ZnCl(2) yields the dimer [ClZn(mu-Cl)(Me(3)SiNPPh(2)CH(3))](2) 2 whereas treatment of 1 with AlCl(3) in THF leads to the monomeric N adduct [Cl(3)Al(Me(3)SiNPPh(2)CH(3))] 3. Compounds 2 and 3 were found to be thermally stable and were fully characterized by NMR spectroscopy, X-ray diffraction, and elemental analysis. On the other hand, treatment of phosphinimine 1 with nBuLi/ZnCl(2) or (CH(3))(2)CHMgCl yields the zinc and magnesium complexes [M(4)(Me(3)SiNPPh(2)CH(2))(4)(mu(4)-O)(mu(2)-Cl)(2)] 5 (M = Zn) and 6 (M = Mg), respectively. These compounds can be considered as new examples of inverse crown ethers in which the oxygen atom is encapsulated by polar organometallic complexes in a tetrameric arrangement. In contrast, reaction of 1 with nBuLi/AlCl(3) in Et(2)O under inert atmospheric conditions leads to the formation of the dimeric species [Cl(2)Al(Me(3)SiNPPh(2)CH(2)O)](2) 7, which displays oxygen insertion into the C-Al bond, while the same reaction in the presence of air yields the compound [mu-(AlCl(2))(NPPh(2)CH(3))](2) 8 with loss of ClSiMe(3) and without oxygen insertion into the C-Al bond.