Reactivity of Zn(ii), Mg(ii) and Al(iii) chlorides with a phosphinimine ligand: New tetrameric inverse crown ether structures

摘要

Reaction of [Me_3SiNPPh_2CH_3] 1 with ZnCl_2 yields the dimer [ClZn(μ-Cl)(Me_3SiNPPh _2CH_3)]_22 whereas treatment of 1 with AlCl _3 in THF leads to the monomeric N adduct [Cl_3Al(Me _3SiNPPh_2CH_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) _2CHMgCl yields the zinc and magnesium complexes [M _4(Me_3SiNPPh_2CH_2)_4(μ _4-O)(μ_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_2O under inert atmospheric conditions leads to the formation of the dimeric species [Cl _2Al(Me_3SiNPPh_2CH_2O)]_27, which displays oxygen insertion into the C-Al bond, while the same reaction in the presence of air yields the compound [μ-(AlCl_2)(NPPh _2CH_3)]_28 with loss of ClSiMe_3 and without oxygen insertion into the C-Al bond.