Synthesis of zinc trisubstituted hydrazido complexes and ortho-metalation of 4-(dimethylamino)pyridine

Abstract

The zinc hydrazide complexes [EtZn(N(SiMe₃)NMe₂)]₂, [EtZn(N(Me)NMe₂)]₄, and Zn₃Et₄(N(Et)NMe₂)₂ were synthesized by allowing excess hydrazine, HN(R)NMe₂, to react with diethyl zinc. The product of the reaction between ZnEt₂ and HN(i-Pr)NMe₂ortho-metalated 4-(dimethylamino)pyridine (DMAP) at room temperature, producing the complex Zn[(NC₅H₃-p-NMe₂)ZnEt(N(i-Pr)NMe₂)]₂. At elevated temperatures, Zn₃Et₄(N(Et)NMe₂)₂ also ortho-metalated DMAP, but [EtZn(N(Me)NMe₂)]₄ did not. Single-crystal X-ray diffraction studies revealed that the hydrazide ligands in [EtZn(N(SiMe₃)NMe₂)]₂ act as bridging mono-hapto amide ligands, and in Zn₃Et₄(N(Et)NMe₂)₂ and Zn[(NC₅H₃-p-NMe₂)ZnEt(N(i-Pr)NMe₂)]₂ the hydrazide ligands are di-hapto.