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

The zinc hydrazide complexes EtZn(N(SiMe(3))NMe(2))](2), EtZn(N(Me)NMe(2))](4), and Zn(3)Et(4)(N(Et)NMe(2))(2) were synthesized by allowing excess hydrazine, HN(R)NMe(2), to react with diethyl zinc. The product of the reaction between ZnEt(2) and HN(i-Pr)NMe(2)ortho-metalated 4-(dimethylamino)pyridine (DMAP) at room temperature, producing the complex Zn(NC(5)H(3)-p-NMe(2))ZnEt(N(i-Pr)NMe(2))](2). At elevated temperatures, Zn(3)Et(4)(N(Et)NMe(2))(2) also ortho-metalated DMAP, but EtZn(N(Me)NMe(2))](4) did not. Single-crystal X-ray diffraction studies revealed that the hydrazide ligands in EtZn(N(SiMe(3))NMe(2))](2) act as bridging mono-hapto amide ligands, and in Zn(3)Et(4)(N(Et)NMe(2))(2) and Zn(NC(5)H(3)-p-NMe(2))ZnEt(N(i-Pr)NMe(2))](2) the hydrazide ligands are di-hapto.