Synthesis, structure, and properties of magnesium complexes containing cyclopentadienyl and amidinate ligand sets

N,N′-Bis(2,6-diisopropylphenyl)(tert-butyl)amidine and N,N′-bis(2,4,6-trimethyl-phenyl)(tert-butyl)amidine were prepared and treated with [CpMgMe(Et2O)]2 in diethyl ether or tetrahydrofuran to afford the monomeric amidinate complexes [CpMg(η2-tBuC(N(2,6-iPr2C6H3))2] (87%) and [CpMg(η2-tBuC(N(2,4,6-Me3C6H2))2)(THF)] (76%). The solid-state structures of the amidines and resultant magnesium complexes were determined by X-ray diffraction methods. In the solid-state, the magnesium complexes are monomeric and contain one η5-cyclopentadienyl ligand and one η2-amidinate ligand, as well as one tetrahydrofuran ligand for the latter. [CpMg(η2-tBuC(N(2,6-iPr2C6H3))2)] can be sublimed unchanged with 80% recovery at 180 °C/0.05 torr, while [CpMg(η2-tBuC(N(2,4,6-Me3C6H2))2)(THF)] decomposes to Cp2Mg (77%) and [Mg(η2-tBuC(N(2,4,6-Me3C6H2)))2] (83%) under similar conditions. [Mg(η2-tBuC(N(2,4,6-Me3C6H2)))2] was prepared independently through treatment of dibutylmagnesium with two equivalents of N,N′-bis(2,4,6-trimethylphenyl)(tert-butyl)amidine in toluene at ambient temperature.