Manganese(II) and Magnesium(II) Analogies in Iridium Hydride Coordination Chemistry

Alkane elimination reactions between stable magnesium and manganese dialkyls, [L n M(CH 2 t Bu) 2 ] (M = Mg, Mn), and an iridium polyhydride species, [Cp*IrH 4 ] (Cp* = C 5 Me 5 ), provide a variety of heterobimetallic Mg–Ir and Mn–Ir hydride complexes. In several cases, their solid-state molecular structures are shown to be virtually identical despite fundamentally different electronic properties of Mg(II) (2 p 6 ) and Mn(II) (3 d 5 ). A direct comparison of the paramagnetic Mn with the diamagnetic Mg analog enables a comprehensive characterization based on a combination of analytical techniques (single-crystal X-ray diffraction, IR, and NMR spectroscopies), especially with respect to the hydride ligands, traditionally difficult to identify in open-shell species. Nevertheless, such congruence is not universal: the nuclearity and M:Ir stoichiometry depend on the nature of the Mg and Mn dialkyl precursors, which in turn is determined by the type of coligand L, and on the presence of proton-donating reagents in the reaction mixture, revealing subtle differences between the Mg and Mn systems in certain cases.