Scheme 1.
In the X-ray crystal structure of [LMeFe(µ-H)]2 (3), the hydride ligands are oriented such that the geometry at each iron is between tetrahedral and square planar, and the N2C3Fe planes are perpendicular.4,14 The idealized D2 symmetry is consistent with the low-temperature 1H NMR spectrum, and its fluxional behavior could involve interconversions of two D2 structures through a D2h transition state.