Covalent Metal–Metal-Bonded Mn4 Tetrahedron Inscribed within a Four-Coordinate Manganese Cubane Cluster, As Evidenced by Unexpected Temperature-Independent Diamagnetism

The electronic structures of the manganese­(IV) cubane cluster Mn­(μ3-NtBu)4(NtBu)4 (1) and its one-electron-oxidized analogue, the 3:1 MnIV/MnV cluster [Mn­(μ3-NtBu)4(NtBu)4]+[PF6]− (1+[PF6]), are described. The S = 0 spin quantum number of 1 is explained by a diamagnetic electronic structure where all metal-based d electrons are paired in Mn–Mn bonding orbitals. Temperature- and power-dependent studies of the S = 1/2 electron paramagnetic resonance signal of 1+ are consistent with an electronic structure described as a delocalized one-electron radical.