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.