High-valent, four-coordinate manganese imido- and nitrido-bridged heterodicubane clusters have been prepared and characterized by single-crystal X-ray diffraction and spectroscopic techniques. The title compound, a corner-nitride-fused dicubane with the chemical formula [Mn5Li3(mu(6)-N)(N)(mu(3)-(NBu)-Bu-t)(6)(mu-(NBu)-Bu-t)(3)((NBu)-Bu-t)] (1), has been prepared as an adduct with a nearly isostructural tetramanganese cluster with one Mn atom replaced by Li. An important feature of the reported chemistry is the formation of nitride from tert-butylamide, indicative of N-C bond cleavage facilitated by manganese.