In a third aspect, the invention is a compound having the formula Mo3SkLnQz wherein L represents independently selected ligands, n is from 1 to 4, k is at least 4, for example from 4 to 10, such as 4 to 7, Q is a neutral electron donating compound, and z ranges from 0 to 5, wherein the compound has a core having the structure In a fourth aspect, the invention is a method of lubricating an internal