Coordination complexes containing extended metal–oxygen frameworks have been studied for a number of applications, including catalysis and as optical materials; however, very few neutral complexes that contain extended metal–oxygen frameworks have been characterized. The new hexanuclear, mixed-valence Mo V /Mo VI coordination complex Mo 6 O 13 (Hsal) 2 (sal) 2 (acac) 2 has been synthesized by direct reaction of salicylic acid (2-HOC 6 H 4 CO 2 H; H 2 sal) with Mo(O) 2 (acac) 2 . The mixed-valence compound is composed of two edge-sharing Mo 4 (μ-O) 4 rings, in which four Mo atoms are Mo VI and two are Mo V . The tetranuclear complex Mo 4 O 10 (acac) 4 was obtained from residual washings of the same reaction and is composed of a single Mo 4 (μ-O) 4 ring having only Mo VI atoms. XPS studies confirmed that the hexanuclear complex contains both Mo V and Mo VI . Magnetic measurements reveal that the hexanuclear complex is diamagnetic suggesting an electron–electron coupling between the two Mo V centers through an oxo-bridge.