Mo2(OR)6 compounds, where R = -Pr and neo-Pe (neo-Pe = neopentyl), and W2(0-/-Pr)6L2, where L = pyridine and HNMe2, react in hydrocarbon solvents with either 9,10-phenanthrenequinone or tetrachloro-l,2-benzoquinone to generate M2(OR)6(QO)2, M2(0R)3(00)3, and M2(0R)2(00)4 compounds in a sequential manner, where OO represents the fully reduced form of the quinone ligand, i.e. catecholate. Though it has not proved possible to isolate each member of the series in a pure state, at least one compound from the series has been fully characterized by a single-crystal X-ray study. In these reactions the (M=M)6+ unit is oxidized to (M-M)10+ and every product contains a M-M single bond supported by a pair of bridging alkoxide ligands. Each molybdenum atom is in a distorted-octahedral environment with respect to a set of six oxygen atoms and the M-M distances are in the range 2.7-2.8 Á. *H NMR spectra are generally supportive of the structures found in the solid state, though for M2(OR)4(OD)3 compounds temperature-dependent behavior indicative of stereochemical lability is observed. The reaction between Mo2(0-z-Bu)6 and tetrachloro-l,2-benzoquinone (2 equiv) is more drastic in regard to the decomposition of the alkoxide ligand. By the subsequent addition of pyridine (py) the red crystalline salt [pyH]2[(Mo02(02C6Cl4)py)20] has been isolated and shown to contain two cts-Mo022+ units linked by an oxo bridge. Crystal data: (i) Mo2(0-/-Pr)6(02C6Cl4)2 at -160 °C, a = 10.579 (5) Á, b = 11.014(5) A, c = 9.619 (4) A, a = 108.38 (2)°, 0 = 108.44 (2)°, 7 = 84.49 (2)°, Z = 1, d^= 1.711 g cm"3, space group Pi; (ii) Mo2(0-neo-Pe)6(02C6Cl4)2 at -160 °C, a = 11.826 (7) A, b = 14.176 (10) A, c = 17.682 (12) A, 0 = 96.34 (3)°, Z = 2, da]Bi = 1.353 g cm'3, space group P2,/c; (iii) Mo2(0-t-Pr)4(02Cl4H8)3-2THF at -163 °C, a = 18.520 (10) A, b = 13.76 (6) A, c = 12.920 (6) A, a = 114.69 (3)°, 0 = 110.56 (2)°, 7 = 71.97 [(Mo02(02C6Cl4)2py)20] at -162 °C, a = 31.613 (15) A, b = 1.880 g cm"1 23, space group P2¡/c.