The reactions of Mo 2 (μ-O 2 CMe) 4 with the ligands 2-(diphenylphosphino)-6-(pyrazol-1-yl)pyridine (L 1 ) and 2-chloro-6-(diphenylphosphino)pyridine (L 2 ) in dichloromethane in the presence of HBF 4 ·Et 2 O afford the complexes trans-[Mo 2 (μ-O 2 CMe) 2 (μ-L 1 ) 2 ](BF 4 ) 2 (1) and trans-[Mo 2 (μ-O 2 CMe) 2 (μ-L 2 ) 2 ](BF 4 ) 2 (3), respectively, in which the bridging ligands L 1 and L 2 exhibit P ∩ N ∩ N and P ∩ N coordination to the [Mo 2 ] 4+ cores. The compound Mo 2 (μ-O 2 CMe) 4 reacts with Me 3 SiCl in the presence of L 1 and L 2 to give Mo 2 Cl 4 (μ-L 1 ) 2 (2) and Mo 2 Cl 4 (μ-L 2 ) 2 (4), respectively. The structural identities of these pairs of complexes have been established by single crystal X-ray structure determinations of 1 and 4.