Synthesis and structural characterization of trans-[Mo2(H2DMepyF)2(CH3CN)4](BF4)6 (HDMepyF=N,N′-di(6-methyl-2-pyridyl)formamidine)

Reaction of Mo2(O2CCH3)2(DMepyF)2 (HDMepyF=N,N′-di(6-methyl-2-pyridyl)formamidine) with HBF4 in CH2Cl2/CH3CN afforded the complex trans-[Mo2(H2DMepyF)2(CH3CN)4](BF4)6 (1), which crystallized in two forms, trans-[Mo2(H2DMepyF)2(CH3CN)4](ax-CH3CN)2(BF 4)6 · 2CH3CN (1a), and trans- [Mo2(H2DMepyF)2(CH3CN)4](ax-BF4) 2(BF4)4 · 2CH3CN (1b). The molecular structures of complexes (1) consist of two quadruply bonded molybdenum atoms, which are spanned by two trans-bridging formamidinate ligands and coordinated by four trans-CH3CN. Each H2DMepyF+ ligand adopts an s-cis,s-cis- conformation. The difference between 1a and 1b is that complex 1a contains two CH3CN molecules as axial ligands, while 1b contains two BF4− anions as axial ligands. Complex 1 is the first dimolybdenum complex containing a pair of trans bridging ligands and two pairs of trans-CH3CN ligands.