The molecular and crystal structures of (η⁷-cycloheptatrienyl)molybdenum(II)- μ-bromo-μ-dihydroxo-(η⁷-cycloheptatrienyl)molybdenum(II) tetrafluoroborate tetrahydrofuran solvent

The molecular and crystal structures of (η⁷-cycloheptatrienyl)molybdenum(II)-μ-bromo-μ-dihydroxo-(η⁷ -cycloheptatrienyl)molybdenum(II) tetrafluoroborate as a tetrahydrofuran solvate have been determined by the analysis of three-dimensional X-ray diffraction data. Crystals are monoclinic, space group P2₁ a with cell dimensions a = 18.936(18), b = 11.530(14), c = 9.955(4) Å, β = 90.06(6)° and Z = 4. Intensity data were recorded at room temperature on a Syntex P2₁ autodiffractometer using graphite monochromated Mo K_α radiation. The structure was solved by Patterson and Fourier techniques, and refined by least-squares to a conventional R factor of 0.106. The crystal structure is built of equal numbers of |(C₇H₇)Mo(Br)(OH)₂Mo(C₇H₇)|⁺ cations, BF₄^- anions and C₄H₈O solvent molecules. The cation features a metal-metal bond, 2.882(2) Å, and cycloheptatrienyl rings which, although individually planar, are bent symmetrically away from the bromide bridge to subtend a mutual dihedral angle of ca. 17°. The tetrafluoroborate anion and tetrahydrofuran solvent molecule show no unusual geometrical features the latter adopting an envelope conformation with β-carbon apical. The role of these species in locating the hydroxy-H atoms of the cation through possible intermolecular hydrogen bonding is discussed.