Dioxidomolybdenum(VI) complex featuring a 2,4-difluoro-substituted amine bis(phenolate) ligand

Abstract

Synthetic complexes containing a cis-[MoO2]2+ core are well-established models for the molybdenum co-factor (Moco). Here we report the crystal structure of such a model complex bearing a tetradentate amine bis(phenolate) ligand with fluorine substituents on the phenolate rings, namely, [2,2′-({[2-(dimethylamino)ethyl]azanediyl}bis(methylene))bis(4,6-difluorophenolato)]dioxidomolybdenum(VI)), [Mo(C18H18F4N2O2)O2]. Distortion from idealized octahedral symmetry about the Mo center is evident in the large O=Mo=O angle [108.54 (4)°] and the small N–Mo–Ophenolate angles [79.79 (4), 81.21 (3), 77.83 (3), and 84.59 (3)°]. The dihedral angle between the phenolate rings is 60.06 (4)°, and π–π stacking is observed between aromatic rings related by inversion (1 − x, 1 − y, 1 − z). The lower data-collection temperature of 150 K vs room-temperature data collection reported previously [KOWXIF; Cao et al. (2014). Transit. Met. Chem. 39, 933–937] and larger 2θ range for data collection (5.8–66.6° versus 6–54.96°) led to a structure with lower R 1 and ωR 2 values (0.019 and 0.049 vs 0.0310 and 0.0566 for KOWXIF). Comparison of the metrical parameters with KOWXIF suggests that this dataset offers a more realistic depiction of bonding within the MoVI=O moiety.