We present here the isolation, characterization and catalytic activities for C-C and C-N bond coupling of a new family of octahedral Mo(IV) compounds. In opposition to the well-developed π-allyl metal complex-based coupling reactions catalyzed by precious metals such as iridium and palladium,^[2,3] molybdenum has found much fewer applications.^[4,5] This stands in contrast to its earth abundancy, rich redox-chemistry, and capability to easily undergo metal-carbon bond formation and cleavage, rendering molybdenum an attractive choice for the development of new metal-based catalysts for a variety of different organic transformations.

We have optimized the preparation and fully analyzed a series of Mo(IV) bis-β-diketonate complexes.^[6,7] Detailed solid- and solution state studies gave unprecedented insights into the geometry and coordination chemistry of these compounds, e.g. displaying solvent dependent dynamic equilibria involving cis- and trans-isomers in solution.

Reactivity and catalytic activity of the complexes were further explored, providing one of the most active and stable earth abundant metal-based molecular catalyst for the substitution of allylic alcohols by electron-rich carbon-centered nucleophiles (e.g. phenols). Reactivity studies involving the isolation of a catalytically active intermediate provided insights into the present mechanistic pathway.

[1] F. Masero, V. Mougel, manuscript in preparation.
[2] Q. Cheng, H. Tu, C. Zheng, J. Qu, G. Helmchen, S.-L. You, Chem. Rev. 2019, 119, 1855.
[3] B. Sundararaju, M. Achard, C. Bruneau, Chem. Soc. Rev. 2012, 41, 4467.
[4] A. V. Malkov, P. Spoor, V. Vinader, P. Kočovský, J. Org. Chem. 1999, 64, 5308.
[5] M. Salman, Y. Xu, S. Khan, J. Zhang, A. Khan, Chem. Sci. 2020, 11, 5481.
[6] G. Doyle, Inorg. Chem. 1971, 10, 2348.
[7] den B. A. Van, K. Murray, B. West, Aust. J. Chem. 1972, 25, 705.