Structural characterization of MoOCl3(THF)2, the pre-reagent for Kauffmann olefination reactions

Crystal structure and Hirshfeld surface analysis of the elusive trichlorobis(diethyl ether)oxomolybdenum(V)

First reported in 1930, MoCl3O(Et2O)2 is a by-product of the reductive synthesis of MoCl4(OEt2)2 from MoCl5. We report herein the X-ray crystal structure and Hirshfeld surface characteristics of mer-MoCl3O(Et2O)2, or [MoCl3O(C4H10O)2]. The compound crystallizes in the orthorhombic space group P212121. The molybdenyl (Mo=O) bond length is 1.694 (3) Å and the cis- and trans-Mo—O distances are 2.157 (3) and 2.304 (3) Å, respectively. Intermolecular Mo=O...H bonding is present in the lattice, with the shortest distance being 2.572 Å.

Isolation of a Homoleptic Non-oxo Mo(V) Alkoxide Complex: Synthesis, Structure, and Electronic Properties of Penta-tert-Butoxymolybdenum

Treatment of [MoCl₄(THF)₂] with MOtBu (M = Na, Li) does not result in simple metathetic ligand exchange but entails disproportionation with formation of the well-known dinuclear complex [(tBuO)₃Mo≡Mo(OtBu)₃] and a new paramagnetic compound, [Mo(OtBu)₅]. This particular five-coordinate species is the first monomeric, homoleptic, all-oxygen-ligated but non-oxo 4d¹ Mo(V) complex known to date; as such, it proves that the dominance of the Mo═O group over (high-valent) molybdenum chemistry can be challenged. [Mo(OtBu)₅] was characterized in detail by a combined experimental/computational approach using X-ray diffraction; UV/vis, MCD, IR, EPR, and NMR spectroscopy; and quantum chemistry. The recorded data confirm a Jahn-Teller distortion of the structure, as befitting a d¹ species, and show that the complex undergoes Berry pseudorotation. The alkoxide ligands render the disproportionation reaction, leading the formation of [Mo(OtBu)₅] to be particularly facile, even though the parent complex [MoCl₄(THF)₂] itself was also found to be intrinsically unstable; remarkably, this substrate converts into a crystalline material, in which the newly formed Mo(III) and Mo(V) products cohabitate the same unit cell.