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

Abstract

Treatment of [MoCl 4 (THF) 2 ] with MO t Bu (M = Na, Li) does not result in simple metathetic ligand exchange but entails disproportionation with formation of the well-known dinuclear complex [( t BuO) 3 Mo≡Mo(O t Bu) 3 ] and a new paramagnetic compound, [Mo(O t Bu) 5 ]. This particular five-coordinate species is the first monomeric, homoleptic, all-oxygen-ligated but non-oxo 4d 1 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(O t Bu) 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 d 1 species, and show that the complex undergoes Berry pseudorotation. The alkoxide ligands render the disproportionation reaction, leading the formation of [Mo(O t Bu) 5 ] to be particularly facile, even though the parent complex [MoCl 4 (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.

Canopy Catalysts for Alkyne Metathesis: Investigations into a Bimolecular Decomposition Pathway and the Stability of the Podand Cap

“…[ 35 , 36 ] What had been isolated in the past was a dimetallatetrahedrane complex of type B as the presumed key intermediate of this type of transformation;[ 8 , 37 , 38 ] this species had been taken as an indication that collision of two metal alkylidynes might constitute a previously undescribed catalyst decomposition pathway. [8] The present result confirms this interpretation and shows that the coupling process does not stop at this intermediate stage but goes to completion with release of a low‐valent triple‐bonded Mo(+3) dimer, [39] if a small‐enough ligand set is chosen. Although other as yet unidentified molybdenum‐containing side products might be present in the crude mixture, bimolecular metathetic coupling of 1 a is obviously facile in the presence of but‐2‐yne (i. e., under the conditions of a catalytic alkyne metathesis reaction) and constitutes the major decomposition pathway.…”

Carborane Stabilized “19-Electron” Molybdenum Metalloradical

“…The computed EPR parameters are in good agreement with the experimental values considering the low spin density at the phosphorus center and rather complicated electronic structure of the Mo atom. 24 , 25 …”

A Unified Approach to Polycyclic Alkaloids of the Ingenamine Estate: Total Syntheses of Keramaphidin B, Ingenamine, and Nominal Njaoamine I

“…In the future, the significance of alkyne metathesis will also be defined by the upstream and/or downstream alkyne chemistry. Therefore, our laboratory is committed to explore opportunities along these lines in parallel to our ongoing work on fundamental and applied aspects of alkyne metathesis proper. ,,,, …”

“…Therefore, our laboratory is committed to explore opportunities along these lines 136 in parallel to our ongoing work on fundamental and applied aspects of alkyne metathesis proper. 35,36,114,137,138 ■ ASSOCIATED CONTENT * sı Supporting Information…”