Interconversion of Quadruply and Quintuply Bonded Molybdenum Complexes by Reductive Elimination and Oxidative Addition of Dihydrogen

Experimental and Theoretical Studies on Arene‐Bridged Metal–Metal‐Bonded Dimolybdenum Complexes

“…On these grounds, it was thought worthwhile to expand our knowledge of these molecules, and in this vein this study focuses on a range of arenes, which in addition to benzene and toluene,12b includes anisole, 1,4‐C 6 H 4 Me 2 , and the fluoroarenes C 6 H 5 F and 1,4‐C 6 H 4 F 2 . The complexes 3⋅arene were synthesized by one or more of the pathways A‐ ‐ C in Scheme .…”

“…The computational studies developed in our earlier communication12b for the benzene complex 3⋅C 6 H 6 have now been extended to other 3⋅arene adducts (arene=C 6 H 5 Me, p ‐C 6 H 4 Me 2 , and p ‐C 6 H 4 F 2 ) and their rotameric preferences. Geometry optimization yields in all cases structures that are in excellent agreement with the experimental ones in the MoMo and MoC distances, in the CC distance distribution pattern of the aromatic ring, and in the N‐Mo‐Mo‐N hinge angles, as well as in the orientation of the substituted arene rings.…”

“…Focusing the discussion on the orbitals with A 2 and B 2 symmetries that are responsible for the back‐bonding interactions,12b despite the fact that in the independent fragments the two B 2 orbitals are occupied and the two A 2 ones are empty (the Supporting Information, Figure S13), in the Mo 2 C 6 H 6 adduct the antibonding B 2 combination is empty whereas the bonding orbital with A 2 symmetry is occupied. As a consequence, the MoMo bonding δ(B 2 ) orbital is partially depopulated and its antibonding counterpart δ*(A 2 ) is partially occupied, resulting in a decreased MoMo bond order 12b. Similarly, the CC bonding π(B 2 ) orbital is in part depopulated and the antibonding π*(A 2 ) is partly occupied, ensuing in a weakening of the CC bonds.…”

“…In collaboration with the group of Power, we reported recently the formation of some mono‐ and bis(terphenyl) dimolybdenum compounds of unusual unsaturated structures 12a. Latterly, our group also communicated that the bis(hydride) bis(amidinate) derivative, [Mo 2 (H) 2 {HC( N ‐2,6‐ i Pr 2 C 6 H 3 ) 2 } 2 (thf) 2 ], 2 , with a Mo II 2 core, and Tsai’s complex,8 [Mo 2 {HC( N ‐2,6‐ i Pr 2 C 6 H 3 ) 2 } 2 ], 4 , interconvert readily by formal dinuclear reductive elimination and oxidative addition of H 2 12b. This work also demonstrated that interesting Mo I 2 ⋅arene structures, compounds 3⋅arene , could be generated starting from either 2 or 4 , under suitable conditions.…”

The MoMo Quintuple Bond as a Ligand to Stabilize Transition‐Metal Complexes

“…[9] Since then, many quintuple bonded homounivalent Group VI dinuclear compounds containing nitrogen donors were subsequently characterized. [10] Preliminary reactivity examinations on these low-coordinate dinuclear species revealed that the presence of d-bond charge density enable them to react with small inorganic molecules [11] and organic functionalities. [11,12] For example,t hese species underwent reductive complexation with the pnictogen elements [13a] and unsaturated hydrocarbons.…”