Experimental and Computational Studies on Quadruply Bonded Dimolybdenum Complexes with Terminal and Bridging Hydride Ligands

This contribution focuses on complex [Mo 2 (H) 2 (μ‐Ad Dipp2 ) 2 ] ( 1 ) and tetrahydrofuran and pyridine adducts [Mo 2 (H) 2 (μ‐Ad Dipp2 ) 2 (L) 2 ] ( 1⋅thf and 1⋅py ), which contain a trans ‐(H)Mo≣Mo(H) core (Ad Dipp2 =HC(NDipp 2 ) 2 ; Dipp=2,6‐ i Pr 2 C 6 H 3 ). Computational studies provide insights into the coordination and electronic characteristics of the central trans ‐Mo 2 H 2 unit of 1 , with four‐coordinate, fourteen‐electron Mo atoms and ϵ ‐agostic interactions with Dipp methyl groups. Small size C‐ and N‐donors give rise to related complexes 1⋅L but only one molecule of P‐donors, for example, PMe 3 , can bind to 1 , causing one of the hydrides to form a three‐centered, two‐electron (3c‐2e) Mo‐H→Mo bond ( 2⋅PMe 3 ). A DFT analysis of the terminal and bridging hydride coordination to the Mo≣Mo bond is also reported, along with reactivity studies of the Mo−H bonds of these complexes. Reactions investigated include oxidation of 1⋅thf by silver triflimidate, AgNTf 2 , to afford a monohydride [Mo 2 (μ‐H)(μ‐NTf 2 )(μ‐Ad Dipp2 ) 2 ] ( 4 ), with an O,O’‐bridging triflimidate ligand.