Oxidative Addition of Dihydrogen to Divanadium in Solid Ne: Multiple‐Bonded Triplet HVVH and Singlet V2(μ‐H)2

Dinuclear compounds of early transition metals with a high metal-metal bond-order are of fundamental interest due to their intriguing bonding situation and of practical interest because of their potential involvement in catalytic processes. In this work, two isomers of V 2 H 2 have been generated in solid Ne by reaction between V 2 and H 2 and detected by infrared spectroscopy. The linear HVVH molecule ( 3 Sigma g - ground term), being the product of the spin-allowed reaction between V 2 ( 3 Sigma g - ground term) and H 2 , and a lower-energy, folded V 2 (mu-H) 2 isomer ( 1 A 1 ground term) with two bridging hydrogen atoms. Both isomers are characterized by metal-metal bonding with a high bond-order, the orbital occupations point to quadruple bonding. Irradiation with ultraviolet light induces the transformation of linear HVVH to folded V 2 (mu-H) 2 , whereas irradiation with visible light initiates the reverse reaction.