Unfortunately, obtaining binding enthalpies stronger than -10 kJ/mol has proven difficult when utilizing strategies such as linker functionalization, formation of interpenetrated frameworks, and post-synthetic metalation of frameworks. Since the first demonstration of increased H2 uptake in a MOF by creating coordinatively unsaturated metal sites (open metal sites), we and others have synthesized a variety of MOFs with open metal sites to identify critical factors in strengthening metal-H2 interactions. Indeed, the strength of the metal-H2 interaction at Lewis acidic metal sites mostly follows the Irving-Williams series (Mn II < Fe II < Co II < Ni II ), which is often used to explain stability constants of high-spin octahedral transition metal complexes. Among the Ni II -based frameworks, Ni2(mdobdc) (m-dobdc 4-= 1,3-dioxido-4,6-benzenedicarboxylate) has a high density of charge-dense Ni II sites, achieving a record-high volumetric H2 adsorption capacity at (sub)ambient temperatures of 223-298 K and 100 bar. However, most MOFs with Lewis acidic open metal sites, including Ni2(m-dobdc), still do not reach the optimal H2 binding strength and struggle with minimal tunability of H2 adsorption enthalpy. In particular, even upon changing the identity of metal ions, functionality of the organic linker, and/or the coordination environment of the first coordination sphere, differences in adsorption enthalpy of less than 5 kJ/mol are observed in most cases. Recently, coordinatively unsaturated square pyramidal V II sites in the triazolate-based framework V2Cl2.8(btdd) (H2btdd = bis(1H-1,2,3-triazolo- [4,5-b],[4′,5′-i])dibenzo [1,4]dioxin) were shown to adsorb π-acidic small molecules such as N2 and H2 via favorable orbital interactions, leading to much stronger gas adsorption enthalpies than classical Lewis acidic metal sites. Notably, V2Cl2.8(btdd) is the first example of a porous material within the optimal H2 binding range, exhibiting an adsorption enthalpy of -21 kJ/mol at its V II sites. While V2Cl2.8(btdd) demonstrates the importance of orbital-interaction-mediated H2 binding to enhance H2 binding strength, the V II sites are highly susceptible to irreversible oxidation by trace O2. Moreover, the synthesis of analogous V II frameworks, such as V2X2(bbta) (H2bbta = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) or V2(dobdc) (dobdc 4-= 2,5-dioxido-1,4-benzenedicarboxylate) has not been achieved.