Sulfur-MOP: A Highly Robust Metal-Organic Polyhedron Built with Nickel Thiocarboxylate Paddlewheels

Metal-organic polyhedra (MOPs) are promising for their use as porous elementary building blocks in materials' design, but their application is strongly limited by the low number of water-stable structures built with abundant first period transition metals. Here, we introduce the first MOP presenting metal-sulfur bonds (SMOP), built with the water-stable nickel(II) thiocarboxylate four-fold paddlewheel unit Ni₂(RCOS)₄. To overcome the uncontrolled reactivity of free thiocarboxylate with metal ions, we used a double-modulation approach involving in situ hydrolysis of the ligand precursor and use of nickel thiobenzoate as the metal precursor, achieving the gram-scale synthesis of SMOP with good crystallinity. The resulting SMOP presented a diameter of 20 Å with an inner cavity of 10 Å. Furthermore, the SMOP possessed a high accessible microporosity (S_BET = 410 m²/g) and remarkable stability in organic solvents and in water from pH 2 to 12.