Reversible Water-Induced Structural and Magnetic Transformations and Selective Water Adsorption Properties of Poly(manganese 1,1′-ferrocenediyl-bis(H-phosphinate))

A flexible and hydrolytically stable metal–organic framework [Mn(H2O)2(Fc(PHOO)2)·2H2O]n has been synthesized using ferrocene-based ligand bearing phosphinic groups (Fc(PHOOH)2 = 1,1′-ferrocenediyl-bis(H-phosphinic acid)). In this compound manganese atoms are bound by phosphinate fragments to give infinite chains, and the latter are interconnected by ferrocene groups to form two-dimensional coordination polymer. The elimination of both coordinated and lattice water molecules during heating up to 150 °C produced the compound, which is nonporous for nitrogen, but can selectively adsorb water over methanol and other solvents at 298 K. The reversible structural transformation during adsorption/desorption of water is also reflected in a change of magnetic properties of the metal–organic framework.