Erbium fumarate [Er2(fum)3(H2O)4]·8H2O, 1, (fum = fumarate dianion) crystallizes at room temperature in a silica gel column. The structure is three-dimensional and consists of layers of erbium fumarate pillared by fumarate dianions acting in the bis-chelating mode. The layers contain arrays of erbium cations bridged by fumarate dianions acting in the bis-bidentate bridging mode. The relatively large channels formed in the direction of the a and c axes are filled by water molecules that form a hydrogen bonded layer, comprising cyclic hexamers with both boat and chair conformations and cyclic decamers with boat−chair−boat conformation. The water molecules are reversibly removed at 90 °C. The evacuated metal−organic framework, 2, is stable up to 400 °C. Both compounds 1 and 2 exhibit weak antiferromagnetic interactions.

The selectivity of reactant rotational and vibrational energy upon reactive cross sections for the reaction OH + Cl2 → HOCl + Cl is investigated in detail by performing quasiclassical trajectory (QCT) calculations on a six-dimensional, analytically constructed potential energy surface (PES). The construction of the PES was based on ab initio molecular orbital calculations of the HOClCl system using the unrestricted second-order Møller−Plesset perturbation theory approach. The quantum mechanical investigation produced three stationary points relevant to the title reaction, a transition-state configuration and two HOCl···Cl-type complexes. Geometries, energies, and vibrational frequencies are reported for these structures. The analytical functional form for the PES has been developed following the Schatz−Elgersma formulation incorporating the Sorbie−Murrell potential energy term for the HOCl molecule. Extended three-dimensional QCT calculations at low and moderate collision energies covered several rotational and vibrational reactant states to produce a detailed study of the selectivity upon the reactivity of the system. The resulting dynamical features are the strong enhancement of reactivity when the vibrational content of the breaking bond is raised and the exactly opposite effect when the vibrational excitation of the spectator OH bond is increased. The initial reactant rotation is shown to have a very minor influence on the dynamics.