title: Reversible gas uptake by a nonporous crystalline solid involving multiple changes in covalent bonding.
abstract: Hydrogen chloride gas (HCl) is absorbed (and reversibly released) by a nonporous crystalline solid, [CuCl2(3-Clpy)2] (3-Clpy = 3-chloropyridine), under ambient conditions leading to conversion from the blue coordination compound to the yellow salt (3-ClpyH)2[CuCl4]. These reactions require substantial motions within the crystalline solid including a change in the copper coordination environment from square planar to tetrahedral. This process also involves cleavage of the covalent bond of the gaseous molecules (H-Cl) and of coordination bonds of the molecular solid compound (Cu-N) and formation of N-H and Cu-Cl bonds. These reactions are not a single-crystal-to-single-crystal transformation; thus, the crystal structure determinations have been performed using X-ray powder diffraction. Importantly, we demonstrate that these reactions proceed in the absence of solvent or water vapor, ruling out the possibility of a water-assisted (microscopic recrystallization) mechanism, which is remarkable given all the structural changes needed for the process to take place. Gas-phase FTIR spectroscopy has permitted us to establish that this process is actually a solid-gas equilibrium, and time-resolved X-ray powder diffraction (both in situ and ex situ) has been used for the study of possible intermediates as well as the kinetics of the reaction.
authors.affiliation: Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
authors.forename: Guillermo Mínguez
authors.initials: GM
authors.lastname: Espallargas
authors.forename: Michael
authors.initials: M
authors.lastname: Hippler
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Florence
authors.forename: Philippe
authors.initials: P
authors.lastname: Fernandes
authors.forename: Jacco
authors.initials: J
authors.lastname: van de Streek
authors.forename: Michela
authors.initials: M
authors.lastname: Brunelli
authors.forename: William I F
authors.initials: WI
authors.lastname: David
authors.forename: Kenneth
authors.initials: K
authors.lastname: Shankland
authors.forename: Lee
authors.initials: L
authors.lastname: Brammer
mesh_terms: D003460:Crystallization; D005740:Gases / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D044367:Phase Transition; D016062:Porosity; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D005740:Gases; D014867:Water; D006851:Hydrochloric Acid