title: Polymorphism and inclusion properties of three-dimensional metal-organometallic frameworks derived from a terephthalate sandwich compound.
abstract: An organometallic sandwich compound of terephthalic acid, namely, [(eta(5)-Cp)Fe(II){eta(6)-(1,4-C(6)H(4)(COOH)(2))}](+) (H(2)1(+)), is reported, along with X-ray single crystal structures of [H1 x H(2)1][PF(6)] and H1. [H(2)1 x H1][PF(6)] was reacted with the nitrate salts of Co(II) and Ni(II) to yield a series of three-dimensional (3D) metal-organometallic framework (MOMF) materials of the composition [M(3)(1)(4)(mu-H(2)O)(2)(H(2)O)(2)][NO(3)](2) x xsolvent (M = Co(II) (2), Ni(II) (3); xsolvent = 4EtOH, or 2DMF x 2 H(2)O). These framework structures were shown by single crystal and powder X-ray diffraction to be polymorphic, possessing identical 3D body-centered tetragonal network topologies, but differing in the manner by which the [CpFe](+) groups are arranged within the two-dimensional, square grid sheets of the 3D networks. alpha-2-EtOH, beta-2-EtOH, alpha-3-EtOH, beta-2-DMF, and beta-3-DMF were thermally desolvated, giving rise to isolable apohosts of composition [M(3)(1)(4)(mu-H(2)O)(2)(H(2)O)(2)][NO(3)](2) (M = Co(II) (2), Ni(II) (3)) that were shown by PXRD to possess different, as yet unknown, crystal structures. The desolvated apohosts were studied with respect to their ability to selectively reabsorb water and/or alcohols. They show a modest preference for the absorption of water and short chain, linear alcohols (<C4), with modest selectivity for 1-PrOH.
authors.affiliation: Department of Chemistry, Georgetown University, Washington, District of Columbia 20057, USA.
authors.forename: Sayon A
authors.initials: SA
authors.lastname: Kumalah
authors.forename: K Travis
authors.initials: KT
authors.lastname: Holman