| The research described in this thesis centers on the investigation of the solid-state and structural chemistry of metal coordination polymers.; In Chapter II, the irradiation of solid bis(trans-2-butenoato)calcium (1a) with {dollar}sp{lcub}60{rcub}{dollar}Co {dollar}gamma{dollar}-rays leads to conversion of 1a to the calcium salt of cis, trans-nepetic acid (2a) in 7.6% yield (based on recovered 1a). The structure of the acidified product 2b was established by the identity of the {dollar}sp1{dollar}H and {dollar}sp{lcub}13{rcub}{dollar}C NMR spectra with those of an authentic sample. The cyclodimerization process providing 2 exhibits several remarkable characteristics. Since recovered bis(trans-2-butenoato)calcium may be recycled, the reaction is an efficient, chemo- and stereospecific, solid-state synthesis of a small molecule using ionizing radiation. Cyclodimerization of trans-2-butenoate in solution or in the solid state is unprecedented. Nepetate 2a forms in 76% yield at 10% conversion as established by NMR, GC and GC/MS data. In order to establish whether the intermolecular orientation and distances suggest that this process might be topochemical, an X-ray structure determination was carried out on single crystals of 1. Calcium trans-2-butenoate is a two-dimensional coordination polymer. Each Ca{dollar}sp{lcub}2+{rcub}{dollar} ion occupies a site of crystallographic {dollar}Csb2{dollar} symmetry; the dihedral angle between adjacent pairs of butenoate planes in this structure is 14.4{dollar}spcirc.{dollar} Short contacts arise between pairs of 2-butenoate moieties coordinated to a single calcium ion. The product is not the diastereomer predicted from the ground-state crystal structure. A mechanism consistent with the production of the cis, trans-nepetate has been proposed. The successful characterization of reactant and product materials promises to clarify the relationship between ground-state crystal structure and product stereochemistry in radiation-induced solid-state reactions.; In Chapter III and IV, the crystal structures of La, Eu, Pr, and Gd(III) complexes of the trans-cinnamate ligand are all isomorphous (space group R3c). On the other hand, Y and Er complexes of the trans-cinnamate ion and the trans-{dollar}alpha{dollar}-methylcinnamate ion were isomorphous; these complexes crystallized in space groups P2{dollar}sb1{dollar} and P2{dollar}sb1/a{dollar} (a non-standard setting of space group P2{dollar}sb1/c),{dollar} respectively. All of the trans-cinnamate complexes are polar, linear coordination polymers, while the {dollar}alpha{dollar}-methylcinnamates are monomeric. (Abstract shortened by UMI.)... |
