| In Chapter I, the structure, solid-state reactivity, and topotactic relationships between monomer and polymer phases of bis(tris(2-cyanoethyl)phosphine) nickel(II) halide complexes (NiX2CEP2) were re-examined. At temperatures of 115 and -5°C, crystals of NiCl2CEP2 were reproducibly observed with well-defined reaction fronts, propagating along the [001] reactant direction, whereas NiBr2CEP2 exhibited a large number of closely-spaced nucleation sites and a lack of front motion at temperatures of -5°C. The (100), (010), and (001) direct-space planes of monomer NiCl2CEP2 correspond to (-100), (010), and (00-1) of one polymer orientation, respectively, and to (-30-2), (010), and (30-2) of a second polymer orientation, respectively. The (100), (010), and (001) direct space planes of monomer NiBr2CEP2 correspond approximately to (-1-10), (013), and (-120) of the polymer, respectively.;In Chapter II, structures and proposed solid-state polymerization of diacetylenes (ETCD, PUDO, IPUDO) and three different cyanoaromatic acid/isonicotinamide co-crystals were investigated. For the diacetylenes, near-identical values of R, d, and ϕ were consistent with the observed solid-state reaction. The non-planarity observed for IPUDO was likely caused by isopropyl groups in the molecule, which induced a gauche-conformation of the flexible n-butyl arms. For the co-crystals, different hydrogen bonding motifs were observed despite the similarity of the chemical structures. Structural elucidation for two of the co-crystals showed no infinite C≡N···C≡N contacts, which supports the absence of thermal reactivity. Analysis of structural parameters and hot-stage microscopy indicated that the third sample polymerized upon heating.;In Chapter III, the structure and polymerization of three previously unknown beta-cinnamic acid derivatives (2-nitro, 2-chloro, and 3,4-chlorocinnamic acid) were investigated. UV-irradiation for various cinnamic acid crystals yielded respective photodimers, consistent with the topochemical postulate, where the reaction occurs between nearest neighbors within 4.2 A.;In Chapter IV, the structures of the elusive sodium trans-2-butenoate and potassium propanoate were investigated. The triclinic potassium propanoate may be considered polymorph and polytypes of the previously known monoclinic potassium propanoate. Additional CSD search concluded that a limited number of the potassium alkyl and alkenyl carboxylates exhibit a pseudo-5-coordinate configuration. |
