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Cages and rings of monoorganostannoxanes and cyclic phosphoranes
Abstract
The following dissertation contains projects in two areas of main group inorganic chemistry, specifically tin(IV) and phosphorus(V). Focus on the tin research is on the structural and solution state characterization of monoorganostannoxane cages. The phosphorus study encompasses the isolation and characterization of monocyclic and spirocyclic phosphoranes. Although these topics are not directly related, the research in both is directed toward understanding the principles which lead to the stabilization of cyclic structures. Monoorganostannoxanes. The following sections on monoorganostannoxane cage compounds, focus on the incorporation of small R groups on the parent acid center and on the use of arsenic acids as bridging ligands between tin centers in the clusters. Both these areas showed that different cages were stabilized which elucidates the dependence of steric bulk on the cage formation. Earlier the drum cage was not found for phosphinic acids but dimethylphosphinic acid coupled with n-BuSnOOH produces a drum form as its most stable form. In arsenic acid derivatives the butterfly cage is the most stable and exists if any extra acid is in solution. The butterfly cage is the only form which exists when mixed arsenic acid systems are introduced. This contrasts the mixed carboxylate, phosphinate systems which undergo ligand exchange instead of insertion. Cyclic phosphoranes. Isolation of large ring cyclic phosphoranes has shown that the axial equatorial placement of such rings is most stable for the solid state. The inclusion of sulfur or nitrogen for oxygen and bulky substituents have not been shown to favor diequatorial placement of the ring. Ring effects still predominate over electronegativity rule, changes in ring size and substituent size. Solution state $\sp{31}$P NMR and $\sp1$H NMR has been studied for many of the new cyclic phosphoranes. The chemical shift of the phosphorus signal shows a dependence on each cyclic and/or acyclic substituent. Variable temperature protron spectra are reported which show the inhibition of fluctional behavior and energies of activation were calculated.
Subject Area
Inorganic chemistry|Chemistry
Recommended Citation
Burton, Sarah Dexter, "Cages and rings of monoorganostannoxanes and cyclic phosphoranes" (1991). Doctoral Dissertations Available from Proquest. AAI9132824.
https://scholarworks.umass.edu/dissertations/AAI9132824