This thesis is primarily concerned with the investigation of a structure-reactivity relationship in a series of pentacyclic Isodrin derivatives. These compounds undergo a two-hydrogen atom dyotropic rearrangement at vastly differing rates when apparently small structural changes are made. Two pairs of these isomers (with the formulas C(_16)H(_8)Cl(_10) and C(_16)H(_9)Cl(_9) ) have been investigated using both X-ray and neutron single crystal diffraction studies, at ambient and low temperatures. The experimental details of these studies are given for five experiments and the results of the least-squares refinements made using the data from these experiments are reported herein. In addition to conventional crystallographic studies, an experimental charge density study of one of these compounds, C(_16)H(_9)Cl(_9), has been made at 123K. The electron density was modelled using a multipole model which allows explicitly for the aspherical nature of the electron density. The results of this study, including a topological analysis of the charge density are reported in this thesis. The structures of six organometallic, four molybdenum bis(imido) and two half-sandwich niobium imido complexes, are also reported herein. Their structures were determined from single crystal diffraction data. These compounds show the expected structures predicted using the pseudo-isolobal relationship to the Group 4 bent metallocenes of which they may be considered analogues.