Inaug.-diss.--Basel. / Vita. "Literatur": on fold. plates.

Thesis (Ph. D.)--Indiana University, 1937. / Reproduced from typewritten copy. "Literature cited": Numb. l. 21.

Inaug.-diss.--Basel. / Vita. "Literatur": on fold. plates.

Thesis (PH. D)--Columbia University, 1932. / Vita. Bibliography: p. 36.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 85-89).

The family of polycyclic aromatic hydrocarbons naphthalene, acenaphthene and acenaphthylene, containing rigid organic backbones, allow the study of non-bonded intramolecular interactions. Due to the rigid framework, heteroatoms that are substituted at the peri-positions (positions 1- and 8- of the naphthalene ring and positions 5- and 6- of the acenaphthene and acenaphthylene rings) are forced to occupy space that is closer than the sum of their van der Waals radii, resulting in severe steric strain and unique interactions. In spite of this, a vast amount of peri-substituted naphthalenes have been prepared, however acenaphthene and acenaphthylene compounds have received much less attention. Preparation of these sterically crowded systems is possible because of the backbones ability to relieve strain as a result of both attractive and repulsive interactions. Attractive interactions relax the backbone via formation of weak or strong bonds between the substituents. Alternatively, repulsive interactions can result in the deformation of the backbone away from its natural geometry by buckling the ring system and causing the peri-bonds to distort in-plane and out-of-plane. Peri-substituted systems can also ease strain by forming compounds with bridging atoms or through bidentate coordination to form metal complexes with, for example, metal bis(phosphine) or bis(thiolate) moieties. The competition between attractive and repulsive forces, the method by which peri-substituted compounds relieve steric strain, is investigated in this thesis using a variety of different peri-moieties and the aforementioned organic backbones. Chapter 2 initially focuses on the formation of a series of platinum bis(phosphine) complexes, constructed from corresponding peri-substituted naphthalenes, 1,8-naphthosultone and 1,8-naphthosultam, the chemistry of which is outlined in Chapter 1. A corresponding study of platinum bis(phosphine) complexes, constructed from analogous 5,6-dihydroacenaphtho[5,6-cd]-1,2-dithiole and 5,6-dihydroacenaphtho[5,6-cd]-1,2-diselenole bidentate ligands is provided in Chapter 6. The chemistry of peri-substituted naphthalenes is well documented and a number of reviews have been written on this subject. Chapter 3, meanwhile, reviews the chemistry of related acenaphthene and acenaphthylenes which have seen increasing use in the literature over the last few years. Chapter 4 investigates the relationship between repulsive and attractive interactions that occur between the peri-substituents in a series of bis-chalcogen, mixed chalcogen-chalcogen and mixed halogen-chalcogen acenaphthylenes. By comparison with their known naphthalene and acenaphthene counterparts, the effect the rigid aromatic ring system has on the molecular geometry is examined. Finally, Chapter 5 looks at a series of acenaphthene and acenaphthylene compounds containing ArTe peri-substituents and explores how repulsive and attractive interactions affect molecular conformation and Te•••Te spin-spin coupling constants.

Donor–acceptor complexes have been known for over a century and enjoy a long list of applications in chemistry. In this thesis, the dative interaction between phosphorus and its two heavier congeners, arsenic and antimony, are explored. Utilising peri-substitution atoms can be forced in close proximity to one another, resulting in a repulsive (nonbonding) interaction or an attractive (bonding) interaction. Hence, peri-substitution can be used to support traditionally ephemeral species. A range of phosphorus, arsenic and antimony containing peri-substituted compounds were synthesised and characterised using multi-nuclear NMR, mass spectrometry, elemental microanalysis and single crystal X-ray diffraction. The reduction of a peri-substituted dichloroarsine, led to the formation of a primary arsine, which underwent spontaneous elimination of hydrogen gas forming the first structurally characterised cyclic arsanylidene–σ⁴–phosphorane, the formation of which is essentially thermoneutral. With no sterically demanding groups shielding the arsenic atom, the reactivity and spectroscopic characteristics of this compound were explored through reactions with selected metal complexes. Reaction of the arsanylidene–phosphorane with a limited amount of oxygen reveals arsinidene–like reactivity via the formation of cycloarsines, supporting the formulation that the bonding can be described as a Lewis base–stabilised arsinidene R₃P→AsR. A series of phosphine–stibine and phosphine–stiborane peri-substituted acenaphthenes containing all permutations of pentavalent groups –SbCl[sub]nPh[sub](4-n) as well as trivalent groups –SbCl₂, –Sb(R)Cl, and –SbPh₂ (R = Ph, Mes), were synthesised and characterised by multi-nuclear NMR, MS, microanalysis and X-ray crystallography. The bonding in these species was studied by DFT computational methods. The P–Sb dative interactions range from strongly bonding to nonbonding as the Lewis acidity of the Sb acceptor is decreased. Unexpectedly, the phosphine–stiborane complexes represent the first examples of σ⁴P→σ⁶Sb structural motif. A study of unsymmetrical bis(phosphino)acenaphthenes showed the presence of a 3c–4e interaction, supported by the short P∙∙∙P distances and the large J[sub](PP) through-space couplings. Severely strained bis(sulfides) of the unsymmetrical phosphines experience pronounced displacements of the exocyclic peri-atoms. The resulting nonbonded intramolecular P∙∙∙P distances (ca. 4.05 Å) are among the largest ever reported peri-separations, independent of the heteroatoms involved. In addition, three metal complexes with square planar, tetrahedral and octahedral geometry are reported. In all three cases, the acenaphthene backbone is distorted to a greater extent than in the free bis(phosphine) but notably less than in the bis(sulfides).

Organic frameworks with rigid backbones, such as acenaphthene, are highly suitable for the study of interatomic interactions. The short “natural” peri-distance (2.44 Å) and the rigidity of the aromatic system causes considerable steric strain between peri-substituted heteroatoms. As a consequence, substitution at both peri-positions leads to in- and out-of-plane distortions, which often result in buckling of the ring system. In order to relax this geometric strain, weak bonding interactions can also exist between the peri-substituents. This thesis focuses on the synthesis, structural characterisation and investigation of a range of sterically crowded peri-substituted acenaphthene compounds. This involves the study of the acenaphthene geometry, through X-ray crystallography when different peri-substituents occupy the close 5,6-positions; our main focus is to study weak non-bonded interactions that can occur across the peri-gap, for example weakly attractive three-centre four-electron (3c-4e) type interactions which are known to prevail in such compounds under the appropriate conditions. Repulsion within these systems, resulting from the steric crowding of the peri-space is also investigated, employing changes in bond lengths, bay-region angle splay, displacement of atoms from the mean plane and central acenaphthene torsion angles to help quantify the degree of acenaphthene distortion, which are all conveniently probed by the peri-distance. To this end we have synthesised a range of novel sterically crowded mixed bromo-tin acenaphthene derivatives (Chapter 3), chalcogen-tin acenaphthene molecules (Chapter 4), phosphorus–tin derivatives (Chapter 5) and a series of homologous tin-tin acenaphthenes (Chapter 6). All the compounds studied in this thesis were characterised by multinuclear NMR spectroscopy and X-ray crystallography in an effort to gain a greater understanding of the deformation that occurs when disparate functionalities are located in close proximity and explore the potential for weak non-covalent intramolecular interactions to occur.