The protonation of very weak organic bases of the carbonyl type has been studied in order to determine both their absolute and relative magnitudes of basicity. These results have been used to establish the preferred modes of protonation in those cases where alternative sites of attachment of the proton are possible. The basicities of twenty m- and p-substituted acetophenones have been determined by a spectrophotometric method in sulphuric acid media. The simple Hammett relation does not hold for the ionization of these bases but a very good correlation exists between pK(BH+) and σ⁺. The basicities of seven m- and p-substituted benzaldehydes have been determined in the same way. The ionization of these bases exhibits a similar modified linear free energy relationship, and the results are compared with those for acetophenones. The basicity of o-tolualdehyde was determined in an attempt to estimate the steric effects of ortho substitution. The effects of symmetrical trisubstitution on the basicity of benzaldehyde and acetophenone are compared and discussed. The basicities of twenty-three similarly substituted benzoic acids and ten substituted benzamides have also been determined and the linear free energy relationships for these ionizations examined with respect to the model carbonyl compounds discussed above. The similarity of behaviour of the benzoic acids to that of the aldehydes and ketones indicates that protonation at the carbonyl oxygen is the preferred mode. On the other hand the ionization of benzamides follows a conventional linear free energy relationship, indicating absence of direct resonance interactions in the conjugate acids and thus that protonation on nitrogen is the preferred mode. The order of basicity of the various types of basic group has been established and the significance of the p-values for these ionizations is discussed. Correlations between observed ultraviolet spectral displacements produced by substitution in the various bases and conjugate acids provide supporting evidence for the preferred modes of protonation described above. A good correlation is found between pK(BH+) and the carbonyl stretching frequencies in the ketones but it appears that a similar correlation in the benzoic acid series cannot be used as an effective criterion of protonation site. The infrared spectra of amides and amide salts have been investigated and the changes in spectra produced on protonation support an N-protonated form for their conjugate acids. Other aspects of the problem of protonation of benzoic acids and benzamides including available n.m.r. evidence have been examined and discussed. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 143-152).

214 leaves : ill., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1979

Thesis (Ph.D.) -- University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1979.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The structures of four di-(tertiary arsine) derivatives of metal carbonyls have been determined by a selection of direct, Patterson, and Fourier methods, applied to Mo-[formula omitted] diffractometer data. 1,2- bis(dimethylarsino) tetrafluorocyclobutene-tri-iron decacarbonyl, Me₂AsC=C(AsMe₂) CF₂CF₂ .Fe₃ (CO)₁₀, crystallizes in the monoclinic space group P2₁/c, with a = 11.60, b = 20.04, c = 22.11 Å, β = 93.7°, Z = 8 (two molecules per asymmetric unit). The structure was refined by least-squares procedures (a total of 74 atoms) to a final R of 0.09 for 2524 observed (of a total of 3234) reflections. The molecule is best described as a derivative of Fe₃(CO)₁₂, in which one terminal carbonyl group on each of the two equivalent iron atoms is replaced by an arsenic atom of the di-(tertiary arsine) ligand. The central Fe₃As₂ cluster is significantly bent in one of the molecules of the asymmetric unit, but is more nearly planar in the other molecule. The Fe-Fe bond distances in the iron triangle (2.53,2.65,2.65 Å) do not differ significantly from those in the parent compound. Crystals of bis(1,2- bis(dimethylarsino)tetrafluoro cyclobutene)triruthenium octacarbonyl,(Me₂AsC=C(AsMe₂)CF₂CF₂)₂. Ru₃(CO)₈, are orthorhombic, space group Pbcn, a = 9.07, b = 18.53, c = 21.81 Å, Z = 4 (one-half molecule per asymmetric unit). The structure was refined by least-squares procedures to a final R of 0.078 for 1507 observed (of a total of 1712) reflections. The molecule lies on a crystallographic two-fold axis, and is best described as a derivative of Ru₃(CO)₁₂ in which two carbonyls on one ruthenium and one carbonyl on each of the other ruthenium atoms are replaced by the arsenic atoms of the bidentate di-(tertiary arsine) ligands, in such a way that each ligand bridges two ruthenium atoms, and one Ru-Ru bond remains unbridged. This unbridged Ru-Ru bond (2.785 Å) is significantly shorter than the bridged ones (2.853 Å) and than those of the parent Ru₃(CO)₁₂ (average 2.848 Å). The skeletons of the di-(tertiary arsine) ligands do not deviate significantly from exact planarity, the plane of each ligand being twisted 18° with respect to the plane of the ruthenium triangle. The mean Ru-As bond length is 2.407 Å. 1,2- bis(dimethylarsino)tetrafluorocyclobutene-triruthenium decacarbony1, Me₂AsC=C(AsMe₂)CF₂CF₂.Ru₃(CO)₁₀, crystallizes in orthorhombic space group. P2₁2₁2₁, a = 8.594, b = 18.795, c = 16.69 Å, Z = 4. The structure was refined by least-squares procedures to a final R of 0.076 for 1828 observed (of a total of 2028) reflections. The compound is a derivative of Ru₃(CO)₁₂ in which one equatorial carbonyl group on each of two ruthenium atoms is replaced by an arsenic atom of the di-(tertiary arsine) ligand in such a way that the plane of the ligand is twisted 18° with respect to the plane of the ruthenium triangle. Ru-Ru bond distances are 2.831, 2.831, and 2.858 Å, the difference between the short and long bond lengths being statistically significant and explicable in terms of the bonding characteristics of the ligand. 1,2- bis(dimethylarsino)hexafluoropropanemolybdenum tetracarbonyl, Me₂AsCF(CF₃)CF₂AsMe₂.Mo(CO)₄, crystallizes in the monoclinic space group C2/c, a = 25.06, b = 13.27, c = 11.56 Å, 6 = 102.8°, Z = 8. The structure was refined by least squares methods to a final R of 0.073 for 1510 , observed (of a total of 1750) reflections. The molecule is derived from Mo(CO)₆by replacing two carbonyl groups with the arsenic atoms of the chelating di-(tertiary arsine) ligand. Two of the carbon-fluorine bond distances (mean 1.505 Å) are significantly longer than the others (mean 1.30 Å) and the distance between the carbon atoms of the ligand skeleton is remarkably short (1.40). The weighted mean Mo-As bond length is 2.572 Å. / Science, Faculty of / Chemistry, Department of / Graduate

An improved method for preparing (L-L)Fe2(CO)6 complexes (L-L is a fluorocarbon-bridged ditertiary arsine or phosphine) has been developed. The reactions of these complexes with monodentate L and bidentate L-L ligands give rise to eight types of products. These include L[sup m](L-L)Fe2(CO)5 and (L-L) [sup m] (L-L)Fe2(CO)5 in which the mono-dentate ligand replaces one carbonyl group from Fe[sup A]; (L[sup m])2[sup s] (L-L)Fe2(CO)4 c A and (L-L) (L-L)Fe2(CO)4 in which two carbonyl groups on Fe have been replaced; (Lm)2(L-L)Fe2(CO)^, (L-L)b(L-L)Fe2(CO) and (dppp) [sup B] (L-L)Fe2(CO)4 in which one carbonyl group on each iron has been replaced; and (Lm)3(L-L)Fe2(CO) in which the ligands replace two carbonyl groups from Fe[sup A] and one from Fe[sup B] . The spectroscopic properties and some reactions of these derivatives are described. The reactions of Co2(CO)8 and (ir-alkyne)Co2(CO)6 with some monodentate and bidentate ligands and that of [LCo(CO)3]2 with bidentate ligands have been investigated. Several new compounds have been isolated; these include bridged derivatives (L-L) [sup b]2Co2(CO) [sup t]2(C0) [sup b]2 and L(L-L) [sup c]Co2(CO)3[sup t] (CO) [sup b]2, non-bridged derivatives (L-L)Co2(CO)^[sup t]7and [(L-L)Co(CO)3]2, ionic products [L2(L-L)Co(CO)]2+[sub 2](X⁻)2 and L4(L-L)Co2(CO)4[sup 2+](X⁻ )2, and substitution products L[sub n](RC = CR)Co2(CO)[sub 6-n](n = 1-4), (L-L)[sup c][sub 2](RC = CR)Co2(CO)4> (dppp)°(RC = CR)Co2(CO)2 (L-L)b2(RC = CR)Co2(CO)2 and (L-L)2(RC = CR)Co2(CO)2. The proposed molecular structures are based on chemical and spectroscopic information. In parallel with the preparative work, 59Co nqr studies on cobalt carbonyl complexes have been carried out. The effects of Y on the nqr spectra of the [Y3PCo(CO3)2 (Y = oph, 0Me, 0Et> Bu[sup n]) compounds are found to be both inductive and conjugative. The coupling constants of the L2Co(CO)+3X (L = Ph3P; X = Co(CO)4, BPh4) compounds appear to be insensitive to the formal oxidation state of the Co atom. The spectra of some substituted derivatives of Co2(C0)8 have been interpreted z o in the light of their structures. The nqr data of (RC = CR')Co2(CO)6 (R = R' = H, CH2OH, Ph, CF3; and R = Bu[sup t], R' = H) are found to be sensitive to the inductive and conjugative effects of the R and R' groups. Some 35Cl nqr studies on fluoroalicyclic YC = CC1(CF2)n (Y = substituent, n= 2 to 4) compounds were also undertaken. The 35 Cl nqr frequencies of these compounds are roughly related to the electronegativity of the substituents Y and to the ring size, suggesting that the inductive effect is the main factor responsible for the change. It also seems that the substituents F, OMe, N3, Me2 show both inductive and conjugative effects. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

The oxidative elimination reactions of (5-X-phen)Mo(C0)₄ (X = H, CH₃, Cl, NO₂; phen = o-phenanthroline) and (3,4,7,8-(CH₃)₄-phen)Mo(CO)₄ with mercuric chloride in acetone have been investigated. In these reactions, a carbon monoxide group is replaced by two univalent ligands, accompanied by the corresponding increase in coordination number and formal oxidation state of the central metal atom, to give products of the type, (X-phen)Mo(CO)₃(Cl)HgCl. With the exception of (3,4,7,8-(CH₃)₄-phen), the substituted o-phenanthrolines were selected so as to minimize steric differences from one substrate to another while obtaining the widest range of pKₐ of the ligand.

No description available.