Photoelectron spectroscopy is used to investigate the electronic structure of molybdenum-molybdenum quadruple bonds in dimolybdenum tetracarboxylates. The variable energy photoelectron spectra of the valence region of dimolybdenum tetraacetate are reported for a range of incident photon energies. The pi components of the metal-metal bond contain the most molybdenum 4d character. The sigma component has contribution from both the ligand and the molybdenum 4p orbitals on the adjoining molybdenum. The delta component has significant overlap with the ligand orbitals. A comparative gas phase and surface ultraviolet photoelectron study of dimolybdenum tetrabenzoate is also reported. This is the first dimolybdenum tetracarboxylate where the ligand is capable of large resonance overlap with the metal center. There is significant orbital overlap between the ligand and the metal-metal bond, especially with the delta component. Both of these studies show that there is electronic communication between the metal-metal bond and the carboxylate ligand.

The first tris(imido) complex of a group 6 transition metal, [Li(THF)₄][W(=NAr)₃Cl] (8) (Ar = 2,6 iPr-C₆H₃) was prepared from W(=NAr)₂Cl₂(THF)₂ (2) and 2 equiv of the corresponding lithium amide, LiNHAr in THF. Complex (8) crystallizes in the monoclinic space group P2(1/n) with a = 13.787 (4) Å, b = 17.348 (5) Å, c = 22.781 (8) Å, and β = 90.43 (3)° with Z = 4. The crystal contains discrete C₃ᵥ [W(=NAr)₃Cl]⁻ anions with imido W-N-C(ipso) angles averaging 170.8 (15)° and imido W-N bonds averaging 1.782 (15) Å. The neutral imido species W(=NAr)₃(PMe₃) (15) was made by adding 10 equiv of PMe₃ to (8). "Coupling" of the imido ligand in (15) with CO₂ and O=C=NR (R = Ph, ᵗBu) gave W[NArC(O)O] (=NAr)₂ PMe₃ (20) and W[NArC(O)NR](=NAr)₂PMe₃ (19) respectively. 2,6 Diisopropylaniline was added to (8) to give the complex W(=NAr)₂(NHAr)₂ (9). The chloride ligand of complex (8) was replaced by Li alkyl reagents to yield alkylated product [Li(THF)₄][W(=NAr)₃R] (R = Me, ᵗBu and Np') (11-13). The cation of (8) was substituted by adding ⁿBu₄NBr to afford [ⁿBu₄N][W(=NAr)₃Br] (10). These and related synthetic and reactivity studies will be described.

The environmental behavior of the actinide elements will depend on their redox and complexation chemistries. Chapter I of this Dissertation briefly reviews actinide solution chemistry on the fundamental and applied (i.e. environmental) levels. Three projects involving the hexavalent actinides are then discussed. / Solvent extraction by thenoyltrifluoracetone was found suitable for investigation of tracer-level actinide redox reactions. This technique was employed in the study of reactions of Np(VI) with water-soluble carboxylates, phenols, and other oxygen-containing organic ligands. Results from this study are presented in Chapter II. Ligand properties necessary to effect reduction were identified as aromaticity and the presence of a hydroxy function. A rate equation for the reduction of Np(VI) by salicylate was derived which shows first order dependency on ligand and metal and inverse dependency on hydrogen ion concentration. Ligand substitution para to a phenolic group was found to slow ligand oxidation by Np(VI). Reasons for this effect are suggested. / Chapter III describes the development and characteristics of a coated-wire electrode specific for actinyl cations. The electrode was found to respond rapidly and reproducibly to 10('-5) - 10('-2) M U(VI) with a slope almost twice that predicted by the Nerst equation. Tri- and tetravalent class a cations did not interfere with uranyl detection by the electrode, but pentavalent interference was severe. Possible mechanisms for the function of the ion-sensitive membrane are suggested, and potential uses of the electrode in actinide redox studies are discussed. / The results of an investigation of the thermodynamics of Pu(VI) complexation by bicarbonate at pH 8 are presented in Chapter IV. From the previously determined 1:1 stability constant and from calorimetric data, the stability constant for formation of the 1:2 complex was estimated, and the enthalpy and entropy of formation of both complexes were determined. Based on thermodynamic cycles and comparison with literature data, PuO(,2)(OH)(HCO(,3)) and PuO(,2)(CO(,3))(,2)('2-) were proposed as structures for the 1:1 and 1:2 complexes, respectively. / Source: Dissertation Abstracts International, Volume: 42-11, Section: B, page: 4411. / Thesis (Ph.D.)--The Florida State University, 1982.

The complex formation of UO(,2)('+2), Ca('+2) and Th('+4) with halates, acetate and haloacetates has been studied by means of solvent extraction. The stability constants have been determined for UO(,2)('+2), Ca('+2) and Th('+4) with halates, acetate and haloacetates at 25(DEGREES)C. The enthalpies were determined by titration calorimetry. From the value of the enthalpy and entropy, model were developed for assignment of relative inner vs outer sphere character to the complexes. It has been found that inner sphere character increases with the charge density of the cation and with the pka of the ligands. / Source: Dissertation Abstracts International, Volume: 43-03, Section: B, page: 0719. / Thesis (Ph.D.)--The Florida State University, 1982.

Complexation of calcium and magnesium with adenosine mono, di and tri phosphates has been studied at 25(DEGREES)C and 0.1 M ionic strength. Stability constants for the complexes with unprotonated as well as the monoprotonated forms of these ligands have been determined by potentiometric technique. The enthalpy changes for the complexation reactions have been determined by titration calorimetry. / Complexation of lanthanide ions with adenosine mono and tri phosphates has been studied at 0.1 M ionic strength (NaClO(,4)). The stability constants for unprotonated and monoprotonated complexes have been determined by potentiometry and the heat of complexation have been determined by temperature dependence study of the corresponding stability constants. / Complexation of sodium ions with adenosine triphosphate has been studied to evaluate its effect on the metal complexation study. The corrections are estimated for the observed complexation constants and the thermodynamic parameters. / The studies show that the adenosine phosphates are bound to the alkaline earth cations mainly through the phosphate chain. The interaction of the base (adenine) is either not present or is negligible. The complexation of lanthanide ions by adenosine monophosphate is also mainly through the phosphate chain. However, the complexation of lanthanide ions by adenosine triphosphate is best interpreted in terms of complexation through the phosphate chain as well as the heterocyclic ring. / Source: Dissertation Abstracts International, Volume: 43-01, Section: B, page: 0134. / Thesis (Ph.D.)--The Florida State University, 1982.

The development and investigation of bimetallic systems that undergo proton-coupled intramolecular electron-transfer are reported. Initial studies involved the synthesis of a new family of synthetically versatile ruthenium complexes containing various $\beta$-diketonates (R$\sb2$mal) and 2,6-bis(N-pyrazolyl)pyridine and its methyl substituted derivatives (Me$\sb{\rm n}$bpp). These coordinatively saturated complexes are stable in water and exhibit low redox potentials which can be fine-tuned over a broad potential range. These complexes were used to prepare bimetallic systems in order to study optical electron transfer as a function of ligand substituent effects. In subsequent studies these (Me$\sb{\rm n}$bpp)(R$\sb2$mal)Ru- metal centers were linked to ruthenium centers containing a ligand with an ionizable proton. The general formula of these bimetallic complexes is (((Et$\sb2$N)$\sb2$bpy)$\sb2$Ru(pyz-LH)Ru(Me$\sb{\rm n}$bpp)(R$\sb2$mal)) $\sp{3+}$, where (Et$\sb2$N)$\sb2$bpy is 4,4$\sp\prime$-bis($N,N \sp\prime$-diethylamino)-2,2$\sp\prime$-pyridine and pyz-LH is 3-methyl-5-pyrazyl-pyrazole or 2-pyrazylbenzimidazole. These bimetallic complexes were specifically designed to investigate the relationships between the electrochemically measured proton-coupled electron-transfer process and the spectroscopically measured intervalence (IT) band in the mixed-valence complex. The reversible pH-dependent behavior of the IT-bands gives direct evidence of reversible pH-induced electron transfer between the metal centers. / Source: Dissertation Abstracts International, Volume: 54-12, Section: B, page: 6199. / Major Professor: Kenneth A. Goldsby. / Thesis (Ph.D.)--The Florida State University, 1993.

My work involved the synthesis, physical characterization, and studies into the chemical reactivity of various titanium, vanadium and chromium complexes of the macro-cyclic ligand (C(,22)H(,22)N(,4))('2-). These compounds were characterized using a variety of physical methods including ESR, NMR, IR Spectroscopy, cyclic voltammetry, and X-ray diffraction structure analysis, where appropriate. / The reaction of vanadyl acetate with the free ligand yields VO(C(,22)H(,22)N(,4)), which was structurally characterized. The vanadyl oxygen may subsequently be removed to give an extremely reactive (very water and oxygen sensitive) intermediate V((,22)H(,22)N(,4))Cl(,2)(.)HCl. The dihalovanadium (IV) complex reacts with a variety of small molecules including H(,2)S, NH(,3), and H(,2)O forming the sulfo, (mu)-nitrido dimer, and the starting vanadyl derivatives, respectively. / The analogous Ti(C(,22)H(,22)N(,4))Cl(,2) complex, prepared from TiCl(,4) and the free ligand, is less readily hydrolyzed than V(C(,22)H(,22)N(,4))Cl(,2)(.)HCl. An X-ray diffraction analysis of the structure revealed cis coordination of the two chloride ligands, leading to an approximate trigonal prismatic geometry of the inner coordination sphere. Several other complexes with cis geometry were prepared from a variety of ligands including catechol, 3,4dimercaptotoluene, oxalate, and 2,4pentanedione. A number of oxygen containing derivatives were isolated and characterized including the oxo compound TiO(C(,22)H(,22)N(,4)), the dimer O{Ti(C(,22)H(,22)N(,4))}(,2)X(,2), and a peroxo complex TiO(,2)(C(,22)H(,2)N(,4)). Two novel sulfur derivatives were prepared TiS(C(,22)H(,22)N(,4)) and TiS(,2)(C(,22)H(,22)N(,4)). The latter compound contains a coordinated persulfo ligand and is the only example of this type of coordination (that we are aware of) among the first row transition metals. Both TiS(,2)(C(,22)H(,22)N(,4)) and TiO(,2)(C(,22)H(,22)N(,4)) react with the atom transfer reagent P(C(,6)H(,5))(,3) to give S=P(C(,6)H(,5))(,3) and O=P(C(,6)H(,5))(,3), respectively. / Studies of chromium reaction chemistry in this ligand are currently being completed. The chromium chemistry is complicated by sensitivity to H(,2)O and O(,2), leading to irreversibly oxidized and decomposition products. The reaction of anhydrous CrCl(,3) with free ligand, in the presence of Zn, produces Cr(C(,22)H(,22)N(,4))(S)Cl where S is a coordinated solvent molecule, typically CH(,3)CN. Excess pyridine can be displaced both the solvent and the coordinated chloride. A bis-methoxy complex Cr(C(,22)H(,22)N(,4))(OMe)(,2) is prepared by the action of NaOMe or Cr(C(,22)H(,22)N(,4))(CH(,3)CN)Cl. A novel product in whichCH(,3)CN has added at the methine carbon atom of the pentanedionato / chelate ring to produce a pentadentate macrocyclic ligand can beisolated as the SCN('-) adduct,(' )Cr(C(,22)H(,22)N(,4))(-C=N)NCS. / (VBAR) / CH(,3) / Source: Dissertation Abstracts International, Volume: 43-08, Section: B, page: 2547. / Thesis (Ph.D.)--The Florida State University, 1982.

The rate constants for thorium dissociation from humic acid, PMA (polymaleic acid) and PMVEMA (poly -methylvinylether/maleic acid ) were measured in the pH range of 4.20 to 5.94. The rate of thorium dissociation from these polyelectrolytes was determined by measuring the rate at which thorium was complexed with an exchange ligand. Arsenazo III was employed as the exchange ligand and its complexation of thorium was monitored by visible spectroscopy. / The dissociation of thorium from these polyelectrolytes occurred by several first order pathways. These pathways fit into two categories based on their dependence on pH, temperature and the amount of time thorium was in contact with the polyelectrolyte prior to dissociation. The first category was interpreted as dissociation of territorial bound thorium and thorium bound to specific sites on the surface of the polyelectrolyte. These types of bound thorium formed quickly and had large dissociation rate constants. Dissociation of territorial bound thorium as well as thorium bound to sites on the surface of the polyelectrolyte would be expected to have small activation energies and large negative activation entropies (from solvation of the charged group of the polyelectrolyte which releases thorium). Less than 6 (+OR-) 1 KJ/mole activation energy and between -250 (+OR-) 20 and -300 (+OR-) 20 joule/mole-(DEGREES)K of activation entropy was found for this category of thorium dissociation. / The second category of dissociation pathways was interpreted as dissociation of thorium from binding sites located within the coiled structure of the polyelectrolyte. This type of bound thorium formed very slowly and had small dissociation rate constants. The dissociation of internally site bound thorium should have large activation energies and activation entropies comparable to that for thorium bound to the surface of the polyelectrolyte. Between 20 (+OR-) 2 and 30 (+OR-) 2 KJ/mole activation energy and from -200 (+OR-) 20 to -250 (+OR-) 20 joule/mole-(DEGREES)K activation entropy was found for this category of thorium dissociation. / Source: Dissertation Abstracts International, Volume: 46-10, Section: B, page: 3433. / Thesis (Ph.D.)--The Florida State University, 1985.

The chemistry of early transition elements (Ti, V, Mo, W) with the macrocyclic ligands C(,22)H(,24)N(,4) and H(,2)TPP (tetraphenylporphyrin) has been demonstrated to be more versatile than the exhaustively studied macrocyclic complexes of transition metal from the right hand side of the periodic table. / New (mu)-oxo bridged heterobinuclear dimer complexes have been obtained from the reaction of titanyl and vanadyl species with other metal complexes. The V=O group of VO(C(,22)H(,22)N(,4)) reacts with highly oxophilic Lewis acids such as B(C(,6)H(,5))(,3) and -Si(CH(,3))(,3) yielding (mu)-oxo heterobinuclear compounds (C(,22)H(,22)N(,4))V=O-B(C(,6)H(,5))(,3) and C(,22)H(,22)N(,4)) V-O-Si(CH(,3))(,3) ('+). The Ti=O bond of Ti(O)(C(,22)H(,22)N(,4)) is much more reactive than the V=O group, it forms donor-acceptor complexes with a variety of metal complexes to give (mu)-oxo bridged heterobinuclear complexes of the type, (C(,22)H(,22)N(,4))Ti-O-M'L(M'=Fe('2+), Fe('3+), V('3+), Mn('2+), Cr('3+), Sn('4), MO(DEGREES), L = salen, TPP('2-), CO). The IR spectra and crystal structures indicate that Ti-O bond largely retains its double character. / Mo(CO)(,6) reacts with H(,2)TPP to yield a molybdenum-molybdenum quadruply bonded dimer complex. This discovery, in essence, corrects a fifteen year old literature report, which originally reported the synthesis of Mo(O)(OH)(TPP). The crystal structure shows the geometry of Mo(,2)N(,8) is nominally eclipsed with a twist angle of 18(DEGREES). The temperature dependent ('1)H NMR spectra show two distinguishable species at -95(DEGREES)C as result of minimum rotation of the Mo-Mo (delta) bonding. The activation barrier to rotation was estimated to be 6.3 kcal/mol from NMR line shape analysis. / W(V) porphyrin complexes react with H(,2)O(,2) yielding an unusual tungsten (VI) porphyrin complex having oxo and peroxo groups in cis coordination positions. Furthermore these groups are eclipsed with respect to the porphyrin nitrogen atoms. Two quite different W-N bond distances are observed. This non-equivalence of two types of trans bonding with respect to the nitrogen atoms leads to the most warped porphyrin skeleton known to data. W(O)(O(,2))(TPP) undergoes an intramolecular oxidative reaction at room temperature in which it appears that the coordinated peroxide oxygenates and breaks up the porphyrin ligand. / Ti(C(,22)H(,22)N(,4))Cl(,2) reacts with NaC(,5)H(,5) yielding a new type of sandwich complex Ti(C(,22)H(,22)N(,4))(C(,5)H(,5)). It consists of a minicycle (C(,5)H(,5)('1-)) and the tetraazo macrocyclic C(,22)H(,22)N(,4)('2-). / Source: Dissertation Abstracts International, Volume: 47-08, Section: B, page: 3352. / Thesis (Ph.D.)--The Florida State University, 1986.

This dissertation seeks to determine the differences in the lanthanides and later actinides in non-aqueous media. Research in the f-elements is significantly understudied compared to the other metals of the periodic table. Even more so are the later actinides which were largely unstudied for an extended period as it was believed later actinides were identical to lanthanides. A review by Neidig et al, "The Covalency in f-element Complexes" has ignited significant interest in the bonding of the actinides.1 A tremendous amount of research in the f-elements, particularly the actinides, has been performed in aqueous conditions at high temperatures and pressures. Chemistry under these conditions limit the research possible for lower oxidation states. Additionally, non-aqueous techniques allow for the investigation of these elements in more organic environments. The goal of this work is to pave a greater understanding of knowledge for lanthanides and actinides by examining their redox and coordination chemistries in these environments that could lead to applications other than nuclear energy and weapons. The first portion of this dissertation examines the chemistry that is already heavily acknowledged about f-elements: coordination chemistry. When modeling later actinides, a common notion is to utilize the isoelectronic lanthanide as the surrogate. Although for electronic comparisons this is useful, it is often not the case for examining isostructural compounds. The isoelectronic lanthanide is often smaller in ionic radius, which is a factor that dominates the chemistry of the lanthanides. Despite this, isolation of isostructural coordination compounds was obtained for the isoelectronic and size analogs of americium; europium and neodymium. This seemingly mundane study showed that americium portrays a small amount of covalency in its bonds which is not observed in the lanthanides. These small differences lead to profound changes in chemical properties as observed later in this work. The second portion of this work focuses on analyzing the divalent oxidation state of f-elements with crown ethers. The divalent oxidation state has been obtained for all lanthanides using potassium and 2.2.2-cryptand. The next step was to determine the extent to which crown ethers and solvents have on the redox properties of f-elements. Because all the lanthanides had been obtained in the divalent oxidation state in a similar matter, it was expected that the redox chemistries would behave identically. To surprise, ytterbium behaves differently and shows greater reversibility than the most stable divalent lanthanide, europium. Additionally, it was found that californium also behaves like ytterbium electrochemically, even though it would be expected to behave like samarium. It was proposed that this may be attributed to the 5f orbitals. The last of this work involves obtaining californium in the divalent oxidation state as a molecular system. This was done by modeling with samarium which is the most similar to californium in its redox and coordination properties. Quick and simple routes to synthesizing divalent samarium structures were obtained in ordinary glovebox conditions for attempts with californium. Under identical reaction conditions, isolation of Cf(II) crystals in the solid state were unsuccessful. However, interesting spectroscopic properties where observed that portrayed divalent californium as having tunable luminescence similar to divalent europium compounds. To our surprise, even though samarium resembles californium, the chemistry between the two elements are very different, further broadening the gap between the 4f and 5f elements. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2018. / September 28, 2018. / Actinides, Californium and Americium, Coordination Chemistry, Divalent Samarium, Lanthanides, Redox Chemistry / Includes bibliographical references. / Thomas E. Albrecht-Schmitt, Professor Directing Dissertation; Samuel L. Tabor, University Representative; Kenneth G. Hanson, Committee Member; Yan-Yan Hu, Committee Member.