Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 242-243) Also available online.

Thesis (Ph. D.)--University of Florida, 1986. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 277-289).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references.

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

This thesis describes the synthesis and chemistry of triangular phosphido-bridged iridium clusters. The cluster [Ir3(μ-PPh2)3 (CO)6] was obtained analytically pure for the first time. In the solid state this 48 electron cluster exhibits one short iridium-iridium bond of 2.6702(3) Å and two long iridium-iridium bonds, 2.9913(3) Å on average. Two phosphido bridges rest closely within the plane of the metal triangle while the unique phosphido group, bridging the short metal-metal bond, is almost orthogonal to this plane. NMR data suggest that this structure is also adopted in solution below 183 K. At higher temperature however the phosphido bridges give rise to an average signal which is presumably due to a rapid flip-flop motion of these groups. Addition of one molar equivalent of dimethylacetylendicarboxylate to [Ir3(μ-PPh2)3(CO)6] results in formation of [Ir3(μ-PPh2)3(CO) 6(μ-DMAD)] which contains a diiridacyclobutene. Addition of excess alkyne leads to the CO-inserted [Ir3(μ-PPh2) 3(CO)5(μ-DMAD){κ2-MeO 2CCC(CO2Me)C(O)}] which photochemically decarbonylates, to give [Ir3(μ-PPh2)3(CO)5(μ-DMAD) 2]. The 50 electron cluster [Ir3(μ-PPh2) 3(CO)5(t-BuNC)2] also reacts with dimethylacetylendicarboxylate to yield the CO-inserted [Ir3(μ-PPh2)3(CO) 3(t-BuNC)2{κ2-MeO2CCC(CO 2Me)C(O)}2] in two isomeric forms. The new CO-insertion products represent stable iridacyclobutenones which are reluctant to undergo further insertion reactions involving carbon monoxide, tert-butylisocyanide or dimethylacetylenedicarboxylate. Addition of dimethylacetylendicarboxylate to cluster mixtures containing predominantly [Ir2Rh(μ-PPh2)3(CO) 5] and [Ir3(μ-PPh2)3(CO)6] results in selective reaction at the tri-iridium cluster which allowed for the isolation of the heterometallic cluster by chromatography. In contrast to the tri-iridium parent, [Ir2Rh(μ-PPh2)3(CO) 5] is much less reactive to dimethylacetylendicarboxylate and inert to CO. Similarly, the heterometallic [Ir2Rh(μ-PPh2) 3(CO)4(RNC)3] (R = tert-butyl; 1,1,3,3-tetramethylbutyl) are reluctant to undergo oxidative addition reactions with dimethylacetylendicarboxylate and iodomethane which readily afford addition products with the homometallic parent clusters. The kinetic difference is a consequence of electronic rather than steric factors in the clusters. / Graduate

The synthesis of a variety of new lanthanoid phosphine complexes has been achieved by complexing either one or two amido-diphosphine ligands to yttrium, lutetium or lanthanum. At room temperature, the seven-coordinate bis(amido- diphosphine) complexes, MCl[N(SiMe₂CH₂PR₂)₂]₂- are fluxional and display NMR spectra indicative of complexes where the phosphorus donors are rapidly exchanging, probably via a dissociation-reassociation pathway. It is possible to generate thermally unstable hydrocarbyl complexes of the type, M(R)[N(SiMe₂CH₂PMe₂)₂]₂, which undergo a clean first order elimination of R-H to generate cyclometallated complexes of the type, M[N(SiMe₂CHPMe₂)(SiMe₂CH₂PMe₂)][N(SiMe₂CH₂PMe₂)₂]; the yttrium derivative was crystallographically characterized. These thermally robust compounds will undergo a-bond metathesis with H₂ and D₂ at high temperature, but appear to be too sterically congested to react with larger molecules. The synthesis of a series of mono(amido-diphosphine) lanthanoid complexes, MCl₂ [N(SiMe₂CH₂PR₂)₂], (R = Me, Ph, Pr', Bu[symbol omitted]) has also been achieved. Complexes of the type, MCl₂[N(SiMe₂CH₂PMe₂)₂], are insoluble in hydrocarbon solvents, presumably because they are oligomeric in nature. They will however, dissolve in THF probably forming seven-coordinate bis(THF) monomers. Attempts to alkylate these compounds generally led to decomposition; the cyclometallated bis(ligand) complex, M[N(SiMe₂CHPMe₂)(SiMe₂CH₂PMe₂)] [N(SiMe2CH2PMe2)2], was identified as the major product. A route to a dimeric mono(amido-diphosphine) allyl complex, {YCl(allyl)[N(SiMe₂CH₂PMe₂)₂]}₂ (characterized by crystallography) was found via the reaction of allyl-MgCl or Mg(allyl)₂(dioxane) with YCl[N(SiMe₂CH₂PMe₂)₂]₂. The mono(ligand) complexes containing bulky phosphine donors (R = Ph, Bu[symbol omitted], Pr[symbol omitted]) are soluble in hydrocarbon solvents; YCl₂[N(SiMe₂CH₂PPr[symbol omitted]₂)₂] can be isolated as either a THF adduct or as the base-free dimer. A new reaction, mediated by a zirconium or hafnium amido-diphosphine complex, where allyl and butadiene moieties are coupled together to generate a coordinated [ɳ⁴:ɳ¹-CH₂=CHCH=CHCH₂CH₂CH₂]¹- fragment has been investigated. The process is very sensitive to the nature of the ancillary ligands at the metal. For MCl(ɳ⁴-C₄H₆)[N(SiMe₂CH₂PR₂)₂] complexes, after the addition of allylMgCl, the transformation takes about one hour when M = Hf & R = Pr[symbol omitted], two hours when M = Zr & R = Pr[symbol omitted], a week when M = Hf & R = Me, and results only in decomposition when M = Zr & R = Me. Similarly, for the zirconium mediated coupling of 1-methylallyl with butadiene, when R = Me, decomposition occurs and when R = Pr[symbol omitted], after two hours the coupling is complete. Two of the four possible coupled products are formed in unequal amounts, and the coupling occurs exclusively at the substituted end of the 1-methylallyl unit as determined by X-ray crystallography. Which diastereomer is formed in excess was not determined. The reduction of ZrCl₃[N(SiMe₂CH₂PR₂)₂] (R = Pr[symbol omitted] or Bu[symbol omitted]) with Na/Hg amalgam under nitrogen results in the formation of a binuclear zirconium dinitrogen complex, {ZrCl[N(SiMe₂CH₂PR₂)₂]}₂ (μ-ɳ²:ɳ²-N₂). X-ray crystallography (for R = Pr[symbol omitted]) reveals that the N₂ ligand is symmetrically bound in a side-on fashion to both metals. In addition, the N—N bond length of 1.548 (7) Å, the longest bond length ever reported for a dinitrogen complex, indicates that the dinitrogen has been reduced to a N₂⁴⁻ hydrazido ligand. Protonation of the complex with HCl results in a quantitative formation of hydrazine. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

The tricobalt cluster PhCCo₃(CO)₉ (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic thioanhydride (bta) with added Me₃NO to yield PhCCo₃(CO)₇(bta) (2), which upon heating overnight yields Co₃(CO)₆(μ₂-η²,η¹-C(Ph)C=C(PPH₂)C(O)SC(O)) (μ₂-PPh₂) (3). Cluster (3) has been isolated and characterized by FT-IR and ³¹P NMR spectroscopy. Structural determination of the cluster has been demonstrated by X-ray diffraction analysis. Cluster (3) is analogous to the cluster synthesized by Richmond and coworkers. The redox properties of (3) have been examined by cyclic voltammetry and the data are reported within.