Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.

Clusters of metal ions that possess large numbers of magnetically coupled unpaired electrons have attracted much interest in recent years due to their fascinating magnetic behavior. With an appreciable component of magnetic anisotropy, these large-spin paramagnetic molecules can exhibit an energy barrier to inversion of their magnetic dipole, leading to spontaneous magnetization and magnetic hysteresis below a critical temperature. Since this behavior is a property of an individual clusters rather than a collection of molecules, this phenomenon has been dubbed ??Single Molecule Magnetism??. Our approach to the study of new high-spin systems has been to exert a measure of synthetic control in the preparation of clusters. Specifically we are employing highly anisotropic metal ions with the anticipation that these ions would engender large overall magnetic anisotropy in the resulting clusters. The first step in this process was the development of the chemistry of two new d5 ReII (S = ??) complexes, namely [ReII(triphos)(CH3CN)3][PF6]2 and [Et4N][ReII(triphos)(CN)3]. The magnetic, optical and electrochemical properties were studied and theoretical models were developed to describe the origin of the large temperature independent paramagnetism that was observed. Next, we successfully employed transition metal cyanide chemistry using the ReII building blocks to prepare a family of isostructural, cubic clusters of the general formula {[MCl]4[Re(triphos)(CN)3]4} M = Mn, Fe, Co, Ni, Cu, Zn whose 3d ions adopt local tetrahedral geometries. Within the clusters, magnetic exchange is observed between the paramagnetic ions, which has been modeled using an Ising exchange model to account for the dominating anisotropy of the ReII ion. Despite the high pseudo-symmetry of the clusters (Td), this work has yielded a rare example of a metal-cyanide single molecule magnet, {[MCl]4[Re(triphos)(CN)3]4} with an S = 8 ground state, D = -0.39 cm-1 and an effective energy barrier for magnetization reversal of Ueff = 8.8 cm-1. The elucidation of this family of isostructural clusters has also allowed us to pursue fundamental work on the structure/property relationships of the exotic, paramagnetic ReII ion. As the clusters are soluble, stable compounds, the future of this chemistry lies in the development of a true building-block approach to ??super-clusters?? that exhibit very high ground state spin values.

This dissertation focuses on the synthetic exploratory synthesis of molybdenum chalcogenides and rare earth metal-rich ternary tellurides as a part of an effort to produce molecular building blocks of molybdenum chalcogenide clusters and to explore their structural relationships with solid state cluster networks. The tightly cross-linked Mo3nSe3n+2(n = 2, 3, ...∞) clusters and chain compounds react with alkali metal cyanide or cyanide salt mixtures at temperatures of 450-675 °C to yield reduced, cyanide-terminated molybdenum chalcogenide clusters that are thermodynamically stable. At temperatures of 650-675 °C, linear chain compounds I6[Mo6Se8(CN)4(CN)2/2] (MI = K, Cs) were prepared from reactions of Mo6Se8 or elemental starting materials, Mo and Se with excess molten cyanide (KCN, CsCN). These are the first known compounds to feature linking of Mo6Se8 clusters via cyanide bridges. Magnetic susceptibility and EPR measurements indicate that there is one unpaired electron per cluster. A new reduced molecular octahedral complex, Na8[Mo6Se8(CN)6]•20H2O was prepared by the reduction of [Mo6Se8(CN)6]7-with Zn in an aqueous NaCN solution. Single crystal structure was determined. Cyclic voltammetric measurements in basic aqueous media show multiple reversible redox waves corresponding to [Mo6Se8(CN)6]6-/7-, [Mo6Se8(CN)6]7-/8-, [Mo6Se8(CN)6]8-/9-redox couples with half-wave potentials of E1/2 = -0.442 V, -0.876 V, and 11.369 V respectively versus the standard hydrogen electrode (SHE). UV-Vis studies support the presence of the reduced cluster compound. New reduced molecular tetrahedral complexes, K7Na[Mo4Se4(CN)12]•5H2O•MeOH, Na4Cs7[Mo4Se4(CN)12]Cl3, Na8[Mo4Se4(CN)12], and Na4K4[Mo4Se4(CN)12]•12H2O were prepared. Preparation of Na8[Mo4Se4(CN)12] is an improved method for the synthesis of the Mo4Se4 core. Half-wave potentials of E1/2 for the [Mo4Se4(CN)12]6-/7-and [Mo4Se4(CN)12]7-/8-couples are 0.233 V, and -0.422 V respectively versus SHE. The molecular cubane clusters [Mo4Se4(CN)12]7-/8-play an essential role in the process by which the discrete [Mo6Se8(CN)6]6-and [Mo6Se8(CN)6]are excised from the CN-linked chain compound, K6Mo6Se8(CN)5. A new rare-earth telluride compound with the empirical composition of Gd4NiTe2 was synthesized from a high-temperature solid-state reaction. Gd4MTe2 (M = Ni) crystallizes in the orthorhombic space group Pnma. This unprecedented structure consists of a cluster condensation of Ni-centered gadolinium tricapped trigonal prisms along the rectangular faces of the trigonal prism such that the Ni atoms act as two of the caps to the trigonal prisms.

Clusters of metal ions that possess large numbers of magnetically coupled unpaired electrons have attracted much interest in recent years due to their fascinating magnetic behavior. With an appreciable component of magnetic anisotropy, these large-spin paramagnetic molecules can exhibit an energy barrier to inversion of their magnetic dipole, leading to spontaneous magnetization and magnetic hysteresis below a critical temperature. Since this behavior is a property of an individual clusters rather than a collection of molecules, this phenomenon has been dubbed ??Single Molecule Magnetism??. Our approach to the study of new high-spin systems has been to exert a measure of synthetic control in the preparation of clusters. Specifically we are employing highly anisotropic metal ions with the anticipation that these ions would engender large overall magnetic anisotropy in the resulting clusters. The first step in this process was the development of the chemistry of two new d5 ReII (S = ??) complexes, namely [ReII(triphos)(CH3CN)3][PF6]2 and [Et4N][ReII(triphos)(CN)3]. The magnetic, optical and electrochemical properties were studied and theoretical models were developed to describe the origin of the large temperature independent paramagnetism that was observed. Next, we successfully employed transition metal cyanide chemistry using the ReII building blocks to prepare a family of isostructural, cubic clusters of the general formula {[MCl]4[Re(triphos)(CN)3]4} M = Mn, Fe, Co, Ni, Cu, Zn whose 3d ions adopt local tetrahedral geometries. Within the clusters, magnetic exchange is observed between the paramagnetic ions, which has been modeled using an Ising exchange model to account for the dominating anisotropy of the ReII ion. Despite the high pseudo-symmetry of the clusters (Td), this work has yielded a rare example of a metal-cyanide single molecule magnet, {[MCl]4[Re(triphos)(CN)3]4} with an S = 8 ground state, D = -0.39 cm-1 and an effective energy barrier for magnetization reversal of Ueff = 8.8 cm-1. The elucidation of this family of isostructural clusters has also allowed us to pursue fundamental work on the structure/property relationships of the exotic, paramagnetic ReII ion. As the clusters are soluble, stable compounds, the future of this chemistry lies in the development of a true building-block approach to ??super-clusters?? that exhibit very high ground state spin values.

This dissertation focuses on the synthetic exploratory synthesis of molybdenum chalcogenides and rare earth metal-rich ternary tellurides as a part of an effort to produce molecular building blocks of molybdenum chalcogenide clusters and to explore their structural relationships with solid state cluster networks. The tightly cross-linked Mo3nSe3n+2(n = 2, 3, ...∞) clusters and chain compounds react with alkali metal cyanide or cyanide salt mixtures at temperatures of 450-675 °C to yield reduced, cyanide-terminated molybdenum chalcogenide clusters that are thermodynamically stable. At temperatures of 650-675 °C, linear chain compounds I6[Mo6Se8(CN)4(CN)2/2] (MI = K, Cs) were prepared from reactions of Mo6Se8 or elemental starting materials, Mo and Se with excess molten cyanide (KCN, CsCN). These are the first known compounds to feature linking of Mo6Se8 clusters via cyanide bridges. Magnetic susceptibility and EPR measurements indicate that there is one unpaired electron per cluster. A new reduced molecular octahedral complex, Na8[Mo6Se8(CN)6]•20H2O was prepared by the reduction of [Mo6Se8(CN)6]7-with Zn in an aqueous NaCN solution. Single crystal structure was determined. Cyclic voltammetric measurements in basic aqueous media show multiple reversible redox waves corresponding to [Mo6Se8(CN)6]6-/7-, [Mo6Se8(CN)6]7-/8-, [Mo6Se8(CN)6]8-/9-redox couples with half-wave potentials of E1/2 = -0.442 V, -0.876 V, and 11.369 V respectively versus the standard hydrogen electrode (SHE). UV-Vis studies support the presence of the reduced cluster compound. New reduced molecular tetrahedral complexes, K7Na[Mo4Se4(CN)12]•5H2O•MeOH, Na4Cs7[Mo4Se4(CN)12]Cl3, Na8[Mo4Se4(CN)12], and Na4K4[Mo4Se4(CN)12]•12H2O were prepared. Preparation of Na8[Mo4Se4(CN)12] is an improved method for the synthesis of the Mo4Se4 core. Half-wave potentials of E1/2 for the [Mo4Se4(CN)12]6-/7-and [Mo4Se4(CN)12]7-/8-couples are 0.233 V, and -0.422 V respectively versus SHE. The molecular cubane clusters [Mo4Se4(CN)12]7-/8-play an essential role in the process by which the discrete [Mo6Se8(CN)6]6-and [Mo6Se8(CN)6]are excised from the CN-linked chain compound, K6Mo6Se8(CN)5. A new rare-earth telluride compound with the empirical composition of Gd4NiTe2 was synthesized from a high-temperature solid-state reaction. Gd4MTe2 (M = Ni) crystallizes in the orthorhombic space group Pnma. This unprecedented structure consists of a cluster condensation of Ni-centered gadolinium tricapped trigonal prisms along the rectangular faces of the trigonal prism such that the Ni atoms act as two of the caps to the trigonal prisms.

A series of experiments were carved out to study the effect of dietary enzyme inclusion or flaxseed processing on feeding value of flaxseed for broilers. The feed enzymes tested containing xylanase activities failed to produce any positive performance response when used in a 10% flaxseed diet with manufacturer recommended dosage for broilers (D 1 to 21). / Autoclaving of flaxseed at 16.5 kg/cm2 and 120°C for 15 min slightly improved the performance of young broilers fed a 10% flaxseed diet. This improvement was not observed at lower temperature and shorter period of autoclaving, but was magnified at higher flaxseed level. Autoclaving, microwave roasting, pelleting significantly (P < 0.05) reduced HCN content in flaxseed. The greatest HCN reduction was observed with repeated pelleting (54.9%) and microwave roasting (83.2%), from its 377 mg/kg of raw flaxseed. / When tested with roosters, flaxseed processing effectively increased ME values, dry matter, and ether extract utilization. The raw flaxseed TME and TMEn of 3343 and 3225 kcal/kg, respectively, was significantly (P < 0.01) increased by repeated pelleting (44%) and microwave roasting (32%). It was the result of significant improvement (P < 0.05) of EE utilization by the relevant processing. These improvements had a similar effect on total FA and linolenic acid utilization. / The processing method and flaxseed level had a very significant effect on deposition of total T-3 FAs in breast and thigh meat (P < 0.001) of 40 days old broilers. The highest level of T-3 FAs in muscle lipids of 23.04% and 26.46% for breast and thigh, respectively, was achieved with the highest flaxseed level (14% in days 1 to 21 days, and 17% in days 22--40) and pellet-then-mash processing, which lead to low T-6/T-3 ratios of 0.81 and 0.80 in breast and thigh muscle lipid, respectively. The proper flaxseed processing allowed more flaxseed (up to 12%) to be included in broiler diets without obvious growth depression, while achieving the higher desired T-3 FAs deposition in meat.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 90-97). Also available on the World Wide Web.

Inaug.-Diss.--Basel. / Curriculum vitae.

Inaug.-Diss.--Basel. / Curriculum vitae.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.