| Chapter 1 discusses preparation of the cluster series [Fe6S 8(PEt3)6]n+ (n = 0--3). Structures were determined by X-ray crystallography at 223 K, revealing trends in metric parameters indicative of population of core antibonding orbitals upon reduction. Zero-field Mossbauer spectra were consistent with a delocalized electronic description, and magnetic susceptibility measurements established ground states S = 3/2, 3, 7/2, and 3 for oxidation states n = 3, 2, 1, and 0 respectively.; Chapter 2 deals with the synthesis and characterization of carboxylate-bridged heme-copper assemblies relevant to the formate-bound form of the heme a 3-CuB active site in the enzyme cytochrome c oxidase. Carboxylate-bridged complexes [FeIII-(RCO2)-Cu II] (R = CH3, H) and [FeIII-(HCO2)-Cu II)2] were synthesized and structurally characterized, revealing three-atom bridges oriented in either anti-anti or syn-anti configurations. Mossbauer and magnetization studies concluded weak antiferromagnetic coupling (J = 18 cm-1) for the dinuclear formate-bridged species and weak ferromagnetic coupling (J = -0.30 cm-1 ) for the trinuclear formate-bridged species, contradictory to the strong coupling found in the formate-bound active site.; In Chapter 3, the synthesis of a new dinucleating compartmental ligand (L) containing a N2-(mu-S)-N2 atom donor set is discussed. Complexation of L with two equivalents of Cu(I) resulted in a tetranuclear Cu4L2 complex which was characterized by X-ray crystallography.; Chapter 4 reports the first systematic study of bis(dithiolene)tungsten complexes pertinent to the active sites in tungstoenzymes. Silylation of oxotungsten(IV/VI) complexes resulted in the first examples of monooxo WVI and desoxo WIV complexes with bis(dithiolene) coordination. Reactivity, including oxygen atom transfer, oxidative sulfur transfer, oxo/sulfido exchange, silylation, and chloride ligand exchange, is treated thoroughly. Reaction products were characterized by 1H NMR, X-ray crystallography, and cyclic voltammetry.; Chapter 5 concludes with the synthesis and characterization of the biologically relevant chalcogenide series [WQ(S2C2Ph2) 2]2- (Q = O, S, Se). Structures have been determined by X-ray crystallography for Q = O and S, as well as for certain derivatives. The series has been characterized by UV-vis spectroscopy and electrochemistry, revealing Q dependent and independent trends. Series members are reactive toward alkylating agents, with stereospecific mono-S-alkylation observed for Q = O. One-electron oxidation products and the related complex [WO(S 2C2Me2)2]2- are also described. |
