Synthesis and characterization of transition metal clusters: From the isolation of ligand-stabilized solid fragments to the tuning of magnetic anisotropy and host-guest selectivity, and, Approaches to science teaching: Development of an observation instrument with a measurement model based on item response theory

Part I. The work presented herein describes efforts to develop general techniques for the synthesis of transition metal clusters and the manipulation of their properties. In Chapter 2, it is demonstrated that a modified metal atom reactor allows for the vaporization, passivation, and isolation of metal-chalcogenide clusters from their parent binary solids. Among the clusters produced by this method were Cr6S8(PEt3)6, Fe4S 4(PEt3)4, Co6S8(PEt 3)6, Cu6S4(PEt3)6, Cu12S6(PEt3)8, and Cu26Se 13(PEt3)14. To create single-molecule magnets with higher demagnetization barriers, we are developing metal-cyanide systems which exhibit highly adjustable magnetic behavior. Chapter 3 reports an attempt to introduce magnetic anisotropy into a MnCr6 cluster. Replacement of CrIII with Mo III resulted in the assembly of K[(Me3tacn)6MnMo 6(CN)18](ClO4)3 (Me3tacn = N,N',N″ -trimethyl-1,4,7-triazacyclononane)---the first well-documented example of a cyano-bridged single-molecule magnet. Recently, it was demonstrated that replacing Me3tacn with the less sterically hindering tach (tach = cis,cis-1,3,5-triaminocyclohexane) in the face-centered cubic cluster [(tach)8Cr8Ni 6(CN)24]Br12 provides greater access to the cluster cavity. Chapter 4 describes my efforts to probe the selectivity of this cluster toward inclusion of various guests. Part II. Successful implementation of student-centered curricula reforms requires the creation of a measurement instrument for monitoring whether the curricula are being used as intended. The creation and development of an observation instrument would greatly contribute to this effort. To develop a theoretically sound construct map, it is necessary to review the literature and conduct our own investigations of approaches to science teaching. Chapter 2 presents the findings of these investigations and their contributions to our understanding of the construct. Using these findings, the Science Teaching Observation Protocol (STOP) was created and designed to measure two subconstructs: intentions and strategies. Chapter 3 details the first pilot test of STOP and analysis of the collected data. In Chapter 4, the theoretical shortcomings of the instrument are analyzed and discussed. Modified versions of the intention and strategy subconstruct maps are presented.