Koordinationschemie von sterisch anspruchsvollen alkyl-substituierten cyclopentadienyl und indenyl Liganden mit Mangan, Eisen und Cobalt

In this dissertation, the coordination chemistry of bulky alkyl substituted indenyl and cyclopentadienyl ligand with manganese, iron and cobalt was investigated. A series of manganese, iron and cobalt complexes bearing sterically demanding 1,3-disubstituted indenyl ligands, 1,3-(Me3C)2C9H5 (2tBuInd) and 1,3-(c-C6H11)2C9H5 (2CyInd) has been prepared and characterized by various spectroscopic techniques, elemental analysis, and X-ray diffraction analysis. In addition the electronic properties and steric influences of these ligands have been evaluated. Although the cone angles and electronic properties are similar to 1,2,4-(Me3C)3C5H2 (Cp’), indenyl iron half-sandwich complexes are only stable at low temperature. This has been demonstrated for [(2tBuInd)FeI] using suitable trapping experiments such as NaCp’ or CO addition to yield [(2tBuInd)(Cp’)Fe] and [(2tBuInd)Fe(CO)2I], respectively. Overall the metal–ligand bonds in these indenyl compounds are weaker than in the corresponding cyclopentadienyl derivatives. The series of halide-bridged Cp’Co half-sandwich complexes [Cp’CoCl]2, [Cp’CoBr]2 and [Cp’CoI]2 was synthesized. The single crystal X-ray analyses, EPR spectroscopy and solid state magnetic susceptibility measurements were investigated. The reactions of [Cp’CoI]2 toward KHBEt3 and MeLi to yield [Cp’CoH]2 and [(Cp’Co)2(µ-CH2)(µ-H)], respectively, were studied. Reactions of [Cp’FeI]2 and [Cp’MnI(thf)]2 with pseudohalides were investigated. In contrast to the halides, the pseudohalides do not give salt-metathesis products. A series of nitrido-, sulfido-, cyanato-, diselenido- and thiocyanato-bridged iron and manganese complexes [Cp’FeN]2, [Cp’FeS]2, [Cp’Fe(NCO)]2, [Cp’Fe(Se2)]2 and [Cp’Mn(NCS)(thf)]2 were prepared and spectroscopically and crystallographically characterized. These new complexes exhibit different oxidation states, thus their electronic structures were also investigated by Mössbauer spectroscopy and SQUID magnetometry. These results suggest a rich redox chemistry of the Cp’Fe-fragment. Salt mehathesis of [Cp’FeI]2 and 2 equiv. NaBH4 yields the low-spin iron complex [Cp’Fe(BH4)], which is thermally unstable and trimerizes to [CpFe(BH2)]3 under H2 release. [Cp’Fe(BH4)] and [CpFe(BH2)]3 have been fully characterized by various spectroscopic methods.In dieser Dissertation wurde die Koordinationschemie von sterisch anspruchsvollen alkyl- substituierten Indenyl- und Cyclopentadienylliganden mit Mangan, Eisen und Cobalt untersucht. Die Serie von Mangan-, Eisen- und Cobaltkomplexen mit den sterisch anspruchsvoll 1,3-disubstituierten Indenylliganden, 1,3-(Me3C)2C9H5 (2tBuInd) und 1,3-(c-C6H11)2C9H5 (2CyInd) wurde dargestellt und durch diverse spektroskopische Methoden, Elementaranalyse und Röntgenbeugungsanalyse charakterisiert. Außerdem wurden die elektronischen Eigenschaften und der sterische Einfluss von diesen Liganden ausgewertet. Obwohl die Kegelwinkel und die elektronischen Eigenschaften dem 1,2,4-(Me3C)3C5H2 (Cp’) ähneln, sind Indenyl-Eisen Halbsandwich-Komplexe nur bei tiefen Temperaturen stabil. Dies wurde für [(2tBuInd)FeI] durch die Abfangexperimente mit NaCp’ oder durch CO Addition zur Bildung von [(2tBuInd)(Cp’)Fe] und [(2tBuInd)Fe(CO)2I] bewiesen. Die Metal–Ligand Bindung in den Indenylkomplexen sind generell schwächer als die in den entsprechenden Cyclopentadienyl- Derivaten. Die Serie von halogen-verbrückten Cp’Co Halbsandwich-Komplexen [Cp’CoCl]2, [Cp’CoBr]2 und [Cp’CoI]2 wurde synthetisiert. Für die Komplexe wurden Röntgenbeugungsanalyse, EPR-Spektroskopie und die magnetische Suszeptibilitätsmessung durchgeführt. Die Reaktivität von [Cp’CoI]2 gegenüber KHBEt3 und MeLi, zur Bildung von [Cp’CoH]2 und [(Cp’Co)2(µ-CH2)(µ-H)], wurde untersucht. Die Reaktionen von [Cp’FeI]2 und [Cp’MnI(thf)]2 mit Pseudohalogeniden wurde untersucht. Im Gegenteil zu den Halogeniden ergeben sich die Pseudohalogenide keine Salzmetatheseprodukte. Eine Serie von nitrido-, sulfido-, cyanato-, diselenido- und thiocyanato-verbrückte Eisen- und Mangankomplexe [Cp’FeN]2, [Cp’FeS]2, [Cp’Fe(NCO)]2, [Cp’Fe(Se2)]2 und [Cp’Mn(NCS)(thf)]2 wurde dargestellt und spektroskopisch und kristallographisch charakterisiert. Diese neuen Komplexe zeigen unterschiedliche Oxidationszustände. Deswegen wurden ihre elektronischen Strukturen mittels Mössbauer Spektroskopie und SQUID Manganometrie untersucht. Die Ergebnisse weisen auf eine reiche Redoxchemie vom Cp’-Fragment hin. Eine Salzmetathese von [Cp’FeI]2 und 2 equiv. NaBH4 führt zur Bildung von dem low-spin Eisenkomplex [Cp’Fe(BH4)], der thermisch instabil ist und zu [CpFe(BH2)]3 unter H2-Freisetzung trimerisiert. [Cp’Fe(BH4)] und wurde vollständig durch diverse spektroskopische Methoden charakterisiert

The role of morphological awareness in word reading skills in Japanese : A within-language cross-orthographic perspective

We examined the relationship between morphological awareness and word reading skills in syllabic Hiragana and morphographic Kanji. Participants were 127 Grade 1 Japanese-speaking children who were followed until Grade 2. The results showed that Grade 1 morphological awareness was uniquely and comparably associated with word reading skills in both Hiragana and Kanji in Grade 1 after controlling for nonverbal and verbal cognitive abilities, phonological awareness, and rapid automatized naming. The effect of Grade 1 morphological awareness on Grade 2 Kanji word recognition was slightly stronger (∆R2 = .10) than the effect on Grade 2 Hiragana reading fluency (∆R2 = .03). The findings suggest that morphological awareness plays an important role in early word reading skills across the two scripts, and with reading skill development it may become more important for mastering morphographic Kanji characters

The bRPS6-Family Protein RFC3 Prevents Interference by the Splicing Factor CFM3b during Plastid rRNA Biogenesis in Arabidopsis thaliana

Plastid ribosome biogenesis is important for plant growth and development. REGULATOR OF FATTY ACID COMPOSITION3 (RFC3) is a member of the bacterial ribosomal protein S6 family and is important for lateral root development. rfc3-2 dramatically reduces the plastid rRNA level and produces lateral roots that lack stem cells. In this study, we isolated a suppressor of rfc three2 (sprt2) mutant that enabled recovery of most rfc3 mutant phenotypes, including abnormal primary and lateral root development and reduced plastid rRNA level. Northern blotting showed that immature and mature plastid rRNA levels were reduced, with the exception of an early 23S rRNA intermediate, in rfc3-2 mutants. These changes were recovered in rfc3-2 sprt2-1 mutants, but a second defect in the processing of 16S rRNA appeared in this line. The results suggest that rfc3 mutants may be defective in at least two steps of plastid rRNA processing, one of which is specifically affected by the sprt2-1 mutation. sprt2-1 mutants had a mutation in CRM FAMILY MEMBER 3b (CFM3b), which encodes a plastid-localized splicing factor. A bimolecular fluorescence complementation (BiFC) assay suggested that RFC3 and SPRT2/CFM3b interact with each other in plastids. These results suggest that RFC3 suppresses the nonspecific action of SPRT2/CFM3b and improves the accuracy of plastid rRNA processing

Activity of Lipase and Chitinase Immobilized on Superparamagnetic Particles in a Rotational Magnetic Field

<div><p>We immobilize hydrolases such as lipase and chitinase on superparamagnetic particles, which are subjected to a rotational magnetic field, and measure the activities of the enzymes. We find that the activities of lipase and chitinase increase in the rotational magnetic field compared to those in the absence of a magnetic field and reach maximum at certain frequencies. The present methodology may well be utilized for the design and development of efficient micro reactors and micro total analysis systems (μ-TASs).</p></div

Dependence of the relative activities on the frequency of the external rotational magnetic field.

<p>(a) Lipase. (b) Chitinase. The ordinate axis represents the activity of the enzymes immobilized on particles in a rotational magnetic field, which is normalized by that in the absence of a magnetic field. The diameter of each particle is 130 nm. The strength of the magnetic field is 9.55 kA m⁻¹. The activities increase and become maximum at certain frequencies.</p

Outline of the experimental system.

<p>Lipase and chitinase molecules are immobilized on superparamagnetic particles, the average diameter and magnetic dipole moment of which are 130 nm and 3.31×10⁻²³ Wb m, by mixing the particles with aqueous solution, in which lipase and chitinase molecules are dispersed. Dc and rotational magnetic fields are generated by modulating the phase of the electric current supplied to each pair of electromagnets using a function generator. The strength of the magnetic field is set at 9.55 kA m⁻¹, which corresponds to a magnetic flux density of 12 mT, and the frequency of the magnetic field is changed; 1, 3, 5, 7, 10 and 30 Hz. The enzyme-substrate reaction experiment is carried out at 25°C for 30 minutes and the enzyme activity is estimated by measuring the absorbance of 410 nm photons.</p