The synthesis of o-(N,N-dimethylamino)methylphenyl tris (trimethylsilyl) silane (II), a photochemical precursor of o- (N,N-dimethylamino) methylphenyl (trimethylsilyl) sila ammonium ylide (intramolecular silylene complex) and otolyl(trimethylsilyl)silylene is reported. Photolysis of II at room temperature in a cyclohexane solution of triethyl silane produced the silylene ylide and the presumably uncomplexed isomer, a silylene, which is trapped to afford the 2-(o-(N,N-dimethylamino)methylphenyl) -1,1,1-triethyl 3,3,3-trimethyltrisilane, 33% yield. A second decomposition pathway, a photodeamination, produced o-tris(trimethyl silyl) silyltoluene. UV spectra of the silaammonium ylide formed in the photochemical reaction of II was observed at 77k in hard or soft matrices.

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We report the attempted syntheses of two photochemical dimethylsilene precursors, both of which are derived from polyphenyl silanorbornadiene skeletons. Possible synthetic schemes and our results are reported herein. Photolysis of 1,2-divinyl-1,1,2,2-tetramethyl-1,2-disilane at room temperature in a cyclohexane solution of 1,3-butadiene produces 1,1-dimethyl-2-(vinyldimethylsilylmethyl) silene which is trapped in high yields to afford the E- and Z-1,1-dimethyl-2-(vinyldimethylsilylmethyl)-3-vinyl-1-silacyclobutanes in 42 and 29% yields, respectively, along with minor amounts of 1,1-dimethyl-2-(vinyldimethylsilylmethyl)-1-silacyclohex-3-ene, 9%. Low Pressure Flow Pyrolysis at 450º C of either the E- or Z-isomer provides a relatively mild thermal source of the silene in the gas phase. Two products, 1,1,3,3-tetramethyldisilacyclohex-3-ene and 2,2,5,5-tetramethyl-2,5-disilabicyclo[2.2.1]hexane, are formed from an intramolecular rearrangement of the silene. Other reactions of the 3-vinylsilacyclobutanes include geometric isomerization, ring expansion to the silacyclohex-3-ene, and a homodienyl-1,5-hydrogen shift to 3,3,6,6-tetramethyl-3,6-disiladeca-1,4,8-triene. Synthetic schemes, successful and unsuccessful, for hydrido silene, acylpolysilene, and fluorine substituted silene precursors are discussed in the final chapter.

This thesis reports on unsaturated silicon compounds, as well as excursions from these into germanium chemistry, single molecule electronics, and silyl protective group chemistry. Both experimental and computational investigations were performed. Potassium germenolates were synthesized through reactions of tris(timethylsilyl) substituted acyl- and carbamylgermanes with potassium tert-butoxide. The potassium germenolates calculated by density functional theory have pyramidal structures at the Ge atoms, similar to the Si in the corresponding potassium silenolates, indicating negative charge on germanium rather than on oxygen. Germenolates also display germyl anion-like reactivity instead of germene-like reactivity as they are alkylated at Ge and initiate anionic polymerization of dienes rather than form [4+2] cycloadducts. The NMR chemical shifts reveal more negative charge at Ge in germenolates than at Si in analogous silenolates. Computations indicate that silabenzenes and silapyridines are reachable via [1,3]-silyl shifts from cyclic conjugated acylsilanes. Differently sized substituents were considered to prevent dimerizations, and 1-triisopropylsilyl-2-triisopropylsiloxy-6-tert-butylsilabenzene is a good synthetic target. Computations also show that silaphenolates are species with negative charge primarily localized at oxygen atom. Their planar structures, bond lengths, and NICS values reveal significant influence of aromaticity. Electrostatic repulsion should increase their stability, however, steric bulk is also important. Furthermore, it was found computationally that [1,3]-silyl shift from an acylsilane to a silene can function as a molecular switch reaction. Conductance calculations support this proposition.   Finally, tris(trimethylsilyl)silylmethaneamide (hypersilylamide) together with catalytic amounts of triflic acid were found to be efficient for protection of a range of alkyl and aryl alcohols and thiols in good to excellent yields. The protocol can be used to protect the less hindered OH group of a diol and has a broad functional group tolerance. A catalytic cycle is proposed. Hypersilyl protected alcohols and thiols are deprotected efficiently under photolytic conditions.

Most life forms, including plants, are more or less susceptible to infection by pathogens. Whereas plant-pathogen interactions are well studied in human-managed systems they are less known in natural ecosystems. In this thesis the interactions between the sterilising anther-smut fungus Microbotryum silenes-dioicae and the host plant Silene dioica were studied in natural habitats in the Skeppsvik archipelago in northern Sweden. The purpose was to study some population characteristics that can potentially influence the colonization of anther-smut (Microbotryum silenes-dioicae) in young Silene dioica populations. Specifically, it was tested whether the population age, floral-  and total density, population size and distances to nearest diseased populations affect incidence of disease (presence of disease) and prevalence of disease (proportion of diseased individuals in populations) in younger host populations. It was found that incidence and prevalence of disease increased with host population age and size. In addition, it was seen that distances to diseased populations could not explain incidence or prevalence of disease. These results can potentially be used to predict disease risk in similar plant-pathogen systems.

The aim of the thesis is the establishment of genomic resources for genus Silene with an emphasis to study heavy metal tolerance. The genus Silene has been widely used as a model system for addressing ecological and evolutionary questions in plants, but available genomic resources within Silene remain limited and thus broad utilisation of this genus is still capped. Next generation sequencing (NGS) has proven to be a rapid and cost-effective and it serves for quick whole genome characterization non-model organisms. In this study, the unique transcriptome databases are reported for two populations of Silene vulgaris with different tolerance to copper. Due to these databases, we were able to identify putative genes that could be responsible for heavy metal tolerance. We provide closer characterisation of two genes acting on the different levels in a detoxification pathway. Expression of these genes is influenced by copper stress conditions and functional analysis in yeast confirmed the function in copper tolerance. We supposed that these genes participated in heavy metal detoxification and serve as epistatic modificators of heavy metal tolerance in S. vulgaris. Silene latifolia is the most studied species within genus Silene presenting an ideal candidate with a similar role as Arabidopsis thaliana plays in Brassicacea. Therefore we have established haploid and dihaploid S. latifolia plants for further forward and reverse genetic studies in this and related species including S. vulgaris. Taken together, our genomic resources can serve for evolutionary and ecological studies and they are freely available to broad scientific community.

The reaction of tert-butyllithium with chloromethylphenylvinylsilane at low temperatures in hexane gave a 48% yield of a mixture of the five isomers of 1,3-dimethyl-1,3-diphenyl-2,4-dineopentyl-1,3-disilacyclobutane, formed by the head-to-tail dimerization of both E- and Z-1-methyl-1-phenyl-2-neopentylsilenes, along with an acyclic dimer. These were separated and their stereochemistry was established by ('1)H- and ('13)C-NMR spectroscopy. The E- and Z-silenes were also trapped as their {4 + 2} cycloadducts with cyclopentadiene, 2,3-dimethyl-1,3-butadiene and anthracene, which also were separated and stereochemically characterized. A consistent mole ratio of 70:30 for the E- and Z-silene adducts is interpreted as evidence for stereochemical induction in the silene generation reaction. It is also suggested that the dimerization of the silenes to give the 1,3-disilacyclobutanes occurs by a nonstereospecific stepwise pathway. When E- or Z-1-methyl-1-phenyl-2-neopentylsilene was generated by the retro-Diels-Alder flow vacuum thermolysis of its corresponding cyclopentadiene or anthracene adduct at temperatures between 400 and 600(DEGREES)C and then trapped with 2,3-dimethyl-1,3-butadiene, the stereochemical distribution of the products is independent of the stereochemistry of the silene precursor, indicating that the silene is not configurationally stable towards cis-trans isomerization at these temperatures. Evidence that the intermolecular ene reaction and the {4 + 2} cycloaddition which occur with 2,3-dimethyl-1,3-butadiene are concerted is presented. When either the E- or Z-silene, generated by the sealed tube thermolysis of its anthracene adduct by 300(DEGREES)C, was trapped with trimethylmethoxysilene, the diastereomer obtained depended on the stereochemistry of the silene precursor, showing that the silene is configurationally stable towards cis-trans isomerization up to 300(DEGREES)C. The temperature dependence of the ratio of the two diastereomers obtained when the silene formed from the pure E- or Z-anthracene adduct was trapped at higher temperatures permitted the determination of an activation energy for the silene isomerization. The activation energies for the E- and Z- and Z- to E-silene isomerization are 45 (+OR-) 6 and 20 (+OR-) 4 kcal mol('-1), respectively. The significance of these values is discussed.

This project is focused on transformation of Silene vulgaris mediated by Agrobacterium tumefaciens and A. rhizogenes. S. vulgaris is a good model plant to study gynodioecy, an evolutionary step from bisexuality to dioecy. Gynodioecious plants form in some individuals bisexual flowers, while the others possess only female flowers. The aim of this research is do develop a technique to introduce foreign genes into this plant to study its developmental consequences. Using A. rhizogenes we successfuly prepared hairy root cultures, which unfortunately do not form shoot regenerants. We have prepared a protocol to induce plant regenerants from S. vulgaris leaf fragments. The first results do not confirm that A. tumefaciens infected plant regenerants harbor reporter transgenes. We used Nicotiana tabacum as a positive control.

The solid state structures and the physical, solution magnetic, solid state magnetic, and spectroscopic (NMR and UV/Vis) properties of a range of oxygen- and nitrogen-free dialkylmanganese(II) complexes are reported, and the solution reactivity of these complexes towards H2 and ZnEt2 is described. The dialkyl compounds investigated are [{Mn(μ-CH2SiMe3)2}∞] (1), [{Mn(CH2CMe3)(μ-CH2CMe3)2}2{Mn(μ-CH2CMe3)2Mn}] (2), [Mn(CH2SiMe3)2(dmpe)] (3) (dmpe = 1,2-bis(dimethylphosphino)ethane), [{Mn(CH2CMe3)2(μ-dmpe)}2] (4), [{Mn(CH2SiMe3)(μ-CH2SiMe3)}2(μ-dmpe)] (5), [{Mn(CH2CMe3)(μ-CH2CMe3)}2(μ-dmpe)] (6), [{Mn(CH2SiMe3)(μ-CH2SiMe3)}2(μ-dmpm)] (7) (dmpm = bis(dimethylphosphino)methane), and [{Mn(CH2CMe3)(μ-CH2CMe3)}2(μ-dmpm)] (8). Syntheses for 1-4 have previously been published, but the solid state structures and most properties of 2-4 had not been described. Compounds 5 and 6, with a 1:2 dmpe:Mn ratio, were prepared by reaction of 3 and 4 with base-free 1 and 2, respectively. Compounds 7 and 8 were accessed by reaction of 1 and 2 with 0.5 or more equivalents of dmpm per manganese atom. An X-ray structure of 2 revealed a tetrametallic structure with two terminal and six bridging alkyl groups. In the solid state, bis(phosphine)-coordinated 3-8 adopted three distinct structural types: (a) monometallic [LMnR2], (b) dimetallic [R2Mn(μ-L)2MnR2], and (c) dimetallic [{RMn(μ-R)}2(μ-L)] (L = dmpe or dmpm). Compound 3 exhibited particularly desirable properties for an ALD or CVD precursor, melting at 62-63 °C, subliming at 60 °C (5 mTorr), and showing negligible decomposition after 24 h at 120 °C. Comparison of variable temperature solution and solid state magnetic data provided insight into the solution structures of 2-8. Solution reactions of 1-8 with H2 yielded manganese metal, demonstrating the thermodynamic feasibility of the key reaction steps required for manganese(II) dialkyl complexes to serve, in combination with H2, as precursors for metal ALD or pulsed-CVD. By contrast, the solution reactions of 1-8 with ZnEt2 yielded a zinc-manganese alloy with an approximate 1:1 Zn:Mn ratio. Wilkinson’s manganese(I) ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (10) can react as a source of a low-coordinate manganese(I) ethyl complex. This is illustrated in the reactivity of 10 towards a variety of reagents in this work (vide infra). The proposed low-coordinate intermediate, [(dmpe)2MnEt] (13), was not observed spectroscopically, but could be trapped using isonitrile ligands; reaction of 10 with CNR (R = tBu, o-xylyl) afforded the manganese(I) ethyl complexes [(dmpe)2MnEt(CNR)] (14a: R = tBu, 14b: R = o-xylyl). Ethyl complex 14a did not react further with CNtBu at 80 °C. By contrast, complex 14b reacted with excess o-xylyl isonitrile to form 1,1 insertion products, including the iminoacyl complex [(dmpe)Mn(CNXyl)3{C(=NXyl)CEt(=NXyl)}] (15, Xyl = o-xylyl). Complexes 14a-b and 15, as well as previously reported 10, were crystallographically characterized, and DFT calculations were employed to probe the accessibility of cis ethylene hydride and ethyl isomers of 10. Reaction of the ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (10) with H2SiEt2 at 20 °C afforded the silylene hydride [(dmpe)2MnH(=SiEt2)] (16Et2) as the trans isomer. By contrast, reaction of 10 with H2SiPh2 at 60 °C afforded [(dmpe)2MnH(=SiPh2)] (16Ph2) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn–H–Si interaction in the former. The reaction to form 16Ph2 also yielded [(dmpe)2MnH2(SiHPh2)] (18Ph2); [(dmpe)2MnH2(SiHR2)] {R = Et (18Et2) and Ph (18Ph2)} were accessed cleanly by reaction of 16R2 with H2. Both 16Et2 and 16Ph2 engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe)2MnH(R2Si=CHMe)] {R = Et (19Et2) and Ph (19Ph2)}. Compounds trans-16Et2, cis-16Ph2, and 19Ph2 were crystallographically characterized, and bonding in 16Et2 and 19Et2 was probed computationally. trans-[(dmpe)2MnH(C2H4)] (10) reacted with primary hydrosilanes H3SiR (R = Ph, nBu) at 60 °C to afford ethane and the manganese disilyl hydride complexes [(dmpe)2MnH(SiH2R)2] (20Ph: R = Ph, 20Bu: R = nBu). 20R reacted with ethylene to form silene hydride complexes [(dmpe)2MnH(RHSi=CHMe)] (19Ph,H: R = Ph, 19Bu,H: R = nBu). Compounds 19R,H reacted with a second equivalent of ethylene to generate [(dmpe)2MnH(REtSi=CHMe)] (19Ph,Et: R = Ph, 19Bu,Et: R = nBu), resulting from apparent ethylene insertion into the silene Si–H bond. Furthermore, in the absence of ethylene, silene complex 19Bu,H slowly isomerized to the silylene hydride complex [(dmpe)2MnH(=SiEtnBu)] (16Bu,Et). Reactions of 20R with ethylene likely proceed via low-coordinate silyl {[(dmpe)2Mn(SiH2R)] (17Ph: R = Ph, 17Bu: R = nBu)} or silylene-hydride {[(dmpe)2MnH(=SiHR)] (16Ph,H: R = Ph, 16Bu,H: R = nBu)} intermediates accessed from 20R by H3SiR elimination. DFT calculations and high temperature NMR spectra support the accessibility of these intermediates, and reactions of 20R with isonitriles or N-heterocyclic carbenes yielded the silyl isonitrile complexes [(dmpe)2Mn(SiH2R)(CNR')] (21a-d: R = Ph or nBu; R' = o-xylyl or tBu), and NHC-stabilized silylene-hydride complexes [(dmpe)2MnH{=SiHR(NHC)}] (22a-d: R = Ph or nBu; NHC = 1,3-diisopropylimidazolin-2-ylidene or 1,3,4,5-tetramethyl-4-imidazolin-2-ylidene), respectively, all of which were crystallographically characterized. Manganese silyl dihydride complexes [(dmpe)2MnH2(SiHR2)] {R = Ph (18Ph2) or Et (18Et2)} and [(dmpe)2MnH2(SiH2R)] {R = Ph (18Ph) or nBu (18Bu)} were generated by exposure of silylene hydride complexes, [(dmpe)2MnH(=SiR2)] (16R2), and disilyl hydride complexes, [(dmpe)2MnH(SiH2R)2] (20R), respectively, to H2 at room temperature. In solution, 18R and 18R2 exist as an equilibrium mixture of a central isomer with a meridional H–Si–H arrangement of the silyl and hydride ligands {this isomer may be considered to contain an η3-coordinated silicate (H2SiR3–) anion}, and a transHSi isomer with trans-disposed hydride and nonclassical hydrosilane ligands (the latter is the result of significant but incomplete hydrosilane oxidative addition). Additionally, DFT calculations indicate the thermodynamic accessibility of lateralH2 and transH2 isomers with cis- and trans-disposed silyl and dihydrogen ligands, respectively. Compounds 18Ph2 and 18Ph crystallized as the central isomer, whereas 18Bu crystallized as the transHSi isomer. Bonding in the central and transHSi isomers of 18R and 18R2 was further investigated through 29Si_edited 1H–1H COSY solution NMR experiments to determine both the sign and magnitude of J29Si,1H coupling (negative and positive values of J29Si,1H are indicative of dominant 1-bond and 2-bond coupling, respectively). These experiments afforded J29Si,1H coupling constants of –47 Hz for η3-(H2SiR3) in the central isomer of 18Et2 (calcd. –40 to –47 for 18R and 18R2), –38 to –54 Hz for η2-(R3Si–H) in the transHSi isomer of 18R and 18R2 (calcd. –26 to –47 Hz), and 5 to 9 Hz for the terminal manganese hydride ligand in the transHSi isomer of 18Et2, 18Ph, and 18Bu (calcd. 12 to 14 Hz for 18R and 18R2), experimentally supporting the nonclassical nature of bonding in the central and transHSi isomers. Exposure of disilyl hydride complexes 20R to diisopropylcarbodiimide {C(NiPr)2} afforded manganese(I) amidinylsilyl complexes [(dmpe)2Mn{κ2-SiHR(NiPrCHNiPr)}] {R = Ph (25Ph,H) or nBu (25Bu,H)}. DFT calculations and analysis of XRD bond metrics suggest that the structure of 25R,H involves a contribution from a resonance structure featuring a neutral base-stabilized silylene and an anionic amido donor on manganese. Reactions of 20R, as well as the silylene hydride complex 16Et2, with CO2 yielded the manganese(I) formate complex trans-[(dmpe)2Mn(CO)(κ1-O2CH)] (26), with a polysiloxane byproduct. Compound 26 was found to undergo reversible CO2 elimination at room temperature, and was only stable under an atmosphere of CO2. Complexes 25R,H and 26 were crystallographically characterized. Silyl, silylene, and silene complexes in this work were accessed via reactions of [(dmpe)2MnH(C2H4)] (10) with hydrosilanes, in some cases followed by ethylene. Therefore, ethylene (C2H4 and C2D4) hydrosilylation was investigated using [(dmpe)2MnH(C2H4)] (10) as a pre-catalyst, resulting in stepwise conversion of primary to secondary to tertiary hydrosilanes. Various catalytically active manganese-containing species were observed during catalysis, including silylene and silene complexes, and a catalytic cycle is proposed. The proposed catalytic cycle is unusual due to the involvement of silylene hydride and silene hydride complexes, potentially as on-cycle species. The reaction of [(dmpe)2MnH(C2H4)] (10) with H2 at 60 °C afforded ethane and the dihydrogen hydride complex [(dmpe)2MnH(H2)] (11), which has previously been prepared by an alternative route. Complex 10 reacted with hydroborane reagents 9-BBN or HBMes2 at 60 °C to afford EtBR2 and Mn(I) borohydride complexes [(dmpe)2Mn(μ-H)2BR2] (29: R2 = C8H14, 30: R = Mes); two intermediates were observed in each of these reactions. Deuterium labelling experiments using the deuterated hydroborane DBMes2 suggest that this reaction proceeds via the 5-coordinate ethyl isomer of 10; [(dmpe)2MnEt] (13). By contrast, exposure of 10 to BH3∙NMe3 required a higher temperature (90 °C) to yield [(dmpe)2Mn(μ-H)2BH2] (28), and ethylene was formed as the reaction byproduct; this reaction presumably proceeded by ethylene substitution. Deuterium incorporation into both the MnH and BH environments of 28 was observed under an atmosphere of D2 at 90 °C. Reactions of 10 with free dmpe yielded ethylene and a mixture of [{(dmpe)2MnH}2(μ-dmpe)] (31) and [(dmpe)2MnH(κ1-dmpe)] (32), which could be isolated by washing/recrystallization or sublimation, respectively. Similar reactivity was observed between 10 and HPPh2, which afforded ethylene and [(dmpe)2MnH(HPPh2)] (33) at 90 °C. Exposure of 10 to HSnPh3 yielded the manganese(II) stannyl hydride complex [(dmpe)2MnH(SnPh3)] (34) along with ethylene and, presumably, additional unidentified products. However, the mechanism for formation of 34 is unclear, it could not be isolated in pure form due to decomposition to form various species including SnPh4, and the mechanism of the decomposition process remains obscure. Previously reported complex 11, along with new complexes 28-31 and 33-34, were crystallographically characterized. This work provides valuable insights to unusual metal–ligand bonding motifs and reactions, and as such contributes to the fundamental understanding of organometallic chemistry. / Dissertation / Doctor of Philosophy (PhD) / The focus of this work is the synthesis and investigation of manganese-containing complexes with Mn–P, Mn–C, Mn–H, and/or Mn–Si linkages. Many of these complexes feature unusual bonding motifs, including the first group 7 complexes bearing an unstabilized silylene (:SiR2) ligand and the first 1st row transition metal complexes bearing an unstabilized silene (R2Si=CR2) ligand. Variable temperature Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography were employed to investigate the structures of these complexes, while Density Functional Theory (DFT) calculations and trapping experiments were employed to understand the mechanisms for various unusual chemical transformations. Some of the complexes were evaluated for activity towards catalytic hydrosilylation of ethylene. This work provides valuable insights to unusual metal–ligand bonding motifs and reactions, and as such contributes to the fundamental understanding of organometallic chemistry.

Considerable variation exists both within and between species in nuclear DNA content. Despite there being no obvious functional role for much of this DNA, many studies have reported phenotypic correlations with genome size at various taxonomic levels. This suggests that DNA plays a functional role beyond the traditionally understood mechanisms. One such example of a phenotypic correlation with DNA content is present in the genus Silene, where a negative correlation between DNA content and flower size exists within and between species. This relationship is consistent with the direction of sexual dimorphism in DNA content (caused by heteromorphic sex-chromosomes) and flower size in the most studied species in the genus: S. latifolia. This thesis takes a comparative approach between two closely related species in the genus (S. latifolia and S. marizii), which differ markedly in their nuclear DNA content, in order to investigate the nature and phenotypic impacts of variation in DNA content. A phenotypic survey from a number of S. marizii populations reveals that the pattern of DNA content variation in this species is very different to that in S. latifolia. In particular, phenotypic correlations with DNA content appear be much weaker, whilst sexual dimorphism in DNA content, when present, appears to occur in either direction. A survey of interspecific hybrids suggests that this may be due to an enlarged S. marizii X-chromosome and that DNA content in hybrids may be biased with regard to their parents. Repetitive elements may be significant constituents of plant genomes. A study of Ty1-copia class retrotransposons in the two species reveals that they are present as a large and highly heterogeneous population. Phylogenetic analysis of these elements suggests a substantial degree of genetic isolation between the two species. Finally, an assessment of the flow-cytometric method, used to estimate DNA content, reveals substantial error associated with the method, but only limited evidence for stoichiometric effects.