The reactions of the transient silylenes SiMe2, SiPh2, and SiMes2 with enolizable and non-enolizable carbonyl compounds have been studied in solution by steady state and laser flash photolysis methods. These reactions have been shown to involve the initial formation of a silacarbonyl ylide intermediate, which has been detected directly in several cases and found to exhibit a broad absorption band in the λmax ≈ 500 – 650 nm range in solution. The ensuing chemistry of these intermediates depends on the nature of the carbonyl compound. The reactions of silylenes with enolizable carbonyl compounds generate ene-adducts formed via H-migration in the silacarbonyl ylide. Kinetic isotope effects were investigated in the reactions of the three silylenes with acetone(-d6) and camphor(-d2). The results show an isotope effect for camphor, which indicates the H-migration step is the rate-determining step in the reaction. The effects of ring strain in the carbonyl compound were investigated with dicyclopropyl ketone, relative to diisopropyl ketone. The introduction of ring strain causes a systematic decrease in the rate constants. On the other hand, the reactions of silylenes with non-enolizable carbonyl compounds proceed via cycloaddition. The reactions of SiMes2 with 2,2,5,5-tetramethylcyclopentanone and SiPh2 with 2-adamantanone afford [1+2] and [1+2+2]-cycloadducts, respectively. The kinetic behavior of the silylene and silacarbonyl ylide of these systems are reflective of their corresponding reaction mechanism. However, the kinetic behavior of the silacarbonyl ylides in the reactions of SiMe2 with SiPh2 with 2,2,5,5-tetramethylcyclopentanone and di-tert-butyl ketone are more complex to interpret because a stable cycloadduct is not observed. The trends in the reactivity of the three silylenes, and in some cases the silacarbonyl ylides, with the series of enolizable and non-enolizable carbonyl compounds studied in our group are discussed in this thesis. / Thesis / Master of Science (MSc)

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Cette thèse est consacrée à l'étude de la réactivité d'un silacyclopropylidène hautement réactif, dû à l'incorporation du fragment silylène dans un cycle tendu à 3 chaînons. Les travaux réalisés portent plus particulièrement sur ses applications en synthèse de nouvelles molécules et en chimie de coordination. Le premier chapitre est une introduction bibliographique permettant de présenter les différents modes de stabilisation des silylènes, ainsi que les spécificités du silylène à cycle tendu. Le deuxième chapitre est consacré à l'étude de la réactivité du silacyclopropylidène au travers de ses propriétés nucléophiles et électrophiles. Le caractère nucléophile prononcé du silylène permet la stabilisation d'un fragment dichlorogermylène via la formation d'un adduit silylène-germylène. Cette espèce peut être considérée comme un précurseur pour la synthèse de nouveaux composés à base de germanium. En présence de trichlorophosphine, le silacyclopropylidène montre une réactivité originale conduisant à la formation d'un phosphirane cyclique, par l'insertion formelle de l'atome de phosphore dans les liaisons Si-C. Le troisième chapitre décrit la synthèse et la caractérisation du premier complexe stable de dioxyde de silicium. La complexation du fragment SiO2 est obtenue par coordination d'un système donneur-accepteur ainsi que d'une base de Lewis sur le centre silicié. Il est important de noter que le fragment SiO2 peut être extrait du complexe par la réaction avec deux équivalents de silane, démontrant que ce complexe peut être considéré comme une source stable et soluble de SiO2. Enfin, le quatrième chapitre de cette thèse présente la synthèse et la caractérisation de deux nouveaux ligands bidentates iminosilylène et iminogermylène. L'étude porte également sur l'application du ligand iminosilylène en synthèse de complexes d'or(I). / The main subject of this PhD thesis is the application of a silacyclopropylidene in synthesis and in coordination chemistry. This three membered cyclic silylene stabilized by coordination of Lewis base presents a unique and high reactivity due to the highly strained small cyclic structure. The first chapter is a bibliographic study that describes the different stabilization methods of silylenes, as well as the specific properties of the highly strained cyclic silylene. In the second chapter, the reactivity of the silacyclopropylidene toward various non-metallic species was presented. Its pronounced nucleophilic character allows the synthesis of a stable silylene-dichlorogermylene complex. The silacyclopropylidene shows an original reactivity toward trichlorophosphine leading to the formation of a cyclic phosphirane. These results demonstrate the unique properties of silacyclopropylidene, mainly related to the strained small cyclic structure. The third chapter concerns the synthesis and the characterization of the first stable silicon dioxide complex. The SiO2 complex was obtained by the coordination of a donor-acceptor system as well as an additional Lewis base on the silicon center. It is important to note that the SiO2 fragment can be extracted from the complex by reaction with two equivalents of silane, demonstrating that this complex is a stable and soluble SiO2 source. Finally, the fourth chapter of this thesis presents the synthesis and the characterization of two new bidentate iminosilylene and iminogermylene ligands. The study deals also on the application of the iminosilylene ligand for the synthesis of gold(I) organometallic complexes.

In this dissertation, catalytic C-F bond activation mediated by alumenium and silylium species, improved methods for the synthesis of highly chlorinated carboranes and dodecaborates, new type of P2Si= pincer silylene Pt complexes and PBP pincer Rh complexes are presented. In Chapter II, the design and synthesis of P2Si= and PBP ligand precursors is described. BrC6H4PR2 is shown to be a useful building block for PXP type of ligands with o-arylene backbone. RLi reagents displayed high chemoselectivity towards electrophiles, such as Si(OEt)4 and BX3 (X = Hal). In Chapter III, new chlorination methods to synthesize [HCB11Cl11]- and [B12Cl12]2- are presented. [HCB11Cl11]- was obtained via reactions of Cs[HCB11H11] with SbCl5 or via reactions of Cs[HCB11H11] with Cl2 in acetic acid and triflic acid. Heating Cs2[B12H12] in mixtures of SO2Cl2 and MeCN led to the isolation of Cs2[B12Cl12] in high yield. In Chapter IV, Et2Al[HCB11H5Br6] or Ph3C[HCB11H5Br6] were shown to be robust catalysts for sp3 C-F bond activation with trialkylaluminum as the stoichiometric reagent. Trialkylaluminum compounds were also shown to be able to be used as “clean-up” reagent for the C-F bond activation reactions, which led to ultra high TON for the catalytic reactions. In Chapter V, a series of (TPB)M complexes (M = Ni, Pd, Pt) were synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallography. The resulting metal complexes displayed strong dative M→B interaction and unusual tetrahedral geometry for four-coordinate 16ē species, due to the cage structure of the ligand. In Chapter VI, (PSiHP)PtCl was synthesized via the reaction of the ligand precursor and Pt(COD)Cl2, which was used to obtain a series of (PSiHP)PtX complexes(X= I, OTf, Me, Ph, Mes). After hydride abstraction by Ph3C[HCB11Cl11], the X ligand (X= I, OTf, Me, Ph) migrated from the Pt center to silicon center to give a cationic pincer silyl species. The migration was not observed when mesityl was used as the X ligand, which resulted in the first known pincer complex with central silylene donor. Our approaches towards PNP pincer boryl Rh complexes were summarized in Chapter VII. (PBPhP)Rh pivalate complex underwent C-Ph bond activation to yield the pivalate-bridging Rh borane complex.

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.

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.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22663号 / 工博第4747号 / 新制||工||1742(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 村上 正浩, 教授 大江 浩一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Samples with thin layer of poly[methyl(phenyl)silylene] were prepared for cathodoluminescence measurement. Dependence of cathodoluminescence on temperature was studied on these samples. Spectra of emitted light were measured on the samples when they were gradually heated to 20, 50, 75, 100 and 125°C. Kinetics of the process of poly[methyl(phenyl)silylene] regeneration at higher temperature was observed. Samples of polysilylene were displayed by scanning electron microscopy.

<p>The complexation reactions of silylenes (SiMe₂, SiPh₂ and SiMes₂) and germylenes (GeMe₂, GePh₂ and GeMes₂) with a series of O-, S-, N- and P-donors have been studied in hexanes solution. The equilibrium constants for complexation of SiMes₂ and GeMes₂ with 7 Lewis bases were determined, and demonstrate that the silylene is more Lewis acidic than the germylene by ca. 1 kcal mol^-1. Diethyl ether reacted with the six tetrellylenes with equilibrium constants that decrease in the order SiPh₂ > SiMe₂ > GePh₂ > GeMe₂ > SiMes₂ > GeMes₂, establishing a trend in the Lewis acidities of the silylenes and germylenes. Experimental results are complemented by calculated (G4) binding enthalpies of the MMe₂-donor complexes, which were found to correlate with Drago’s E and C parameters leading to the classification of SiMe₂ and GeMe₂ as borderline soft Lewis acids.</p> <p>A number of sigma-bond insertion reactions by transient silylenes was examined, namely the O-H, N-H and Si-O insertion reactions with alcohols, amines and siloxanes, respectively. In all cases the reactions were found to proceed via a two step mechanism in which the first step is a reversible formation of a Lewis acid-base complex. The second step was found to be a catalytic H-migration in the reactions with alcohols and amines; the catalysis by the alcohol is at least 10⁴ times faster than that by the amine. Complexes of silylenes with alkoxysilanes and siloxanes transform into the final products via a unimolecular [1,2]-silyl migration.</p> <p>Chalcogen abstraction reactions by silylenes (SiMe₂, SiPh₂, SiTmp₂ and SiMes₂) and germylenes (GeMe₂ and GePh₂) from oxiranes (cyclohexene oxide (CHO) and propylene oxide (PrO)) and thiiranes (cyclohexene sulfide (CHS) and propylene sulfide (PrS)) were investigated by laser flash photolysis and steady-state photolysis methods. The results indicate that the reaction proceeds via a two step mechanism, in which the first step is a reversible complexation followed by a unimolecular decomposition of the complex to yield products of chalcogen abstraction, namely alkenes and the corresponding R₂M=X transients (R = Me, Ph, Tmp and Mes, M = Si or Ge, X = O or S). Diphenylsilanethione was directly detected and identified on the basis of its spectra and reactivity with amines and alcohols. The O- and S- abstraction by silylenes proceed with ca. 50% efficiency; in contrast, no evidence for O-abstraction by GeMe₂ from CHO could be found, while propene was formed in ca. 35% yield in the reaction of GeMe₂ with PrS.</p> / Doctor of Philosophy (PhD)