The iridoids are a large family of monoterpenoid natural products that possess a wide range of biological activities. A great deal of research has already been done in the field of iridoid total synthesis, but limitations still remain. Specifically, few syntheses of iridoid β-glycosides have been reported. This work describes the 14 step asymmetric total synthesis of the iridoid β-glycoside (+)-geniposide utilizing a phosphine-catalyzed [3+2] cycloaddition as the key step. Other noteworthy steps in the synthesis include a palladium-catalyzed kinetic resolution and a previously unutilized method for iridoid glycosidation. In addition to describing the synthesis of (+)-geniposide, this dissertation will also review 1) phosphine-catalyzed cycloaddition reactions and 2) previous enantioselective total syntheses of iridoid glycosides. / text

The techniques of valence photoelectron spectroscopy (PES), X-ray diffraction, molecular orbital calculations, and multi-nuclear NMR are combined in a comparison of metal-phosphine bonding in a series of phosphine substituted molybdenum and tungsten metal carbonyl complexes, M(CO)(6-n)(P)(n) [n = 1,2,3,4,6]. The phosphine, P, represents either the mono-dentate phosphine, PMe₃, or one phosphine unit in the diphosphines, Me₂P(CH₂)ₓPMe₂, [x = 1, bis(dimethylphosphino)methane (DMPM); x = 2, 1,2-bis(dimethylphosphino)ethane (DMPE)]. Comparison of PMe₃ and the diphosphines in mono-dentate coordination (i.e. η¹-Mo(CO)₅DMPE) indicates the σ-donor strength is essentially identical for the three phosphines studied. Comparison of PMe₃ and the diphosphines in cis-chelating geometries reveals essentially identical charge at the coordinated phosphorus atoms and nearly identical charge at the metal center for cis-M(CO)₄(PMe₃)₂ and cis-M(CO)₄DMPE despite different local P-M-P bond angles. The X-ray crystal structures reveal a "twist" of the phosphine ligand when in sterically strained coordination geometries. The phosphine twist results in a "bent" metal-phosphine bond and is evaluated based on both electronic and steric considerations. The phosphine twist principle is used in studies on the nature of phosphine ligand electronic effects in the M(CO)(6-n)(P)(n) series at high substitution numbers, n. The PES data of the DMPE complexes for n = 4, cis-Mo(CO)₂(DMPE)₂, and n = 6, Mo(DMPE)₃, show symmetric metal electronic structure, but also a deviation from the previously observed additive behavior of phosphine electronic effects. The PES data for cis-Mo(CO)₂(PMe₃)₄ reveal a symmetric metal electronic structure due to sterically induced ligand-ligand interactions in this metal carbonyl complex. Multi-nuclear NMR data (³¹P and ⁹⁵Mo) are presented and the results discussed in light of the important ligand-ligand interactions observed in the PES studies. In addition, comparison of the NMR results for the mono-dentate and chelating phosphine complexes and the PES metal electronic structures provides a possible contribution to the ring chelate effect that is observed in the ³¹P and ⁹⁵Mo chemical shifts. The ring chelate effect refers to the unexplained relative differences between the ³¹P and ⁹⁵Mo chemical shifts of the cis-(PR₃)₂ complexes and the chelating diphosphine analogues.

Das Ziel der vorliegenden Arbeit war es, erstmals einen Komplex mit einem verbrückenden Phosphanliganden darzustellen. Dies sollte ausgehend von den zweikernigen Rhodiumkomplexen des Typs [Rh2XX’(CPh2)2(SbR3)] und geeigneten Phosphanen erreicht werden. Es galt zunächst, eine möglichst große Palette von Stiban-verbrückten Verbindungen zu synthetisieren und ihr chemisches Verhalten im Allgemeinen und im Hinblick auf das gesteckte Ziel insbesondere ihre Reaktivität gegenüber Phosphanen zu studieren. Die im eigenen Arbeitkreis synthetisierten Komplexe [Rh2XX’(CPh2)2(SbiPr3)] (X, X’ = Cl, acac) reagieren mit CNtBu, SbEt3 oder Sb(CH2Ph)3 unter Substitution des SbiPr3-Liganden, wobei die Zweikernstruktur erhalten bleibt. Die Verbindungen [Rh2XX’(CPh2)2(SbiPr3)] [X = Cl, X’ = acac (7), acac-f3 (8), dpm (9); X = X’ = -acac (10), -dpm (11), Br (12), I (13)] können ausgehend von [Rh2Cl2(CPh2)2(SbiPr3)] und Na(acac), Na(acac-f3), Na(dpm), NaBr bzw. NaI dargestellt werden. Der Komplex 11 ist nur NMR-spektroskopisch charakterisiert. Stiban-verbrückte Carboxylatokomplexe sind durch Umsetzung von 10 mit CR3COOH (R = F, H) erhältlich. Mit äquimolaren Mengen an Säure bilden sich die gemischten Komplexe [Rh2(acac)X(CPh2)2(SbiPr3)] [X = O2CCF3 (14), O2CCH3 (15)]. Setzt man die Säure im Überschuß ein, so gelangt man zu den Bis(carboxylato)-Komplexen [Rh2X2(CPh2)2(SbiPr3)] [X = O2CCF3 (16), O2CCH3 (17)]. Die Struktur der Verbindung 17 ist röntgenographisch belegt. Ausgehend von den Verbindungen des Typs [Rh2XX’(CPh2)2(SbiPr3)], welche mindestens einen starken Chelatliganden wie acac, acac-f3 oder Acetat aufweisen, gelingt die Einführung der sterisch wenig anspruchsvollen Phosphane PMe3, PEt3 und PMe2Ph in eine semiverbrückende bzw. verbrückende Position. Die Verbindungen 18 und 21 sind kristallstrukturanalytisch charakterisiert. Während die PMe3- und PMe2Ph-Komplexe 21 und 40 in Lösung beständig sind und sich beim Erhitzen zersetzen, lagern sich die Komplexe [Rh2(acac)2(CPh2)2(PR3)] [R = Et (36), nBu (37)] in Lösung nahezu quantitativ in die gemischtvalenten Rh0-RhII-Verbindungen [(R3P)Rh(CPh2)2Rh(acac)2] [R = Et (38), nBu (39)] um. Der intramolekulare Reaktionsverlauf konnte durch kinetische Messungen bestätigt werden. Bei der Reaktion von 10 mit PMePh2 entsteht, ohne dass eine Phosphan-verbrückte Zwischenstufe nachweisbar ist, der Komplex [(MePh2P)Rh(CPh2)2Rh(acac)2] (41). Bei der Reaktion von 21 mit CO wird der PMe3-Ligand aus der verbrückenden auf eine terminale Position verdrängt und es bildet sich der Komplex 22, der einen verbrückenden Carbonylliganden aufweist. Analog zur Synthese der Stiban-verbrückten Carboxylatokomplexe 14 - 17 können auch die PMe3-Komplexe 26 - 28, die durch Stibansubstitution nicht zugänglich sind, ausgehend von 21 und einer äquimolaren Menge bzw. einem Überschuß CR3COOH (R = F, H) dargestellt werden. Bei der Umsetzung von 21 mit einem Äquivalent Essigsäure erhält man allerdings ein Gemisch, das den Komplex 27 als Hauptprodukt enthält. Im Unterschied zur Reaktion von 21 mit CR3COOH, wird bei der Umsetzung mit einem Überschuß Phenol nur ein acac-Ligand durch Phenolat ersetzt und die Verbindung 29 gebildet. Bei der Reaktion von 21 mit einem Moläquivalent Me3SiX (X = Cl, Br, I) erfolgt selektiv die Substitution eines acac-Liganden durch einen Halogenoliganden. Die Darstellung der Komplexe [{Rh2X2(CPh2)2(PMe3)}n] [X = Cl (32), Br (33), I (34)] gelingt durch Umsetzung von 21 mit einem großen Überschuß Me3SiCl bzw. mit 2 Äquivalenten Me3SiX (X = Br, I). Während der Dichloro-Komplex 32 im Kristall als dimere Einheit vorliegt besitzt der Diiodo-Komplex 34 eine zweikernige Struktur. Dies konnte kristallstrukturanalytisch belegt werden. Der PMe2Ph-Komplex 43 ist durch Umsetzung von 40 und der PEt3-Komplex 44 durch Umsetzung von 19 mit Me3SiCl im Überschuß erhältlich. Nicht nur sterisch wenig anspruchsvolle Trialkylphosphanliganden sind in der Lage, zwei Metallzentren zu verbrücken. So erhält man durch Umsetzung der Verbindungen [(R3P)Rh(CPh2)2Rh(acac)2] (R = iPr, Ph) mit HCl die Phosphan-verbrückten Komplexe [Rh2Cl2(CPh2)2(PR3)] [R = iPr (45), Ph (46)]. Die Darstellung des ersten Arsan-verbrückten Komplexes [Rh2(acac)2(CPh2)2(AsMe3)] (47) gelingt ausgehend von Verbindung 10 und AsMe3. Der verbrückende AsMe3-Ligand in 47 kann leicht durch SbiPr3, PEt3, PnBu3 oder PMe2Ph substituiert werden. Analog zum PMe3-Komplex 21 reagiert 47 mit einem Äquivalent Me3SiCl zum gemischten Komplex [Rh2(acac)Cl(CPh2)2(AsMe3)] (48) und mit einem großen Überschuss Me3SiCl zum Vierkernkomplex [{Rh2Cl2(CPh2)2(AsMe3)}2] (49). Die Struktur von 49 ist kristallographisch gesichert. / The aim of this thesis was to prepare for the first time a complex containing a phosphane ligand in a bridging position. This should be achieved starting from dinuclear rhodium complexes of the general composition [Rh2XX’(CPh2)2(SbR3)] and suitable phosphanes. At first, a series of stibane-bridged compounds should be prepared to investigate their chemical properties and in particular their reactivity towards phosphanes. The complexes [Rh2XX’(CPh2)2(SbiPr3)] (X, X’ = Cl, acac), which were previously prepared, react with CNtBu, SbEt3 and Sb(CH2Ph)3 resulting in the substitution of the SbiPr3 ligand. The dinuclear structure, however, is maintained. The compounds [Rh2XX’(CPh2)2(SbiPr3)] [X = Cl, X’ = acac (7), acac-f3 (8), dpm (9); X = X’ = acac (10), dpm (11), Br (12), I (13)] were prepared starting from [Rh2Cl2(CPh2)2(SbiPr3)] and NaX (X = acac, acac-f3, dpm, Br, I). Complex 11 has been characterized only by NMR spectroscopy. Stibane-bridged complexes containing carboxylato ligands can be obtained from 10 and CR3COOH (R = F, H) as starting materials. With equimolar amounts of acid the mixed complexes [Rh2(acac)X(CPh2)2(SbiPr3)] [X = O2CCF3 (14), O2CCH3 (15)] are formed. If an excess of acid is used, the bis(carboxylato) complexes [Rh2X2(CPh2)2(SbiPr3)] [X = O2CCF3 (16), O2CCH3 (17)] are formed. The molecular structure of 17 was confirmed by a X-ray crystal structure analysis. By using compounds of the general composition [Rh2XX’(CPh2)2(SbiPr3)], which contain at least one strong chelating ligand like acac, acac-f3 or acetate, the coordination of sterically less hindered phosphanes such as PMe3, PEt3 and PMe2Ph in a semibridging or bridging position is possible. Compounds 18 and 21 were crystallographically characterized. While the PMe3 and PMe2Ph complexes 21 and 40 are stable in solution and decompose only at higher temperatures, the complexes [Rh2(acac)2(CPh2)2(PR3)] [R = Et (36), nBu (37)] rearrange in solution nearly quantitatively to form the mixed-valence Rh0-RhII-compounds [(R3P)Rh(CPh2)2Rh(acac)2] [R = Et (38), nBu (39)]. The intramolecular mechanism of the reaction was confirmed by kinetic measurements. The reaction of 10 with PMePh2 leads to the formation of the complex [(MePh2P)Rh(CPh2)2Rh(acac)2] (41). An intermediate with a bridging phosphane unit could not be detected. By treatment of 21 with CO, the PMe3 ligand migrates from the bridging to a terminal position and a product containing a bridging carbonyl ligand is formed. Following the synthesis of the stibane-bridged carboxylato complexes 14 – 17, the corresponding trimethylphosphane complexes 26 - 28, which are not accessible by bridge-ligand exchange, can be prepared from 21 and either an equimolar amount or an excess of CR3COOH (R = F, H), respectively. The reaction of 21 with acetic acid in the ratio of 1:1 gives a mixture containing 27 as the major component. In contrast to the reaction of 21 with CR3COOH, treatment of 21 with an excess phenol results in the replacement of only one acac ligand and affords the unsymmetrical compound 29. The reaction of 21 with Me3SiX (X = Cl, Br, I) in the molar ratio of 1:1 leads to the substitution of one acac by one halogeno ligand. The preparation of the complexes [{Rh2X2(CPh2)2(PMe3)}n] [X = Cl (32), Br (33), I (34)] succeeds if 21 is treated with two equivalents of Me3SiX (X = Br, I) or with a large excess of Me3SiCl, respectively. As the X-ray diffraction investigation confirms the dichloro complex 32 is a dimer in the crystal. In contrast to 32 the diiodo complex 34 is a monomer. The phosphane-bridged complexes 43 and 44 can be obtained by treatment of 40 and 19 with an excess of Me3SiCl. Not only sterically less hindered trialkylphosphane ligands are able to bridge two metal centers. The has been proved by the preparation of the complexes [Rh2Cl2(CPh2)2(PR3)] [R = iPr (45), Ph (46)] from the mixed-valence compounds [(R3P)Rh(CPh2)2Rh(acac)2] (R = iPr, Ph) and HCl. The synthesis of the first arsane-bridged complex [Rh2(acac)2(CPh2)2(AsMe3)] (47) has been performed using 10 and AsMe3 as the precursers. The bridging AsMe3 ligand in 47 is readily displaced by SbiPr3, PEt3, PnBu3 or PMe2Ph. Similarly to the corresponding PMe3 complex 21, compound 47 reacts with one equivalent of Me3SiCl to afford the mixed complex [Rh2(acac)Cl(CPh2)2(AsMe3)] (48) in good yield. With a large excess of Me3SiCl the tetranuclear complex [{Rh2Cl2(CPh2)2(AsMe3)}2] (49) has been obtained, the structure of which was confirmed by a single crystal X-ray diffraction study.

The design of ligands is one of the most important and simultaneously challenging fields of research in modern inorganic chemistry. The aim is to synthesise ligands that can serve as coordination units for a broad variety of metal fragments and different purposes. The ligands have to be very flexible concerning their donating behaviour and geometrical prerequisites in order to correspond to the required metal fragments. / Ziel der vorliegenden Arbeit war die Synthese eines Januskopfliganden der zweiten Generation und die Untersuchung seiner Reaktivität und seines Koordinationsverhalten. Als Zielverbindung wurde Di(benzothiazol-2-yl)phosphan (1) gewählt (Schema 7.1). Neben harten Koordinationsstellen enthalten die heteroaromatischen Substituenten dieses Liganden zusätzlich weiche, die das System im Vergleich zu z. B. Di(pyrid-2-yl)phosphan im Bezug auf mögliche koordinierte Metallfragmente flexibler machen sollten.

The development of safe and efficient hydrogen storage materials will aid in the transition away from fossil fuels toward a renewable, hydrogen-based energy infrastructure. Boron-nitrogen (BN) containing materials have attracted much attention due to their high hydrogen storage capacity and fast kinetics of hydrogen release. Furthermore, computational studies predict that hydrogen storage materials based on the BN-heterocycle 1,2-azaborine may enable reversible H2 uptake and release, with little additional energy input. This thesis develops the basic science needed for a hydrogen storage platform based on BN-heterocycles such as 1,2-azaborine. Chapter I is a review of recent developments in azaborine chemistry. Chapter II describes a regeneration scheme from a "spent" 1,2-azaborine hydrogen storage material to "fully charged" fuel using molecular H2 and H-/H+ equivalents. Chapter III describes the experimental determination of the resonance stabilization energy of 1,2-azaborines using reaction calorimetry. Chapter IV explores the effect of boron-substitution on the rate and extent of hydrogen release from BN materials. Chapter V describes work on a project unrelated to hydrogen storage, the synthesis and electronic parameter determination of the first 1,2- azaborine-containing phosphine ligand analog. This dissertation includes previously published and unpublished co-authored material.

This thesis describes the synthesis and coordination chemistry of self-assembled multidentate iron(II) phosphine complexes. Chapter 1 introduces the background to phosphine ligands, their properties, interactions with transition metals and applications. The chapter then discusses macrocyclic and medium ring P,N-containing ligands, as well as some water soluble phosphines. The chapter also introduces the novel self-assembled macrocyclic phosphine complex [FeL1(H2O)2]SO4 (1) and its tetradentate cyclic phosphine ligand L1. Chapter 2 describes the synthesis of [FeL1(H2O)2]SO4 (1) and its coordination chemistry with a variety of ligands, including halides, pseudo-halides, and CO. 57Fe labelled versions of complex 1 and the related dicarbonyl complex [FeL1(H2O)2]SO4 (9) were synthesised as models for the hydrogenase protein Hmd in a Nuclear Resonance Vibrational Spectroscopy study. Reactions were also undertaken to functionalise the hydroxymethyl groups in order to alter the properties of the complexes. The reaction of 1 with acetic anhydride afforded complex [Fe(L2)(k2-O2SO2)] (13), possessing the acylated ligand L2 and a coordinated sulfate ligand. The coordination chemistry of 13 was explored with a variety of neutral and anionic ligands, including halides, pseudohalides, carbonate, and CO. Electrochemical cyclic voltammetric investigations of L1 and L2 complexes were also explored. Chapter 3 reports the investigations carried out to explore the effect of altering the reagents of the self-assembly reaction. The self-assembly reaction to synthesise complex 1 was also attempted with copper(II), nickel(II), copper(II) and zinc(II) salts, as well as in the absence of a metal template, which all did not lead to the formation of any isolable species. The syntheses of the novel iron(II) complexes [Fe(L3)2(SO4)] (23) and cis-[Fe(L3)2Cl2] (24a) containing the new bidentate phosphine ligand L3 are also reported, as well as the coordination chemistry of 24a with a variety of ligands. The reaction of 24a with NaBH4 gave the trans hydride-chloride complex trans-[Fe(L3)2(H)Cl] (29). Electrochemical investigations of the L3 complexes were also carried out. Chapter 4 provides the experimental details for the reactions described in chapters 2 and 3.

Song Haibin. / "March, 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 137-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Lai Chi Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 63-68). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgments --- p.iii / Abbreviations --- p.iv / Abstract --- p.v / Chapter Chapter 1 --- General introduction / Chapter 1.1 --- Background of phosphines and arsines ligands in metal catalysis --- p.1 / Chapter 1.2 --- Electronic effect of phosphines and arsines ligands in metal catalysis --- p.2 / Chapter 1.3 --- Synthesis of Aryl Phosphines --- p.7 / Chapter 1.4 --- Synthesis of Aryl Arsines --- p.9 / Chapter 1.5 --- The objective of this work --- p.11 / Chapter Chapter 2 --- Palladium catalyzed phosphination of aryl triflates / Chapter 2.1 --- Synthesis of aryl triflates --- p.12 / Chapter 2.2 --- Palladium catalyzed phosphination of aryl triflates --- p.15 / Chapter 2.3 --- Mechanistic studies of phosphination --- p.19 / Chapter Chapter 3 --- Palladium catalyzed arsination of aryl triflates --- p.22 / Chapter 3.1 --- Solvent and catalyst screening in palladium catalyzed arsination --- p.23 / Chapter 3 2 --- Stoichiometry of triphenylarsine --- p.24 / Chapter 3.3 --- Temperature effect of arsination --- p.25 / Chapter 3.4 --- Results of palladium catalyzed arsination --- p.26 / Chapter 3.5 --- Mechanistic studies of arsination --- p.28 / Chapter Chapter 4 --- Green chemistry approach 一 solventless phosphination and arsination / Chapter 4.1 --- Introduction to green chemistry --- p.30 / Chapter 4.2 --- Results of solventless phosphination --- p.31 / Chapter 4.3 --- Results of solventless arsination --- p.33 / Conclusion --- p.36 / Experimental --- p.37 / Reference --- p.63

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A series of bi- and tri-dentate amido phosphine ligands H[Ph-PNP] (bis(2-diphenylphosphinophenyl)amine), H[iPr-PNP] (bis(2-diisopropylphosphino- phenyl)amine), H[Cy-PNP] (bis(2-dicyclohexylphosphinophenyl)amine), H[iPr-NP] (N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline), and H[Me-NP] (N-(2-diphenylphosphinophenyl)-2,6-dimethylaniline) have been synthesized in high yield. Lithiation of these compounds with n-BuLi in ethereal solutions afforded the corresponding lithium complexes. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPr-NP]Li(THF)2 or [Me-NP]Li(THF)2 in toluene produced the corresponding [iPr-NP]MCl3(THF) and [Me-NP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [Me-NP]MCl3(THF) and [iPr-NP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPr-NP]MCl3(THF) and [Me-NP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. Treatment of PdCl2(PhCN)2 with [iPr-NP]Li(THF)2 in THF afforded dimeric {[iPr- NP]PdCl}2, which was reacted with tricyclohexylphosphine to produce [iPr-NP]PdCl(PCy3). The two phosphorus donors in [iPr-NP]PdCl(PCy3) are mutually cis as indicated by the solution NMR and X-ray crystallographic studies. Both {[iPr-NP]PdCl}2 and [iPr-NP]PdCl(PCy3) are highly active catalyst precursors for Suzuki coupling reactions of a wide array of aryl halides, including those featuring electronically deactivated and sterically hindered characteristics. The metathetical reaction of NiCl2(DME) (DME = dimethoxyethane) with [iPr-PNP]Li(THF) and [Cy-PNP]Li(THF), respectively, produced the diamagnetic nickel complexes [iPr-PNP]NiCl and [Cy-PNP]NiCl. These nickel chloride complexes were reacted with Grignard reagents to afford thermally stable nickel alkyl and aryl complexes [iPr-PNP]NiR and [Cy-PNP]NiR (R = Me, Et, n-Bu, Ph). A series of divalent nickel alkoxo, amido, thiolate complexes [iPr-PNP]NiX and [Cy-PNP]NiX (X = OPh, NHPh, SPh) were also easily prepared. Reaction of H[Ph-PNP] with Ni(COD)2 (COD = cycloocta-1,5-diene) produced the transient [Ph-PNP]NiH, which underwent COD insertion to give [Ph-PNP]Ni(£b1- cyclooctenyl). Instead, reactions of Ni(COD)2 with H[iPr-PNP] and H[Cy-PNP], respectively, afforded isolable diamagnetic complexes [iPr-PNP]NiH and [Cy-PNP]NiH without alkene insertion. The reactivity of these nickel hydride complexes was investigated.