Graduate / 0485

No description available.

This work involves the characterisation of reaction products of transition metals from the 1st, 2nd and 3rd rows of the Periodic Table with guanidines and their lithiated derivatives. Physical methods such as infrared spectroscopy, (^1)H, (^13)C and (^19)F nuclear magnetic resonance spectroscopy, microanalysis, and conductivity measurements have been used to characterise the materials. The transition metal compounds used in this work can be divided into two groups: (i) metal carbonyls and (ii) metal halides. The metal carbonyls group consists of [M(CO)(_5)L] (M = Mn, L = Br; M = Cr, Mo, W, L = CO), [Mo(Cl)L(CO)(_3)] (L = Ƞ-C(_5)H(_5)) and [MoL(CO)(_3)][BF(_4)] (L = Ƞ-C(_7)H(_7) ), and the metal halide group consists of MCl(_2) (M = Pd, Pt), MLCl(_2) (M = Pd and L = C(_8)H(_12)), K(_2)MCl(_4) (M = Pd, Pt) and WCl(_4). Studies have involved two substituted guanidines, 1,2,3-triphenylguanidine and syn-1,2- diphenylguanidine and the Uthiated derivative of 1,2,3-triphenylguanidine.The reactions were undertaken using a variety of conditions. The type of solvent, temperature and molar ratio are important parameters, particularly for the complexes of manganese. Similar conditions were explored for the complexes of palladium, platinum, chromium, molybdenum, tungsten and arylmolybdenum derivatives. Carbonyl complexes of the type [Mn(Br)(CO)(_3)L(_2)] (L = 1,2,3- triphenylguanidine), [Mn(Br)(CO)(_4)L] (L = 1,2,3-triphenylguanidine), [Mo(Ƞ-C(_5)H(_5))L(CO)(_2)] (L = 1,2,3-triphenylguanidino) and complexes of the type [M2CI4L2] (M = Pd, Pt; L = 1,2,3-triphenylguanidine, 1,2-diphenylguanidine), [Pt(_2)Cl(_4)L(_3)] (L = syn-1,2-diphenylguanidine), [Pt(_2)Cl(_4)L(_2)L'] (L = syn-1,2-diphenylguanidine, L' = N,N'-diphenylurea), [Pt(_2)Cl(_2)L(_2)L'(_2)] (L = syn-l,2-diphenylguanidino, L(^1) = syn-l,2- diphenylguanidine ), [PtCl(_2)L] (L = HNC(Me)NHC(Me)NH) and [PdCl(_2)(C(_8)H(_12))L] (L = 1,2,3-triphenylguanidine, syn-1,2-diphenylguanidine), were isolated. A product containing BF(_3) was isolated, and the bonding of the BF(_3) studied. The guanidine ligand adopts various bonding modes towards transition metals, and studies have been directed towards determining the mode adopted in each of the new complexes synthesised. Guanidines are found to act as strong o- bonding ligands, having consequences on the remaining ligands. Comparison is made throughout with the related amidine ligands. Mechanisms of reactions, consistent with experimental data, are discussed throughout the thesis.

No description available.

This thesis details the synthesis and characterisation of alkaline earth metal complexes of phosphonium ylides and iminophosphoranes, together with some related phosphine oxide species. This thesis also contains the synthesis and structural characterisation of a number of novel phosphonium ylides and iminophosphoranes. Chapter 1 provides an introduction to the field of phosphonium ylides and related compounds, describing their preparation and subsequent reactivity. Chapter 2 contains an explanation of the experimental techniques and analytical tools used, whilst Chapter 3 details the syntheses and analyses for all of the complexes discussed in the thesis. Chapter 4 discusses novel alkaline earth metal phosphonium ylide complexes. The chapter contains the first structurally characterised neutral phosphonium ylide complexes of calcium, strontium and barium with the general formula (Ph(_3)PCH(_2))(_2) M[N(SiMe(_3))(_2)](_2), where M = Ca, Sr and Ba. The analogous iminophosphorane and phosphine oxide complexes are discussed in detail in chapter 5. Complexes of the general formula (Ph(_3)PNH)(_2) M[0C(_6)H2(Me)(^1)Bu(_2)](_2),(Ph(_3)P0)(_2) M[0C(_6)H(_2)(Me)’Bu(_2)](_2) and (Ph(_3)PO)(_2) M[N(SiMe(_3))(_2)](_2), are described where M =Ca, Sr and Ba. Chapter 6 details the synthesis of novel litbiated iminophosphoranes and related compounds as well as the synthesis of a novel dianion [Ph(_2)(PhCH')PN"] for use in synthetic organic chemistry. The final Chapter (7) details the synthesis and structural characterisation of a number of novel phosphonium ylides Ph(_2)R'PCHR" and iminophosphoranes Ph(_2)R’’’PNH and their corresponding salts e.g Ph(_2)R'PTH(_2)R"X and Ph(_2)R 'P+NH(_2)X .

This thesis describes the synthesis and properties of some extended donor-acceptor dyads with the donor being a ferrocenyl moiety and a fluorescent naphthalimide group as the acceptor. Two series of extended ferrocenyl-naphthalimide dyads were prepared in reasonable yield depending on the synthetic route. The first are a series of three ferrocenyl-CH=CH-spacer-C[triple bond]C-naphthalimide dyads in which the spacers are phenyl, biphenyl and anthryl and the second are a series of three ferrocenyl-C[triple bond]C-spacer-C[triple bond]C-naphthalimide dyads in which the spacers are 2,2� -bithiophene, 2,5-dimethoxybenzene and tetrafluorobenzene groups. The molecular structures of some compounds have been determined by X-ray diffraction although with many challenges because of the extensive [pi]-[pi] stacking of molecules that leads to ready aggregation in the solid state, particularly for the ferrocenyl-CH=CH-spacer-C[triple bond]C-naphthalimide dyads, in which the naphthalimide bears a methyl head group. In order to reduce the [pi]-[pi] stacking effect between the molecules and also to produce chiral molecules for the potential nonlinear optical applications, a chiral α-methylbenzylamine was introduced as the head group of naphthalimide for the ferrocenyl-C[triple bond]C-spacer-C[triple bond]C-naphthalimide dyads. The resulting comounds successfully gave crystals of sufficient quality for X-ray structural investigation. While the oxidative electrochemistry of the ferrocenyl compound in the two series of dyads was largely predictable (E� ~ 0.55 V for ferrocenyl-CH=CH- and ~ 0.72 V for ferrocenyl-C[triple bond]C-), the presence of spacers in the dyads appeared to afford stability to the reduced naphthalimide species. This was exhibited by the appearance of chemically reversible one-electron reduction processes for each of the compounds investigated. Similar unusual chemical reversibility was also shown by the spacer-C[triple bond]C-naphthalimide precursor systems. For the ferrocenyl-CH=CH-spacer-C[triple bond]C-naphthalimide dyads, the oxidation and reduction potentials closely resembled those of the simple ferrocenyl-CH=CH-spacer systems. This suggested that augmentation of the simple ferrocenyl-CH=CH-phenyl, -biphenyl and -anthryl systems with an alkyne linked naphthalimide unit showed little influence on the oxidation of the ferrocenyl moiety or the reduction of the naphthalimide unit. However, for the ferrocenyl-C[triple bond]C-spacer-C[triple bond]C-naphthalimide dyads, the oxidation and reduction potentials are influenced by the inductive effects of the spacers. While an anodic shift was observed for the dyad with the electron-withdrawing spacer tetrafluorobenzene, a cathodic shift was displayed for the dyads with the electron-donating spacers 2,2�-bithiophene and 2,5-dimethoxybenzene compared to that in the simple ferrocenyl-C[triple bond]C-naphthalimide system. The spectroscopic properties of the ferrocenyl-CH=CH-spacer-C[triple bond]C-naphthalimide dyads showed that interpolation of the aromatic spacers does not interfere with the internal charge separation. Oxidation of the ferrocenyl moiety resulted in bleaching of the metal-to-ligand charge transfer band at ~ 500 nm and the growth of a new band in the near infrared region at ~ 1000 nm. This new band can be assigned to a ligand-to-metal charge transfer transition, where the ferrocenium now acts as an acceptor to the naphthalimide donor. For the ferrocenyl-C[triple bond]C-spacer-C[triple bond]C-naphthalimide dyads, the spectroscopic properties showed that the mutually electron-withdrawing tetrafluorobenzene and naphthalimide units had little interaction despite their connection by a conductive alkyne link. In contrast, the dyads containing the electron-donating 2,2�-bithiophene and 2,5-dimethoxybenzene showed some degree of interaction between the spacer and the naphthalimide fragments. This was evidenced by the appearance of a broad absorption band in the range 410 - 440 nm, which is associated with an orbital that is delocalised between the spacer and the naphthalimide fragments. Again, the roles of donor and acceptor were reversed on oxidation of the ferrocenyl moiety. This resulted in the growth of a new near infrared band at ~750 mn for the dyad containing the tetrafluorobenzene spacer and at ~ 1000 nm for the dyads with 2,2�-bithiophene and 2,5 -dimethoxybenzene spacers. The ferrocenyl unit went from being a net donor to ferrocenium, which was acting as an acceptor, with the tetrafluorobenzene spacer adopting the donor role more reluctantly than the delocalised 2,2�-bithiophene-C[triple bond]C-naphthalimide and 2,5-dimethoxybenzene-C[triple bond]C-naphthalimide moieties. 1,3,5-Tri- and 1,2,4,5-tetra-substituted benzene cores were also used as spacers for the preparation of extended arrays of ferrocenyl-naphthalimide dyads. Utilisation of the 1,3,5 -tri-substituted benzene core enabled the core to be embellished in three directions, resulting in Y-motif extended arrays containing either one ferrocenyl unit [(ethenylferrocenyl)-C₆H₃-(C[triple bond]C-C₆H₅)₂] or one naphthalimide moiety [(4-piperidino-N-propargyl-naphthalimide)-C₆H₃-(Br)₂]. With the 1,2,4,5-tetra-substituted benzene core, the extension of the core was possible in four directions and gave extended arrays in an X-motif. Again, these systems contained either ferrocenyl units [bis(alkoxyferrocenyl)-C₆H₂-(C[triple bond]C-C₆H₅)₂] or naphthalimide moieties [(tetrakis-naphthalimide)-C₆H₂]. Attempts to incorporate both ferrocenyl and naphthalimide fragments into the X- or Y-motif extended arrays were unsuccessful. By adding C₂Co₂(CO)₆dppm across the triple bonds of two of the four alkyne groups in the X-motif naphthalimide system [(tetrakis-naphthalimide)-C₆H₂], it was possible to incorporate two oxidisable C₂Co₂(CO)₄dppm cluster units into the molecule. The electrochemistry of the resulting system showed two discrete oxidation processes, suggesting the possibility of some interaction between the dicobalt cluster redox centres.

Chapter One outlines the different methods described in the literature for the synthesis of diynyl, symmetric and asymmetric diyndiyl complexes. The extension to complexes containing a central bridging group within the carbon chain is also introduced with the description of two different linking groups, either an organic or organometallic moiety. A brief overview of molecular electronics and one method of evaluation of electronic communication, cyclic voltammetry, are also addressed. Chapter Two describes the synthesis of novel symmetric and asymmetric bis(diyndiyl) ruthenium(II) complexes of general formula {LnM}-C≡CC≡C-{M”L”p}- C≡CC≡C-{M’L’m}, featuring two transition metal fragments linked by either a Ru(dppe)2 moiety or a trinuclear copper(I) or silver(I) cluster M3(μ-dppm)3 (M = Cu, Ag). Through the use of cyclic voltammetry, it was shown that the inclusion of these three particular bridging groups allows electronic communication between the two terminal end-groups. The chemistry of the starting material trans-Ru(C4H)2(dppe)2 (1) is also described, forming novel complexes when reacted with AuCl(PPh3) or TCNE. Chapter Three describes a new convenient synthetic route to diynyl and diyndiyl ruthenium(II) complexes. Lithiation of the ruthenium(II) diynyl complexes Ru(C≡CC≡CH)(dppe)Cp* and Ru(C≡CC≡CH)(PPh3)2Cp with n-BuLi yields the lithium complexes Ru(C≡CC≡CLi)(dppe)Cp* and Ru(C≡CC≡CLi)(PPh3)2Cp. The most favorable conditions for their formation are examined by using NMR spectroscopy and different assay reactions. These lithium species are further reacted with a range of metal halides to give new asymmetric diyndiyl complexes of general formula [Ru](C≡CC≡C){MLn} (where [Ru] = Ru(dppe)Cp*, Ru(PPh3)2Cp). Chapter Four investigates the reactivity of the novel lithium complex Ru(C≡CC≡CLi)(dppe)Cp* synthesised in Chapter Three. The nucleophilic nature of this complex is assessed with a range of electrophiles such as organic substrates or polyfluoroaromatic compounds. A number of new complexes are prepared and singlecrystal X-ray structure determinations are reported for many of the complexes. The electrochemistry of some of these complexes is also described. Chapter Five summarises the reactions of diynyl ruthenium(II) complexes Ru(C≡CC≡CR)(dppe)Cp* (where R = H, TMS, Au(PPh3)) with three azide reagents TMSN3, TsN3 and AuN3(PPh3). The reactions are suggested to undergo a Huisgen 1,3-alkyne-azide cycloaddition to generate 1,2,3-triazoles which further react to give the various products. The complexes synthesised are characterised by spectroscopic methods and, where possible, by X-ray structure determination. Furthermore, the reactions of the complexes Ru(C≡CC≡CH)(PPh3)2Cp and Ru(C≡CH)(dppe)Cp* with azides to give the ruthenium azido complexes [Ru]N3 (where [Ru] = Ru(PPh3)2Cp, Ru(dppe)Cp*) are described. / Thesis (Ph.D.) - University of Adelaide, School of Chemistry and Physics, 2008

This thesis describes investigations into the catalysed syntheses of amines and imines using organoiridium and organorhodium complexes with N-donor ligands as the catalysts. These catalysed syntheses were achieved via hydroamination, hydrosilylation, and hydrogenation reactions, as well as tandem hydroamination/imine reduction reactions. An in situ catalysis study found that the most active catalysts for the hydroamination of 4-pentyn-1-amine (1) to give 2-methyl-1-pyrroline (4) were formed from a combination of catalyst components that resulted in an electron deficient metal centre, indicating that an alkyne binding mechanism was most likely. The kinetics of the hydroamination of 4-pentyn-1-amine (1), catalysed by the complexes [Rh(bim)(CO)2][BPh4] (7), [Ir(bim)(CO)2][BPh4] (8), [Rh(bpm)(CO)2][BPh4] (9),and [Ir(bpm)(CO)2][BPh4] (10) (bpm = bis(1-pyrazolyl)methane and bim = bis(Nmethylimidazol- 2-yl)methane) were modelled and compared. The nature of the metal centre was found to have the most influence on the rate of the product release step, while the nature of the N-donor ligand was found to have the most influence on the rate of the substrate binding step. The investigation of the catalysed hydroamination of the phenyl substituted alkynylamines 5-phenyl-4-pentyn-1-amine (2), 4-phenyl-3-butyn-1-amine (13) and 2- phenyl-4-pentyn-1-amine (34) revealed a difference in catalytic activity between the rhodium and iridium complexes depending on the alkyne substituent. A series of novel rhodium(I) complexes were synthesised: [RhClCO(Mes-DAD(Me))] (38), [RhClCO(Mes-BIAN)] (22), [Rh(COD)(Mes-BIAN)][BF4] (39), [Rh2(COD)2(bmimen)](BPh4)2 (40) and [Rh2(CO)4(bmimen)](BPh4)2 (41), where Mes- DAD(Me) = biacetylbis(2,4,6-trimethylphenylimine), Mes-BIAN = bis(2,4,6- trimethylphenylimino)acenapthene and bmimen = 1,2-bis[(1-methyl-2- imidazolyl)methylene-amino]ethane. The cationic complex 40 was found to be an active hydroamination catalyst, while the neutral complexes 38 and 22 were only active in the presence of the tetraphenylborate counterion. A range of imines was found to be efficiently reduced to their respective amines via hydrosilylation or hydrogenation using the iridium(I) complex [Ir(bpm)(CO)2][BPh4] (10) as catalyst. The hydrosilylation reaction was found to be significantly faster in a protic solvent (methanol), giving the desilylated amines without the need for a desilylation step. The mechanism of this reaction was proposed to involve a monohydride iridium(I) complex as a key intermediate. The tandem hydroamination/hydrosilylation of a series of alkynylamine substrates was achieved using the iridium complexes 8 and 10, in which the iridium complex catalyses the two mechanistically distinct reactions in the one-pot. Catalysed tandem hydroamination/hydrogenation reactions were also achieved, but were less facile.

This thesis describes investigations into the catalysed syntheses of amines and imines using organoiridium and organorhodium complexes with N-donor ligands as the catalysts. These catalysed syntheses were achieved via hydroamination, hydrosilylation, and hydrogenation reactions, as well as tandem hydroamination/imine reduction reactions. An in situ catalysis study found that the most active catalysts for the hydroamination of 4-pentyn-1-amine (1) to give 2-methyl-1-pyrroline (4) were formed from a combination of catalyst components that resulted in an electron deficient metal centre, indicating that an alkyne binding mechanism was most likely. The kinetics of the hydroamination of 4-pentyn-1-amine (1), catalysed by the complexes [Rh(bim)(CO)2][BPh4] (7), [Ir(bim)(CO)2][BPh4] (8), [Rh(bpm)(CO)2][BPh4] (9),and [Ir(bpm)(CO)2][BPh4] (10) (bpm = bis(1-pyrazolyl)methane and bim = bis(Nmethylimidazol- 2-yl)methane) were modelled and compared. The nature of the metal centre was found to have the most influence on the rate of the product release step, while the nature of the N-donor ligand was found to have the most influence on the rate of the substrate binding step. The investigation of the catalysed hydroamination of the phenyl substituted alkynylamines 5-phenyl-4-pentyn-1-amine (2), 4-phenyl-3-butyn-1-amine (13) and 2- phenyl-4-pentyn-1-amine (34) revealed a difference in catalytic activity between the rhodium and iridium complexes depending on the alkyne substituent. A series of novel rhodium(I) complexes were synthesised: [RhClCO(Mes-DAD(Me))] (38), [RhClCO(Mes-BIAN)] (22), [Rh(COD)(Mes-BIAN)][BF4] (39), [Rh2(COD)2(bmimen)](BPh4)2 (40) and [Rh2(CO)4(bmimen)](BPh4)2 (41), where Mes- DAD(Me) = biacetylbis(2,4,6-trimethylphenylimine), Mes-BIAN = bis(2,4,6- trimethylphenylimino)acenapthene and bmimen = 1,2-bis[(1-methyl-2- imidazolyl)methylene-amino]ethane. The cationic complex 40 was found to be an active hydroamination catalyst, while the neutral complexes 38 and 22 were only active in the presence of the tetraphenylborate counterion. A range of imines was found to be efficiently reduced to their respective amines via hydrosilylation or hydrogenation using the iridium(I) complex [Ir(bpm)(CO)2][BPh4] (10) as catalyst. The hydrosilylation reaction was found to be significantly faster in a protic solvent (methanol), giving the desilylated amines without the need for a desilylation step. The mechanism of this reaction was proposed to involve a monohydride iridium(I) complex as a key intermediate. The tandem hydroamination/hydrosilylation of a series of alkynylamine substrates was achieved using the iridium complexes 8 and 10, in which the iridium complex catalyses the two mechanistically distinct reactions in the one-pot. Catalysed tandem hydroamination/hydrogenation reactions were also achieved, but were less facile.

Thesis (M.Sc.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1959. / Typewritten copy. Includes bibliographical references.