No description available.

No description available.

The synthesis and reactions of hydrotris(pyrazolyl)borate, (TpR,R) supported ytterbium(II) borohydride and lanthanide(III) dialkyl (Ln = Yb, Lu) complexes were investigated. The lanthanide(III) dialkyl complexes were found to undergo both hydrogenolysis reaction and protonolysis reaction with terminal alkynes. Reaction of [(TptBu,Me)YbH]2 (1) with NH3BH3 and (TptBu,Me)YbI(THF) (2) with NaBH4 afforded the corresponding mono-ligand complexes, (TptBu,Me)Yb(BH4) (3) and (TptBu,Me)Yb(BH4)(THF) (4), respectively. Compounds 3 and 4 represent rare examples of lanthanide(II) tetrahydroborate complexes. IR spectroscopy data, in the B-H stretching region are consistent with the 3-BH4 bonding mode found in the solid state of compound 4 and the corresponding deuterium labelled BD4 analogue of 4 shows the expected IR isotope shifts. Mono-ligand lanthanide dialkyl complexes, (TpR,R)Ln(CH2SiMe2R)2(THF)0/1 (5-9) were synthesized from the homoleptic Ln(CH2SiMe2R)3(THF)2 (Ln = Yb, Lu; R = Me, Ph) complexes by two alternative and complementary methods: alkyl abstraction with the thallium salts of the ligands, TlTpR,R and protonolysis using the acid form of the ligands, HTpR,R. Hydrogenolysis of the dialkyl complexes (TpMe2)Ln(CH2SiMe3)2(THF) (7a, Yb; 8a, Lu) afforded the corresponding tetranuclear hydride complexes, [(TpMe2)LnH2]4 (11, Yb; 12, Lu). Similarly, hydrogenolysis of (Tp)Yb(CH2SiMe3)2(THF) (9) afforded the hexanuclear hydride [(Tp)YbH2]6 (13). When treated with a variety of terminal alkynes, the dialkyl complexes, (TpR,Me)Ln(CH2SiMe3)2(THF) (14a, Y; 8a, Lu), gave the corresponding bis-alkynide complexes, (TpR,Me)Ln(CCR)2 (15-27). The structures of the complexes depend on the steric size of both the alkyne substituents and the substituent on position 3 of the pyrazolyl ring. Except for the bulkiest substituents, the compounds are dimeric with two asymmetric 2-alkynide bridging groups and a coupled alkynide unit bridging the two lanthanide centers via an unusual enyne bonding motif. The synthesis of Lu(CH2Ph-4-R)3(THF)3 (R = H, 28a; R = Me, 28b) was achieved by salt metathesis reactions between KCH2Ph-4-R and LuCl3. Variable temperature NMR studies in THF shows that the formation of these complexes is accompanied by a small amount of the anionic ate K[Lu(CH2PH-4-R)4(THF)n] (30) complexes, which can be prepared independently by reaction of pure Lu(CH2Ph-4-R)3(THF)3 with one equiv. of KCH2Ph-4-R. One of the coordinated THF of 28a could be removed by trituration with toluene to give Lu(CH2Ph-4-R)3(THF)2 (29a). Protonolysis reaction with HTpR,R afforded the corresponding dibenzyl complexes, (TpR,R)Ln(CH2Ph-4-R)2(THF)n (31-33). X-ray crystal structures of complex 4, the dialkyl complexes 5b, 6b, 7 and 8; dihydride complexes 11, 12 and 13; bis-alkynide complexes 15, 16, 17, 21, 22 and 24 as well as the tribenzyl compounds 28a and 29a and dibenzyl complexes 31-33 were determined. The solution behaviour, solid state structures and structural diversity of these complexes are discussed.

No description available.

No description available.

Hydrocarbons are an abundant resource of carbon and hydrogen. For example, fossil can be used to produce useful organic compounds. However hydrocarbons seem to be inert. Thus, the activation of the C-H bond is a popular research area. Metals play the main role in most catalysts that convert hydrocarbons to starting materials in industry. The study of metals is important because the properties of the metal core greatly influences the reactivity of a catalyst.1 The study of the chemistry of metals in the gas phase provides valuable information about the properties of metals. This information can be expanded to the chemistry of metals in the condensed phase. Furthermore, it is often both more accurate and more manageable to study the profile of a reaction in the gas phase than in the condensed phase.2,3 There are many studies about metal cations in the gas phase due to ease of their production. However metals have low electronegativity, limiting the study of gas phase metal anions. Recently, a simple and efficient method to generate atomic metal anions was developed at the University of Ottawa in Dr. Mayer's research laboratory.4-6 Atomic metal anions of Fe-, Co-, Cu-, Ag-, Cs- and K- were generated in an electrospray ionization (ESI) source of a mass spectrometer (MS). In this thesis study generated metal anions were reacted with small hydrocarbons of pentane, 1-pentene, 2-pentene and 1-pentyne to investigate the role of different metal anions in the activation of the C-H bond. Also metal anions were reacted with small alcohols of 1-butanol, 2-butanol and 2-methyl-2-propanol to compare the results. Metal anions showed a variety of reactions with these hydrocarbons and alcohols. Fe- was the only metal anion to show the electron transfer reaction, indicating that alcohols are more electronegative than Fe- and less electronegative than other metal anions. Fe-, Co- and Ag- showed the complex formation reaction. All metal anions showed the deprotonation reaction. A deprotonation reaction follows the harpoon mechanism, the long range proton abstraction7, and depends on the gas phase acidity of fragments. The most informative reaction observed was the dehydrogenation reaction because a metal-containing fragment is observed as a product in the spectrum of this reaction. The observation of a metal-containing fragment in the spectrum is significant because it emphasizes the important role that metal anions play in this reaction. This suggests that a dehydrogenation reaction involves metal insertion into a C-H bond. Among the transition metal anions, it was observed that Fe- and Cu- are more reactive than Co- and Ag- with regards to the dehydrogenation reaction, probably because Fe- and Cu- have a greater hydrogen affinity than Co- and Ag- that facilitates the hydrogen abstraction reaction. Another reason could be that Fe- and Cu- have a greater gas phase acidity that leads to a more stable intermediate in the course of the reaction. The results of this thesis study revealed that Cs- and K- could not abstract H from these substrates, probably due to the absence of occupied d orbitals that would facilitate insertion into a C-H bond. Some metal anions not only can insert into a C-H bond of alcohols but also can insert into a C-O bond of alcohols to form metal hydroxide anions. Alcohols are more reactive than hydrocarbons with regards to reactions with metal anions because they contain a functional group. This thesis study shows that some atomic metal anions are able to activate the C-H bond and abstract two hydrogens to form a double bond in hydrocarbons. It is probable that the electronic configuration, gas phase acidity and hydrogen affinity of the metal anions governs their reactivity.

Hydrocarbons are an abundant resource of carbon and hydrogen. For example, fossil can be used to produce useful organic compounds. However hydrocarbons seem to be inert. Thus, the activation of the C-H bond is a popular research area. Metals play the main role in most catalysts that convert hydrocarbons to starting materials in industry. The study of metals is important because the properties of the metal core greatly influences the reactivity of a catalyst.1 The study of the chemistry of metals in the gas phase provides valuable information about the properties of metals. This information can be expanded to the chemistry of metals in the condensed phase. Furthermore, it is often both more accurate and more manageable to study the profile of a reaction in the gas phase than in the condensed phase.2,3 There are many studies about metal cations in the gas phase due to ease of their production. However metals have low electronegativity, limiting the study of gas phase metal anions. Recently, a simple and efficient method to generate atomic metal anions was developed at the University of Ottawa in Dr. Mayer's research laboratory.4-6 Atomic metal anions of Fe-, Co-, Cu-, Ag-, Cs- and K- were generated in an electrospray ionization (ESI) source of a mass spectrometer (MS). In this thesis study generated metal anions were reacted with small hydrocarbons of pentane, 1-pentene, 2-pentene and 1-pentyne to investigate the role of different metal anions in the activation of the C-H bond. Also metal anions were reacted with small alcohols of 1-butanol, 2-butanol and 2-methyl-2-propanol to compare the results. Metal anions showed a variety of reactions with these hydrocarbons and alcohols. Fe- was the only metal anion to show the electron transfer reaction, indicating that alcohols are more electronegative than Fe- and less electronegative than other metal anions. Fe-, Co- and Ag- showed the complex formation reaction. All metal anions showed the deprotonation reaction. A deprotonation reaction follows the harpoon mechanism, the long range proton abstraction7, and depends on the gas phase acidity of fragments. The most informative reaction observed was the dehydrogenation reaction because a metal-containing fragment is observed as a product in the spectrum of this reaction. The observation of a metal-containing fragment in the spectrum is significant because it emphasizes the important role that metal anions play in this reaction. This suggests that a dehydrogenation reaction involves metal insertion into a C-H bond. Among the transition metal anions, it was observed that Fe- and Cu- are more reactive than Co- and Ag- with regards to the dehydrogenation reaction, probably because Fe- and Cu- have a greater hydrogen affinity than Co- and Ag- that facilitates the hydrogen abstraction reaction. Another reason could be that Fe- and Cu- have a greater gas phase acidity that leads to a more stable intermediate in the course of the reaction. The results of this thesis study revealed that Cs- and K- could not abstract H from these substrates, probably due to the absence of occupied d orbitals that would facilitate insertion into a C-H bond. Some metal anions not only can insert into a C-H bond of alcohols but also can insert into a C-O bond of alcohols to form metal hydroxide anions. Alcohols are more reactive than hydrocarbons with regards to reactions with metal anions because they contain a functional group. This thesis study shows that some atomic metal anions are able to activate the C-H bond and abstract two hydrogens to form a double bond in hydrocarbons. It is probable that the electronic configuration, gas phase acidity and hydrogen affinity of the metal anions governs their reactivity.