Pyrolysis Of Carbonyl Hydrazine To Activate Alkyne Ketones And Carboxylic Acids

Ru₃?CO?₁₂ as the representative of transition metal carbonyl clusters has been applied in various organic synthesis. Currently, Much more attention has been paid to the scope of substrates and reaction conditions to improve catalytic activity, but not to the corresponding catalytic mechanisms, that is to say, there is serious deficiencies on the study of catalytic active species and thus limit the research for employing Ru₃?CO?₁₂ as an efficient catalyst for new catalytic systems. In this situation, some researchers focus their interest on activation of small molecules with Ru₃?CO?₁₂. Low valence ruthenium clusters containing alkynes or alkyne-derived ligands have been of interest for many years. These ligands offer a fascinating versatility in coordination modes with possibility of donating different electron numbers to ruthenium atoms, and it is found that the interaction of Ru with O atoms is very important to comprehend the specific catalytic cycle. So we paid our attention to the activation of small molecules containing ketone carbonyl with Ru₃?CO?₁₂.1-?4-methoxyphenyl?-3-phenylprop-2-yn-1-one, phenyl-propiolic acid, and a few carboxylic acid containing no alkenyl functional groups were studied. This thesis mainly includes the following three aspects:Firstly, the thermolysis reactions of Ru₃?CO?₁₂ ?1? with 1-?4-methoxyphenyl?-3-phenylprop-2-yn-l-one ?2? were systematically investigated to explore transformation of ruthenium-carbonyl clusters induced by a robust "soft and hard" alkyne ligand. A diverse range of products were formed via finely tuning the molar ratio of the reactants. When 1 reacted with one equivalent of 2, triruthenium cluster [Ru₃?CO?₉??-CO?{?3-?¹:?²:?¹-?Ph?CC?4-CH₃O-PhC?O??}] ?3? and tetraruthenium cluster [Ru₄?CO?10??-CO?2{?⁴-?¹:?²:?¹:?¹-?Ph?CC?4-CH₃0PhC?O??}] ?4? were isolated. Increasing molar ratio of 2 to 1 led to the formation of three ruthenoles [Ru?CO?₃{?⁴-?¹:?²:?¹:?¹-?4-CH₃OPhC?O??CC?Ph?-C?4-H₃OPhC?O??C?Ph?Ru-?CO?₃] ?5a?, [Ru?CO?₃{?⁴-?¹:?²:?¹:?¹-?4-CH₃O-PhC?O??CC?Ph?C?Ph?C?4-CH₃OPh-C?O??Ru ?CO?₃}?-CO] ?5b? and [Ru?CO?₃?⁴-?¹:?²:?¹:?¹-?Ph?CC?4-CH₃OPhC-?O??C?4-CH₃O PhC?O??-C?Ph?Ru ?CO?₃}] ?5c?. To elucidate the formation pathway of the ruthenoles, the reaction of 2 and 3 was investigated. The experimental results confirmed that compound 4 is the key intermediate for the formation of those three ruthenoles.Secondly, we study the reaction of Ru₃?CO?₁₂ with phenylpropiolic and different types carboxylic acids including aliphatic and aromatic acids. When reaction of Ru₃?CO?₁₂ ?0.3 mmol? and phenylpropiolic acid ?0.3 mmol? was performed in toluene at 110? for 3h, three new compounds ??-H?Ru₃?CO?₉?C=CPh? ?6?, Ru₄?CO?₁₂ ?HC?CPh? ?7? and trace Ru₄?CO?₉?HC=CPh???⁶-C₆H₅CH₃? ?8? were collected. When reaction of Ru₃?CO?₁₂ ?0.3 mmol? and phenylpropiolic acid ?0.9 mmol? was performed in toluene at 110? for 3h, compounds 6-8 and the ruthenol [Ru?CO?₃ {?⁴-?¹:?²:?¹:?¹-PhCC?H?PhCC?H?Ru?CO?₃??-CO?}] ?9? was collected. During the reaction process, it was found that compound 6 transformed finally into 7. When the reaction temperature was elevated to 130? from 110? after compound 7 completely transformed into compound 8 and then quickly observed the existence of compound Ru6??6-C???-CO??CO?16 ?10? and Ru6??6-C???-CO??CO?13??⁶-C₆H₅CH₃? ?11?. If the reaction time was extended at 110?, compound 10 could also be afforded. In the reaction of Ru₃?CO?₁₂ with other carboxylic acids in toluene at 130?, we obtained that the tetranuclear ?-H2Ru₄?CO?13 ?12? characterized by its reductive ability and also found that 12 finally transformed into 10. The further investigations showed that the formation mechanism of 10 comes from the combination of the ruthenium hydrid clusters with a dinuclear ruthenium unit formed in the reaction system.Thirdly, the thermolysis of Ru₃?CO?₁₂ with heterocyclic carboxylic acids were thoroughly studied. Three ruthenium carbonyl products, Ru₄?CO?8??2-O,?¹-N-pic?4 ?14? ?pic= picolinate?, [Ru2?CO?4?fur?2]m ?15? ?fur= 2-furoate? and [Ru2?CO?4?thi?2]n ?16? ?thi= 2-thiophene-carboxylate? were isolated. Compound 14 is a tetraruthenium cluster with two Ru2?CO?4 units in an unexpected criss-cross geometry, while compounds 15 and 16 exhibit the classical sawhorse structure. Compound 12 was stable to common donor ligands and formed the solvated compounds Ru₄?CO?8??2-O,?¹-N-pic?4·H2O ?17? and Ru₄?CO?8??2-O,?¹-N-pic?4-CH₃CN ?18? in hydrous toluene and acetonitrile, respectively; Compounds 15 and 16 converted into monomers Ru2?CO?4?fur?2 ?H2O?2·H2O ?15b? and Ru2?CO?4?thi?2?CH₃OH?2·CH₃OH ?16b? in hydrous dichloro-methane and methanol, respectively. [Ru2?CO?4?pic?2]2 ?14a?, Ru2?fur?2?CO?6 ?15a? and Ru2?thi?2?CO?6 ?16a? were proposed as the corresponding intermediates of compounds 14-16 based on the in-situ FT-IR spectroscopy.