Why does ethane have a higher heat capacity than ethene?
Ulrich Abram Disputation am For the investigation of electronical and sterical properties with IR spectroscopy, Ir I carbonyl complexes of the oxazoline ligands were prepared.
The application of the same Ir I metal center guaranteed a high comparability of the carbonyl complexes and the pre-catalysts for C-H activation and hydrogentation. Furthermore, the oxazolines were applied as ligands in heteroleptic Ru II complexes for surface immobilisation. For the synthesis of box structures, a three-step procedure and for pyrox, mepyrox and quinox a two-step procedure was developed.
Both procedures were optimized to obtain high conversions and to allow easy workup of the single steps. In the first step, commercially available chiral aminols were coupled with carboxylic acids.
Since a large variety of substituted starting materials is commercially available, a comprehensive variation of the target structures is possible. Good to excellent total yields were achieved for 20 structurally related compounds which were prepared in half-gram-scale.
To prepare the complexes, [Ir cis,cis-1,5-cyclooctadiene Cl]2 was initially treated with different silver salts AgPF6, AgBF4, Ag[tetrakis 3,5-bis trifluoromethyl phenyl borate ], to exchange the chloride for a non-coordinating counterion.
Subsequently, the ligand was added to give complexes of the general composition [Ir ligand cod ]X. These complexes were converted into dicarbonyl complexes by addition of stoichiometric amounts of CO gas at atmospheric pressure.
The carbonyl stretching frequencies of the square planar dicarbonyl complexes[ir ligand co 2]pf6 turned out to be mainly influenced by the steric properties of the oxazoline ligands, while trigonal bipyramidal monocarbonyl complexes [Ir ligand cis,cis-1,5-cyclooctadiene CO ]PF6 reflected more the electronical properties of the ligands.
The formation of heteroleptic Ru II complexes of the general composition [Ru oxazoline bipyridine X2] was investigated. The complexes were designed to contain an oxazoline ligand carrying the chiral information and a substituted bipyridine ligand, suitable for further functionalisation and immobilisation on an electrode surface.
If the oxazoline was introduced as first ligand, the addition of a bipyridine led to bisheteroleptic bipyridine complexes. If the oxazoline was introduced as second ligand, an inseperable mixture, probably isomers, was obtained.
VII 8 The prepared oxazolines were tested as ligands in direct aromatic and aliphatic borylation. As catalytic system [Ir cis,cis-1,5-cyclooctadiene OCH3 ]2 was used in combination with the respective ligand and bis picanolato diboron served as boron source.
Aromatic borylations were carried out in the neat monosubstituted arenes such as toluene, tert-butylbenzene, anisole, cyclohexylbenzene, trifluorotoluene and ethyl benzoate. Aliphatic borylations of n-octane and n-hexane were unsuccessful under the applied conditions. Hydridosilylether directed -C-H activation was carried out with a catalytic system of [Ir cis,cis-1,5cyclooctadiene OCH3 ]2 and an oxazoline ligand instead of the usually applied 3,4,7,8-tetramethylphenanthroline ligand.
Initially ketones or alcohols were transformed into their hydrido silyl ether derivatives, followed by a -C-H activation which led to the formation of an oxasilolane.
Norbornene was added stochiometrically as hydrogen acceptor. The hydrido silyl ether formation was optimized and the stereochemical influence of the chiral ligands in the C-H activation step was investigated.
A racemic mixture of 3,7-dimethyloctanyl oxy diethylsilane served for this purpose as substrate regarding its kinetic resolution.CHEM Lecture 6: Chapter 6- Alkenes II continued Loved by over million students that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes.
Now I can be the all-star student I want to be. Saarim — University of Michigan. 99 Chapter 5: Structure and Preparation of Alkenes: Elimination Reactions Alkenes (olefins) are hydrocarbons that contain a carbon-carbon double bond and are said to be "unsaturated.".
Chaper 6 rxn Alkenes lecture notes CH – Lecture Outline Chapter 6: Reactions of Alkenes Carbocations How are carbocations classified? What stabilizes a carbocation and why? What is the Hammond Postulate? How does the stability of the carbocation intermediate effect the number of products and why?
Chapter 6: Reactions of Alkenes Part I (Sec B) Reaction time Chemical reactions In a reaction the molecule changes. Addition reactions are found in organic compounds with multiple bonds: alkenes. a molecule loses atoms or groups from adjoining carbon (or other atomic) centers.
of an alkyl halide to form an alkene.+ H2O C H The above reaction is a dehydrohalogenation. All complexes depicted in Scheme were applied as precatalysts in catalytic hydrogenation which will be discussed in chapter Synthesis of Carbonyl Complexes Carbonyl complexes were initially prepared as described by Mestroni and co-workers (cf.