Module 4 Flashcards
(22 cards)
Sigma-bond Metathesis
Common for early transition metal complexes where there are not enough electrons on the metal atom for it to participate in oxidative addition.
1,1-Migratory Insertion Reaction
1,1: X-group was one bond away from the metal atom ends up on atom that is one bond away from the metal atom.
1,2 Insertions/Beta-hydride Elimination
1,2: X-group was one bond away from the metal atom ends up on atom that is two bonds away from the metal atom.
Cyclometallation
Metal inserts into the remote C-H bond
Catalyst
A substance that increases the rate of a reaction but is not itself consumed. This is done by introducing new pathways with lower Gibbs energy of activation.
Catalytic Cycle
A sequence of reactions that consumes the reactants and forms products, with catalytic species being regenerated after the cycle.
Selectivity
A selective catalyst yields a high proportion of the desired product with minimum amounts of side products.
Homogenous Catalyst
Present in the same phase as reagents, often well defined.
Heterogeneous Catalyst
Present in different phases.
Alkene Metathesis
Redistribution of C – C double bonds.
Hydrogenation of Alkenes
Addition of hydrogen to an alkene
Wilkinson’s Catalyst
[RhCl(PPh3)3] Rh(I) Complex
Hydroformylation
A reaction of alkene, CO, and H2 to form an aldehyde that contains one more C than the original alkene.
Wacker Oxidation of Alkenes
Primarily production of ethanal (acetaldehyde) from ethene and oxygen.
Pd-catalyzed C – C Bond-forming Reaction
Heck, Stille, Suzuki “coupling reaction”. Ex: coupling of Grignard reagents with an alkyl halide.
Oligomerization/Polymerization
Ethene into linear alkenes: homogenous catalysis with Ni catalyst. Alkene polymerization: heterogeneous Ziegler-Natta catalysts.
Facts about d-Block Elements
(1) All metallic
(2) High density, high melting/boiling points
(3) Form colorful compounds (d-d transitions, charge-transfer transitions)
(4) Form compounds in many oxidation states
(5) Form paramagnetic compounds (unpaired electrons) (6) Show homo- and heterogeneous catalytic activity
The occurrence of d-Block elements
Early 3d metals occur in nature (oxides, metal cations in combination with oxoanions)
Which compound is most difficult to reduce?
TiO2
Which 3 ions oxidizes reduced with carbon?
Cr-, Mn-, and Fe
Which metals occur mainly as sulfides and arsenides?
Co, Ni, Cu, Zn
Which rows transition to mostly sulfides sooner?
Row 2 and 3.
