Transition metals are defined by their partially filled d orbitals, enabling them to act as effective catalysts in various reactions due to their ability to form compounds in multiple oxidation states. The document outlines various reactions facilitated by transition metals and specific catalysts, including the Gilman reagent, Ullmann coupling, and the Sonogashira reaction, highlighting their roles in organic synthesis. Additionally, it discusses the factors contributing to the effectiveness of transition metals in catalysis, such as bonding ability and variable coordination numbers.

2.  A transition metal as an element whose atom has a
partially filled d subshell, or which can give rise to
cations with an incomplete d sub-shell .
 The transition metal ions the outermost d orbitals are
incompletely filled with electrons so they can easily
give and take electrons. This makes transition metals
prime candidates for catalysis.
 Here transition metals are used as catalysts .

3. Zinc, cadmium, and mercury are generally excluded
from the transition metals as they have the electronic
configuration [ ]d 10s 2 , with no incomplete d shell.

4.  The formation of compounds in many oxidation states, due
to the relatively low energy gap between different
possible oxidation states eg, Fe(II), Fe(III) or switch
oxidizing state .
 Form complexes with reagents by adsorption at active site
.
 Colour in transition-series metal compounds is generally
due to electronic transitions of two principal
types.
 Charge transfer transitions
 d-d transitions

5. •Charge transfer transitions:
An electron may jump from a predominantly ligand orbital to a
predominantly metal orbital, giving rise to a ligand-to-metal
charge-transfer (LMCT) transition. These can most easily
occur when the metal is in a high oxidation state.
For example, The colour of chromate, dichromate and
permanganate ions is due to LMCT transitions.
Another example is that mercuric iodide, HgI2, is red because
of a LMCT transition .
•d-d transitions:
An electron jumps from one d-orbital to another d-orbital and
leads to d-d transitions .

6. The principal reasons why transition metals
contribute the essential ingredient in catalyst
systems can be summarized as the following
headings:
(a) Bonding ability
(b) Catholic choice of ligands
(c) Ligand effects
(d) Variability of oxidation state
(e) Variablility of co-ordination number

7. Sr.no Transition metal Type of reaction
1 Rhodiam Wilkinson’s reaction
2 Copper 1. Gilman reaction
2. Ullman Coupling Reaction
3. Reactions of organo copper
reagent
3 Palladium 1. Heck Reaction
2. Negishi Reaction
3. Stille Reaction
4. Buchwalt-Hartwig amination
5. Suzuki Reaction
6. Sonogashira reaction
7. Hiyama coupling Reaction
4 Nickel Kumada coupling Reaction

8. It is used in the selective hydrogenation of alkenes
and alkynes without affecting the functional groups
like: C=O, CN, NO2, Aryl, CO2R etc.

9.  A Gilman reagent is a lithium and copper
(diorganocopper) reagent compound, R2CuLi (Lithium
dimethylcuprate), where R is an alkyl or aryl.
 They react with organic halides to replace the halide
group with an R group . Such displacement reactions
allow for the synthesis of complex products from simple
building blocks

10.  Generalized chemical reaction showing Gilman reagent
reacting with organic halide to form products and showing
Cu(III) reaction intermediate
 In the reaction, the Gilman reagent is a methylating reagent
reacting with an alkyne in a conjugate addition forming a
cyclic enone

11.  Ullmann coupling is a coupling reaction between
aryl halides in the presence of copper as a transition
metal catalyst to produce Diaryl compounds .
 A typical example is the coupling of 2 ortho-
chloronitrobenzene reactants to form 2,2'-
dinitrobiphenyl with a copper - bronze alloy .

12.  Carbocupration is a nucleophilic addition of organocopper
reagents (R-Cu) to acetylene or terminal alkynes resulting in
an alkenylcopper compound (RC=C-Cu).It is a special case of
carbometalation and also called the Normant reaction.
A. Substitution Reactions
 oxidative addition of copper(I) into the carbon-leaving
group bond takes place, generating a copper(III)
intermediate which then undergoes reductive elimination
to generate the coupled product .

13. B.Conjugated addition reaction
 Carbocupration across the carbon-carbon double bond may then
generate a copper enolate, Subsequent reductive elimination and
protonation leads to the product.
C. Enantioselective Variants
 Diastereoselective conjugate addition reactions of chiral
organocuprates provideβ-functionalized ketones in high
yield and diastereoselectivity

14.  It is the chemical reaction of an alkyl halide with
an alkene in the presence of a base and a
palladium catalyst (or palladium nanomaterial-
based catalyst) to form a substituted alkene .

15.  The reaction couples alkyl or aryl halides with
organozinc/tin compounds, forming carbon-carbon bonds
(c-c) in the process.
• It involves the coupling of an organotin compound (also
known as organostannanes) with a variety of organic
electrophiles via palladium catalyzed coupling reaction .

16.  Used for the synthesis of carbon–nitrogen bonds
via the palladium catalyzed cross-coupling of
amines with aryl halides .
In this coupling occurs between a boronic acid and an
organohalide which is catalyzed by a palladium(0)
complex .

17. The Sonogashira reaction is a cross-coupling reaction used in
organic synthesis to form carbon–carbon bonds. It employs
a palladium catalyst to form a carbon–carbon bond between
a terminal alkyne and an aryl or vinyl halide .
The Hiyama coupling is a palladium-catalyzed cross-coupling
reaction of organosilanes with organic halides used in organic
chemistry to form carbon–carbon bonds (C-C bonds) .

18.  The Kumada coupling is a type of cross coupling
reaction, useful for generating carbon–carbon
bonds by the reaction of a Grignardreagent and an
organic halide.
 The procedure uses transition metal catalysts,
typically nickel orpalladium, to couple a
combination of two alkyl, aryl or vinyl groups

19.  www.wikipeadia.com
 Textbook of organic chemistry by morrisons and boyd
seventh edition pg no 350
 Textbook of Organic chemistry by Arun bahl and B.S.
bahl Pg no 356