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ORGANOMETALLICS
S04
ORGANOMETALLIC COMPOUNDS
Compounds that contain a metal-carbon bond, R-M
Nucleophilic carbon:
Nomenclature:
Properties:
Structure:
Ionic character:
NaR and KR
LiR and MgR

208
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ORGANOMETALLICS
S04
Reactivity:
Basicity:
Explain the pKa order: ethane > ethene > ethyne
Compound
2-methylpropane
Structure
ethane
(CH3)3C
CH3CH2
methane
CH3
ethene
CH2=CH
ethyne
NH2
HC
C
ethanol
CH3CH2O
water
HO
209
H
71
H
62
60
H
benzene
ammonia
pKa
45
H
H
43
H
36
H
H
H
25
16
15.7
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ORGANOMETALLICS
S04
General Mechanisms
1. Nucleophilic Substitution
Nu
C
C
LG
LG
Nu
2. Nucleophilic Addition
O
Nu
Nu
C
O
C
H
Nu
C
OH
3. Nucleophilic Acyl Substitution
O
O
Nu
Nu
C
LG
C
LG
210
O
Nu
C
LG
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ORGANOMETALLICS
Organolithium Reagents
+ RX + 2 Li  RLi + Li X
(X = I, Br, Cl)
Limitations:
Questions:
What is the oxidation state change for the C in the
reaction methyl iodide to methyl lithium?
What is the oxidation state change for the Li in the
reaction methyl iodide to methyl lithium?
What is the oxidation state change for the I in the
reaction methyl iodide to methyl lithium?
211
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ORGANOMETALLICS
Organomagnesium Reagents
Et2O
RX + Mg  RMgX
(X = I, Br, Cl)
Limitations:
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ORGANOMETALLICS
S04
Common reactions with carbonyl groups:
Aldehydes or Ketones:
RLi
or
O
H
RMgX
C
C
H
H
RMgX
C
C
OH
H
C
H
H
R'
RLi
or
O
R'
RMgX
C
C
R"
C
R'
R'
R'
H
H
O
R'
OH
H
RLi
or
H
H
R"
OH
H
C
+
OH
OH
OH
R"
Reactions usually in Et2O or THF followed by H3O work-ups
Esters:
213
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ORGANOMETALLICS
Grignard reactions:
214
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ORGANOMETALLICS
Organocopper Reagents
Et2O
+ 2 RLi + CuX  R2CuLi + Li X
(X = I, Br, Cl)
Limitations:
Alkane synthesis using R2CuLi
R2CuLi + R’-X  R-R’ + RCu LiX
215
S04
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ORGANOMETALLICS
S04
Organozinc Reagents
Et2O
RX + Zn  RZnX
(X = I, Br, Cl)
Synthesis of Cyclopropanes using RZnX
Et2O
ICH2I + Zn  I-CH2-ZnI
Cu
Et2O
I-CH2-ZnI + =—R 
CH2
CH2—CH—R + ZnI2
CH3
CH3
I-CH2ZnI
ZnI2
CH3
Et2O
CH3
I-CH2ZnI
ZnI2
CH3
CH3
Et2O
216
CH3
CH3
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ORGANOMETALLICS
S04
MECHANISM OF THE SIMMONS-SMITH REACTION
+
ZnI2
CH2
I
CH2
ZnI
Acetylenic Reagents
-
-
B:
(B: = NaNH2)
R—CΞC—H  R—CΞC: + B-H
Or
B: (B: = R’MgX)
R—CΞC—H  R—CΞC: MgX + R’-H
RC
CLi
O
H
CMgX
C
C
or
RC
RC
H
H
RC
RC
CMgX
C
C
CLi
O
or
RC
R'
R'
R'
CMgX
R'
R"
H
C
H
H
R'
R'
C
C
C
H
O
H
H
H
CLi
or
H
R"
H
C
+
Reaction usually in Et2O followed by H3O work-up
217
R"