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Organometallic Chemistry
IntroductionPaula Diaconescu
TA: Wenliang Huang
E-mail: [email protected]; [email protected]
Office hours: after classTextbook A: Introduction, History, Chapters 1.1 - 1.3
Textbook H: Chapters 1.1 - 1.3.4
Textbooks Required texts:
Organotransition metal chemistry: From bonding to catalysis by John F. Hartwig, University Science Books, 2010
Organometallic chemistry and catalysis by Didier Astruc, Springer, 2007 UCLA subscription: http://www.springerlink.com/content/r36568/
Recommended: Organometallics 1: Complexes with Metal-Carbon Bonds and Organometallics
2: Complexes with Metal-Carbon Bonds by Manfred Bochmann, Oxford University Press, 1993 (beginner level)
Applied Organometallic Chemistry and Catalysis by Robin Whyman, Oxford University Press, 2003 (beginner level)
Organometallic Chemistry by Gary O. Spessard and Gary L. Miessler, Prentice Hall, Inc., 1997 (intermediate level)
The Organometallic Chemistry of the Transition Metals by Robert H. Crabtree, Wiley Interscience; 2nd edition – 1994 or 3rd edition - 2005 (advanced level)
Homogeneous Catalysis; Understanding the art by Piet W. N. M. van Leeuwen, Kluwer Academic Publishers, 2004 (advanced level)
Article references given during lecture http://www.ilpi.com/organomet/index.html
Grading Grading:
Midterm: 30% Final: 50% Literature presentation: 20% (10% for content, 5% for answering
questions, 5% for asking questions)
3
Bonus (calculated based on the highest grade): 5% for writing a paper on a given topic + 5% for writing an original proposal
undergraduates: 5% for attending all seminars listed belowall: 5% for asking at least 5 good questions during the seminars listed below
Winter organometallic seminars: 2/22/2012: Zhaomin Hou, RIKEN Advanced Science Institute 2/29/2012: Parisa Mehrkhodavandi, University of British Columbia 3/7/2012: Davit Zargarian, University of Montreal 3/14/2012: Malcolm Chisholm, Ohio State University
Administrative details
All lecture notes will be posted before class on http://vohweb.chem.ucla.edu/voh/
Questions: http://vohweb.chem.ucla.edu/voh/ Midterm: February 3 (revision on Jan 30 in class) Literature presentations are on Mondays. First
presentation will be on January 23. There will be no classes on Jan 16 and Feb 20 (university holidays).
TA’s discussion section: Tuesday, 1-2 pm, YH 1337 TA’s office hours: Wednesday, 6-7pm, MSB1210
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Frontiers in organometallic chemistry Definition of organometallic chemistry: transformations of organic
compounds using metals.
Organometallic chemistry is at the interface between inorganic and organic chemistry. Inorganic: subset of coordination chemistry Organic: subset of synthetic methods
Other interdisciplinary areas Bioorganometallic chemistry Surface organometallic chemistry Fullerene-metal complexes
5
Energy Consumption, 2009
http://www.eia.doe.gov/oiaf/ieo/highlights.html
Catalysis for Energy
• Understand mechanisms and
dynamics
• Design and control the
synthesis of catalyst structures
DOE workshop 2007 DOE workshop 2007
Catalysis
– Environmental : green chemistry, atom efficiency, waste remediation, recycling
– Polymeric materials: new polymers and polymer architectures, new monomers, new processes
– Pharmaceuticals and fine chemicals: demand for greater chemo-, regio-, stereo-, and enantioselectivity
– Feedstocks: practical alternatives to petroleum and natural gas
History: first organometallic compound 1760 Louis Claude Cadet de Gassicourt (Paris) investigates inks
based on cobalt salts and isolates cacodyl from cobalt minerals containing arsenic (CoAs2 and CoAsS2) :
As2O3 + 4 CH3COOK [AsMe2]2 first organometallic compound
See editorial: Organometallics 2001, 20, 1488 -1498
Timeline:
1751 - Benjamin Franklin: Lightning is electrical1767: Carbonated water: Joseph Priestley1778 - Antoine Lavoisier (and Joseph Priestley): discovery of oxygen leading to end of Phlogiston theory
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First transition metal organometallic compound 1827 Zeise’s salt is the first platinum - olefin complex
See editorial: Organometallics 2001, 20, 2-6
Timeline: 1827: Friction match: John Walker1827: Fountain-pen : Petrache Poenaru1827 - Georg Ohm: Ohm's law (Electricity)1827 - Amedeo Avogadro: Avogadro's law (Gas laws)1828 - Friedrich Wöhler synthesized urea, destroying vitalism1829: Steam locomotive: George Stephenson
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Pt
Cl
ClCl
H
H
H
H
KCl + PtCl2EtOH
K- H2O
History: 1900 – 1950 1863 Charles Friedel and James Crafts prepare organochlorosilanes 1890 Ludwig Mond discovers Ni(CO)4 1893 Alfred Werner develops the modern ideas of coordination chemistry 1899 introduction of Grignard reagents
1912 Nobel prize Victor Grignard and Paul Sabatier
1917 Schlenk prepares Li alkyls via transalkylation from R2Hg 1930 Ziegler and Gilman simplify organolithium preparation, using ether
cleavage and alkyl halide metallation, respectively
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R XMg
R MgXR'-CO-R"
R
R' R"OMgXEt2O
CrCl3 + PhMgBr [Cr(-Ph)n]0,+1 n = 2, 3, 4
later: complex
1919, Hein:
PtMe
Me Me
I
first -alkyl complexPope, 1909
FeOC CO
CO
first dienecomplexReilhen, 1930
FeOC
OC CO
CO
H
H
first hydridecomplexHieber, 1931
History: 1950 – 1960 1951 – 1952 Discovery of ferrocene, Fe(5-C5H5)2
Keally, Pauson, and Miller report the synthesis Wilkinson and Woodward report the correct structure
1973 Nobel prize Geoffrey Wilkinson and Ernst Otto Fischer on sandwich compounds
1955 Ziegler and Natta develop olefin polymerization at low pressure using mixed metal catalysts (transition metal halide / AlR3)
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FeFeH
H
Pauson, 1951correct structure
Woodward and Wilkinson, 1952
R2Al-R +n
Transition Metal
Catalyst
Ziegler/Natta polymerization
http://www.nobel.se/chemistry/laureates/1963/
• Giulio Natta: Italian chemist, Nobel prize 1963• Learned of Ziegler’s research, and applied findings to other -olefins such as propylene and styrene.• Resulting polypropylene was made up of two fractions: amorphous (atactic) and crystalline (tactic). Polypropylene is not produced in radical initiated reactions.
propylene polypropylene
n
1963 Nobel prize for Karl Ziegler and Giulio Natta on Ziegler-Natta catalysts
Control of polymer tacticity:
Zr
X
X Zr
X
XZr
X
X
racemic: C2 meso: Cs
History: 1960 – 1980: catalysis 1962: Vaska’s complex
1964: Fischer reports the first metal carbene.
14
WOC
OC CO
CO
CO
CMe OMe
stabilized carbene complexFischer, 1964
WOC
OC CO
CO
Br
C
carbyne complexFischer, 1973
Me
IrIII
OC
Ph3P O
PPh3
O
Cl
IrI
OC
Ph3P Cl
PPh3
O2 H2IrIII
OC
Ph3P H
PPh3
H
Cl
Vaska's complex
History: olefin metathesis 1964: Banks reports the first example of olefin metathesis.
1971: Yves Chauvin proposes mechanism.
1974: Schrock synthesizes first metal alkylidene complex.
15
LnMR
R'R'
LnMR
R'R'
MLn
R
R'R'
R1
R1
R1
R1
R2
R2
R2
R2
+catalyst R2
R2
R1
R1
2
Ta
tButBu
tBu
tBu
first alkylidene complexSchrock, 1974
TaMe
CpCH2
Cp
first methylene complexSchrock, 1975
TaMe2P
tBuH2CC-tBu
Cl
PMe2
first alkylidyne complexSchrock, 1976
2005 Nobel prize in chemistry
16
ORf
RfOMo
N
H
CMe2Ph
iPr
iPr
ORf
RfO W
N
H
t-Bu
iPriPr
OF3C
F3C
Schrock catalysts
= ORf
Grubbs catalysts
N N
PCy3
Cl
Cl
Ru
Ph
Ru
PCy3
PCy3
Cl
Cl
Ph
1st generation
2nd generation
2010 Nobel prize in chemistry
17
Akira SuzukiPd(PR3)2
ArPd(II) X
Ar Pd(II) Ar'
ArPd(II)
Ar'
Ar-X
oxidativeaddition
Ar-Ar'
reductiveelimination
Ar'M
MX
transmetallation
R3P
R3P
R3P
PR3
PR3
PR3
Pd(PR3)3
- PR3PR3
isomerization
catalystR X R' M+ R R' MX+
XPd(OAc)2/tppts
Na2CO3/H2O
Precursor for the "sartan" type drugs(blood pressure regulation, Clariant)
CN CN
B
HO
HO+
2010 Nobel prize in chemistry
18
Richard F. Heck
Ei-ichi Negishi
ZnBr3
O
O
Br
+DIBAL 3 O
O
(Ph3P)2PdCl2
Ligands in organometallic chemistry
19
Neutral 2e donors: PR3 (phosphines), CO (carbonyl), R2C=CR2 (alkenes), RC≡CR (alkynes, can also donate 4e), N≡CR (nitriles)
Anionic 2e donors: X- (halide), CH3- (methyl), CR3
- (alkyl), Ph- (phenyl), H- (hydride) The following can also donate 4e if needed, but initially count them as 2e donors (unless they are acting as bridging ligands): OR- (alkoxide), SR- (thiolate), NR2
- (inorganic amide), PR2- (phosphide)
Anionic 4e donors: C3H5- (allyl), O2- (oxide), S2- (sulfide), NR2-
(imide), CR22- (alkylidene)
and from the previous list: OR- (alkoxide), SR- (thiolate), NR2-
(inorganic amide), PR2- (phosphide)
Anionic 6e donors: Cp- (cyclopentadienyl), O2- (oxide) Z ligands: do not bring e to the metal: BR3, AlR3
Nomenclature
x
5-Cp 3-Cp 3-allyl 1-allyl
M
M PPh2 PPh2 1-dppe / 1-dppex
x
20
- bridging ligand
Ordering: from ACS publications In formulas with Cp (cyclopentadienyl) ligands, the Cp usually comes
first, followed by the metal center: Cp2TiCl2 Other anionic multi-electron donating ligands are also often listed in front
of the metal.
In formulas with hydride ligands, the hydride is sometimes listed first. Rule # 1, however, takes precedence over this rule: HRh(CO)(PPh3)2 and
Cp2TiH2
Bridging ligands are usually placed next to the metals in question, then followed by the other ligands Note that rules 1 & 2 take precedence: Co2(-CO)2(CO)6, Rh2(-
Cl)2(CO)4, Cp2Fe2(-CO)2(CO)2
21
Coordination geometriesCN Geometry Example
2
3, trigonal
3, T shape
4, tetrahedron
4, square planar
[NC–Ag–CN]–
Pt(PPh3)3
[Rh(PPh3)3]+
Ti(CH2Ph)4
22
M LL
L ML
L
L M
L
L
L
M
LL
L
L
ML L
L
Pt
Cl
ClCl
H
H
H
H
Coordination geometriesCN Geometry Example
5, trigonal bipyramid
5, square pyramid
6, octahedron
6, pseudo-octahedron
[Co(CNPh)5]2+
W(CO)6
FeCp2
23
L ML
L
L
L
axial
equator ial Mes TaMes
Mes
Cl
Cl
ML
L L
L
L apical
basal
ML
L L
L
L
L
M
LL
L
Coordination geometries
CN Geometry Example
6, antiprism
7, capped octahedron
7, pentagonal biprism
WMe6
[ReH(PR3)3(MeCN)3]+
[IrH5(PPh3)2]
24
ML
LL
L
L
L
ML
L L
L
L
L
L
ML
L L
L
L
L
L