Organometallic Chemistry

IntroductionPaula Diaconescu

TA: Wenliang Huang

E-mail: pld@chem.ucla.edu; huangwenl@ucla.edu

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)

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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

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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.

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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.

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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

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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

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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

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Richard F. Heck

Ei-ichi Negishi

ZnBr3

O

O

Br

+DIBAL 3 O

O

(Ph3P)2PdCl2

Ligands in organometallic chemistry

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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

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- 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

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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

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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

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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]

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ML

LL

L

L

L

ML

L L

L

L

L

L

ML

L L

L

L

L

L