Organometallic ChemistryOrganometallic ChemistryC21J, 4 LecturesC21J, 4 Lectures

Mohammed Bakir, Office #8Mohammed Bakir, Office #8�� IntroductionIntroduction�� BondingBonding�� ππππππππ--acidsacids�� Metal Carbonyl CompoundsMetal Carbonyl Compounds�� Organometallic CompoundsOrganometallic Compounds�� Preparation and reactions of organometallic Preparation and reactions of organometallic

compounds.compounds.�� Reference: Chapters 10Reference: Chapters 10�� Textbook: B. Douglas, D. H. McDaniel, & J. J. Textbook: B. Douglas, D. H. McDaniel, & J. J.

Alexander, Concepts & Models of Inorganic Alexander, Concepts & Models of Inorganic Chemistry, 2Chemistry, 2ndnd edition, Wiley, New Yorkedition, Wiley, New York

What is Organometallic?What is Organometallic?�� Organometallic is the chemistry of MOrganometallic is the chemistry of M--C bond C bond

formation and reactivity.formation and reactivity.�� Although ZnAlthough Zn--alkyls alkyls e.g.e.g. Zn(CHZn(CH33))22 were were

prepared by Frankland in 1827, prepared by Frankland in 1827, organometallic chemistry has undergone a organometallic chemistry has undergone a renaissance in the last 50 years due to the renaissance in the last 50 years due to the importance of many organometallic importance of many organometallic compounds in many important chemical compounds in many important chemical processes that include catalysis, sensors and processes that include catalysis, sensors and others. others.

Metal Carbonyl CompoundsMetal Carbonyl Compounds

�� ππ--acid Ligands.acid Ligands.�� What are What are ππ--acid ligands? acid ligands? �� Ligands with a pair of electrons available Ligands with a pair of electrons available

for donation to the metal center and for donation to the metal center and vacant orbital p, vacant orbital p, ππ*, or d available for *, or d available for accepting electron density from the metal.accepting electron density from the metal.

�� e.g. CO, and PPhe.g. CO, and PPh33 where Ph = Cwhere Ph = C66HH55. .

MO EMO E--L Diagram for COL Diagram for CO

1s

2s

2p

1s

2s

2s

σσσσ1s

σσσσ∗∗∗∗1s

σσσσ∗∗∗∗

ππππ∗∗∗∗

σσσσnb

ππππ

σσσσ

σσσσnb

O

C

M.O. Diagram for COM.O. Diagram for CO

σσσσ1s

σσσσ∗∗∗∗1s

σσσσ∗∗∗∗

ππππ∗∗∗∗

σσσσnb ©

ππππ

σσσσ

σσσσnb (O)

ΗΟΜΟΗΟΜΟΗΟΜΟΗΟΜΟ

LUMO

Full

Empty

Sketches of the M.O. for COSketches of the M.O. for CO

O

O

O

O

C

C

C

C

+

+

+

+

+

+

-

-

- -

-

-

-

(σσσσnb) C (σσσσnb) o

σσσσ

(ππππx) or ππππy ┴

(ππππx*) or ππππy

* ┴

Metal Carbonyl CompoundsMetal Carbonyl Compounds

�� RequirementsRequirements�� Metal should be in low oxidation state 0, 1 or Metal should be in low oxidation state 0, 1 or

2; i.e. electron rich.2; i.e. electron rich.�� Ligand should a Ligand should a ππ--acceptor ligand, acceptor ligand, i.e.i.e. σσ--

donor or electron acceptor through empty p, donor or electron acceptor through empty p, ππ* or d orbitals.* or d orbitals.

BondingBonding

�� Sequence of bondingSequence of bonding�� A pair of electrons is donated from the A pair of electrons is donated from the ππ--

acid to the metal centeracid to the metal center�� The excess electron density around the The excess electron density around the

metal center is donated back to the empty metal center is donated back to the empty orbitals on the ligand. orbitals on the ligand.

Synergic BondingSynergic Bonding

C CO OM M+ + ++

+

+ +-

- -

--

Ligand→Metal σσσσ bonding Metal→ ligand ππππ-back bonding(one of a mutual ┴ is shown)

The back donation to the ππππ* orbitals should stronglyaffect the bond order of C≡≡≡≡O.

IR data can be correlated C-O bond order.

ππ--acid Ligandsacid Ligands

�� Examples of 2Examples of 2--e’s donors & have empty orbitals e’s donors & have empty orbitals of of ππ--symmetry include isocyanides CNR and symmetry include isocyanides CNR and carbenes :C(X)(Y) have empty 2pcarbenes :C(X)(Y) have empty 2pzz orbital.orbital.

�� ππ--acids without C, NOacids without C, NO++ (isoelectronic with CO), (isoelectronic with CO), :phosphines PR:phosphines PR33 , arsines AsR, arsines AsR33, stibenes SbR, stibenes SbR33, , bipyridine (bipy) and phenanthroline (Phen)bipyridine (bipy) and phenanthroline (Phen)

�� Bipy & phen possess Bipy & phen possess ππ* orbital * orbital ┴┴ molecular molecular plane.plane.

The Effective Atomic # Rule or The Effective Atomic # Rule or the 18ethe 18e-- RuleRule

�� The rule predicts the stability of organometallic The rule predicts the stability of organometallic compounds and simply states that stability is compounds and simply states that stability is attained or gained when all of the bonding and attained or gained when all of the bonding and nonnon--bonding orbitals are occupied. bonding orbitals are occupied.

�� The rule is useful in predicting the stoichiometry The rule is useful in predicting the stoichiometry of stable species and also reactivity patterns.of stable species and also reactivity patterns.

�� CO donates 2eCO donates 2e-- to the system from the to the system from the σσnbnborbitals on C. orbitals on C.

Metal Carbonyl CompoundsMetal Carbonyl Compounds

�� MM--CC≡≡OO’’s are important for their rich s are important for their rich properties and applications in many properties and applications in many industrial processes that include catalysis, industrial processes that include catalysis, medical diagnostics and molecular medical diagnostics and molecular sensors.sensors.

�� Mond Pprocess, 1890Mond Pprocess, 1890�� Ni(CO)Ni(CO)44 →→ NiNi00 + 4CO+ 4CO�� Fe(CO)Fe(CO)55 →→ FeFe00 + 5CO+ 5CO

Mononuclear Metal CarbonylsMononuclear Metal Carbonyls�� M(CO)x M(CO)x ––hydrophobic (lacking affinity for hydrophobic (lacking affinity for

water, i.e. water insoluble), volatile, soluble water, i.e. water insoluble), volatile, soluble in nonin non--polar solvents.polar solvents.

�� e.g. e.g. V(CO)V(CO)66 OOhh

Cr(CO)Cr(CO)66 OOhh

Mo(CO)Mo(CO)66 OOhh

W(CO)W(CO)66 OOhh

Fe(CO)Fe(CO)55 tbptbpRu(CO)Ru(CO)55 tbptbpNi(CO)Ni(CO)44 TTdd

Mononuclear Metal CarbonylsMononuclear Metal Carbonyls

�� Stable homoleptic carbonyls of transition metal Stable homoleptic carbonyls of transition metal elements can be predicted using the EAN rule.elements can be predicted using the EAN rule.

�� VanadiumVanadium-- 2323V 1sV 1s2 2 2s2s222p2p66 3s3s22spsp663d3d3 3 4s4s22

�� VV00 5 e5 e--

�� 6xCO6xCO 12 e12 e--

�� 1x1e1x1e-- 1e1e--

�� TotalTotal 18e18e--

�� Stable V(CO)Stable V(CO)66--

Metal carbonylsMetal carbonyls�� M = Cr, Mo, & W M = Cr, Mo, & W –– 3d3d4 4 4s4s22

�� MM00 = 6 e= 6 e--�� 6xCO 6xCO = 12 e= 12 e--�� TotalTotal = 18 e= 18 e--�� Stable Stable M(CO)M(CO)66 ––stablestable

Mn, Tc, ReMn, Tc, ReM0M0 77∴∴ Need 11 eNeed 11 e--∴∴ PossibilitiesPossibilities∴∴ 1. M(CO)1. M(CO)55

--

∴∴ 2. M(CO)2. M(CO)66++

∴∴ 3. (CO)3. (CO)55MM--M(CO)M(CO)55 Metal metal bond donates Metal metal bond donates 1e to each metal1e to each metal

MnMn22(CO)(CO)1010

Mn - Mn

CO

CoCo22(CO)(CO)88

Co - Co CO

CO

COCO

CO CO

CO

OC

Co - Co CO

COC

=OC=O

CO CO

CO

OC

All C≡O terminal

Bridging C=O)

Metal CarbonylsMetal Carbonyls

M M

C≡≡ ≡≡O

C≡≡ ≡≡O

M M

C=O

C=O

I.R. νννν(C≡≡≡≡O) ~ 2150 -1850 cm-1

νννν(C=O) -1850-1750 cm-1

νννν(C-O) ~ <1600 cm-1

fac-Re(CO)3(dpk.oxime)Cl and fac-Re(CO)3(dpk)Cl

6001000140018002200260030003400

a

b

Wavenumber, cm-1

MM22(CO)(CO)99

�� Fe(CO)Fe(CO)55 FeFe22(CO)(CO)99

33--bridging CO’s (Dbridging CO’s (D3d3d))

�� M(CO)M(CO)55 MM22(CO)(CO)99

11--bridging CO’s bridging CO’s M= Ru, OsM= Ru, Os

hνννν, CH3COOH

hνννν, heptane, -40

MM33(CO)(CO)1212

�� Higher nuclearityHigher nuclearity

�� 3M(CO)3M(CO)55 MM33(CO)(CO)1212

�� M = Fe, Ru, OsM = Fe, Ru, Os�� 3 M = 24 e3 M = 24 e--

�� 12 CO = 24 e12 CO = 24 e--

�� Need 3x18 = 54eNeed 3x18 = 54e-- for EANfor EAN�� 6e6e-- short, then need 3 (Mshort, then need 3 (M--M) bondsM) bonds

∆∆∆∆

MM44(CO)(CO)1212

�� 4xM = 36 e4xM = 36 e--

�� 12 CO = 24 e12 CO = 24 e--

�� Total = 60 eTotal = 60 e--

�� Need 4x18 = 72 eNeed 4x18 = 72 e--

�� ∴∴ need 6(Mneed 6(M--M) bondsM) bonds

M(CO)3

M(CO)3

M(CO)3

(CO)3M

M(CO)2

M(CO)2

(CO)2M

M(CO)3

= bridging CO

RhRh66(CO)(CO)1616

�� 6xRh = 546xRh = 54�� 16xCO = 3216xCO = 32�� Total 86Total 86

�� 6x18 = 108, then 6x18 = 108, then need 22 electrons, i.e. need 22 electrons, i.e. 11 M11 M--M bondsM bonds

Preparation of metal carbonyl CompoundsPreparation of metal carbonyl Compounds

�� Two procedures are usedTwo procedures are used�� Direct reaction of a metal with CODirect reaction of a metal with CO

e.g. Fe(CO)e.g. Fe(CO)55 and Ni(CO)and Ni(CO)44..Fe + xs. COFe + xs. CO→→ Fe(CO)Fe(CO)55

Ni + xs. CO Ni + xs. CO →→ Ni(CO)Ni(CO)44

Note only Ni & Fe are prepared this way, xs. Note only Ni & Fe are prepared this way, xs. ≡≡excess.excess.

�� Reductive Carbonylation of metal salts using a Reductive Carbonylation of metal salts using a reducting agent or CO as a reducing agent.reducting agent or CO as a reducing agent.e.g.e.g.

Reductive Carbonylation Reductive Carbonylation �� 2Co(H2Co(H22O)O)44(O(O22CCHCCH33))22 + 8 (CH+ 8 (CH33CO)CO)22O + 8 CO + 2HO + 8 CO + 2H22→→ CoCo22(CO)(CO)88 + 20CH+ 20CH33COCO22HH

HH22 is the reducing agentis the reducing agent�� CoCOCoCO33 + H+ H22 + 8 CO + 8 CO →→ CoCo2 2 (CO)(CO)88 + 2CO+ 2CO22 + 2H+ 2H22OO

HH22 is the reducing agentis the reducing agent�� CrClCrCl33 + Al + 6 CO + Al + 6 CO →→ CrCr (CO)(CO)66

Al is the reducing agentAl is the reducing agent�� VClVCl33 + Na(xs) + CO + Na(xs) + CO →→ Na[VNa[V (CO)(CO)66]]

�� ReRe22OO77 + 17 CO + 17 CO →→ ReRe22 (CO)(CO)1010 + 7 CO+ 7 CO22

CO is the reducing agentCO is the reducing agent

∆∆∆∆

Polynuclear CarbonylsPolynuclear Carbonyls

�� Higher carbonyls can be prepared Higher carbonyls can be prepared from the thermolysis or photolysis of from the thermolysis or photolysis of lower carbonylslower carbonyls

�� 3OsO3OsO44 + CO(xs) + CO(xs) →→ OsOs33(CO)(CO)1212 + 12 CO+ 12 CO22

��3Os(CO)3Os(CO)55 →→ OsOs33 (CO)(CO)1212

��2Fe(CO)2Fe(CO)55 →→ FeFe22(CO)(CO)99

∆∆∆∆hνννν

∆∆∆∆

Substituted Carbonyls & Carbonylate AnionsSubstituted Carbonyls & Carbonylate Anions

�� The carbonyl group in metal carbonyls are The carbonyl group in metal carbonyls are labile and can be replaced with of other labile and can be replaced with of other ligands.ligands.

�� The EAN role can be used to predict the The EAN role can be used to predict the stability of the substitution product.stability of the substitution product.

�� e.g. e.g. �� Cr(CO)Cr(CO)66 + CNR + CNR →→ Cr(CO)Cr(CO)55(CNPh) + CO(CNPh) + CO�� IrIr44(CO)(CO)1212 + 2 PPh+ 2 PPh33 →→ IrIr44(CO)(CO)1010(PPh(PPh33))22 + 2 CO+ 2 CO�� Mo(CO)Mo(CO)66 + Br+ Br-- →→ MoMo(CO)(CO)55Br Br -- + CO+ CO

Lewis Bases & # of valence e’sLewis Bases & # of valence e’s

�� HH--, X, X--, NCS, NCS--, CN, CN-- where X = halide = 2ewhere X = halide = 2e-- donordonor�� CO, CNR, NOCO, CNR, NO++, PR, PR33, P(OR), P(OR)33, AsR, AsR33, NR, NR33, SbR, SbR33, SR, SR22, ,

:CXY:CXY= 2 e= 2 e-- donor ligandsdonor ligands

�� RR--, C(O)R, C(O)R--, Ar, Ar-- = 2e= 2e-- donor donor ligandsligands

�� NONO = 3e= 3e-- donor Liganddonor Ligand

Metal Carbonyls Reactions 1Metal Carbonyls Reactions 11. Direct Substitution1. Direct Substitution�� 2 e2 e-- ≡≡≡≡≡≡≡≡ 1 CO1 CO�� e.g. e.g.

�� Cr(CO)Cr(CO)66 + CNPh + CNPh →→ Cr(CO)Cr(CO)55(CNPh) + CO(CNPh) + CO�� IrIr44(CO)(CO)1212 + 2 PPh+ 2 PPh33 →→ IrIr44(CO)(CO)1010(PPh(PPh33))22 + 2 CO+ 2 CO�� Mo(CO)Mo(CO)66 + Br+ Br-- →→ MoMo(CO)(CO)55Br Br -- + CO+ CO

Triphenylphosphine

PPh3

PC N R

Isonitrile, R = Aryl or alkyl

::

Metal Carbonyl Reactions 2Metal Carbonyl Reactions 2

2. Oxidation2. OxidationMnMn00

22(CO)(CO)1010 + Cl+ Cl22 →→ MnMnII(CO)(CO)55ClClFeFe00(CO)(CO)55 + Br+ Br22 →→ FeFeIIII(CO)(CO)44BrBr22

CoCo0022(CO)(CO)88 + H+ H22 →→ HH++[[Co(CO)Co(CO)44]]--

Substitution Reactions 3Substitution Reactions 33. Rearrangements3. Rearrangements2RhCl2RhCl33 + 4 CO + 4 CO →→ [Rh(CO)[Rh(CO)22((µµµµµµµµ--Cl)]Cl)]22 + 2Cl+ 2Cl22

OCOC Cl:Cl: COCORhRh RhRh

OCOC :Cl:Cl COCO

Bridging chloride in this case is 3 eBridging chloride in this case is 3 e-- donor, donor, explain? And predict if EAN is satisfied!explain? And predict if EAN is satisfied!

~90º C

Reactivity of OrganometallicsReactivity of Organometallics

�� 2Mn(CO)2Mn(CO)55Cl Cl WWWWWWWW MnMn22(CO)(CO)88((µµµµµµµµ--BrBr22))

�� ReRe22(CO)(CO)1010 + Cl+ Cl22 →→ ReRe22(CO)(CO)88((µµµµµµµµ--ClCl22))

�� [Rh(CO)[Rh(CO)22((µµµµµµµµ--Cl)] + 2 PPhCl)] + 2 PPh33 →→transtrans--Rh(PPhRh(PPh33))22(CO)Cl + CO(CO)Cl + CO

∆∆∆∆, -CO

++++CO, pressure

Carbonylate AnionsCarbonylate Anions

�� SynthesisSynthesis�� Reaction of metal carbonyls with base.Reaction of metal carbonyls with base.�� e.g.e.g.1313MnMn22(CO)(CO)1010 + 40 OH+ 40 OH-- →→ Mn(CO)Mn(CO)55

-- + 2 + 2 MnMn2+2+ + 20 H+ 20 H22OO

FeFe22(CO)(CO)99 + 4 OH+ 4 OH-- →→ FeFe22(CO)(CO)8822-- + CO+ CO33

22-- + + 20 H20 H22OO

CoCo22(CO)(CO)88 + 5 RNC + 5 RNC →→ [Co[CoII(CNR)(CNR)55]]+ + [Co[Co--

II(CNR)(CNR)44]]-- + 4CO+ 4CO

Reaction of Metal Carbonyls with a reducing agentReaction of Metal Carbonyls with a reducing agent

�� FeFe(CO)(CO)55 + 2 Na + 2 Na →→ NaNa22Fe(CO)Fe(CO)4 4 + CO+ CO

�� CrCr(CO)(CO)66 + Na/Hg + Na/Hg →→ NaNa22[Cr(CO)[Cr(CO)55] + CO] + CO

�� CrCr(CO)(CO)66 + NaBH+ NaBH44 →→ NaNa22[Cr(CO)[Cr(CO)55] + CO] + CO

�� CoCo22(CO)(CO)88 + 2Li[HB(C+ 2Li[HB(C22HH55))33] ] →→LiLi [Co(CO)[Co(CO)44] + B(C] + B(C22HH55))33 + H+ H22

�� MnMn22(CO)(CO)1010 + 2KH + 2KH →→ KMn(CO)KMn(CO)55 + H+ H22

NH3(l)

NH3(l)

THF

THF

THF

Reactions of Metal Carbonyls with AnionsReactions of Metal Carbonyls with Anions

�� MnMn(CO)(CO)55-- + + ReRe(CO)(CO)55Cl Cl →→

(CO)(CO)55ReRe--Mn(CO)Mn(CO)55 + Cl+ Cl--

�� ReRe(CO)(CO)55Cl + 2 KCN Cl + 2 KCN →→K[Re(CO)K[Re(CO)44(CN)(CN)22] + KCl + 2 CO] + KCl + 2 CO

�� Reactions with alky, acyl halides Reactions with alky, acyl halides ReRe(CO)(CO)55

-- + CH+ CH33I I →→ (CO)(CO)55ReRe--CHCH33 + I+ I--

MnMn(CO)(CO)55-- + CH+ CH33C(=O)Cl C(=O)Cl →→

(CO)(CO)55MnMn--C(=O)CHC(=O)CH33 + Cl+ Cl--

Protonation of Carbonylate anionsProtonation of Carbonylate anions

�� MnMn(CO)(CO)55-- + H+ H++ →→ HH--Re(CO)Re(CO)55

�� FeFe(CO)(CO)44---- + H+ H++ →→ HH--Fe(CO)Fe(CO)44

--

�� HH--Fe(CO)Fe(CO)44-- + H+ H++ →→ HH22--Fe(CO)Fe(CO)44

Oxidation StatesOxidation States�� Always consider the metal in its zero Always consider the metal in its zero

oxidation state.oxidation state.�� e.g. e.g. �� HH--Mn(CO)Mn(CO)55

�� BrBr--Mn(CO)Mn(CO)55

�� CHCH33--Mn(CO)Mn(CO)55

�� Mn in oxidation state of zero, Mn in oxidation state of zero, �� ∴∴ H, CHH, CH33, Br all donate 1 e, Br all donate 1 e--..

Reactivity of polynuclear CarbonylsReactivity of polynuclear Carbonyls�� 1 CO 1 CO ≡≡ 2 e2 e--; ; ∴∴ if 1 CO is removed then if 1 CO is removed then

you need to replace it with two 1 eyou need to replace it with two 1 e--donors such as H, CHdonors such as H, CH33, Br, Br

�� e.g. Ose.g. Os33(CO)(CO)1212

�� OsOs33(CO)(CO)12 12 + H+ H22 →→ HH22OsOs33(CO)(CO)1010

HH22OsOs33(CO)(CO)1111

WW WW

∆

BondingBonding

H

H

H

H

Os3(CO)12

H2H2Os3(CO)10 H2Os3(CO)11

+ CO

- CO

Os

CO

BondingBonding

Cl

Cl

Cl

Cl

Os3(CO)12

Cl2Os3(CO)10Cl2

Os

CO

ClCl

2 e- donor 3 e- donor

BondingBonding

2 Mn(CO)5Br →Mn2(CO)8Br2 + 2 CO

Mn = MnMn - Mn

Mn Mn

Br

Br

Br

Br

Br

Br

Observed

Kinetic product

Thermodymanic product

Nitric Oxide LigandNitric Oxide Ligand�� NO has a very similar M.O. diagram to NO has a very similar M.O. diagram to

that of CO, except that it contains one that of CO, except that it contains one extra electron in the extra electron in the ππππππππ* orbital.* orbital.

M :N≡≡≡≡O:.σσσσ

ππππ

3 e- are donatedto the M.O. scheme

of the complex by NO.In this case L-N-O bond ~ 170 -180 º.

NO is 3 e- donor;∴ NO+ is 2 e- donor∴ i.e. NO+ ≡≡≡≡ CO, i.e. isoelectronic

Compounds of NOCompounds of NO�� Co(CO)Co(CO)44NO; Mn(CO)NO; Mn(CO)44NO; Fe(CO)NO; Fe(CO)22(NO)(NO)22..�� EAN ? Check.EAN ? Check.

�� Bent MBent M--NO, with MNO, with M--NN--O bond angle of 110O bond angle of 110--120120º, then NO is 1 eº, then NO is 1 e-- donor.donor.

NN≡≡OOMM

..

Bonding of Organic Ligands to MetalsBonding of Organic Ligands to Metals

�� Olifin CompoundsOlifin Compounds�� Zeises’ SaltZeises’ Salt

KK22PtClPtCl44 + H+ H22C=CHC=CH22 →→ K[PtClK[PtCl33(H(H22C=CHC=CH22)])]The bonding is best described by the DewerThe bonding is best described by the Dewer--Chatt Chatt

Mode. The olefin here is a total of 2 eMode. The olefin here is a total of 2 e-- donor to donor to the metal center.the metal center.

H2 C

=CH

2

M

H2 C

�C

H2

M metallocyclopropane

AcetyleneAcetylene�� As in the case of olefins, acetylene can use As in the case of olefins, acetylene can use

one of its pone of its p--bonds or both to coordinate to bonds or both to coordinate to metal atoms. Note each metal atoms. Note each ππ--bond is 2ebond is 2e--

donor.donor.

H2 C

≡≡ ≡≡C

H2

M

H2 C

= CH

2

M

Note: this type of bonding is not common

Acetylene (ac) BondingAcetylene (ac) Bonding�� Bridging acetylene bonding is more commonBridging acetylene bonding is more common

�� e.g.e.g.�� CoCo22(CO)(CO)88 + HC + HC ≡≡CH CH →→ CoCo22(CO)(CO)66(ac)(ac)

M - M

HC - CH

Conjugated Olefin SystemsConjugated Olefin Systems�� FerroceneFerrocene�� FeClFeCl22 + 2 NaCp + 2 NaCp →→ FeCpFeCp22

= Cp-

is 5e- donor

Fe

-

Staggered=sandwich

ηηηη5-Cp

Pentahapto

Reactions of CReactions of Cpp--compoundscompounds�� With With OrganometallicsOrganometallics

Fe FeBunLi

Li

FeCO2/H+

CO2H

Reactions of CReactions of Cpp--compoundscompounds

�� Mo(CO)Mo(CO)66 + + NaCNaCpp →→ CpCp--Mo(CO)Mo(CO)33

THF

+H+

ηηηηηηηη55--CpCp--MoH(CO)MoH(CO)33 ηηηηηηηη55--CpCp--Mo(CHMo(CH33)(CO))(CO)33

+CH3I

[[ηηηηηηηη55--CpCp--Mo(CO)Mo(CO)33]]2 2 →→ [[ηηηηηηηη55--CpCp--Mo(CO)Mo(CO)22]]22

∆,∆,∆,∆,

−−−−ΗΗΗΗ2222

∆∆∆∆

-2CO

Mo ≡≡≡≡ MoCp

Cp

Reactions of CReactions of Cpp--compoundscompounds

�� NucleophilicNucleophilic AdditionAddition�� CoCpCoCp22 + CH+ CH33Br Br →→ Co(Co(ηη55--Cp)(Cp)(ηη44--CC55HH55R) + BrR) + Br--

Co

RH

Reactions of CReactions of Cpp--compoundscompounds�� Addition reactions [2 + 2] Addition reactions [2 + 2] cycloadditioncycloaddition�� NiCpNiCp22 + F+ F22C=CFC=CF22 →→ Ni(Ni(ηη55--Cp)(Cp)(ηη33--CC55HH33CC22FF44))

Ni

FFFF

ηηηη3-

Other systemsOther systems�� AllylsAllyls�� NaMn(CO)NaMn(CO)55 + H+ H22C=CHC=CH--CHCH22Br Br →→

Mn(CO)Mn(CO)55((ηη11--CHCH22--CH=CHCH=CH22) ) →→Mn(CO)4(Mn(CO)4(ηη33--CHCH22--CH=CHCH=CH22))

(CO)(CO)44

MMMn(CO)Mn(CO)44

Other systemsOther systems+ Fe(CO)5 →

Fe(CO)3

ηηηη4-

HH

+ Fe(CO)5 →

HH

Fe(CO)3

ηηηη4-

ReactionsReactionsHH

+ Fe(CO)5 →

HH

Fe(CO)3

ηηηη4-

ηηηη5- CpFeH(CO)2Fe - Fe

OC

CO

CO

Cp

Cp

OC

∆∆∆∆

-H2

- CO

Other ring systemsOther ring systems�� CyclobutadieneCyclobutadiene

�� FeFe22(CO)(CO)99 + 2+ 2

Fe(CO)3

+ 3 CO + 2Cl2Cl

Cl

H

Hηηηη4-

Fe(CO)3

COCH3

CH3COCl/AlCl3

Other ring systemsOther ring systems�� BenzeneBenzene

�� PhMgBrPhMgBr + 2 CrCl+ 2 CrCl33 [Cr(PhH)[Cr(PhH)22++]]

ηηηη6-

Et2O/H2O

+ e-

CrCr(CO)6

Cr(CO)3