Organometallics Study Meeting

04/21/2011
H.Mitsunuma

1. Crystal field theory (CFT) and ligand field theory (LFT)
CFT: interaction between positively charged metal cation and negative charge on the non-bonding electrons of the ligand
LFT: molecular orbital theory (back donation...etc)
Octahedral (figure 9-1a)d-electrons closer to the ligands will have a higher energy than those further away which results in the d-orbitals splitting inenergy.
ligand field splitting parameter ( 0): energy between eg orbital and t2g orbital
1) high oxidation state2) 3d<4d<5d3) spectrochemical series
I-< Br-<S2-< SCN-< Cl-< N3-, F-< (H2N)2CO, OH-< ox, O2-< H2O< NCS- <C5H5N, NH3< H2NCH2CH2NH2< bpy, phen< NO2< CH3-, C6H5-< CN- <COcf) pairing energy: energy cost of placing an electron into an already singly occupied orbital
Low spin:
If 0 is large, then the lower energy orbitals(t2g) are completely filled before population of the higher orbitals(eg)High spin:
If 0 is small enough then it is easier to put electrons into the higher energy orbitals than it is to put two into the same low-energy
orbital, because of the repulsion resulting from matching two electrons in the same orbitalex) (t2g)3(eg)n (n= 1,2)
Tetrahedral (figure 9-1b), Square planar (figure 9-1c)
LFT(figure 9-3, 9-4)
Cl-, Br-: lower 0 (figure 9-4 a)
CO: higher 0 (figure 9-4 b)

2. Ligandmetal complex
MRMHM XM OROM

RM

hapticity formal chargeelectron donation metal complex
alkyl
hydridehalogenalkoxide1
1-1-12211-1-122acyl

1-121-alkenyl

1-121-allyl

1-12acetylide

1-12carbene

102carbene

1-24M
M

RRM
RRM
RM

carbyne1-36

M COcarbonyl

102M

2-alkene

202

M

2-alkyne

202

M

3-allyl3-1

4M

4-diene4045-cyclo
pentadienyl

5-1

6M

M
H
M MX
M M
RO
M M
OC
M M
R2C
M M
O
C
MMM
RC
M
MM

hapticity formal chargeelectron donation
6-arene606-hydride

1-12-halogen

1-1

4-alkoxide1-14-carbonyl

102-alkylidene 1-243-carbonyl 1023-36-alkylidine 113. d-electron(OC)4Co Co(CO)4Mo(IV): d2 = 2e2(C5H5)-: 2 x 6e = 12e
2H-: 2 x 2e = 4eMo HHCo(0), d9, 18e

Co(0): d9 = 9e4(CO): 4 x 2e = 8e
Co-Co: 1 x 2e = 2eMo(IV), d2, 18eM(valency), [d-electron of M(0)] - [formal charge], [d-electron of metal] + [electron of ligand]
Early transition metal: smaller d-electron number (group 4, 5...)Late transition metal: larger d-electron number (group 9, 10...)4. 18-electron rule
Valence shells of transition metal consists of nine valence orbitals (s, p, d), which collectively can accommodate 18 electrons(same electron configuration as noble gas) either as nonbinding electron pairs or as bonding electron pairs.
18-electron complex: coordinatively saturated complex
non-18-electron complex: coordinatively unsaturated complex
Violations to the 18-electron rule
Octahedral[Co(H2O)2+6]2+ (19e)[Ni(en)3] (20e)late transition metal: small 0
occupation of egV(CO)6 (17e)W(CH3)6 (12e)Square planar[(C6H5)3P]2PdX2 (16e)[(C6H5)3P]2Ir(CO)X (16e)early transition metal

instability of dx2-y2

stable alkyl complexes
Zr(CH2C6H5)4
W(CH3)6W(VI), d0, 12e Zr(IV), d4, 8e

5. -bonding ligand
5.1 alkyl complex

Ti[CH2C(CH3)3]4Ti(IV), d0, 8e

M-C bond: 130~300 kJmol-1-hydride elimination
CrFe

4Cr(IV), d2, 10e

4Fe(IV), d4, 12e

L2Pt

Pt(II), d8, 16esynthesis of alkyl complexes
1) Metathetical exchange using a carbon nucleophile
PR3Cl Pt Cl
PR3+PR3n-Bu Pt n-Bu
PR32 n-BuLi

Pt(II), d8, 16ePt(II), d8, 16e2) Metal centered nucleophile-OC Fe+OCNa+3) Oxidative addition
Ph3P
COIr
Br
PPh3+ MeClIr(I), d8, 16e

MePh3P
COIr
Br
PPh3ClIr(III), d8, 18e4) Insertion
-Br

OC Fe
OCFe(0), d8, 18e

Fe(II), d6, 18e

PR3
Cl Pt H
PR3+CH2=CH2Pt(II), d8, 16e

PR3
Cl Pt Et
PR3Pt(II), d8, 16e

5.2 hydride complex
M-H bond: 240~350 kJmol-1synthesis of hydride complexes1) Metal halide + reductant3) Oxidative addition

RuCl2(PPh3)3 + NaBH4 + PPh3

RuH2(PPh3)4Ru(II), d6, 18e

6Ru(II), d , 16e2) Protonation
Cp2WH2 + H+W(IV), d2, 18e[Cp2WH3]+W(VI), d0, 18e[Co(CO4)]- + H+Co(-I), d10, 18e

HCo(CO4)
Co(I), d8, 18e

IrCl(CO)(PPh3)2 + H2
8Ir(I), d , 16e
RhCl(PPh3)3 + H2
Rh(I), d8, 16e

IrH2Cl(CO)(PPh3)2Ir(III), d6, 18e
RhH2Cl(PPh3)3Rh(III), d6, 18e24) Ortho metallation, cyclo metallation5) -hydride elimination
RuH2(PPh3)4 + 2KCl + 2 acetone

RuCl2(PPh3)4 + 2KOCH(CH3)2Ru(II), d6, 18e

PMe2
PMe3
W
HPMe
PMe3 3

W[P(CH3)3]6W(0), d6, 18eRu(II), d6, 18e

W(II), d4, 16e
Reactivity of hydride complex
1) H-2) H.

OR

H
Cp2Zr
ClZr(IV), d0, 16e

R

OCHR2
Cl

Cp2Zr

Zr(IV), d0, 16eO

Zr(IV), d0, 16e[Co(CO4)]- + H+Co(-I), d10, 18e2[Co(CN5)]3-Co(II), d6, 18eCo(II), d7, 17e+

OCH2CH3Cl

Cp2Zr

3) H+2[HCo(CN5)]3- +4) insertion to alkene and alkyne
5) H2 elimination

HCo(CO4)
Co(I), d8, 18e

5.3 molecular hydrogen complex
H
H
Cy3P
COW
OC
PCy3COH
H
R3P
PR3Ru
R3P
H
H

H
H
OC
CO
Cr
OC
CO
CO

W(0), d6, 18eRu(II), d6, 18e

Cr(0), d6, 18e

weak back donation to hydrogen

5.4 agostic interaction
agostic interaction: interaction of a coordinately-unsaturated transition metal with a C-H bond(two electrons involved in the C-H bond enter the empty d-orbital of a transition metal, resulting in a two electron three center bond)
ex)

HP Cl
HP Ti
HCl ClP ClP Ti
Cl Cl H

HH

-agostic interaction-agostic interaction

donation,back-donation

6.

6.1 carbonyl complex
ex)
M
dM

M

C On,

HOMO
donation

dM

C On,

O
OCC COCO
OC Co Co COOC
COCONi COOC
COLUMOback-donation...etc

6.2 nitrocyl complex

Ln-1M

M-NO

N O

LnM+
N O

CO equivalent
6.3 molecular nitrogen complex

M

NO

N O

LnM+

basic metal
end-onONPh3PNOIrCl
PPh3

Ph3P Ru NO
Cl
PPh3

6.4 molecular oxygen complex(H3N)5Co O
O Co(NH3)5NNZrNZr NN Nex)

5+PPh2EtOCO
IrClO
PPh2Et

6.5 molecular carbon dioxygen complex
M O C O
1-O

high oxidation
metalOO
M CO-C,O

1CO

M
2-C

low oxidation
metal

3

6.6 phosphine complex
basicity: PR3> PR2Ar> PRAr2> PAr3
acceptor ability: NO> CO> RNC> PF3> PCl3> PCl2R> PBr2R> P(OR)3> PR3> RCN> RNH2> NH3X

Md - * interaction

PXXd - * interaction
a. Structural factor
Tolman cone angle: measure of size of ligand

bite angle: bidentate ligand

PPMP

M

Table 9-7

Table 9-8

b. electronic factor(R3P)Ni(CO)3: there is a strong correlation between

CO and electron donating ability of phosphine ligand.

Table 9-9

6.7 carbene complex
Fisher carbene: electrophilic carbene
low oxidation state
middle and late transition metal-acceptor ligand-donor substituents on methylene

Schrock carbene: nucleophilic carbene
high oxidation state
early transition metal-donor ligandhydrogen and alkyl substituents on carbenoid carbon
R
LnM C
RRR
LnM C
R

LnM
RR

MeTa
H

OMe

OCCOW
OCCOCOTebbe complex

HW(II), d4, 18e0

Ta(V), d , 18e
synthesis of carbene complex
Ta(CH3)3(OAr)2
Me(C5H5)2Ta

Mehv

W(CO)6Ta(=CH2)(CH3)(OAr)2

BF4- + CH2=P(CH3)3(C5H5)2Ta

PhLi(OC)5W

OLi Me O+3(OC)5W

Ph

OMe PhLi

Ph(OC)5W

PhPh

Cl
Cl OEtEtOH
Cl Pt CNC6H5Cl Pt
PPh3
PPh3 NHC6H5CH2MeMeH

Me1-C10H7(OC)5W
NN
HMe1-C10H7NN

W(CO)6 +H

H
Me

1-C10H7

1-C10H7

7. -bonding ligand
7.1 alkene complex
Cl Pt ClCl

Dewar-Chatt-Duncanson modelClRh Rh
ClCC

M
dM,donationMCChigh oxidation stateC
CM
dM

*,

M

back-donation

CC

anionic complex
electron donating ligand4

7.2 alkyne complex
Dewar-Chatt-Duncanson model can be applied to alkyne complex.
OPhOR(OC)3Co Co(CO)3 +OC Mn
OCRRR(OC)3Co Co(CO)3Ph

7.3 -allyl complex

HB
HA

HB

95~120°

HA

HA: anti
HB: synM

dyzdz2syn-anti isomerization
HB
HAallylic rotation

HB

HB
HA

HA
M

HB
HA M

M

M
HB
HA

HA

HB
HA

HB

HA
HB

L1 Mo
L2

L1 Mo
L2cf) crotyl complex: racemization, 1,3-disubstituted allylic complex: syn-anti isomerization
7.4 diene complex
molecular orbital (figure 9-20)
M

M

diene

metallacyclopentene
back donation
Zr, Ta, Nb
R1Zr
R1Zr

racemic

R2

R2(CO)3Fe
R1(CO)3Fe

R2Zr

Zr
R1R2

R1R2R1R1R2(CO)3FeR2

7.5 cyclopentadienyl complex
3-indenylMex) ferrocene 18e
cobaltcene 19enickellocene 20eMM

5-C5H5

1-C5H5ClTi
ClTi(IV), d0, 16eelectrophilic

Cp*= C5(CH3)5

metallocene(figure 9-22)
ClTa Cl
ClTa(V), d0, 18e

HMo
HMo(IV), d2, 18e
nucleophilic

synthesis of cyclopentadienyl complex
1) metal salt + cyclopentadienyl anion
FeCl2 + 2C5H5Na(C5H5)2Fe + 2NaCl2) redutive condition
RuCl3 + 3C5H6 + 1.5Zn(C5H5)2Ru + C5H8 + 1.5ZnCl25

7.5OCbenzene complex

Cr COCOCr(0), d6, 18e

CrFeCr(0), d6, 18e

F(II), d6, 18e

figure 9-24

synthesis of arene complex1) arene + metal salt
CrCl3 + 2C6H6 + 1/3AlCl3 + 2/3AlCr

Na2S2O4
AlCl4-Cr(I), d5, 17eCrCr(0), d6, 18e2) ligand exchange

Mo(CO)6 +OC

Mo CO
CO

Mo(0), d6, 18e3) hydrogen extraction from cyclohexadiene

RuCl3 +ClRu Cl
Cl Ru
ClRu(II), d6, 18e

LL

Mo Cl
ClRu(II), d6, 18e6