2
Topics in Organometallic Chemistry

Editorial Board:
].M. B r o w n P. D i x n e u f
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P. K n o c h e l
S. M u r a i M . R e e t z

A . F i i r s t n e r L.S. H e g e d u s
G. v a n K o t e n T.]. M a r k s


Topics in Organometallic Chemistry
Forthcoming volumes:
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Lanthanides: Chemistry and Use
in Organic Synthesis
Volume Editor: S. Kobayashi

With contributions by
R. Anwander, E.C. Dowdy, H. Gr6ger, Z. Hou, H. Kagan,
S. Kobayashi, G. Molander, I.L. Namy, M. Shibasaki,
Y.Wakatsuki, H. Yasuda

~ Springer


The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry, where new developments are having a
significant influence on such diverse areas as organic synthesis, pharmaceutical research, biology, polymer research and materials science. Thus the scope of coverage
includes a broad range of topics of pure and applied organometallic chemistry. Coverage is designed for a broad academic and industrial scientific readership starting
at the graduate level, who want to be informed about new developments of progress
and trends in this increasingly interdisciplinary field. Where appropriate, theoretical and mechanistic aspects are included in order to help the reader understand the
underlying principles involved.
The individual volumes are thematic and the contributions are invited by the volumes editors.
In references Topics in Organometallic Chemistry is abbreviated
Top. Organomet. Chem. and is cited as a journal
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ISSN 1436-6002
ISBN 3-540-64526-8
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Lanthanides: chemistry and use in organic synthesis / vol. ed.: S. Kobayashi. With
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(Topics in organometallic chemistry ; 2)
ISBN 3-540-64526-8

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Volume Editor
Prof. Shfi Kobayashi
Graduate School of Pharmaceutical Sciences

The University of Tokyo
Hongo, Bunkyo-ku
Tokyo 113-0033, Japan
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Editorial Board
Prof. John M. Brown

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Dyson Perrins Laboratory
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E-maih

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Universit~ de Rennes 1
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F-35042 Rennes Cedex, France
E-maih Pierre.Dixneuf@univ-rennes 1.fr

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Max-Planck-Institut ftir Kohlenforschung
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Department of Chemistry
Colorado State University
Fort Collins, Colorado 80523-1872, USA
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Prof. Paul Knochel

Organisch-Chemisches Institut
Universit~itHeidelberg
Im Neuenheimer Feld 270
D-69120 Heidelberg, Germany
E-maih

Fachbereich Chemie
Philipps -Universit/it Marburg
Hans-Meerwein-Strat~e
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Prof. Gerard van Koten

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Department of Metal-Mediated Synthesis
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Prof. Manfred Reetz

Faculty of Engineering
Department of Applied Chemistry
Osaka University
Yamadaoka 2-1, Suita-shi
Osaka 565, Japan
E-maih

Max-Planck-lnstitut fiir Kohlenforschung
Kaiser-Wilhelm-Platz 1
D-45470 Mfilheim an der Ruhr, Germany
E-maih


Preface

While the lanthanides (strictly defined as the 14 elements following lanthanum
in the periodic table, but as normally used also include lanthanum itself) have
several unique characteristics compared to other elements, their appearance in

the history of the development of organometallic chemistry is rather recent.
Since the f orbitals are filled gradually from lanthanum ([Xe]4f ) to lutetium
([Xe]4fl4), they are regarded as the f-block elements, which are discriminated
from the d-block transition elements.
This book was edited as the second volume of "Topics in Organometallic
Chemistry", aiming at an overview of recent advances of chemistry and organic
synthesis of lanthanides. Since scandium (Sc) and yttrium (Y) (which lie above
the lanthanides and have similar characteristics) are also included, this book
covers rare earth chemistry. Recently, especially in this decade, the chemistry
and organic synthesis of lanthanides have developed rapidly as one of the most
exciting areas. An international team of authors has been brought together in
order to provide a timely and concise review of current research efforts such as
lanthanide catalysis in small molecule organic synthesis especially focused on
carbon-carbon bond-forming reactions, chemistry and organic synthesis using
low-valent lanthanides such as diiodosamarium, asymmetric catalysis, lanthanide-catalyzed polymer synthesis, and polymer-supported lanthanide catalysts
used in organic synthesis. Principles of organolanthanide chemistry are summarized in the first chapter. I am sincerely grateful to Drs. R. Anwander, E. C. Dowdy, H. Gr6ger, Z. Hou, H. Kagan, G. Molander, J. L. Namy, M. Shibasaki, Y. Wakatsuki, and H. Yasuda for participating in this volume. J. Richmond, J. SterrittBrunner, and B. Benner (Springer) are also acknowledged for encouraging me
to organize this work.
Finally, I hope that this volume is helpful to many researchers and students
who are or will be involved in or interested in this truly exciting and hot field.
Tokyo, December 1998

ShU Kobayashi


Contents

Principles in Organolanthanide Chemistry
R. Anwander . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lanthanide Triflate-Catalyzed Carbon-Carbon Bond-Forming Reactions
in Organic Synthesis

S. Kobayashi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

63

Lanthanide- and Group 3 MetaUocene Catalysis in
Small Molecule Synthesis
G. Molander, E. C. Dowdy . . . . . . . . . . . . . . . . . . . . . . . . . . . .

119

Influence of Solvents or Additives on the Organic Chemistry
Mediated by Diiodosamarium
H. Kagan, ].L. Namy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

155

Chiral Heterobimetallic Lanthanoid Complexes: Highly Efficient
Multifunctional Catalysts for the Asymmetric Formation of C-C, C-O
and C-P Bonds
M. Shibasaki, H. Gr6ger . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

199

Reactions of Ketones with Low-Valent Lanthanides:
Isolation and Reactivity of Lanthanide Ketyl and
Ketone Dianion Complexes
Z. Hou, Y.Wakatsuki . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

233


Organo Rare Earth Metal Catalysis for the Living Polymerizations of
Polar and Nonpolar Monomers
H.Yasuda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

255

Polymer-Supported Rare Earth Catalysts Used in Organic Synthesis
S. Kobayashi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

285

Author Index

307

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Pr1nc1p1e51n0r9an01anthan1deChem15try
Re1ner A n w a n d e r
An0r9an15ch-chem15che5 1n5t1tut, 7echn15che Un1ver51tat M1Jnchen, L1chten6er95traf~e 4, D-85747 6arch1n9, 6 e r m a n y
e-ma1h re1ner.anwander ch.tum.de

Dur1n9 the 1a5t decade, the rare earth e1ement5 have 91ven en0rm0u5 5t1mu1u5 t0 the f1e1d
0f 0r9an1c 5ynthe515 1nc1ud1n9 5tere05e1ect1ve cata1y515.7h15 artMe 0ut11ne5 60th the 6a51c
and advanced pr1nc1p1e5 0f the1r 0r9an0meta111c chem15try. 7he 1ntr1n51c e1ectr0n1c feature5
0f th15 17-e1ement 5er1e5 are rev1ewed 1n 0rder t0 6etter under5tand the 5tructura1 chem15try 0f the1r c0mp1exe5 and the re5u1t1n9 5tructure-act1v1ty re1at10n5h1p5. Part1cu1ar empha51515 p1aced 0n 5ynthet1c a5pect5,1.e. 0pt1m12at10n 0f e5ta6115hed pr0cedure5 and a1ternat1ve
meth0d5 w1th 6etter acce55 t0 cata1yt1ca11yre1evant 5pec1e5.Acc0rd1n91y, ta110r-made anc111ary 119and5 are rep0rted 1n deta11 and the react1v1ty pattern 0f 1anthan1de c0mp0und515 exam1ned w1th repre5entat1ve examp1e5.

Keyw0rd5:Lanthan1de5,1ntr1n51c pr0pert1e5, React1v1ty, 5ynthe515, L19and5


L15t 0 f A66rev1at10n5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2

1

1ntr0duct10n

3

2

1ntr1n51c Pr0pert1e5 0f t h e Lanthan1de E1ement5

2.1
2.2

E1ectr0n1c Feature5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5ter1c Feature5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4
7

3

5ynthe515 0f 0 r 9 a n 0 1 a n t h a n 1 d e C 0 m p 0 u n d 5 . . . . . . . . . . . . .

8


3.1
3.2
3.3
3.4

7 h e r m 0 d y n a m 1 c a n d K1net1c 6u1de11ne5 . . . . . . . . . . . . . . .
1n0r9an1c Rea9ent5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Meta10r9an1c Rea9ent5 . . . . . . . . . . . . . . . . . . . . . . . . . .
7herma1 5ta6111ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9
10
15
23

4

L19and C0ncept5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

23

4.1
4.2
4.3

5ter1c 8u1k a n d D 0 n 0 r Funct10na112at10n . . . . . . . . . . . . . . .
Anc111ary L19and5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1mm061112at10n - 5upp0rted L19and5
. ...............


24
27
31

...............................
..........

4


2

5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8

Re1ner Anwander
React1v1ty Pattern 0f 0r9an01anthan1de C0mp1exe5 . . . . . . . . .

32

D0n0r-Accept0r 1nteract10n5 . . . . . . . . . . . . . . . . . . . . . . .
C0mp1ex A9910mer12at10n . . . . . . . . . . . . . . . . . . . . . . . .
L19and Exchan9e and Red15tr16ut10n React10n5 . . . . . . . . . . . .
1n5ert10n React10n5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

E11m1nat10n React10n5- L19and De9radat10n . . . . . . . . . . . . . .
Red0x Chem15try . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
React10n 5e4uence5 - Cata1yt1c Cyc1e5 . . . . . . . . . . . . . . . . .
51de React10n5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32
37
39
41
42
44
46
47

Per5pect1ve5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50

Reference5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50

L15t0f A66rev1at10n5
Ar

81N0L
CN
C07
Cp
Cp*

DME
HMPA

ar0mat1c re51due
61naphth01
c00rd1nat10n num6er
cyc100ctatetraeny1
~15-cyc10pentad1enY 1
~15-PentamethY1cyc10pentad1enY1

1,2-d1meth0xyethane

hexamethy1ph05ph0r1c tr1am1de
H5A8
hard 50ft ac1d 6a5e
L
119and
Ln
1anthan1de (5c, Y, La, Ce-Lu)
MMA
methy1methacry1ate
07f
tr1f1u0r0methane5u1f0nat0 ( tr1f1ate ),
CF3503
Ph
pheny1
PMDE7A N, N, N ,N ,N -pentamethy1d1ethy1enetr1am1ne
Py
pyr1d1ne
R

re51due
5a1en
N,N -615(3,5-d1-tert-6uty15a11cy11dene)ethy1ened1am1ne
7p
tr15(pyra201y1)60rate
7HF
tetrahydr0furan
7MEDA tetramethy1ethy1ened1am1ne
X
119and
2
nuc1ear char9e


Pr1nc1p1e51n0r9an01anthan1deChem15try
1
1ntr0duct10n
7he rare earth e1ement5 c0n5t1tute an 1nte9ra1 part 0f m0dern 0r9an1c 5ynthe515 [ 1].
1t wa5 a60ut 30 year5 a90 that the pecu11ar red0x 6ehav10r 0f 5evera11n0r9an1c rea9ent5 wa5 d15c0vered f0r 5e1ect1vereduct1ve and 0x1dat1ve c0nver510n5 [2]. 1n the 1nter1m per10d f1ne chem1ca15 and p01ymer 5ynthe515 have 1ncrea51n91y 6enef1ted
fr0m the app11cat10n 0f h19h1y eff1c1ent 0r9an01anthan1de precata1y5t5 [3]. Due t0
the1r 1ntr1n51c e1ectr0n1c pr0pert1e5 expre55ed 1n the 1anthan1de c0ntract10n , the
rare earth e1ement5 c0mpr151n9 the 9r0up 3 meta15 5c,Y, La and the 1nner tran51t10n
meta15 Ce-Lu pr0v1de new 5tructura1 and react1v1ty pattern5, emer91n9 1n 5tructure-act1v1ty re1at10n5h1p5 unprecedented 1n ma1n 9r0up and d-tran51t10n meta1
chem15try. 1t 15 a150 the1r 10w t0x1c1ty and ava11a6111tyat a m0derate pr1ce wh1ch
make5 th15 17-e1ement 5er1e5 attract1ve f0r 0r9an1c 5ynthe515. 7he 5pectrum 0f
rare earth rea9ent5 ran9e5 fr0m 1n0r9an1c t0 0r9an0meta111c c0mp0und5 a5 5chemat1ca11y redrawn 1n F19. 1 w1th repre5entat1ve examp1e5.
Wh11e h19h1y eff1c1ent 1n0r9an1c rea9ent5 5uch a5 5m12(thf) 2 and 5c(07f) 3 are
a1ready c0mmerc1a11y ava11a61e, the m0re 50ph15t1cated 0r9an0meta111c rea9ent5
are a5 a ru1e prepared 0n a 1a60rat0ry 5ca1e, 0ften under r190r0u5 exc1u510n 0f
m015ture u51n9 1nert 9a5 techn14ue5 [4]. 1n part1cu1ar, the 1atter c1a55 0f c0mp0und5 0ffer5 acce55 t0 ta110r-made, we11-def1ned m01ecu1ar 5pec1e5 v1a 119and

f1ne-tun1n9. 7he c0n51derat10n 0f the 1ntr1n51c pr0pert1e5 0f the 1anthan1de cat1-

CP*25m (thf)2

/

Y6(meta1)

Cp*2LnCH(51Me3)2

ããCeC13/L1CH3ãã

/

- -

Ln[N(81Me3)213~11111111

5m12(thf)x

--

..... ,Â~

111111111111111. . . . .

,~,~

1111111~ Ln(07f)3


Ln(f0d) 3

Na3[La(5)-81N0L]3(thf)6(H20)

(NH4)20e(N03) 6

Ln(N7f2)3(H20)
Ln[(-)8N P]3

F19.1. Rare earth meta1rea9ent51n 0r9an1c5ynthe515(N7f2=615[tr1f1u0r0methy1)5u1f0ny1]am1de,

(-)8NP=(R)-(-)- 1,1 -61naphthy1-2,2 -d1y1ph05phat0)


4

Re1nerAnwander

0n5 a5 we11 a5 therm0dynam1c and k1net1c fact0r5 are cruc1a1 1n de519n1n9 and
5ynthe5121n9 n0ve1 m01ecu1ar c0mp0und5.7h15 art1c1e a150 1nc1ude5 reference t0
h19h1y react1ve meta10r9an1c c0mp0und5, p5eud0-0r9an0meta111c5, c0nta1n1n9
n0 d1rect meta1 car60n 11nka9e; c0nta1n1n9, h0wever, 0therw15e read11y hydr01y2a61e Ln-X 60nd5. F0r examp1e, 1anthan1de c0mp0und5 5uch a5 am1de and
a1k0x1de der1vat1ve5 n0t 0n1y d15p1ay1mp0rtant 5ynthet1c precur50r5 6ut a150 exh161t exce11ent cata1yt1c 6ehav10r 1n 0r9an1c tran5f0rmat10n5 [5,6]. Macr0cyc11c
119and5 exh161t1n9 Ln-N and Ln-0 60nd5 are n0t c0n51dered 1n th15 5urvey [7].
7he 1a5t 20 year5 have w1tne55ed a rap1d deve10pment 1n 0r9an01anthan1de
chem15try and numer0u5 rev1ew art1c1e5 have 6een pu6115hed, empha5121n9 var10u5 a5pect5 1nc1ud1n9 the1r u5e 1n 0r9an1c tran5f0rmat10n5. A c0mprehen51ve
115t0f re1evant art1c1e5 ha5 6een 91ven recent1y [8]. 7he purp05e 0f th15 art1c1e 15
n0t t0 91ve a c0mprehen51ve 5urvey 0f 0r9an01anthan1de c0mp0und5 6ut rather
t0 addre55 the pr1nc1p1e5 0f the1r chem15try.


2
1ntr1n51c Pr0pert1e5 0f the Lanthan1de E1ement5
7he rare earth e1ement5 repre5ent the 1ar9e5t 5u69r0up 1n the per10d1c ta61e and
0ffer a un14ue, 9radua1 var1at10n 0f th05e pr0pert1e5 wh1ch pr0v1de the dr1v1n9
f0rce f0r var10u5 cata1yt1c pr0ce55e5.7he1r pecu11ar e1ectr0n1c c0nf19urat10n and
the c0nc0m1tant un14ue phy51c0chem1ca1 pr0pert1e5 a150 have t0 6e c0n5u1ted
f0r the purp05e 0f 5ynthet1c c0n51derat10n5.7he h19h1y e1ectr0p051t1ve character
0f the 1anthan1de meta15, wh1ch 15 c0mpara61e t0 that 0f the a1ka11 and a1ka11ne
earth meta15, 1ead5 a5 a ru1e t0 the f0rmat10n 0f pred0m1nant1y 10n1c c0mp0und5, Ln(111) 6e1n9 the m05t 5ta61e 0x1dat10n 5tate [9]. 7h15 and 0ther 1ntr1n51c pr0pert1e5 are 0ut11ned 1n 5cheme 1 wh1ch w1115erve a5 a p01nt 0f reference
1n th15 5ect10n [10-13].

2.1
E1ectr0n1cFeature5
7he Ln(111) cat10n5 0f the 5er1e5 Ce-Lu exh161t the extended Xe-c0re e1ectr0n1c
c0nf19urat10n [Xe]4f~ (n=1-14), a 5ym601 wh1ch perfect1y p1cture5 the 11m1ted
rad1a1 exten510n 0f the f-0r61ta15: 7he 4f5he1115 em6edded 1n the 1nter10r 0f the
10n, we11-5h1e1ded6y the 552 and 5p 6 0r61ta15 [14]. A p10t 0f the rad1a1 Char9e den51t1e5 f0r the 4f, 55, 5p and 65 e1ectr0n5 f0r 6d + v15ua11yexp1a1n5 why Ln(111) cat10n5 are c0mm0n1y th0u9ht 0f a5 a
tr1p1e-p051t1ve1ychar9ed c105ed5he111nert9a5
e1ectr0n c10ud "(F19. 2) [ 14].
10n12at10n ener91e5 0f the e1ement5 [15], 0pt1ca1 pr0pert1e5 [16], and ma9net1c m0ment5 0f numer0u5 c0mp1exe5 [ 17] pr0ve that the f-0r61ta15 are perfect1y
5h1e1ded fr0m 119and effect5. C0n5e4uent1y, 0n1y m1n1ma1 pertur6at10n 0f thefe1ectr0n1c tran51t10n5 re5u1t5 fr0m the c0mp1exat10n 0f d1p01ar m01ecu1e5. 1n
c0ntra5t t0 the 6r0ad d ~ d a650rpt10n 6and5 0f the 0uter tran51t10n e1ement5,
thef--ff6and5 0f the 1anthan1de5 are a1m05t a5 narr0w 1n 5011d and 1n 501ut10n a5


Pr1nc1p1e51n0r9an01anthan1de Chem15try

Ln 4+ [E ° (M4+/M3+), V]

1.74 3.2


Ln 3+ [10]

r/c~P:1Nd1Pm1~6d1(76~]Dy1H01Er[7vm,
J~ Lu1

3.1

Ln 2+ [E ° (M2+/M3+), V]

-1.55 -0.36

0.745~ 1.0321.01f-1

Cat10n 512e (A) [11]
(Ln 3+, 6-c00rd1nat10n)
E1ectr0n1c C0nf19urat10n
(Ln 3+)

[Ar]

-2.1 -1.15

• 0.9381

, 0.861

[Kr] [Xe] [Xe]4f 1

[Xe]4f 14


1

Lew15 Ac1d1ty
(Ln 3+, re1at1ve)
0x0ph111c1ty[12]
[D0(Ln0), (-+ 5 kca1m01-1)]

165 170 190 188L......J167

E1ectr0ne9at1v1ty [1 3]
(Pau11n9)

1.3

1.2

1.1

136 112 1 7 0 L ~ 1 4 4

122 95 159

1.1

1.1

5cheme 1 . 7 r e n d 5 w1th1n 1ntr1n51c pr0pert1e5 0f the 1anthan1de e1ement5

1.4

1.3

~4f

----

•1f

•

- - .
.....

55
5p

1.2
1.1
1.0
.9
.8
P=1,¢1.7
.6
.5
.4

,

f~


,3

,¢

.2

--..

y ,

.1
0.2

.6

L0

L4

..

J.5 2.2 2.5 3.0 ~,.4 .~.e 4.2 4.6 5.0 5.4

.,4, (0u)

5.5 6.2 5.5 7.0

7.4

F19.2. P10t 0f the rad1a1 char9e den51t1e5 f0r the 4f-, 55-, 5p-, and 65-e1ectr0n5 0f 6d + fr0m

[141


6

Reiner Anwander

they are for gaseous ions. These transitions are “LaPorte-forbidden” and result
in weak intensities which are responsible for the pale color of the trivalent species. General principles of d-transiton metal ligand bonding such as σ-donor/πacceptor interaction, the “18-electron rule”, and the formation of classic
carbene, carbyne, or carbon monoxide complexes are not observed in lanthanide chemistry, neither do they form Ln=O or Ln≡N multiple bonds. However,
the lack of orbital restrictions, e.g. the necessity to maximize orbital overlap as
in d-transition metal chemistry, allows “orbitally forbidden” reactions. Because
of very small crystal-field splitting and very large spin-orbit coupling (high Z)
the energy states of the 4fn electronic configurations are usually approximated
by the Russel–Saunders coupling scheme [18]. The peculiar electronic properties of the f-elements have proved attractive for numerous intriguing opto- and
magneto-chemical applications (“probes in life”) [15].
The inert gas-core electronic configuration also implies a conform chemical
behavior of all of the Ln(III) derivatives including Sc(III), Y(III) and La(III). The
contracted nature of the 4f-orbitals and concomitant poor overlap with the ligand orbitals contribute to the predominantly ionic character of organolanthanide complexes. The existing electrostatic metal ligand interactions are reflected
in molecular structures of irregular geometry and varying coordination numbers. According to the HSAB terminology of Pearson [19], lanthanide cations are
considered as hard acids being located between Sr(II) and Ti(IV). As a consequence, “hard ligands” such as alkoxides and amides, and also cyclopentadienyl
ligands show almost constant effective ligand anion radii (alkoxide: 2.21±0.03 Å;
amide: 1.46±0.02; cyclopentadienyl: 1.61±0.03) [20] and therefore fit the evaluation criteria of ionic compounds according to Eigenbroth and Raymond [21].
The ionic bonding contributions in combination with the high Lewis acidity
cause the strong oxophilicity of the lanthanide cations which can be expressed in
terms of the dissociation energy of LnO [12]. The interaction of the oxophilic
metal center with substrate molecules is often an important factor in governing
chemo-, regio- and stereoselectivities in organolanthanide-catalyzed transformations [22]. Complexation of the “softer” phosphorus and sulfur counterions
is applied to detect extended covalency in these molecular systems [23,24].
Scheme 1 further indicates the tendency of the Ln(III) cations to form the

more unusual oxidation states in solution [25]. Hitherto, organometallic compounds of Ce(IV), Eu(II), Yb(II) and Sm(II) have been described in detail [4].
More sophisticated synthetic approaches involving metal vapor co-condensation give access to lower oxidation states of other lanthanide elements [26].
Charge dependent properties such as cation radii and Lewis acidity significantly
differ from those of the trivalent species. Ln(II) and Ce(IV) ions show very intense and ligand-dependent colors attributable to “LaPorte-allowed” 4f→5d
transitions [16b]. Complexes of Ce(IV) and Sm(II) have achieved considerable
importance in organic synthesis due to their strongly oxidizing and reducing behavior, respectively [1,27]. Catalytic amounts of compounds containing the “hot
oxidation states” also initiate substrate transformations. As a rule this implies a
switch to the more stable, catalytically acting Ln(III) species [28].


Pr1nc1p1e51n0r9an01anthan1deChem15try
2.2
5ter1c Feature5

5tructura1 chan9e5 1n h0m01090u5 rare earth c0mp0und5 ar15e fr0m the 1anthan1de c0ntract10n [29], 1.e. the m0n0t0n1ca11y decrea51n910n1c rad11 w1th 1ncrea51n9 at0m1c num6er. 7he 4f-e1ectr0n5 added a10n9 the 1anthan1de 5er1e5 fr0m 1anthanum t01utet1um d0 n0t 5h1e1d each 0ther eff1c1ent1yfr0m the 9r0w1n9 nuc1ear
char9e, re5u1t1n91n the c0ntract10n phen0men0n. 1t 15 0ften th15 vary1n9 cat10n1c 512e wh1ch ha5 a tremend0u5 effect 0n the f0rmat10n, c00rd1nat10n 9e0metry
(c00rd1nat10n num6er5) and react1v1ty 0f the1r c0mp1exe5. Rep0rt5 have accumu1ated where 0r9an1c 5u65trate5 5eem t0 d15cr1m1nate n0t 0n1y 6etween 119and
env1r0nment5 6ut a150 6etween 51n91e 1anthan1de e1ement5 [22]. 5ucce55fu1 exp1anat10n5 0f the5e phen0mena are 6a5ed 0n the 5y5temat1c the0ret1ca11nve5t19at10n and 5tructura1 character12at10n 0f 0r9an01anthan1de c0mp0und5 [4].
5cheme 1 91ve5 the trend 0f 10n1c rad11 0f the5e 1ar9e cat10n5 wh1ch prefer
f0rma1 c00rd1nat10n num6er5 1n the ran9e 0f 8-12 [30]. F0r examp1e, c0n51der1n9 the effect1ve Ln(111) rad11 f0r 6-c00rd1nat10n, a d15crepancy 0f 0.171 .~ 6etween Lu(111) and La(111) a110w5 the 5ter1c f1ne-tun1n9 0f the meta1 center [11].
7he 5tructura11mp11cat10n5 0f the 1anthan1de c0ntract10n are 111u5trated 1n F19. 3
w1th the we11-exam1ned h0m01ept1c cyc10pentad1eny1 der1vat1ve5 [31]. 7hree
5tructure type5 are 065erved depend1n9 0n the 512e 0f the centra1 meta1 at0m: A,
[(r15-Cp)2Ln(6t-r15:r1x-Cp)]00 1-
m0n0mer1c, 8 (P212121)

01190mer1c, A (5ym., P21/c)
CN = 11
La

1 a

CN = 9

Pr Nd
a
a

Pm~m
6

6,C

6d

6

76

6

H0

~1CN = 10-11

01190mer1c, A (a5ym., P21, Pna21)

6

Y Er 7 m Y6 Lu 5c

decrea51n91~
d d d 1 1
1 10n1crad1u5/
1CN = 8

01190mer1c, C (P6c21)

F19.3. C00rd1nat10nm0de51n h0m01ept1c,10n1cLnCp3der1vat1ve5(a 6e10n9 t0 5pace 9r0up
P21; 6 1nd1cat10nfr0m p0wder d1ffract10npattern; c 5h0w add1t10na1m0d1f1cat10n5P6cm
and P211n (c0ntact d1mer - effect 0f cry5ta1112at10nc0nd1t10n5 [316]); d 6e10n9 t0 5pace
9r0up Pna21 and exh161t1en9thened 1nterm01ecu1ar Ln-C c0ntact5)


8

Re1nerAnwander

acc0rd w1th 10n1c60nd1n9, 5ma11chan9e51n 119and 5u65t1tut10n 1ead t0 chan9ed
c00rd1nat10n 6ehav10r and num6er (CN=10), a5 f0und 1n the tetranuc1ear r1n9
5tructure 0f the MeCp
der1vat1ve. M0n0mer1c type 8 15 preferent1a11y f0rmed
w1th 119and5 6ear1n9 6u1ky 5u65t1tuent5.
H19h c00rd1nat10n num6er5 can u5ua11y6e acc0mp115hed 1n 01190mer1c5tructure5 0r h19h1y 501vated c0mp1exe5. H0wever, 60th f0rm5 are unde51ra61e f0r
5ynthe5121n9h19h1yreact1ve c0mp0und5.7he react1v1ty and 5ta6111ty,re5pect1ve1y, 0f 1anthan1de c0mp1exe5 15 c0rre1ated w1th the 5ter1c 51tuat10n at the meta1
center. Eva1uat10n cr1ter1a a5 the pr1nc1p1e 0f 5ter1c 5aturat10n/un5aturat10n/0ver5aturat10n have 6een deve10ped t0 exp1a1nthe d1fference5 1n react1v1ty
[32]. Hence, the ma1n 5ynthet1c eff0rt5 a5 1n d-meta10r9an1c chem15try are put
1nt0 the f1ne-tun1n9 0f the 119and 5phere t0 06ta1n tracta61e (v01at11e,cata1yt1ca11y react1ve, etc.) c0mp0und5.8ecau5e 0f the 1mp0rtance 0f 5ter1c fact0r5,119and
env1r0nment5 have 6een numer1ca11y re915trated, e.9. 6y the c0ne-pack1n9
m0de1 [33], wh1ch repre5ent5 a 3-D exten510n 0f 701man 5 c0ne-an91e m0de1
[34]. 1n th15 m0de1, 5011d an91e5 are ca1cu1ated fr0m 5tructura1 data emp10y1n9

van der Waa15 rad11 [35] and c0n51der1n9 effect5 0f 5ec0nd 0rder pack1n9. 7he 1ntr0duct10n 0f 5ter1c c00rd1nat10n num6er5 f0r var10u5 type5 0f 119and5 6a5ed 0n
5011d an91e rat105 further empha512e5 the 1mp0rtance 0f 5ter1c c0n51derat10n5 1n
0r9an0-f-e1ement chem15try [36].
7he Lew15 ac1d1tywh1ch 15 affected 6y the char9e den51ty (2/r) 15 1e55d15t1nct
1n c0mp1exe5 der1ved fr0m the 1ar9e Ln(111) cat10n5. Hence, the5e 5y5tem5 are 0ften rep0rted a5 m11d Lew15 ac1d1c cata1y5t5 1n 0r9an1c 5ynthe515 [1]. H0wever,
5c(111) a5 6y far the 5ma11e5tLn(111) cat10n 1510cated 1n a p01e p051t10n n0t 0n1y
w1th re5pect t0 Lew15 ac1d1ty.1t5 a1um1num/1anthan1de/ear1y tran51t10n meta1
hy6r1d character [37] ha5 revea1ed 1t5 5uper10r1ty 1n many cata1yt1capp11cat10n5
[37,38]. 8a5ed 0n the1r re1at1vepreference5 f0r pyr1d1ne, Lappert 5u99e5ted a re1at1ve Lew15 ac1d1ty5ca1e: Cp25cMe>A1Me3>Cp2YMe-~Cp2LnMe(here: Ln=1ar9e
1anthan1de e1ement5) [39]. Max1mum e1ectr05tat1c meta1/119and 1nteract10n and
10n1c60nd 5tren9th (enhanced c0mp1ex 5ta6111ty)15 a150 expected f0r 5cand1um,
the 5ma11e5te1ement. 7he Ln(111) char9e den51ty and the c0nc0m1tant c0mp1exat10n tendency a150 pr0ve u5efu1when 5tudy1n9 the nature 0f C a 2+ 61nd1n91n 6101091ca1 macr0m01ecu1e5 exp101t1n9 the 1anthan1de e1ement5 a5 5pectr05c0p1c
and ma9net1c pr06e5 [15].

3
5ynthe5150f 0r9an01anthan1deC0mp0und5
7he ava11a6111ty 0f pure and we11-def1ned 5tart1n9 mater1a15 15 cruc1a1 f0r
5tra19htf0rward and h19h-y1e1d 5ynthe5e5 0f 0r9an0meta111c rare earth c0mp0und5. 7he 5u1ta6111ty0f 60th 5ynthet1c and cata1y5t precur50r5 can 6e jud9ed
6y the c0n51derat10n 0f therm0dynam1c and k1net1c fact0r5. F0r examp1e, the
kn0w1ed9e 0f meta1-119and 60nd 5tren9th5 can a5515t 1n a 6etter ana1y515 0f the
therm0dynam1c5 0f archetyp1ca1119and exchan9e react10n5 and t0 e1a60rate the
mechan15t1c 5cenar105 0f cata1yt1ctran5f0rmat10n5 [40].


Pr1nc1p1e51n0r9an01anthan1deChem15try
3.1
7herm0dynam1c and K1net1c6u1de11ne5
Mark5 and c0-w0rker5 pr0v1ded a m05t va1ua61e exam1nat10n 0f a6501ute 60nd
d15rupt10n entha1p1e5 0f var10u5 re1evant meta10r9an1c 119and5 X 1n Cp*25m-X.
7he data were 06ta1ned 6y an10n1c t1trat10n ca10r1metry 1n t01uene (F19.4) [41].

A1th0u9h the Ln-X 60nd5 5eem t0 6e therm0dynam1ca11y very 5ta61e, they u5ua11yd15p1ayk1net1c 1a6111tydue t0 h19h 119and exchan9e a6111ty,che1at1n9 and 501u6111ty effect5.
5cheme 2 enc0mpa55e5 1mp0rtant 5ynthet1c 6u11d1n9 610ck5 and preferred
5ynthet1c 5trate91e5 1n 0r9an01anthan1de chem15try. A5 ac1d/6a5e-type exchan9e
react10n5 are fundamenta1, the 119and5 are dep1cted acc0rd1n9 t0 the1r 1ncrea51n9
pKa va1ue5 (1n water). 7h15 a150 c0rre1ate5 w1th the tendency t0 hydr01y2e (0r9an0meta111c5) 0r w1th the c0mpet1t10n 6etween 501vat10n and c0mp1exat10n 0n
the 6a515 0f the H5A8 c0ncept (1n0r9an1c5).
7he centra1 p01nt 1n th15 c0n51derat10n 15 the Ln-0H m01ety, the preferred
f0rmat10n 0f wh1ch 15 ca11ed a d11emma 1n 0r9an01anthan1de chem15try . 0r9an01anthan1de and p5eud0-0r9an01anthan1de c0mp0und5 read11y hydr01y2e
when exp05ed t0 a1r and m015ture, w1th the f0rmat10n 0f hydr0x1de and 0x0centered 119and c1u5ter 1ntermed1ate5. Lanthan1de c0mp1exe5 w1th Ln-C 11nka9e5 are c0n51dered a5 0ver5en51t1ve
c0mp0und5 [42]. Even 119and5 w1th 10wer
pKa va1ue5 than water, a5 exemp11f1ed6y 5u65t1tuted phen01119and5, tend t0 hydr01y2e 1n 0r9an1c 501vent5 6ecau5e the 1n501u61e hydr0x1de5 f0rmed act a5 a
dr1v1n9 f0rce. H0wever, the pre5ence 0f hard d0n0r funct10na11t1e5 0r mu1t1p1y
char9ed an10n5 wh1ch are capa61e 0f che1at10n, can aff0rd m015ture-5ta61e a1k0x1de and am1de c0mp1exe5, a5 ha5 6een 5h0wn f0r 81N0L [43], p01ypyra201y160rate [44] and p0rphyr1n-11ke c0mp1exe5 [45]. Neverthe1e55, a11 0f the 0r9an01anthan1de c0mp1exe5 5h0u1d r0ut1ne1y 6e hand1ed under an 1nert 9a5 atm05phere
6y app11cat10n 0f h19h vacuum and 910ve-60x techn14ue5 [46].

E

E

E

(/)

09

09

1

1

1

1

33(21

E

09

E

09

1 1 111

E

r.,0

: : : : : : :1

43(5) 45(2) 47(1) 48(2) 5 2 ( 2 ) /

71•
E
E
rE)

111

69(2)73(2)

D(Ln--778)
47(2) [8y]- 72(2)[Y]
F19.4.80nd

(/)

E

E

09

0"3

1

1

1 1

81(1)84(2)

0,E
,89

E

09

1 1

1

93

1

97(3)

[D(Cp*25m-R ), (kca1m01-1)]

d15rupt10n entha1p1e50f 0r9an01anthan1de(111) c0mp1exe5.7he9 r a y area 1nd1cate5 the 60nd d15rupt10n entha1p1e5 0f 0r9an01anthan1de(0) arene 5pec1e5 (778=46C6H3t8u3- 1,3,5)


Re1ner Anwander

10

k
pKa (HL / H20)

0r9an0meta111c5

~ 1n0r9an1c5

V

Ln-CR~
1•

+50

Ln-H
Ln-NR2

Ln-0R

1n-C1

Ln-acac
Ln-N03
Ln-07f

Ln-Ha1

-10

5cheme 2. 5ynthet1c 5trate91e5 t0ward5 0r9an01anthan1de c0mp0und5 [A: am1ne e11m1na-

t10n react10n5, e.9. 511y1am1der0ute; 8: a1ky1at10nv1a a1k0x1de precur50r, e.9. ary10x1de
r0ute; e: a1ky1at10nv1a am1de precur50r; D:hydr09en01y5150f a1ky1m01et1e5]

3.2
1n0r9an1cRea9ent5
Lanthan1de ha11de5, n1trate5 and tr1f1ate5 are n0t 0n1y c0mm0n rea9ent5 1n 0r9an1c 5ynthe515 (F19. 1) 6ut a150 repre5ent, 1n dehydrated f0rm, key precur50r
c0mp0und5 f0r the m0re react1ve 0r9an0meta111c5 (5cheme 2). A5 a ru1e,1n c0mp0und5 0f 5tr0n9 m0n06a51c ac1d5 0r even 5uperac1d5, cat10n 501vat10n c0mpete5

w1th an10n c0mp1exat10n, wh1ch 15revea1ed 6y fu11y0r part1a11y 5eparated an10n5
and 501vated cat10n5 1n the1r 5011d 5tate 5tructure5.7he tendency t0 f0rm 0uter
5phere c0mp1exat10n 1n c00rd1nat1n9 501vent5 [47] 15 u5ed a5 a cr1ter10n 0f the
react1v1ty 0f 1n0r9an1c 5a1t precur50r5 1n 0r9an0meta111c tran5f0rmat10n5.
Ln-Ha11de5
Anhydr0u5 1anthan1de ha11de5 are 10n1c 5u65tance5 w1th h19h me1t1n9 p01nt5
wh1ch take up water 1mmed1ate1y when exp05ed t0 a1r t0 f0rm hydrate5 (1 >8r
>C1 ) [48]. 5tra19htf0rward 5ynthet1c acce55 and a fav0ra61e c0mp1exat10n/501vat10n 6ehav10r make the 1anthan1de ha11de5 the m05t c0mm0n precur50r51n 0r9an01anthan1de chem15try. Many 1mp0rtant Ln-X 60nd5 (X=C, 51, 6e, 5n, N, P, A5,
56, 81, 0, 5, 5e, 7e) can 6e 9enerated v1a 51mp1e 5a1t metathe515 react10n5 [4,8]. 7he
50-ca11ed amm0n1um ch10r1de r0ute e1ther 5tart1n9 fr0m the 1anthan1de 0x1de5 0r


Pr1nc1p1e51n0r9an01anthanJdeChem15try

11

NH401

Ln013(H20)x

=150 °C/10 -4 t0rr, -H20
= 350 °C/10 -4 t0rr, - NH401

X=6,7

=150 °C/10 -2 t0rr, -H20

~

8C203

-~

:11

~

LnC13(thf)x

[0e013(H20)]n

••Ln0X••

80C12, 7HF
- 502, - HC1

8C013(H20)6

7HF
50xh1et

X = 1.33-3.5

> 350 °C/10 -2 t0rr, -H20

HC1(a4.)

LnC13

80 °0

~-

5C013(thf)3

5cheme 3. La60rat0ry pr0cedure5 f0r the preparat10n 0f 1anthan1de ch10r1deprecur50r5

the hydrated ha11de5 15 the m05t p0pu1ar 1a60rat0ry pr0cedure (up5ca11n915 p055161e) t0 anhydr0u51anthan1de(111) ch10r1de5 (5cheme 3) [49]. 51mp1etherma1 dehydrat10n wh1ch w0rk5 we11f0r 1anthan1de tr1f1ate5 1ead5 t0 the f0rmat10n 0f unde51red 1anthan1de 0xych10r1de5. Evan5 and c0-w0rker5 have 5h0wn that the
5tandard rec1pe f0r dehydrat1n9 CeC13(H20)7 t0 make CeC13/RL1w111pr0duce
[CeC13(H20)] n [50]. CeC131RL1
15 a p0pu1ar 6r19nard-type rea9ent 1n 0r9an1c
5ynthe515 [51 ] wh1ch, f0r examp1e, 1ncrea51n91y t01erate5 funct10na19r0up5.
A c00rd1nat1n9 501vent 5uch a5 tetrahydr0furan (7HF) 15 0ften nece55ary t0
react the 0therw15e 1n501u61e1anthan1de ha11de5 v1a 5a1t metathe515.7he5e react10n5 pr0ceed v1a 1n1t1a1f0rmat10n 0f the m0re 501u61e c0mp0und5 LnX3(thf) x,
wh1ch are 06ta1ned v1a 50xh1et extract10n and are p0pu1ar, we11-def1ned5tart1n9
rea9ent5 [52]. 7he extent 0f 7HF c00rd1nat10n depend5 0n 60th the 5tructura1
type 0f the anhydr0u5 1anthan1de ha11de and the preva111n9 cry5ta1112at10n c0nd1t10n5, and affect5 1t5 501u6111tyand hence 1t5 react1v1ty [53]. 5cC13(thf)3
15
6e5t 5ynthe512ed 6y an a1ternat1ve pr0cedure ut11121n9 50C12 a5 a dehydrat1n9
a9ent [54]. Neutra1 d0n0r 119and5 5uch a5 capr01act0ne [53a], 2,6-d1methy1-4-pyr0ne [55] 0r che1at1n9 119and5 5uch a5 DME [56] and cr0wn ether5 [57,58] a150
revea1 unf0re5een and 1ntr19u1n9 c00rd1nat10n chem15try.
0ther 5ma11-5ca1e 1a60rat0ry pr0cedure5 have 6een deve10ped f0r the d1rect
5ynthe515 0f the m0re react1ve 7HF adduct5, av01d1n9 1nc0nven1ent
h19h temperature treatment [59-62]. F0r examp1e, the preparat10n 0f LnC13(thf)x
fr0m
meta1 p0wder and hexach10r0ethane 15 fac111tated 6y 50n1cat10n [E4. (1)] [59].
Add1t10na1 meta1-6a5ed 5ynthet1c r0ute5 1nc1ude the red0x tran5meta11at10n
w1th mercury(11) ha11de5 [E4. (2)] [60] and the react10n w1th tr1methy1511y1ch10r1de and anhydr0u5 methan01 [E4. (3)] [61]. Amm0n1a ha5 6een emp10yed a5 an
a1ternat1ve d0nat1n9 501vent 1n the 5ynthe515 0f 1anthan1de a1k0x1de5 5tart1n9
fr0m 1anthan1de ch10r1de5 [63].

2 Ln

+

02016

7HF

)))

~

2 Ln013(thf)x

+

02014

(1)


Re1nerAnwander

12

+ 1CH2CH21, 7HF
- 0H20H 2
+ 1.5 H912, 7HF

Ln

- 1.5 H9

+1.5 12, H01Pr

J,~

Ln13(thf)3.5

Ln = Nd, 7m

Ln13(thf)3

Ln = 5m, Y6

Ln13(H01Pr)4

Ln = La, Ce, Nd

5cheme 4.5ma11-5ca1e5ynthe5150f 501vatedLn(111)10d1de5

2 Ln

+

7HF
A

3 H9C12

~

2 LnC13(thf)x

+

3 H9

(2)

Ln = Y6 ( x = 3); Er (x = 3.5); 5 m (x = 2); Nd (x = 1.5)

2Ln

+

6Me351C1

+

6Me0H

6Me3510Me

+

3H2

7HF

~--

2 LnC13(thf)x

+

(3)
+

5cheme 4 5h0w5 5ma11-5ca1e 5ynthe5e5 0f 501vated 10d1de5 [64-66]. 5tr0n91y
d0nat1n9 501vent5 5uch a5 N-methy11m1da201e (N-Me1m) can acc0mp115h c0mp1ete an10n/cat10n 5eparat10n a5 5h0wn f0r [5m(N-Me1m)8]13 under anaer061c
c0nd1t10n5 [67]. 7he ch1ef fact0r5 wh1ch affect the 0ften enhanced react1v1ty 0f
the h19her h0m01090u5 ha11de5 are the1r h19her 501u6111ty [48a], a therm0dynam1ca11y m0re 1a611e Ln-X 60nd (F19. 4), the 50ft Lew15 6a51c1ty 0f the 10d1de
an10n, and d1fferent 501u6111typr0pert1e5 0f the e11m1nated a1ka11meta15a1t.
Lanthan1de(11) ha11de5,1n part1cu1ar 10d1de5, are pr0m1nent 5ynthet1c precur50r5 t0 the c0rre5p0nd1n9 Ln(11) 0r9an0meta111c5 [32,68,69]. 5m12 15 a we11-e5ta6115hed reduc1n9 rea9ent 1n 0r9an1c 5ynthe515 and 15 c0mmerc1a11y ava11a61e a5
a 7HF 501ut10n and 1n 5011df0rm [27]. 1t5 7HF 501vate wa5 5ynthe512ed acc0rd1n9
t0 E4. (4) and wa5 5tructura11y character12ed a5 a 7-c00rd1nate 5m12(thf) 5 [70].
7he 1e55 501u61e Y612(thf) 2 can 6e 06ta1ned ana1090u51y [27] and the amm0n1a
c0mp1ex 15 read11y f0rmed acc0rd1n9 t0 E4. (5) [69]. 7m12(dme)3 15 the 0n1y 501u61e 7m(11) c0mp0und 5ynthe512ed 50 far [E4. (6)] [71]. A 1ar9e-5ca1e 5ynthe515
0f 5m8r 2 av01d1n9 the expen51ve meta1 precur50r ha5 6een acc0mp115hed acc0rd1n9 t0 the react10n 5e4uence 5h0wn 1n E4. (7) [68].
5m

+

1CH2CH21

Y6

+

2 NH41

7m13

+

7m

7HF
NH3(114)

,.~

5m12(thf)x

~

Y612(NH3)x

DME
A
"~-

27m12(dme)3

+

+

0H2=0H2

(4)

H2

(5)

(6)


Pr1nc1p1e51n0r9an01anthan1deChem15try
H8ra4.
~

5m203

5m8r3

methy10rth0f0rmate

5m8r3X6H20

L1, 7HF

~

13

J,, 5m8r 3

(7)

5m8r2(thf)x

7he c0mp1ex (pyH)2(CeC16) ha5 6een d15cu55ed a5 an a1ternat1ve Ce(1V) precur50r [72]. P5eud0ha11de5 5uch a5 th10cyanate5 5h0u1d rece1ve 50me attent10n
a5 5pec1f1c 5ynthet1c precur50r5 due t0 the1r dua1119at10n m0de [73]. L1ke the ha11de5 [74], the1r Ln(111) der1vat1ve5 have 6een 5ucce55fu11yemp10yed a5 cata1y5t5
1n 0r9an1c tran5f0rmat10n5 [75].
0ther 1n0r9an1c 5a1t5
A1ternat1ve 1n0r9an1c precur50r5 wh1ch are referred t0 1n 5cheme 2 are a150
ava11a61e 6y treatment 0f 1anthan1de 0x1de5 Ln203 w1th the c0rre5p0nd1n9 ac1d
[76,77]. N1trate 119and5 c00rd1nate 5119ht1y 5tr0n9er t0 the 1anthan1de center5
c0mpared t0 ha11de5, 6ut are rep0rted t0 y1e1d c0ar5e prec1p1tate5 0f a1ka11 n1trate5 1n 5a1t metathe515 react10n5 [78]. N1trate5 are a150 preferred a5 precur50r5
1n macr0cyc11c chem15try where they preferent1a11y 0ccupy the 0uter 119at10n
5phere [7]. 5tr0n9 c0mp1exat10n 0f d0u61y char9ed an10n5(C032 >5042 ) CaU5e5
a C0n51dera61e decrea5e 1n 501U6111ty0f the C0rre5p0nd1n9 Ln2X3 and hence prec1ude5 the1r 6r0ad u5e a5 5ynthet1c precur50r5 [77]. Ln-f1u0r1de5 [79] and ph05phate5 are t0ta11y 1n501u61e 1n 501vent5 5u1ta61e f0r 0r9an0meta111c5 [4,15]. P5eud0-1n0r9an1c 5a1t5 der1ved fr0m 5uperac1d5,1n part1cu1ar der1vat1ve5 0f tr1f1ate,
c0nta1n weak1y c00rd1nat1n9 an10n5 and were 0ften f0und t0 6e 5uper10r t0 1anthan1de ha11de5 1n 5a1t metathe515 react10n5 [80]. Anhydr0u5 Ln(07f) 3 can 6e
ea511y 06ta1ned 6y therma1 dehydrat10n [E4. (8)] [81]. Lanthan1de tr1f1ate5 have
attracted c0n51dera61e attent10n a5 reu5ea61e Lew15 ac1d1c cata1y5t5 1n numer0u5
car60n-car60n 60nd-f0rm1n9 react10n5 [82].
CF3503H, H20
1,,
100 °C, 1h

Ln203

[Ln(H20)9][CF350313

180-200 °C
48h

~

Ln(CF3503)3

(8)

Rare earth 50r0hydr1de5 06ta1ned fr0m the ch10r1de5 [E4. (9)] [83] have 6een
u5ed 1n 5a1t metathe515 react10n5 and were f0und t0 6e attract1ve f0r the 9enerat10n 0f cat10n1c 5pec1e5 [84]. 7he pre5ence 0f m0re weak1y c00rd1nated 8F 4 an10n51n [Eu(MeCN)3(8F4)3] x wh1ch can 6e 5ynthe512ed acc0rd1n9 t0 E4. (10) pr0m0te5 5evera1 cata1yt1c tran5f0rmat10n5 0f n0n-heter0at0m-5u65t1tuted 0r9an1c
5u65trate5,1nc1ud1n9 the p01ymer12at10n 0f 5tyrene [85].
NdC13

+

Eu

3 N08F4

+

3.3Na8H4

7HF, - 3 NaC1
60 °C, 48 h
CH3CN
rt, 1d

~

>

Nd(8H4)3(thf)2

[Eu(0H30N)3(8F4)3]x

+

(9)

3 N0

(10)

Cer1um amm0n1um n1trate [(NH4)2Ce(N03)6, CAN], a key 0x1d121n9a9ent,15 the
m05t c0mm0n Ce(1V) precur50r [86]. 7he u5e 0f acety1acet0nate5 0f cer1ttm(1V) ha5
6een d15cu55ed [87] and Ce(07f) 4 5h0u1d a150 pr0ve t0 6e a va1ua61e precur50r [88].


14

Re1nerAnwander

Meta15

Lanthan1de meta15 wh1ch are c0nven1ent1y prepared fr0m the meta1 ha11de5 are
c0mmerc1a11y ava11a61e1n the f0rm 0f 1n90t5, ch1p5 (f111n95),f0115and p0wder5 and
are a150 hand1ed a5 pr0m1nent 5ynthet1c precur50r5. F0r examp1e, a1k0x1de c0mp1exe5 der1ved fr0m cheap and 10w 60111n9 a1c0h015 are a1ternat1ve1y5ynthe512ed
fr0m meta15 under H9C12 cata1y515 [89]. Repre5entat1ve examp1e5 f0r tran5meta11at10n and tran5meta11at10n/119and exchan9e react10n5 are 91ven 1n E45. (11 )-(13)
[90]. Amm0n1a 501ut10n5 0f ytter61um and eur0p1um react w1th a var1ety 0f 8r0n5ted ac1d1crea9ent5 acc0rd1n9 t0 E4. (14) [91]. Meta10x1dat10n/119and tran5fer 0ccur5 1n 7HF 1n the pre5ence 0f cata1yt1c [E4. (15)] and 5t01ch10metr1c am0unt5 0f
10d1ne [E4. (16)] [92]."Lanthan1de 6r19nard rea9ent5, f0rmu1ated a5 "RLn1 are
prepared 1n 51tu fr0m the meta1 and the a1ky1(ary1)ha11de1n 7HF [E4. (17)] [93].

Ut1112at10n 0f an extreme1y 6u1ky a1ky1 119and a110wed the 1501at10n 0f
{Y6[C(51Me3)3]1(0Et2)}2 acc0rd1n9 t0 a 5a1t metathe515 react10n [94].
7HF
~
80 °C, 20h

Ln

+

5m

+

H9(C6F5) 2

+

H9

Y6

+

+

+

+

2 Ln +

~

-

7HF

~

12h

7HF
80 °C, 8h

~

EU2+(NH3)6X2e-(NH3)n

12(0, 7HF, Py

1.5 Ar55Ar

Ph

2HNR 2

LnCp3(thf)

(11)

3 71

+

5m(NR2)2(thf)4

+

(12)

2 HC6F5

5n[N(51Me3)212

NH3(114)

EU

Ln

3 71Cp

50 °C, 48 h

~

Ph

+ 212

Y6[N(51Me3)212(thf)2

HR
- H2, -NH 3

~,,

~

+

8n

(13)

EUR2(NH3)m

(14)

Ln(5Ar)3(PY)3

7HF
50°C, 48h

(15)

L.a12(thf)2

.

Ph

~

~

Ph

(16)

La12(thf)2

Y6

+

CH31

7HF ~ [CH3Y61 ]
.300C~

(17)

7he c0-c0nden5at10n 0f e1ectr0n-6eam vap0r12ed 1anthan1de meta15 w1th
neutra1 (heter0-)ar0mat1c m01ecu1e5 0r 2,2-d1methy1pr0py11dyneph05ph1ne
(t8uCP) aff0rd5 deep1y c010red c0mp0und5.7he 1501ated, cry5ta111ne 5andw1ch


Pr1nc1p1e51n0r9an01anthan1deChem15try

15
.~p

..~t8U

P(~Q~
~,.~,1~1,p

..,.t8U

t 8 u ~

t 8 u ~ P

8u

t8u

8u

.t8u

...-t8U
R~P

] 1

t8u

t8u, ~
,,t8u
p~---~.~p

~c 1
/

t8u

t8u

p~ p ~ . . . ~ t8u

t8u

t8u
F19.5. Arene c0mp1exe50f 10w-va1ent1anthan1de e1ement506ta1ned 6y c0-c0nden5at10n
meth0d5

and tr1p1e-decker c0mp1exe5 are therma11y 5ta61e and exh161t 1anthan1de center5
1n the f0rma1 0x1dat10n 5tate5 Ln(0), 5c(1) and 5c(11) (F19. 5) [95].

3.3
Meta10r9an1cRea9ent5
Acc0rd1n9 t0 5cheme 2,1n0r9an1c5 and p5eud0-1n0r9an1c5 are 5u1ta61e precur50r5 f0r a var1ety 0f 0r9an0meta111c c0mp0und5. H0wever, 1nc0rp0rat10n 0f a1ka11meta15a1t5 and ate c0mp1ex f0rmat10n acc0rd1n9 t0 the trad1t10na1metathe515
r0ute are 0ften 065erved. A5 th1515 u5ua11yan unde51red feature and part1cu1ar1y
pr0n0unced 1n rare earth a1ky1 [96], am1de [97] and a1k0x1de chem15try [98]
(5ect. 5.1), new 5ynthet1c r0ute5 1nv01v1n9we11-def1nedmeta10r9an1c precur50r
c0mp0und5 have 6een deve10ped. C0n51der1n9 the (p5eud0-)0r9an0meta111c
51de 0f 5cheme 2 (r19ht), u5ua11y a11 0f the c0mp0und5 0n th15 51de are a61e t0

pr0duce the ne19h60r1n9 5y5tem5 0n the1r 1eft 6y 8r0n5ted ac1d/6a5e-type react10n5, e.9. a1ky15m19ht read11yreact w1th am1ne5, cyc10pentad1ene5 and a1c0h015
t0 y1e1d am1de, a1k0x1de and cyc10pentad1eny1 c0mp1exe5, re5pect1ve1y.Lanthan1de 511y1am1deand ary10x1de m01et1e5 4ua11fya5 ver5at11e5ynthet1c precur50r5
due t0 h19h-y1e1dand h19h-pur1ty 5ynthet1c pr0cedure5.7he preparat10n 0f the1r
h0m01ept1c der1vat1ve515 5h0wn 1n E45. (18) and (19) [99,100].
LnC13 +

3 K[N(51Me3)2]

LnC13 + 3 K0Ar

1.7HF, -3 KC1,20 °C
2. 5u611mat10n
1.7HF, -3 KC1,70 °C
2. 5u611mat10n

~"

0Ar = 006H318u2-2,6; 006H2t8u2-2,6-Me-4

J,.

Ln[N(51Me3)213
pure
Ln(0Ar)3
pure

(18)

(19)

7he 511y1am1deR0ute
Rare earth 511y1am1dec0mp1exe5 have n0t 0n1y attracted en0rm0u5 attent10n f0r
the 5ynthe515 0f precata1y5t 5y5tem5 6ut a150 f0r the 1501at10n 0f we11-def1ned


Re1nerAnwander

16

Ln - C---CR
Ln - C p
Ln - 5 n R 3
Ln-

N(51Me3)2

+

Ln
Ln
Ln
Ln
Ln
Ln
Ln

HL

-

NR2
PR 2
0R
5R
5eR
7eR
C1

+

HN(51Me3)2

5cheme 5 . 7 h e 511y1am1de r0ute

c0mp0und5 0f re1evance 1n precur50r chem15try 0f ceram1c and e1ectr0n1c mater1a15, 5uch a5 pure a1k0x1de5 [101,102]. 7he 9enera1 red0x 5ta6111ty 0f the 1anthan1de cat10n5 and the chem1ca1r06u5tne55 0f the 511y1am1de119and ha5 re5u1ted 1n numer0u5119and exchan9e react10n5 w1th 5u65trate m01ecu1e50f 1ncrea5ed
8r0n5ted ac1d1ty5uch a5 a1c0h015,phen015, cyc10pentad1eny15,acety1ene5, ph05phane5, and th1015 a5 115ted1n 5cheme 5 [ 103-113].
Fact0r5 wh1ch 0ften make the 511y1am1der0ute 5uper10r t0 trad1t10na15a1t metathe515 react10n5 are (1) the react10n 1n n0n-c00rd1nat1n9 501vent5 due t0 the
h19h 501u6111ty0f the m0n0mer1c meta1 am1de5, (11)m11dreact10n c0nd1t10n5 0ften at am61ent temperature, (111)av01dance 0f ha11de c0ntam1nat10n, (1v) ea5e 0f
pr0duct pur1f1cat10n [rem0va1 0f the re1ea5ed am1ne a10n9 w1th the 501vent under vacuum (6p HN(51Me3)2:125 C)], (v) 6a5e-free pr0duct5 (c00rd1nat10n 0f
the 5ter1ca11ydemand1n9, re1ea5ed am1ne 15d15fav0red), (v1) 4uant1tat1ve y1e1d ,
and (v11)the fac11eava11a6111ty0f m0n0- and heter061meta111cam1de precur50r5.
A 11m1t1n9fact0r 0f th15 5pec1f1cam1ne e11m1nat10nr0ute 15 the 5ter1c 6u1k 0f
the [N(51Me3)2] 119and,06v10u51n 1nc0mp1ete exchan9e react10n5 w1th 51m11ar1y
6u1ky 119and5 5uch a5 Cp*H [104], H0Ct8u 3 [114] 0r h19h1y 5u65t1tuted ph05phane5 [108]. 1n 0rder t0 6etter c0pe w1th 5uch 5ter1ca11y5uppre55ed 119and exchan9e react10n5 the a1ternat1ve 511y1am1deprecur50r Ln[N(51HMe2)213(thf)2,
wh1ch can 6e prepared 1n h19h y1e1df0r a11 0f the 1anthan1de e1ement5 [yttr1um:
E4. (20)] [115], ha5 6een 1ntr0duced.
YC13(thf)3.5

+

2 . 9 L1N(51HMe2)2

n-hexane, - L1C1
1t, 16h

~

Y[N(51HMe2)213(thf)2

(20)

7he 615(d1methy1511y1am1de)119and [N(51HMe2)2] n0t 0n1y fav0r5 the attack
0f pr0t1c rea9ent5 6y decrea5ed 5ter1c 6u1k,6ut am1ne e11m1nat10n15a150 affected
6y a decrea5ed 511y1am1de6a51c1ty,ea51erw0rkup pr0cedure5 (6p HN(51HMe2)2:
93-99 C) and the pre5ence 0f an exce11ent 5pectr05c0p1c pr06e (51-H).
Acc0rd1n9 t0 th15 extended511y1am1der0ute ,cata1yt1ca11yre1evant c0mp1exe5 w1th
5a1en [116], (5u65t1tuted) 11nked-1ndeny1 [117], and 5u1f0nam1de 119and5 [ 118]
have 6een 5ynthe512ed (F19. 6). 5uch c0ntr011ed 119and a550c1at10n5, wh1ch are


Pr1nc1p1e51n0r9an01anthan1deChem15try

17

t8u

1Pr.

8u

N 0
[ ~
:~L//N(51HMe2)2
Me251~~Ln~N(51HMe2) 2
k~,VJ~,..N4 ~ t h f

%

11~r7--x5,.
/ ~C)
N
~
~Ln~/N(51HMe2)2
L,V,3,,,,. / 11,~thf

t8u

1Pr

• ~0

1pr/L..~/ ~1Pr
F19. 6. C2-5ymmetr1crare earth c0mp1exe5acc0rd1n9 t0 the extended 511y1am1der0ute

+ 3 L1CH251Me3,
n-hexane,-3L1C1
5c013(thf)3
0°C, 1h

8c(CH281Me3)3(thf)2

+ H2L,
]- 251Me4~

NMe2
Me251• 5C
J rt, 30m1n~
•N / ~0H28JM03

1

t8u
5cheme 6.1n 51tu9enerat10n 0f a react1ve a1ky1precur50r

pr0p05ed a5 pr0ceed1n9 v1a 7HF d1550c1at10n, are n0t 06ta1ned w1th the
Ln[N(51Me3)2]3 5y5tem.
7he app11cat10n 0f the m0re 6a51c Ln(N1Pr2)3(thf ) a5 a meta10r9an1c precur50r c0mp0und 15 c0ntr0ver51a1 [119] 6ecau5e 1t5 ava11a6111ty15 hampered 6y ate
c0mp1exat10n [5ect. 5.1, L1Ln(N1Pr2)4] and enhanced therma1 1n5ta6111ty (dec0mp051t10n at 100 C/10 4 70rr) [120]. An eff1c1ent a1kane e11m1nat10n react10n
ut11121n9 the 1n 51tu f0rmed a1ky1 5pec1e5 Ln(CH251Me3)(thf)2 pr0duced c0mp1exe5 w1th 11nked am1d0 cyc10pentad1eny1 119and5 (5cheme 6) [121]. H0wever,
the therma11n5ta6111ty 0f Ln(CH251Me3)(thf)2 and ate c0mp1ex f0rmat10n 5eem
t0 6e 11m1t1n9fact0r5 [122].
7he 511y1am1de r0ute can a150 6e app11ed t0 1anthan1de(11) chem15try
(5cheme 7). A1th0u9h the we11-character12ed c0mp1exe5 Ln[N(51Me3)212(thf)2
exh161t enhanced 5ter1c f1ex16111ty[123], the 5c0pe 0f exchan9e react10n5 15 n0w
11m1ted 6y the reduct1ve pr0pert1e5 0f 5m(11). F0r examp1e, 5m(11) am1de5 tend
t0 9et 0x1d12ed 6y en0112a61e a1c0h015 [124]. H0wever, ary10x1de5 0f type
5m(0Ar)2(thf)x have 6een 1501ated and ate c0mp1exat10n a5 ev1denced 1n
[K5m(0C6H3-2,6-t8u2)3(thf)] n pr0ve5 t0 6e a 5ta611121n9fact0r [125].Acc0rd1n9
t0 th15 1atter appr0ach, m1xed meta111c c0mp1exe5 can 6e 06ta1ned 6y retent10n
0f the 0r191na1 meta1119and c0mp051t10n. Part1a11y exchan9ed heter01ept1c c0mp1exe5 5uch a5 {K5mCp*2[N(51Me3)2](thf)2}n are ava11a61e due t0 5ter1c re5tr1ct10n5 [126]. Eu(11) and Y6(11) 511y1am1de5are acce55161et0 a110f the exchan9e react10n5 115ted1n 5cheme 5 [127].

18

Re1nerAnwander
+ 3n H0Ar,
n-5exane

[K5 m(0C6H2t8U2-2,6- Me-4)3]n

- 3n HN(51Me3)2
{K8m[N(81Me3)213}n --

F
-.

/

•

(thf)2

K

/

•

t01uene/7HF
2n HN(51Me3)2~- H0p*

L

N(81Me3)2

1•

(thf)24
K...

N(81Me3)2

5cheme 7. Heter061meta111c8m(11)c0mp1exe5acc0rd1n9t0 the 511y1am1der0ute

J n12

0r9an0meta111c der1vat1ve5 0f eur0p1um and ytter61um are a150 read11y
f0rmed v1a react10n51n 114u1damm0n1a. 7he act1ve 5pec1e51nthe5e react10n5 are
the hexaamm1ne c0mp1exe5 and the 0n1y 6ypr0duct5 are hydr09en and amm0n1a [E4. (21a-c)]. Acc0rd1n9 t0 th15 pr0cedure, the c0mp0und5 EuCp2 [128],Y6Cp*2(NH3)x [91], Ln(C07) (Ln=Eu,Y6) [129, 130], Eu(C---CMe)2 [131], Eu(Ph2) 2
[132], Y6(0C6H2t8u2-2,6-Me-4)2(thf) 3 [90c], LnX2 (Ln=Eu, Y6; X=C1, 8r, 1)
[133] and deca60rate5, e.9. (NH3)xY6(810H14) [134] have 6een 5ynthe512ed.
Ln

+ m NH3(114)

~-

Ln2+(NH3)6x2e-(NH3)n

(21a)

2 HR + 2 e-(NH3)n

~

2 R-

(216)

Ln2+(NH3)6

=

LnR2

+

2 R-

+
+

H2

+

n NH3

6 NH3

(21c)

6enerat10n 0f Lanthan1de A1ky180nd5
Lanthan1de a1ky1 c0mp0und5 are 1mp0rtant a1ky1tran5fer rea9ent5 and 1n1t1ate
a var1ety 0f cata1yt1creact10n5.7he tran5f0rmat10n 0f 1anthan1de a1k0x1de60nd5
t0 1anthan1de a1ky160nd5 5eem5 t0 6e an attract1ve a1ternat1ve t0 the a1ky1at10n
0f 1anthan1de ha11de5 w1th a1ka11meta1 a1ky1c0mp0und5. F0r examp1e, the ary10x1de r0ute aff0rd5 h0m01ept1c 1anthan1de a1ky151n 900d y1e1d [E4. (22)] [135].
Ln(0C6H2t8u2-2,6)3

+ 3 L1CH(51Me3)2

n-hexane, - 3 L10Ar
rt, 30m1n

~"

Ln[CH(51Me3)213

(22)

Due t0 the h19h 501u6111ty0f the 5tart1n9 and the re5u1t1n9rare earth c0mp1exe5, the react10n can 6e c0nducted 1n n0np01ar 501vent5 fr0m wh1ch the 1n501u61e
a1ka11 ary10x1de5 can ea511y6e 5eparated. H0wever, th15 type 0f k1net1ca11yc0ntr011ed metathe515 react10n 15 very 5en51t1vet0ward5 the react10n c0nd1t10n5 1nc1ud1n9 the type 0f a1k0x1de (ary10x1de) 119and, type 0f meta1, num6er and type
0f c0-119and5, 5ta6111ty and 501u6111ty 0f the e11m1nated a1ka11 meta1 a1k0x1de
(ary10x1de), 501vent, temperature, etc. A5 a re5u1t, 1nc0mp1ete 119and exchan9e,
exchan9e 0f the c0-119and, ate c0mp1exat10n, exchan9e e4u1116r1a and 119and re-