Group 13 Chemistry

Chapter 2

Pentamethylcyclopentadienyl Complexes of the Monovalent Group 13 Elements L . O . Schebaum and P. Jutzi*

Downloaded by TUFTS UNIV on November 18, 2016 | http://pubs.acs.org Publication Date: June 3, 2002 | doi: 10.1021/bk-2002-0822.ch002

Faculty of Chemistry, University of Bielefeld, 33615 Bielefeld, Germany

The group 13 elements can be stabilized in their formal +1 oxidation state by means of the π-bonded pentamethylcyclopentadienyl (Me C , Cp*) ligand. Synthesis, structure, bonding, and chemistry of Cp*El (El = B, A l , Ga, In, Tl) compounds are described. The chemistry is dominated by I) homolytic and heterolytic Cp*-El bond cleavage, II) the donor function of the El centered lone-pair, and III) by a carbene -likebonding situation. 5

5

Introduction The cyclopentadienyl (Cp) chemistry of the Group 13 elements has experienced great progress during the last decade. A prerequisite for this development was the knowledge of the fundamental properties of Cp substituents. Their versatile application is based on the rather flexible bonding mode ( η ^ η ; ionic-covalent), on the steric demand of ring-substituted species (kinetic stabilization), and on the leaving group character (homolytic and heterolytic El-C(Cp) bond cleavage) {1,2). A fascinating aspect of Group 13 element Cp chemistry concerns the possiblity to stabilize the elements boron, aluminium and gallium in their +1 oxidation state with the help of the π-bonded pentamethylcyclopentadienyl (Cp*) ligand. In this article, these compounds together with their indium and thallium analogues are described with respect to their synthesis, structure, bonding and reactivity and with a special emphasis on the effects excerted by the Cp* ligand. 5

16

© 2002 American Chemical Society

Shapiro and Atwood; Group 13 Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 2002.

17


Synthesis Synthetic routes to Cp*El compounds with EI = B, AI, Ga, In, Tl are described in Scheme 1. The synthesis of Cp*Tl (3,4) and Cp*In (5,6) was performed by metathesis reactions starting from stable inorganic precursors and following strategies already known for the preparation of other cyclopentadienyl thallium and indium species. Both compounds are extremely sensitive to decomposition in the presence of air, moisture, and even light. Cp*Tl is soluble in ethereal and aromatic solvents and even in hydrocarbons. Cp*In has limited thermal stability in ethereal and aromatic solvents, in which decomposition to elemental In is observed. It dissolves in cyclohexane without decomposition.

Me C BCl 5

5

2

Me C SiMe 5

5

3

+

K [Fe(CO) ]

+

B C1

x-Et 0 +

4A1C1

2

4 Me C AlCl 5

5

2

+

GaCl-xEt 0

+

Me C GaI

+

2

5

5

2

2

2 Mg(C Me ) 5

5

8K LiC Me 5

2

KC,Me

LiC Me

+

2 NaC Me 5

+

2 KC1

+

Me SiCl 3

—

(Me C Al)

5

5

5

4

5

Me C Ga

5

5

5

5

—»

+

4

+

LiCl

8KC1 +

xEt 0 2

+

Me C Ga Me C In

+ +

LiCl

2 Me C Tl

+

Na S0

5

5

5

2

2

Me C Ga 5

5

5

4

3

(Me C Al) + 2 MgCl + 4xEt 0

5

+

5

5

-*»

2K

+ 4

5

5

InCl 2

5

Me C B-*BCl

4

"Gal"

T1 S0

Me C B-Fe(CO)

4

2

5

5

5

2KI KI

2

4

Scheme 1. Synthetic routes to Cp*El compounds [Cp* = Me$Cy, El = B, Al, Ga, In, Tl; in case of boron only adducts with Lewis acids have been isolated]. A real breakthrough in this field was the first preparation of Cp*Al in the group of Schnôckel. This compound was obtained as a tetrameric species by the reaction of a metastable A1(I)C1 solution in toluene/ether with Cp* Mg as Cp* transfer agent (7). Later on, the compound could be prepared by a more convenient route, namely by reduction of the trivalent aluminum compound C p * A l C l with potassium metal (8). (Cp*Al) is only a little air- and moisturesensitive and is sparingly soluble in aromatic solvents. The compound decomposes at temperatures above 100°C. Interestingly, longer thermal treatment in boiling toluene led to the formation of the C p * A l cation (9). Simlary, the gallium compound Cp*Ga was first prepared in the group of Schnôckel by a metathesis reaction using a metastable Ga(I)Cl solution (70). More convenient synthetic routes were described some years later. The trivalent gallium compound Cp*GaI was reduced with potassium (//), and the easy to 2

2

4

+

2

2


18

prepare gallium compound „GaI" (72) reacted with Cp*K to give Cp*Ga in good yields (73). The compound is very sensitive to air and moisture and is soluble in all aprotic and halogen free organic solvents. No decomposition was observed under irradiation or in boiling toluene. Purification can be performed by distillation in vacuo without any decomposition. So far it has not been possible to synthesize the boron compound of composition (Cp*B) , but there is access to stable adducts of monomeric Cp*B with Lewis aids. Thus, the Fe(CO) stabilized complex Cp*B-Fe(CO) was obtained by a metathesis reaction of C p * B C l with the ferrate complex K [Fe(CO) ] (14), and the BC1 stabilized complex C p * B - B C l was formed in the reaction of Cp*SiMe with B C1 under elimination of Me SiCl (75). These compounds will be discussed in context with comparable adducts of the other Cp*El species. n

4

4

2

2

4

3

3


3

2

4

3

Structure and Bonding Scheme 2 specifies the structures of the Cp*El compounds (El = A l , Ga, In, Tl) in the solid state, in solution, and in the gas phase. In the gas phase, all compounds exist as monomers possessing a C -halfsandwich structure {16,17,5,18). As an example, the structure of Cp*Ga determined by GED (77) is presented in Figure 1. Experimental parameters for these compounds are collected in Table I together with calculated parameters for Cp*B (79). Sv

(Cp*Al)

4

^

(s) (Cp*El)

6

^

(s) (Cp*Tl) (s)

4 Cp*Al (sol)

(g) 6Cp*El

El = Ga,In

(sol)(g) n

^

η Cp*Tl (sol) (g)

Scheme 2. Solid state (s), solution (sol), and gas phase (g) structures of Cp*El compounds. In the solid state, oligomeric or polymeric structures are observed for the Cp*El compounds. A tetrameric structure with a tetrahedral A I core and with 4


19


Figure 1. Drawing of the gas phase structure of Cp*Ga.

Table I: Calculated (El = B) and experimental (El = Al, Ga, In, Tl) parameters for η -Cp*El compounds in the gas phase. a)

5

\(16)

Ga '7)

1.925

2.388(7)

2.405(4)

2.592(4)

2.663(5)

C-C (A)

1.434

1.414(5)

1.420(3)

1.432(4)

1.422(6)

C-C(Me) (A)

1.504

1.529(6)

1.522(3)

1.505(5)

1.520(7)

+ 5.46

+ 5(2)

+0.2(3)

-4.1(3)

-6.4(6)

-

2.063(9)

2.081(5)

2.288(4)

2.372(5)

Cp*El

B

El-C (A)

Ζ C C / C - C (°)

b)

5

CPcentroid'El

A

(

a) measured by GED b) defined as positive when the methyl groups are bent towards the metal atom

5

A l - A l distances of 2.77 A is found for (Cp*Al) ; each A l atom is rj -bonded to a terminal Cp* ring in such a manner that the ring plane is parallel to the opposite A l face of the tetrahedron (7). According to quantum chemical calculations (20,21), the A l cluster with four cluster-binding electron pairs is held together by four 2e3c bonds on the four faces of the tetrahedron. The relative weakness of the A l - A l bonding is inferred from the A l - A l distance, which is considerably longer than a typical single bond distance (2.66 A), and is caused by π-backbonding from the Cp* ligand to the A l center. In contrast to the tetrameric structure of (Cp*Al) , hexameric aggregates with distorted octahedral E l cores are found in the solid state structures of the isomorphous (Cp*Ga) (22) and (Cp*ln) (5,6). Interestingly, the Cp*El vectors do not point towards the center of the octahedron and El-El distances are nearly identical and rather long (-4.10 4

3

4

4

6

6

6


20

Â). It was proposed that both clusters are held together by van der Waals interactions between the Cp* ligands (21) and by only rather weak donoracceptor interactions between the metals (23,24). Finally, Cp*Tl crystallizes in a polymeric chain-like structure with alternating Tl atoms and μ η bonded Cp* rings (13). This type of structure is found also for some alkali metal Cp* compounds (2) and is indicative of predominantly ionic bonding interactions. Representations of the solid state structures of (Cp*Al) , (Cp*El) (El = Ga, In), and (Cp*Tl) are presented in Figure 2. 5

2

4

6


x

Figure 2. Drawings of the structures of (€ρ*ΑΙ)φ (Cp*El)$ (El = Ga, In), and of (Cp*Tl) . (a: Reproduction from reference 7. Copyright 1991; b: Repro duction from reference 22. Copyright 1997) x

In solution, facile degradation to monomeric structures of the half-sandwich type takes place for the Cp* compounds of gallium, indium, and thallium (see Scheme 2). On the other hand, the aluminum compound still exists as a tetramer, at least at room temperature. At higher temperatures, dissociation into monomeric half-sandwich species is observed. Quite different chemical shifts in A1 N M R spectroscopy are found for (Cp*AI) (δ = -80.7 ppm) and for Cp*Al (δ = -149 ppm) (16). The energy for the tetramerisation of Cp*Al was calculated to be-150 (± 20)kJmol- . Cp*El (El = B, A l , Ga, In) compounds have been examined by DFT calculations to establish their ground states and their frontier orbitals (19). Each species possesses a singlet ground state, and the singlet-triplet energy gap is rather large (~ 60 kcal mol" ). In general, there is excellent agreement between 27

4

1

1



21

the DFT calculations and the gas phase electron diffraction data obtained for Cp*Al, Cp*Ga and Cp*In. As expected, the El-C and Cp(centroid)-El distances increase with the atomic number of El, and the Al-C and Ga-C bond distances are almost identical. With the exception of Cp*Ga, the methyl groups are bent out of the plane of the Cp* ring; they are oriented toward the group 13 element in the case of Cp*B and Cp*Al and away from the element in the case of Cp*In and Cp*Tl. These orientations are consistent with the view that covalent interactions dominate and determine the final structures (25). The relative amount of electron transfer between the Cp* ligand and the group 13 element (viewing Cp*" as anion and ΕΓ as cation) can be estimated from the N B O charges on the elements (19), which are collected in Table II. The positive charge on boron turns out to be much lower than that of any other group 13 element.

Table II. NBO charge (q) of EI in Cp*El compounds. El

Β

Al

Ga

In

q

+ 0.07726

+ 0.61591

+ 0.5844

+ 0.6599

2e, le,

2a, le,

0 0

2 e , L U M O : El = A l , Ga, I l e L U M O : E1 = B 2

2a, H O M O : E1 = B , A l l e , H O M O : E l = G a , In

la,

Figure 3. Qualitative MO scheme for rp-Cp*El compounds (El = B, Al, Ga, In). A qualitative M O description for the Cp*El compounds (El = B, A l , Ga, In) is presented in Figure 3. According to the DFT calculations (19), the HOMO of


22

Cp*B and C p * A l exhibits a distinctly lone pair (σ-type) character, whereas the H O M O of Cp*Ga and Cp*In is degenerate and corresponds to π-bonding between the Cp* fragment and the group 13 element. The magnitude of τιoverlap is reflected in the energy gap of the respective orbitals (le, and 2e,). As a result, the symmetry of the L U M O for Cp*B is different from that for the other Cp*El compounds. In Cp*B, the stronger π-interaction renders the antibonding 2e, orbitals higher in energy than the l e orbitals which have no contribution from E l and are localized on the Cp* ligand. For the heavier group 13 elements, the relatively weaker π-overlap leaves the 2e, orbitals as the LUMOs. Downloaded by TUFTS UNIV on November 18, 2016 | http://pubs.acs.org Publication Date: June 3, 2002 | doi: 10.1021/bk-2002-0822.ch002

2

Reaction Chemistry The chemistry of the pentamethylcyclopentadienyl complexes of the monovalent group 13 elements is dominated by I) homolytic and heterolytic Cp*-El bond cleavage, II) the donor function of the El centered lone-pair, and III) the carbene-like bonding situation at the El center On the basis of these phenomena, the reactions performed with Cp*El compounds will be classified and briefly described.

Homolytic and Heterolytic Cp*-El Bond Cleavage It is well known in the cyclopentadienyl chemistry of the p-block elements that the Cp-El bond can be split thermally, photo-chemically, or by attack of nucleophiles, electrophiles, oxidizing agents and reducing agents (/). In the chemistry of the Cp*El compounds, homolytic and heterolytic bond cleavage as depicted in Scheme 3 have been used in synthetic procedures.

Cp*El

£ hv

Cp*El

+

e-

Cp*El

+

MX

-

El

+

Cp*

^

El

+

Cp*-

Cp*M

+

E1X

Scheme 3. Homolytic and heterolytic Cp*-El bond cleavage.


23

The deposition of indium metal in a low-temperature M O C V D process was performed with the help of Cp*In (25); similarity, the deposition of elemental gallium from the precursor Cp*Ga was reported to occur, but only at higher temperatures (~ 600°C) (77). The formation of elemental indium and thallium was observed during irradiation of the corresponding Cp*El compounds in solution and in the solid state (3,4,5,6). Cp*Tl is known to be a synthetically useful reagent for transferring Cp* ligands in a nucleophilic substitution process, for example to d-block element centers (26). Nucleophilic substitution and reduction processes have been observed in the reaction of Cp*In with supersilyl sodium ( Bu SiNa), whereby the novel cluster hexasupersilyl octaindane [( Βυ 8ί) Ιη ] was formed (27). l

3

ι


3

6

8

Cp*EI Compounds as Donors in Donor-Acceptor Complexes The exposed lone-pair at the group 13 element in Cp*El compounds allows the formation of donor-acceptor complexes of the type Cp*El-Acceptor and several of such complexes with trivalent group 13-element compounds and with transition-metal complex fragments as acceptors have already been described; they are collected in Table III and IV. Figure 4 shows the molecular structures of C p * B - B C l and of Cp*Ga-B(C F ) , and Figure 5 shows the molecular structures of Cp*Ga-Cr(CO) , (Cp*Ga) Ni, (CO) Fe^ -Cp*Ga) Fe(CO) , and (Cp*Ga)Pt^ -Cp*Ga) Pt(Cp*Ga). Only a couple of these complexes have been synthesized by routes other than direct combination of Cp*El and the corresponding Lewis-acidic component. Thus, the compound Cp*Al-Fe(CO) was prepared by reaction of C p * A l C l with K [Fe(CO) ] (52); the synthesis of the Cp*B complex has already been described (see Synthesis). 3

6

5

5

2

3

4

3

2

3

3

3

4

2

2

4

Table III. Donor-acceptor complexes with group 13-element acceptors. Cp*B—BC1 (28)

Cp*B—B(SiCl )Cl (28)

C p * A l ~ B ( C F ) (29)

C p * A l - A l ( C F ) (30)

C p * G a - B ( C F ) (31)

Cp*Ga-^Ga Bu (31)

Cp*Ga-~Ga(Cp*)Cl (31)

Cp*Ga—Ga(Cp*)I (31)

3

3

6

6

5

3

5

3

2

6

2

5

3

t

3

2


24 Table IV. Transition-metal complexes with Cp*El ligands. Cp*B-Fe(CO) (14) 4

Cp*Al-Cr(CO) (33)

(CpNi) ^ -AlCp*) (35)

(CO) Co ^ -AlCp*) (36)

Cp*Ga-Fe(CO) (37)

Cp*Ga-Cr(CO) (37)

cis(Cp*Ga) Mo(CO) (38)

cis(Cp*Ga) Pt(dcpe)(34)

(Cp*Ga) Ni(38)

(CO) Co ^ -GaCp*) (37)

(CO) Fe (M -GaCp*) (37)

(CO) Ni^ -Gaep*) (37)

(Cp*Ga) Pt ^ -GaCp*) (39)

(Cp*Ga) Fe(Cp*)GaCl THF(40)

4

2

2

2

4

2

6

2

2


cis(Cp*Al) Pt(dcpe)(34)

Cp*AI-Fe(CO) (32)

2

2

3

2

3

5

6

2

2

2

5

4

6

2

x

2

2

6

2

2

4

2

4

2

Cp*ln-Cr(CO) (41) 5

Cp* = M e C 5

5

dcpe = bis(dicyclohexylphosphino) ethane

Figure 4. Drawings of the molecular structure of Cp*BB&3 and of Cp*GaB(CfiF5)3. (a: Reproduction from reference 28. Copyright 2000; b: Reproduction from reference 31. Copyright 2001)

Figure 5. Drawings of the molecular structures of Cp*Ga-Cr(CO) 5, (Cp*Ga)4Ni, (CO)3Fefa2-Cp*Ga)3Fe(CO)3 and (Cp*Ga)Ptfa2-Cp*Ga)3Pt(Cp*Ga). (a: Reproduction from reference 37. Copyright 1998; b: Reproduction from reference 38. Copyright 1999; c: Reproduction from reference 39. Copyright 2000) f



25

Structure and bonding in these complexes with special emphasis on the donor-acceptor bond have been discussed in detail on the basis of experimental findings and theoretical calculations (32,33,34,36,39). The results can be summarized as follows: I) The non-directional s-orbital character of the lonepair on Cp*El allows unusual geometries with Cp*(centroid)-El-acceptor arrangements deviating from linearity; II) The positive charge on the group 13 element is reduced by a stronger π-bond within the Cp*El unit, as concluded from the observed shorter Cp*(centroid)-El distance; III) In transition-metal complexes, the Cp*El ligand is a strong σ-donor and a weak π-acceptor; the Cp*(centroid)-El distance reflects the donor capability of the Cp*EI unit and can adjust to the electronic requirements on the complexed metal or metalloid (see Table V); IV) The Cp*El ligands are found in terminal (μ,) and in bridging (μ , μ ) positions. In Table V , the Cp*(centroid)-Ga distances of some representative Cp*Ga donor-acceptor complexes are presented. 2

3

Table V. Cp*(centroid)-Ga distances (d [A]) in donor-acceptor complexes. Cp*Ga-B(C F ) 6

5

Cp*Ga-Fe(CO)

3

1.906(5) cis(Cp*Ga) Mo(CO) 2

4

Cp*Ga-Cr(CO)

4

1.863(4)

1.910(4)

(Cp*Ga) Ni

(Cp*Ga) Pt ^ -GaCp*)

2.003(4)

1.969(4)/2.013(4)

2

2

4

1.930(6)

5

2

3

A surprising result was observed in the reaction of Cp*In with the Lewisacid B(C F ) and with H O B ( C F ) in toluene solution, whereby the compound [(η -€ Η )Ιη(μ-η -€ρ*)Ιη(η -€ Η )] [(Ρ € ) ΒΟ(Η)Β(ε Ρ ) ]- was obtained. The central core of the triple-decker cation features an r| -bonded In atom on each face the μ-Cp* group (42). 6

5

3

2

5

5

7

8

6

5

3

6

+

7

8

5

6

3

6

5

3

5

Oxidative Addition, Cycloaddition, and Insertion Reactions A carbene-like bonding situation in Cp*El compounds is the necessary prerequisite for the oxidative addition, cycloaddition and insertion reactions, which have been observed mainly for the aluminium and gallium compounds. Such a constellation is created by haptotropic shifts of the r| -Cp* ligand. Oxidative addition reactions are collected in Scheme 4, cycloaddition reactions in Scheme 5, and insertions reactions in Scheme 6. 5


26

Cp*EI

+

Χ

·•

Cp*El=X

η

(Cp*EI-X)„

X = Ο, N R (Cp*Al) +

4R SiN

3

(Cp*Al) +

4MesN

3

4

4

3

2 (Cp*AlNSiR ) 3

— 2

+

2

4N

(43)

2

[€ρ*Α1{μ-ΝΗ(€ Η -4,6-Μϋ -2-€Η )}] 6

2

2

2

+

2

4N

(44)

2

I

1 (Cp*Al) + 4 M e S i N —(Me Si) NAl(Cp*)N-Al(Cp*)-N(AlCp* )-AlN(SiMe ) 4

3


2 Cp*Ga +

3

2 XyIN

3

2 Cp*Ga + 4 M e S i N

3

3

Cp*Ga

+

N 0

3

2

2

—(Cp*GaNXyl)

2N

3

2

n

2

+

3

N

2

(44) (45)

2

[Cp*{N(SiMe ) }Ga^ -N )] — ( C p * G a O )

2

+

2

3

2

+

2N

(45)

2

η = 6, >6

2

(46)

l

Mes = 2,4,6-Trimethylphenyl; X y l = 2,6-Dimethylphenyl; R = 'Pr, B u , Ph

Scheme 4. Oxidative Addition.

Cp*El

+

RN

RN

NR

NR Ga Cp*

ι

1

5

(Cp*Al) + 4 R N = C H - C H = N R — r | - C p * A l N ( R ) - C H = C H - N R 4

(47)

R = 2,4,6-Trimethylphenyl 1 Cp*Ga

1

+4 R N = C H - C H = N R — • r|'-Cp*GaN(R)-CH=CH-NR

(48)

R = 2,6-Diisopropylphenyl, 2,6-Diethylphenyl Cp*El

+ 2 RN=CH-CH=NR — •

El = A l , Ga R =

R N - C H = C H - ( R ) N G a N ( R ) - C H C H - N R + C p * (48)

x

Bu Scheme 5. Cycloaddition.


27

X

+

Cp*El

1

Cp*El^

X(Y)


1.5(Cp*Al)

4

+

p

X(Y)

4

4

+

4 0BuP)

(Cp*Al)

4

+

CBuAs)

(Cp*Al)

4

+

CBuSb)

(Cp*Al)

4

+

2A1 I

6

+

A1C1

3

+

Ph SiF

4

(Cp*Al)

4

(49)

4 [Cp*Al(PBu)3]

(50)

As (AlCp*)

(51)

4

(Cp*Al)

0.75 ( C p * A l )

[P (Cp*Al) ]

2

2

—

3

4

6

2

Sb (AlCp*)

4

2

—^

C * A1 I P

3

Π

Cp* Al

—

5

+

3

(52)

3

(53)

6

Cp*AlCl

2

[(Cp*AlF) SiPh ]

2

2

2

Ί 3

" +

2Al

(9) (52)

2

Cp*Ga

+ Cp*(CO) FeCl

Cp*(CO) FeGa(Cp*)Cl

(40)

Cp*Ga

+ Cp*(CO) RuBr —

Cp*(CO) RuGa(Cp*)Br

(13)

Cp*Ga

+ Cp(CO) MoCl

Cp(CO) MoGa(Cp*)Cl

(13)

Cp*Ga

+

Cp*(Cp*Ga) FeGaCl (THF)

(40)

2

2

2

2

3

FeCl (THF) 2

n

—^ »»

3

2

2

Scheme 6. Insertion Reactions.

Several organic azides have been used as sources for nitrene fragments (NR) in oxidative addition reactions with (Cp*Al) or with Cp*Ga (45-47). The experiments clearly show that oxidative addition products of the type Cp*El=NR cannot be stabilized under ordinary conditions. They dimerize to give [2+2] cycloaddition products or they undergo further insertion and rearrangement reactions to give structurally more complicated products. Only oligomeric products have been observed in the reaction of Cp*Ga with N 0 (46). [4+1] Cycloaddition products are obtained in the reaction of (Cp*Al) or of Cp*Ga with differently substituted diazabutadienes (47,48). The leaving-group character of the Cp* substituents is the reason for a further reaction with a second equivalent of t-butylazabutadiene. There exist several examples for the insertion of (Cp*Al) or of Cp*Ga into homo- and heteropolar bonds. Thus insertions into P-P, As-As, A U , Al-Cl, Si-F, Fe-Cl, Ru-Br, and into Mo-Cl bonds have been described, which lead to quite novel types of compounds. Given the leaving group character of the Cp* substituent, the novel compounds prepared by oxidative addition, cycloaddition and insertion 4

9

4

4


28

reactions possess the potential for a further interesting reaction chemistry. This has already been demonstrated in a few cases (44,48).


Acknowledgements We thank Prof. P. Shapiro for improving the English. The experimental work reported from our group was accomplished by G. Reumann and T. Pott. The dedication and expertise of these co-workers is gratefully acknowledged. Funding was kindly provided by the Deutsche Forschungsgemeinschaft, by the Fond der Chemischen Industrie and by the University of Bielefeld.

References 1. 2. 3. 4. 5. 6. 7. 8.

9. 10. 11. 12. 13. 14. 15.

Jutzi, P.; Reumann, G . J. Chem. Soc., Dalton Trans. 2000, 2237. Jutzi, P.; Burford, N. Chem. Rev. 1999, 99, 969. Rupprecht, G. Α.; Mersele, L. W.; Fellmann, J. D.; Schrock, R. R. J. Am. Chem. Soc. 1980, 102, 6236. Werner, H.; Otto, H.; Kraus, H. J. Organomet. Chem. 1986, 315, C57. Beachley Jr. O. T.; Churchill, M . R.; Fettinger, J. C.; Pazik, J. C.; Victoriano, L. J. Am. Chem. Soc. 1986, 108, 346. Beachley, Jr. O. T.; Blom, R.; Churchill, M. R.; Faigri Jr. K.; Fettinger, J. C.; Pazik, J. C.; Victoriano, L . Organometallics 1989, 8, 346. Dohmeier, C.; Robl, C.; Tacke, M . ; Schnöckel, H . Angew. Chem. 1991, 103, 594; Angew. Chem. Int. Ed. Engl. 1991, 30, 564. Schulz, S.; Roesky, H . W.; Koch, H . J.; Sheldrick, G . M.; Stalke, D.; Kuhn, A. Angew. Chem. 1993, 105, 1828; Angew. Chem. Int. Ed. Engl. 1993, 32, 1729. Dohmeier, C.; Schnöckel, H.; Robl, C.; Schneider, U.; Ahlrichs, R. Angew. Chem. 1993, 105, 1714; Angew. Chem. Int. Ed. Engl. 1993, 32, 1655. Loos, D.; Schnöckel, H. J. Organomet. Chem. 1993, 463, 37. Jutzi, P.; Neumann, B.; Reumann, G.; Stammler, H.-G. Organometallics 1998, 17, 1305. Green, M . L . H.; Mountford, P.; Smout, G. J.; Speel, S. R. Polyhedron 1990, 9, 2763. Jutzi, P.; Schebaum, L. O. Unpublished results. Cowley, A . H.; Lomeli, V.; Voigt, A. J. Am. Chem. Soc. 1998, 120, 6401. Greiwe, P.; Bethäuser, Α.; Pritzkow, H.; Kühler, T.; Jutzi, P.; Siebert, W. Eur. J. Inorg. Chem. 2000, 1927.



29

16. Haaland, Α.; Martinsen, K.-G.; Shlykov, S. Α.; Volden, H. V.; Dohmeier, C.; Schnöckel, H . Organometallics 1995, 14, 3116. 17. Haaland, Α.; Martinsen, K.-G.; Volden, H . V . ; Loos, D.; Schnöckel, H . Acta Chem. Scand. 1994, 48, 172. 18. Blom, R.; Werner, H.; Wolf, J. J. Organomet. Chem. 1988, 354, 293. 19. Macdonald, C. L . B.; Cowley, A. H. J. Am. Chem. Soc. 1999, 121, 12113. 20. Ahlrichs, R.; Ehrig, M.; Horn, H. Chem. Phys. Lett. 1991, 183, 227. 21. Dohmeier, C.; Loos, D.; Schnöckel, H . Angew. Chem. 1996, 108, 141; Angew. Chem. Int. Ed. Engl. 1996, 35, 129. 22. Loos, D.; Baum. E.; Ecker, Α.; Schnöckel, H.; Downs, A . J. Angew. Chem. 1997, 109, 894; Angew. Chem. Int. Ed. Engl. 1997, 36, 860. 23. Budzelaar, P. H . M.; Boersma, J. Recl. Trav. Chim. Pays-Bas 1990, 109, 187. 24. Janiak, C.; Hoffmann, R. J. Am. Chem. Soc. 1990, 112, 5924. 25. Jang, H . J. Diss. Abstr. Int. B. 1995, 56(7), 3829. In this context it is interesting to note that the parent compound Cpln has been used for the preparation of monodisperse indium nanoparticles: Soulantica, K . ; Maisonnat, Α.; Fromen, M.C.; Casanove, M.-J.; Lecante, P.; Chaudret, B. Angew. Chem. 2001, 113, 462; Angew. Chem. Int. Ed. Engl. 2001, 40, 448. 26. a) Salzer, Α.; Schmalle, H . ; Stauber, R.; Streiff, S. J. Organomet. Chem. 1991, 408, 403; b) Kölle, U.; Ding, T.-Z.; Keller, H.; Ramakrishna, B. L ; Raabe, E.; Krüger, C.; Raabe, G.; Fleischhauer, J. Chem. Ber. 1990, 123, 227; c) Andell, O.; Goddard, R.; Holle, S.; Jolly, P. W.; Krüger, C.; Tsay, Y . H . Polyhedron 1989, 8, 203; d) Herrmann, W. Α.; Thiel, W. R.; Herdtweck, E. J. Organomet. Chem. 1988, 353, 323; e) Hachgenei, J. W.; Angelici, R. J. J. Organomet. Chem. 1988, 355, 359; f) Kraus, H.-J.; Werner, H.; Krüger, C.Z.Naturforsch. Β 1983, 38B(6), 733. 27. Wiberg, N.; Blank, T.; Purath, Α.; Stöβer, G.; Schnöckel, H. Angew. Chem. 1999, 111, 2745; Angew. Chem. Int. Ed. Engl. 1999, 38, 2563. 28. Greiwe, P.; Bethäuser, Α.; Pritzkow, H . ; Kühler, T.; Jutzi, P.; Siebert, W. Eur. J. Inorg. Chem. 2000, 1927. 29. Gorden, J. D.; Voigt, Α.; Macdonald, C. L. B.; Silverman, J. S.; Cowley, A . H. J. Am. Chem. Soc. 2000, 122, 950. 30. Gordon, J. D.; Macdonald, C. L. B.; Cowley, A . H . Chem. Commun. 2001, 75. 31. Jutzi, P.; Neumann, B.; Reumann, G.; Schebaum, L. O.; Stammler, H.-G. Organometallics 2001, 20, 2854. 32. Weiss, J.; Stetzkamp, D.; Nuber, B.; Fischer, R. Α.; Boehme, C.; Frenking, G. Angew. Chem. 1997, 109, 95; Angew. Chem. Int. Ed. Engl. 1997, 36, 70. 33. Yu, Q.; Purath, Α.; Donchev, Α.; Schnöckel, H. J. Organomet. Chem. 1999, 584, 94.



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34. Weiss, D.; Steinke, T.; Winter, M.; Fischer, R. Α.; Fröhlich, Ν.; Uddin, J.; Frenking, G. Organometallics 2000, 19, 4583. 35. Dohmeier, C.; Krautscheid, H . ; Schnöckel, H . Angew. Chem. 1994, 106, 2570; Angew. Chem. Int. Ed. Engl. 1994, 33, 2482. 36. Üffing, C.; Ecker, Α.; Köppe, R.; Schnöckel, H . Organometallics 1998, 17, 2373. 37. Jutzi, P.; Neumann, B.; Reumann, G.; Stammler, H.-G. Organometallics 1998, 17, 1305. 38. Jutzi, P.; Neumann, B.; Schebaum, L. O.; Stammler, Α.; Stammler, H.-G. Organometallics, 1999, 18, 4462. 39. Weiβ, D.; Winter, M.; Fischer, R. Α.; Yu, C.; Wichmann, K.; Frenking, G. Chem. Commun. 2000, 2495. 40. Jutzi, P.; Neumann, B.; Schebaum, L . O.; Stammler, Α.; Stammler, H.-G. Organometallics 2000, 19, 1445. 41. Jutzi, P.; Neumann, B.; Reumann, G.; Schebaum, L . O.; Stammler, H.-G. Organometallics 1999, 18, 2550. 42. Cowley, A . H.; Macdonald, C. L. B.; Silverman, J. S.; Gordon, J. D.; Voigt, A. Chem. Commun. 2001, 175. 43. Schulz, S.; Voigt, Α.; Roesky, H . W.; Häming, L . ; Herbst-Irmer, R. Organometallics 1996, 15, 5252. 44. Schulz, S.; Häming, L.; Herbst-Irmer, R.; Roesky, H . W.; Sheldrick, G. M . Angew. Chem. 1994, 106, 1052; Angew. Chem. Int. Ed. Engl. 1994, 33, 969. 45. Jutzi, P.; Neumann, B.; Reumann, G.; Stammler, H.-G. Organometallics 1999, 18, 2037. 46. Reumann, G. Ph.D. thesis, University of Bielefeld, Bielefeld, Ge, 1999. 47. Cowley, A . H.; Gorden, J. D. Abernethy, C. D.; Clyburne, J. A . C.; McBurnett, B. G. J. Chem. Soc., Dalton Trans. 1998, 1937. 48. Pott, T.; Jutzi, P.; Neumann, B.; Stammler, H.-G. Organometallics 2001, 20, 1965. 49. Dohmeier, C.; Schnöckel, H.; Robl, C.; Schneider, U.; Ahlrichs, R. Angew. Chem. 1994, 106, 225; Angew. Chem. Int. Ed. Engl. 1994, 33, 199. 50. Üffing, C.; von Hänisch, C., Schnöckel, Η. Ζ. Anorg. Allg. Chem. 2000, 626, 1557. 51. von Hänisch, C. K. F.; Üffing, C.; Junker, Μ. Α.; Ecker, Α.; Kneisel, B. O.; Schnöckel, H. Angew. Chem. 1996, 108, 3003; Angew. Chem. Int. Ed. Engl. 1996, 35, 2875. 52. Schulz, S.; Schoop, T.; Roesky, H . W.; Häming, L.; Steiner, Α.; HerbstIrmer, R. Angew. Chem. 1995, 107, 1015; Angew. Chem. Int. Ed. Engl. 1995, 34, 919. 53. Üffing, C.; Baum, E.; Köppe, R.; Schnöckel, H . Angew. Chem. 1998, 110, 2488; Angew. Chem. Int. Ed. Engl. 1998, 37, 2397.


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