117 4. Summary

4 Summary

This work reports the synthesis and characterisation of novel transition metal compounds

containing low valent zinc and gallium ligands. Over the last years substantial progresses

have been made in the field of coordination chemistry of low valent group 13 elements.[10, 17,

18] Nevertheless, several significant restrictions have been observed in the formation of

homoleptic and heteroleptic GaCp* containing complexes as well as in their applications in

the formation of metal-rich molecules at the borderline to intermetallics. Neither coordination

numbers n > 4 in fully homoleptic compounds [M(GaCp*)n] could be prepared, nor have

oligonuclear compounds of the Cu/Ga systems been reported. In addition, while highly

coordinated compounds of the general type [M(ZnR)n] (n ≥ 8) have been prepared from

mononuclear starting materials, no investigations have been carried out using dimeric starting

compounds in order to achieve cluster growth.[43, 207] The presence of GaCp* in the

coordination sphere of the transition metal is necessary to obtain zinc-rich molecules. This

makes the synthesis of such compounds somehow special and limited with respect to the

choice of starting materials. Finally, quite recently, the preparation of [Zn2Cp*2] aroused great

attention.[138] Initial investigations have been made into the exploration of the reactivity of this

unusual compound considering the formation of derivatives[137, 156, 158, 159], studying the

electronic structure[142, 147, 149] and formation of (classical) Lewis acid/base adducts[164, 166, 167],

but the coordination chemistry of this Zn(I) dimer has not been studied at all.

The focus of this thesis lays on further investigations of low valent Ga(I) coordination

chemistry as well as first experimental and theoretical studies on the coordination chemistry

of [Zn2Cp*2] towards transition metals. The most meaningful results include the preparation

of the first oligonuclear CuaGab compounds in which Cu(I) and Cu(0) centres are stabilized by

low valent Ga(I)R species. Furthermore, initial investigations in controllable cluster growth

using dimeric starting materials have been made. Herein, the formation of donor stabilized,

trapped zinc-rich intermediates as well as the formation of a metal-rich palladium dimer are

reported. Finally, in the course of this thesis a previously unknown chemistry has been

discovered: first results in the coordination chemistry of [Zn2Cp*2] towards transition metals

lead to trapped {ZnZnCp*} ligands as well as the first unsupported Zn(0) unit in the

coordination sphere of d10 transition metals.

118 4. Summary

4.1 Synthesis and Characterisation of Homoleptic and Heteroleptic

Molybdenum and Rhodium GaR (R = Cp*, DDP) Containing

Complexes

The highest coordination number of fully homoleptic transition metal GaCp* containing

compounds [M(ER)n] has been restricted to n = 4.[126, 128] Thus, analogues to the classic penta-

or hexa-carbonyl complexes, [M(GaCp*)5] (M = Fe, Ru, Os) and [M(GaCp*)6] (M = Cr, Mo,

W), have not been reported, so far. However, two exceptions have been reported containing

pseudo-homoleptic structural features, namely (1) the C-H activated isomers [M(AlCp*)5][279]

(M = Fe, Ru) as well as (2) the cation [Rh(GaCp*)4(GaCH3)]+.[209] Experimental studies

showed that olefins could not be fully substituted from [M(olefin)x] or [M(olefin)x(PR3)y]

starting materials and heteroleptic products [LnM(GaCp*)m] (L = olefin, PR3) were isolated

instead.[222] Within this thesis first homoleptic compounds [M(GaCp*)n] with n ≥ 5 could be

achieved under suitable conditions. The reaction of the olefin containing Mo(0) compound

[Mo(η4-butadiene)3] with excess GaCp* under hydrogen atmosphere and high temperatures of

around 100°C lead to the formation of the hexa-gallylene compound [Mo(GaCp*)6] (1).

Figure 45. Synthesis of [Mo(GaCp*)6] (1).

119 4. Summary

In comparison, reactivity of the Rh(I) dimer [Rh(coe)2(CF3SO3)]2 towards GaCp* takes place

under mild conditions without the presence of hydrogen, leading to the first fully homoleptic

penta-gallylene compound [Rh(GaCp*)5][CF3SO3] (3). Notably, anion exchange reaction of 3

with NaBArF leads to [Rh(GaCp*)5][BArF] (4) which shows highly unstable character in re-

dissolution processes. These results nicely point out the exceptional position of the Cp* group

in research of this kind. The fluxional behavior and the facile haptotropic shift reduce the

strain of the otherwise steric overcrowded situation in the case of rigid substituents.

Nevertheless, redox chemical processes, which include Cp* transfer reactions, may limit the

stability of compounds of the general type [M(GaCp*)n] (n ≥ 5) as it has been shown for 4.

The importance of co-ligands as well as the selection of the low valent Ga(I) species for these

reaction pathways has been illustrated in the formation of [cis-Mo(GaCp*)2(PMe3)4] (2) and

[(coe)(toluene)Rh{Ga(DDP)}(CF3SO3)] (5). Compound 2 is formed via reaction of

[Mo(N2)(PMe3)5] with GaCp*. Ligand replacement of phosphane groups is limited which is

most likely due to electronic reasons concerning stronger π-back bonding between the

molybdenum centre and the remaining phosphane ligands as it has been discussed for the

corresponding carbonyl containing complexes. Finally, the reaction of [Rh(coe)2(CF3SO3)]2

with Ga(DDP) does not lead to a homoleptic [RhGa5] complex, but rather the heteroleptic

mono gallium complex [(coe)(toluene)Rh{Ga(DDP)}(CF3SO3)] (5) was isolated due to

greater steric bulk and the rigidity of the Ga(I) species. Most interestingly, in compounds 3

and 5 no interaction between the Rh(I) centre and the nucleophilic triflate anion {CF3SO3}

has been observed. The electrophilic character of the Ga centres is significantly increased due

to coordination towards the transition metal. Thus, Lewis acid/base adduct formation can be

observed between electrophilic Ga and the {CF3SO3} counter ion which acts as a weak

nucleophile. These results nicely show the importance of electronic and steric properties of

the two different Ga(I) ligands which effect their reactivity towards substitution labile

transition metal complexes, not only leading to different products but also allowing for

different reaction pathways.

4.2 First Dinuclear Copper/Gallium Complexes: Supporting Cu(0) and

Cu(I) Centres by Low Valent Organogallium Ligands

While the formation of mononuclear and oligomeric d10 metal GaCp* compounds is well

known, fewer investigations have been made for group 11 metal centres.[128, 130-132] For

instance, only three examples exhibiting direct Cu-Ga bond interactions have been reported in

120 4. Summary

the literature.[38, 39] All these structures consist of mononuclear units. In contrast, several

dimeric and polynuclear compounds of Cu(I) or Cu(II) can be found in the literature, at which

the applied ligand system such as N-heterocyclic carbenes as well as bulky ligands such as

phosphines and pyrazolylborates seems to play an important role.[280-282] In the recent past it

has been shown that GaCp* can be employed to stabilize dinuclear compounds of soft

cationic d10 coinage metal centres illustrated by the formation of the Ag(I) dimer

[Ag2(GaCp*)3(µ-GaCp*)2][CF3SO3]2.[39] Additionally, the stabilizing effect and

simultaneously reducing ability of Ga(DDP) has recently been used in several reactions.[225]

In the course of this thesis three dimeric Cu/Ga compounds have been prepared via reductive

coordination reaction of GaCp* and Ga(DDP) with easily available Cu(II) and Cu(I) starting

materials. The reaction of [Cu(CF3SO3)2] with two equivalents of Ga(DDP) results in the

formation of the Cu(I) dimer [{(DDP)GaCu(CF3SO3)}2] (6) via mild reductive pathways

under the elimination of [(CF3SO3)2Ga(DDP)]. Compound 6 features [(DDP)GaCu(CF3SO3)]

dimeric units with a planar four-membered [Cu2Ga2] ring and exhibits the shortest

Cu(I)••••Cu(I) distance known so far. The analogous reaction of [Cu(CF3SO3)2] with five

equivalents GaCp* instead of Ga(DDP) leads to the formation of the unusual [Cu2Ga5]

compound [(Cp*Ga)Cu(µ-GaCp*)3Cu{Ga(CF3SO3)3}] (7).

Figure 46. Synthesis of [(Cp*Ga)Cu(µ-GaCp*)3Cu{Ga(CF3SO3)3}] (7).

121 4. Summary

Herein, several competing reaction sequences have to be taken into account. Firstly, redox

chemical processes at which Ga(I) reduces the Cu(II) centre of the starting compound to

Cu(0) and Ga(I) is oxidized to its favoured oxidation state +III found in the fragment

{Ga(CF3SO3)3}. Secondly, coordination of GaCp* ligands to the present Cu(0) centres giving

rise to the (neutral) 30 valence electron fragment [Cu2(GaCp*)4] and finally, coordination of

the {Ga(CF3SO3)3} ligand to one vacant Cu centre. Thus, 7 can be best described as a Lewis

acid/base adduct at which the Ga(III) ligand acts as the Lewis acid and the Cu centre features

Lewis basic character. Herein, the Lewis acid/base interactions Cu(0)→Ga(III) seem to be

stronger than Cu(I)←Ga(I) and Cu(0)←Ga(I) interactions as it is in good agreement with

structural features found for compound 7. Although, the assignment of formal oxidation states

is based on heuristic reasons, the oxidation states of copper and gallium in the fragment

[Cu2(GaCp*)4] can be best declared as Cu(0) and Ga(I), as mentioned above in course of

redox chemical processes leading to the first known structurally characterised Cu(0) complex

or rather cluster. While Ga(DDP) has been proven to be unusable as reactant with Cu(I)

compounds, GaCp* reacts with [{Cu(cod)2}(CF3SO3)] under the formation of the dimeric

compound [Cu2(GaCp*)3(µ-GaCp*)2][CF3SO3]2 (8). Notably, the (hypothetical) dication

[Cu2(GaCp*)5]2+ described in 8, the (neutral) fragment [Cu2(GaCp*)4] found in compound 7

and the dimeric d10 metal compounds [M2(GaCp*)5] (M = Pd, Pt) all feature an electron count

of 30. Thus, the coordination of one triflate to one Cu(I) centre leads to the suggestion, that

compound 8 can be viewed as a trapped intermediate of electronically saturated, 30 electron

[Cu2(GaCp*)5]2+ fragments. In compound 7, the coordination of triflate to the copper centre

has not been observed due to significantly higher electron density on the formal Cu(0)

centres. However, the ‘naked’ dication [Cu2(GaCp*)5]2+ (M = Cu, Ag) should be a tangible

target for further experimental studies when an appropriate, bulky and very weakly

coordinating anion is chosen. In general, the formation of the first molecular CuaGab units is

an outstanding advancement towards intermediates or starting precursors for soft chemical

synthesis of larger M/E intermetallic clusters or nanoparticles.

122 4. Summary

4.3 Experimental and Theoretical Investigations on the Formation of

Zinc-rich Oligonuclear Cluster Compounds

The reaction of mononuclear transition metal GaCp* compounds with ZnR2 (R = Me, Et)

derived easy access to metal-rich compounds of the general formula [M(ZnR)n] (M = Mo, Ru,

Rh, Ni, Pd, Pt; n = 8-12).[42, 43] While underlying reaction schemes of this class of compounds

have been well investigated, the controlled cluster growth has been proven to be somehow

more puzzling. For instance, [{(CO)4Mo}4(Zn)6(µ-ZnCp*)4][207] is formed from [cis-

Mo(CO)2(GaCp*)4], while the reaction of [fac-Mo(CO)3(GaCp*)3] with ZnMe2 leads to the

mononuclear compound [Mo(CO)3(ZnCp*)3(ZnMe)3].[236] In the course of this thesis, further

experimental and theoretical investigations have been effected to gain more detailed insights

into controllable cluster growth and how it is influenced by the nuclearity of the starting

material, the ratio between inert co-ligand and GaCp* as well as usage of fully homoleptic

dimeric transition metal GaCp* starting compounds.

4.3.1 Zinc-rich Compounds of Iron and Cobalt: Formation of [Fe2Znx] (x = 2-4) and

[Co2Zn3] Cores

The dependency of product formation from the nuclearity, the CO/GaCp* ratio and, most

surprisingly, from the solvent used for crystallisation procedures has been illustrated by the

reactions of heteroleptic mononuclear and dimeric iron and cobalt compounds with ZnMe2.

The reaction of [Fe(CO)4(GaCp*)] with excess ZnMe2 and crystallisation from a saturated thf

solution yields [(CO)4Fe{µ2-Zn(thf)2}2Fe(CO)4] (9). While [(CO)3Fe{µ2-Zn(thf)2}2(µ2-

ZnMe)2Fe(CO)3] (10) has been prepared from [(CO)3Fe(µ2-GaCp*)3Fe(CO)3] under similar

(crystallisation) conditions as has been mentioned for 9. The crystallisation from a

toluene/pyridine mixture leads to the formation of [(CO)3Fe{µ2-Zn(py)2}3Fe(CO)3] (11).

Notably, no influence of the solvent on product formation has been observed in the formation

of [(CO)3Co{µ2-Zn(py)2}(µ2-ZnCp*)2Co(CO)3] (12) and [(CO)3Co{µ2-Zn(thf)2}(µ2-

ZnCp*)2Co(CO)3] (13) prepared from [(CO)3Co(µ2-GaCp*)2Co(CO)3] with excess ZnMe2.

It becomes clear that all novel compounds 9-13 are formed via full replacement of the 2e

donor GaCp*. For this observation two possible explanations have been taken into account.

One possibility is the substitution by formal 2e donor units {Zn0L2} (L = thf, pyridine) and

the second possible explanation is based on replacement by two 1e donor ligands ZnMe or

123 4. Summary

rather ZnCp* based on Cp* transfer reactions from gallium to zinc. Thus, the over-all electron

count between the starting material and the products seems to be unaffected which is in good

agreement with the exchange rate and the 18 valence electron rule predicted for the

mononuclear compounds [M(ZnR)n]. Although, no larger clusters with higher nuclearity have

been observed due to low solutibility of the initially formed solid, compounds 9-13 can be

viewed as trapped, donor stabilized intermediates of greater agglomerates. The new core

structures [Fe2Zn3], [Fe2Zn4] and [Co2Zn3] have not been reported before and are likely to be

not easily accessible by synthesis routes other than the reported one.

Figure 47. Synthesis of [(CO)3Co{µ2-Zn(py)2}(µ2-ZnCp*)2Co(CO)3] (12).

4.3.2 Case Study on the Formation of an Oligonuclear Model System for Intermetallic

Phases: Synthesis, Characterisation and Theoretical Investigations on the

Compound [Pd2Zn6Ga2(Cp*)5(CH3)3]

Controlled cluster growth has been obtained in the reaction of [Pd2(µ-GaCp*)3(GaCp*)2] with

stoichiometric amounts of ZnMe2 leading to the first dimeric cluster compound

[Pd2Zn6Ga2(Cp*)5(CH3)3] (14) featuring a 30 valence electron [Pd2Ga2Zn6] core wrapped into

an all-hydrocarbon shell. Compound 14 consists of two Cs symmetric isomers in a ratio of

approximately 1:3 as determined by NMR spectroscopic measurements. While pure crystals

of 14 are stable for several weeks, dissolution in course of spectroscopic measurements

reveals high instability which leads to undefined decomposition products. The possible

124 4. Summary

existence of Cs symmetric [Pd2Zn4Ga4(Cp*)5(CH3)3] has been ruled out via mass

spectrometry. The structural features determined by singly crystal X-ray diffraction illustrate

a bi-capped trigonal prism. Herein, one palladium atom (Pd1) is embedded in the center of a

Pd/Zn/Ga trigonal prism, with the other palladium atom (Pd2) as well as one EMe unit as

capping ligands. Primary theoretical investigations have been made by MO correlations, AIM

and EDA analysis. They lead to the suggestion of significant attractive Pd-Pd interactions

based on bonding combinations of the dz2 AOs of the metals and bonding combination of the

dxz AOs with additional bonding contributions from the bridging Ga atom. These observations

are verified by calculated atomic partial charges taken from NBO calculations indicating a

large negative charge for Pd1 (-2.99e) and a smaller negative charge for Pd2 (-0.76 e), thus,

donation of electronic charge from Pd1 to the latter Pd2 occurs.

Figure 48. Synthesis of [Pd2Zn6Ga2(Cp*)5(CH3)3] (14).

4.4 Experimental and Theoretical Investigations on the Coordination

Chemistry of [Zn2Cp*2] Towards Transition Metal Compounds

The synthesis and characterisation of [Zn2Cp*2] by Carmona in 2004 has been one of the

latest impressive landmarks in the stabilisation of low valent main group metal centres.[138]

Quite some time after the publication of this Zn(I) dimer, a wide variety of theoretical studies

as well as first investigations on the reactivity have been published, of which the latter has

been mainly based on the synthesis and characterisation of derivative structures [Zn2R2] (R ≠

125 4. Summary

Cp*) and the exploration of Lewis acid/base adducts under the preservation of the intact

Zn(I)-Zn(I) bond. While the coordination chemistry of Cp* stabilized low valent group 13

elements has been well established since their development in the 1990s, nothing was known

about the coordination chemistry of [Zn2Cp*2] towards transition metals. In order to gain

initial insights into the rich chemistry of low valent Zn(I), reactivity studies have been carried

out with suitable transition metal complexes.

4.4.1 Trapping Monovalent {ZnZnCp*} at d10 Transition Metal Centres

First investigations on the reactivity of [Zn2Cp*2] included reactions of homoleptic GaCp*

containing d10 metal complexes [M(GaCp*)4] (M = Pd, Pt) with [Zn2Cp*2] leading to a

product mixture of the hexa-coordinated complexes [M(GaCp*)2(ZnCp*)2(ZnZnCp*)2] (M =

Pd (15), Pt (17)) and the octa-coordinated complexes [M(ZnCp*)4(ZnZnCp*)4] (M = Pd (16)

Pt (18)). Most interestingly, a novel ligand system {ZnZnCp*} could be obtained featuring

fully intact Zn-Zn interactions.

Figure 49. Molecular structures of [Pd(GaCp*)2(ZnCp*)2(ZnZnCp*)2] (15) and [Pd(ZnCp*)4(ZnZnCp*)4] (16)

in the solid state.

Compounds 15-18 show high instability in pure crystalline form even under inert gas

atmosphere, while their stability can be significantly increased when covered with small

amounts of an inert, non-polar solvent such as n-hexane or toluene. In situ NMR

spectroscopic measurements allowed first insights into the possible reaction mechanism

which is mainly based on dissociation/association equilibria rather than redox chemical

126 4. Summary

processes. Herein, GaCp* dissociates from the starting material leading to unsaturated

palladium fragments which trap monovalent ZnCp* ligands. The implementation of

{ZnZnCp*} ligands proceeds most likely via Cp* transfer from the parent compound

[Zn2Cp*2] to ZnCp* under loss of ZnCp*2. The existence of free GaCp* and the Zn(II)

compound ZnCp*2 has been observed as an unstable fluxional intermediate

{Cp*Ga••••ZnCp*2}. In addition, the existence of free GaCp* shifts the dissociation

equilibrium towards the adduct side, so that pure compounds of the fully substituted all-zinc

[MZn12] cores cannot occur. In contrast to the formation of [M(ZnR)n] compounds, no

fulvalene species or Ga(III) by-products have been detected which clearly excludes redox

chemical pathways. One important structural feature of the [M(ZnCp*)4(ZnZnCp*)4] (M = Pd

(16) Pt (18)) compounds is the existence of interior, unsupported penta metal atom chains Zn-

Zn-M-Zn-Zn as they can be found in some solid state intermetallics.

4.4.2 First Reactivity Studies of [Zn2Cp*2] Towards Olefin Containing d10 Transition

Metal Centres

Based on the results obtained from GaCp* containing complexes, further investigations into

the reactivity of this special Zn(I) dimer towards reactive transition metal complexes in the

absence of GaCp* have been carried out. The reaction of [M(cod)2] (M = Ni, Pt) with eight

equivalents [Zn2Cp*2] at 80°C for 30 h results in the formation of [M(ZnCp*)4(ZnZnCp*)4]

(M = Pt (18), Ni (19)). Mechanistic studies derived from NMR spectroscopic measurements

indicate the liberation of 1,3-cod and unreacted [Zn2Cp*2] as well as the formation of ZnCp*2.

In addition, [Cp*M(ZnCp*)3] (M = Ni (20), Pt (21)) could be assigned as a minor by-product.

In summary, the formation of [M(ZnCp*)4(ZnZnCp*)4] (M = Pt (18), Ni (19)) from [M(cod)2]

involves the liberation of 1,3-cod and several redox chemical processes leading to ZnCp*2,

the reduction of Zn(I) to elemental zinc, observed as a grey precipitate and the oxidation of

Ni(0) to Ni(I) attended by Cp* transfer reaction. The reaction sequences in the formation of

18 and 19 are most likely the same as discussed previously: The release of 1,3-cod and the

trapping of monovalent ZnCp* species by unsaturated transition metal centres is followed by

the formation of one electron {ZnZnCp*} fragments. The latter are formed by Cp* transfer

reactions between the starting compound [Zn2Cp*2] and the Zn centres of lower coordinated

intermediate species of the type [LaNi(ZnCp*)b] (L = 1,5-cod; ZnCp*) which lead to the

release of ZnCp*2 as the second by-product. In the formation of [Cp*M(ZnCp*)3] (M = Ni

(20), Pt (21)), [Zn2Cp*2] acts as a smooth oxidizing agent for the transition metal centres as

127 4. Summary

well as a natural source in the formation of ZnCp* ligands via Zn(I)-Zn(I) bond cleavage. The

selective formation of Cp* transfer products 20 and 21 has been successful in the reaction of

[M(cod)2] (M = Ni, Pt) with two equivalents [Zn2Cp*2] at 80°C for 3 h. It could be shown by

NMR spectroscopic measurements, that the reaction pathway includes the loss of 1,3-cod,

Zn(I)-Zn(I) bond cleavage to obtain ZnCp* fragments and, finally, redox chemical processes

leading to Cp* transfer from the ZnCp* fragments to the transition metals, whereas the

transition metal is oxidized M(0)→M(I) and the Zn(I) reduced to its bulk material.

Figure 50. Synthesis of [Ni(ZnCp*)4(ZnZnCp*)4] (19) and [Cp*Ni(ZnCp*)3] (20).

The synthesis and characterisation of compounds 19-21 present the versatile properties of

[Zn2Cp*2] in the formation of transition metal-zinc compounds. Most importantly, significant

differences have occurred in comparison to the preparation of highly coordinated molecules

of the general formula [M(ZnR)n]. While in the latter case M-ZnR bond formation is only

observed from GaCp* containing complexes, product formation in the case of [Zn2Cp*2] can

be obtained from reactive transition metal starting materials in the absence of GaCp*

providing a promising, easier approach to zinc-rich molecules. Furthermore, it has been

shown that reaction pathways are easily controlled by stoichiometry and reaction conditions.

While compounds of the type [M(ZnCp*)4(ZnZnCp*)4] are formed with higher amounts of

[Zn2Cp*2] and over a period of 30 h, the Cp* transfer products [Cp*M(ZnCp*)3] can be

obtained using lower amounts of the Zn(I) dimer and shorter reaction times.

128 4. Summary

4.4.3 Experimental and Theoretical Investigations on the Formation of a Novel

[PdZn7] Compound: [Zn2Cp*2] as a Source for Stabilized Zn(0)

In order to expand the reactivity studies based on substitution labile transition metal starting

materials, [PdMe2(tmeda)] has been chosen due to the ability to form metal-rich compounds.

The reaction of [PdMe2(tmeda)] with four equivalents [Zn2Cp*2] leads to the formation of

[Cp*Pd(ZnCp*)3] (22) and [Pd(ZnCp*)4(ZnMe)2(Zn{tmeda})] (23) as principal products in a

ratio of 1:1. In situ 1H NMR spectroscopic studies revealed several rare by-products such as

[Pd(ZnMe)4(ZnCp*)4] as well as various Zn(II) species. These results indicate competition

between redox chemical reaction pathways, coordination steps of Zn(I)R and Zn(0)L towards

the transition metal centre as well as insertion reactions. The latter can be proceed via

homolytic cleavage of the Zn(I)-Zn(I) or disproportionation of the dimeric Zn(I) unit into

Zn(0) and Zn(II). Continuous shape measurements showed that the solid state structure of 23

can be derived from a trigonal dodechadron as it has been found for [MZn8] cores at which

two corners are replaced by the {Zn(tmeda)} unit. Theoretical calculations based on AIM and

EDA analysis indicate a significant difference between the 1e donor ligands ZnR (R = Cp*,

Me) and the {Zn(tmeda)} ligand which can be best described as an unsupported strong 2e

donor fragment.

Figure 51. Synthesis of [Cp*Pd(ZnCp*)3] (22) and [Pd(ZnCp*)4(ZnMe)2{Zn(tmeda)}] (23).

129 4. Summary

Several sections of this thesis have already been published in peer-reviewed journals. These

articles are reproduced in part.

(1) T. Bollermann, T. Cadenbach, C. Gemel, K. Freitag, M. Molon, V. Gwildies, and R.

A. Fischer, ‘Homoleptic Hexa and Penta Gallylene Coordinated Complexes of

Molybdenum and Rhodium’, Inorg. Chem. 2011, 50, 5808-5814.

(2) M. Molon, T. Bollermann, C. Gemel, J. Schaumann, and R. A. Fischer, ‘Mixed

phosphine and group-13 metal ligator complexes [(PR3)aM(ECp*)b] (M = Mo, Ni; E =

Ga, Al; R = Me, C6H5, cyclo-C6H11)’, Dalton Trans. 2011,

DOI:10.1039/C1DT10583C.

(3) T. Bollermann, G. Prabusankar, C. Gemel, R. W. Seidel, M. Winter, and R. A.

Fischer, ‘First dinuclear Copper/Gallium Complexes: Supporting Cu(0) and Cu(I)

centres by low valent Organogallium Ligands’, Chem.-Eur. J. 2010, 16(29), 8846-

8853.

(4) T. Bollermann, K. Freitag, C. Gemel, R. W. Seidel, M. von Hopffgarten, G. Frenking,

and R. A. Fischer, ‘Chemistry of [Zn2Cp*2]: Trapping monovalent .ZnZnCp* in the

metal rich compounds [(Pd, Pt)(GaCp*)a(ZnCp*)4-a(ZnZnCp*)4-a] (a = 0, 2)’, Angew.

Chem. Int. Ed. 2011, 50(3), 772-776.

(5) T. Bollermann, K. Freitag, C. Gemel, R. W. Seidel, and R. A. Fischer, ‘Reactivity of

[Zn2Cp*2] towards Transition Metal Complexes: Synthesis and Characterisation of

[Cp*M(ZnCp*)3] (M = Ni, Pd, Pt)’, Organometallics 2011, 30 (15), 4123-4127.