Synthesis and Characterisation of Organic Antimony and Bismuth

Synthesis and Characterisation of Organic Antimony and

Bismuth Chains and Cycles

Ioan Ghesner

Dissertation submitted as a partial fulfillment of the requirements for the degree

Doctor of Natural Science (Dr. rer. nat.)

Faculty of Chemistry and Biology

University of Bremen

Bremen 2002

1. Referee: Prof. Dr. H. J. Breunig 2. Referee: Prof. Dr. G.-V. Röschenthaler

Date of doctoral examination: 22. August 2002 Contents

CONTENTS

Introduction ...... 1 Aims of the present study ...... 4 Results and Discussion ...... 6

1. The trialkylantimony(V) dibromide R3SbBr2 [R = CH(SiMe3)2] and the

trialkylantimony(V) hydroxy halide R3Sb(Br)OH (R = CH2SiMe3) ...... 6 1.1 Introduction ...... 6

1.2 Synthesis and characterisation of R3SbBr2 [R = CH(SiMe3)2] and of

R3Sb(Br)OH (R = CH2SiMe3) ...... 6 2. Chiral organoantimony and -bismuth compounds, RR’SbCl, RR’BiCl,

and RR’SbH; R = 2-(Me2NCH2)C6H4, R’ = CH(SiMe3)2...... 13 2.1 Introduction ...... 13 2.2 Synthesis and characterisation of RR’SbCl, RR’BiCl, and RR’SbH;

R = 2-(Me2NCH2)C6H4, R’ = CH(SiMe3)2 ...... 15

3. Organo antimony chain compounds, catena-R2Sb(SbR)nSbR2 ...... 22 3.1 Introduction ...... 22

3.2 Synthesis and characterisation of cyclo-[Cr(CO)4(R´2Sb-SbR-SbR-SbR´2)]

(R´= Ph or Me, R = Me3SiCH2), cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)],

and cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) . 22 3.3 Synthesis and characterisation of the open-chain polystibanes, catena- t t Bu2Sb(SbCH3)nSb Bu2, catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2) and

catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4]. Molecular and

crystal structures of [(CO)5Cr(Me2Sb-SbMe2)Cr(CO)5] ...... 31

4. Bis(diorganobismuth)chalcogenides, (R2Bi)2E

[E = S, Te; R = CH(SiMe3)2] ...... 39 4.1 Introduction ...... 39 Contents

4.2 Synthesis and characterisation of {[(Me3Si)2CH]2Bi}2S and

{[(Me3Si)2CH]2Bi}2Te ...... 39

5. Transition metal complexes with cyclo-(RSbX)n

[X = S, Se; R = CH(SiMe3)2] ligands ...... 44 5.1 Introduction ...... 44

5.2 Synthesis and characterisation of cyclo-(RSbX)2[W(CO)5]2

[X = S, Se; R = CH(SiMe3)2] ...... 44 6. Experimental section ...... 51 6.1 General comments ...... 51 6.2 Organoantimony- and bismuth halides ...... 53

Tris[bis(trimethylsilyl)methyl]antimony, [(Me3Si)2CH]3Sb ...... 53

Tris[bis(trimethylsilyl)methyl]antimony dibromide, [(Me3Si)2CH]3SbBr2 . . 53 Tris[(trimethylsilyl)methyl]antimony bromide hydroxide,

(Me3SiCH2)3Sb(OH)Br ...... 54 Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]-

stibine, [(2-Me2NCH2)C6H4][(Me3Si)2CH]SbCl ...... 55 Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]-

bismuthine, [(2-Me2NCH2)C6H4][(Me3Si)2CH]BiCl ...... 56 [2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]stiban,

[(2-Me2NCH2)C6H4][(Me3Si)2CH]SbH ...... 56 6.3 Organoantimony chains ...... 58

Reactions of cyclo-(Me3SiCH2Sb)n (n = 4, 5) with distibanes ...... 58

Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2) ...... 59

Cyclo-[Cr(CO)4(Ph2Sb-SbR-SbR-SbPh2)] and

Cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)] (R = Me3SiCH2) ...... 60

Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) . . . . . 61

Reaction of CH3SbCl2 and R2SbBr (R = Me3SiCH2)with Mg ...... 62

Contents

t t Catena- Bu2Sb(SbCH3)nSb Bu2 (n = 1, 2) ...... 63

Catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2) ...... 64

Catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4] ...... 64 6.4 Bis(diorganobismuth) chalcogenides ...... 65

Bis[bis(bis(trimethylsilyl)methyl)bismuth]sulfide, {[(Me3Si)2CH]2Bi}2S . . . 65

Bis[bis(bis(trimethylsilyl)methyl)bismuth]telluride, {[(Me3Si)2CH]2Bi}2Te . 66

6.5 Transition metal complexes with cyclo-(RSbE)n ligands ...... 66

Cyclo-(RSbS)2[W(CO)5]2 [R = CH(SiMe3)2] ...... 66

Cyclo-(RSbSe)2[W(CO)5]2 [R = CH(SiMe3)2] ...... 67 7. Summary ...... 68 8. References ...... 73 9. Appendix ...... 81 9.1 Abbreviations ...... 81 9.2 Details of crystal structure determination ...... 83 CURRICULUM VITAE ...... 110 Publications ...... 111 Contributions to professional reports ...... 113 Acknowledgements ...... 114

Introduction

The chemistry of organic antimony and bismuth compounds has expanded during the last decades, as illustrated by numerous recent reviews.[1-18] Considerable attention has been directed towards the synthesis and structure of novel compounds containing bonds between antimony or bismuth and group13-16 elements. Several research groups have focused on the preparation of compounds containing bonds between group 13 elements and the higher homologues of group 15, Sb and Bi. Research in this field was dedicated to the investigation of the E-X bond (X = gr. 13 element, E = Sb, Bi) and of the potential use of these compounds as precursors for semiconductors. An important result is the isolation by Schulz of the first complexes with dibismuthane donor ligands and group 13 acceptors (A).[19]

Et tBu E 3 Et Bi Bi (A) Et EtBu Et 3

E = Al, Ga

Among group 14-15 compounds those containing localised E=C (E = Sb, Bi) bonds have attracted considerable attention. Three examples of compounds containing localised Sb=C bonds in the solid state[20,21] have been described by Jones (B) but no reports of any stibaalkyne or bismaalkyne, or systems containing localised Bi=C bonds have been made.

Me3SiO C R Sb R Sb Sb (B)

COSiMe3 O O H R

t t t R = C6H2 Bu3-2,4,6 R = C6H2 Bu3-2,4,6 or C6H2 Bu3-2,4,6

Introduction

Noteworthy results reported by Okazaki, Tokitoh and Power in the field of compounds containing bonds between group 15 elements are the synthesis and isolation of the first distibene, RSb=SbR[22], dibismuthene, RBi=BiR[23], stibabismuthene, RSb=BiR[24], and phosphabismuthene, RP=BiR[25]. However, doubly-bonded systems such as As=Sb or As=Bi remain unknown. Compounds with single Sb-Sb or Bi-Bi bonds such as cyclo-stibanes, cyclo-(RSb)n (n = 3 - 6), cyclo- bismuthanes, cyclo-(RBi)n (n = 3, 4), distibanes, R2Sb-SbR2, and dibismuthanes, [5,6] R2Bi-BiR2, are known mainly due to the work of Breunig. As far as catena- stibanes are concerned well-defined examples are rare and the isolation of oligomers of the type catena-R2Sb(SbR)nSbR2 (n = 1, 2) has not yet been achieved. The existence of catena-tri- and tetrastibanes in ring-chain equilibria is however well established.[26] On the other hand, extensive studies on the synthesis and structural characterisation of well defined catena-phosphanes of the type catena-R2P(PR)nPR2 (n = 1, 2) [27, 28] have led in the last decade to the X-ray structure determination of several catena-tri-[29, 30] and tetraphosphanes[31] (C).

R R R R R R P R P P (C) P P P P R R R R

Also, complexes with organophosphorus and -arsenic chains have been reported.[32-40] The free catena-phosphanes have been found to be unstable at room temperature whereas their coordination to transition metal fragments results in the formation of stable complexes. Either electrostatic or π-antibonding interactions of the P lone pairs in free catena-phosphanes are believed to destabilise the systems.[41] Studies on organoantimony and -bismuth chalcogenides were dedicated mainly to cyclic, cyclo-(RSbX)n, cyclo-(RBiX)n, cyclo-RnSbnXm, and chain, R2Sb-X-SbR2,

R2Bi-X-BiR2, compounds (X = gr.16 element). X-ray diffraction studies on cyclo-

(RSbX)n compounds are limited to the works of Okazaki and Breunig who reported [22] the crystal structures of two oxides, cyclo-(RSbO)2 [R = 2,4,6-[(Me3Si)2CH]3C6H2] [42] and cyclo-(RSbO)4 [R= CH(SiMe3)2] . No cyclo-(RBiX)n compounds were

Introduction structurally characterised. Possible intermediates by the synthesis of cyclo-(REX)n (E = Sb, Bi; X = gr.16 element) are the double-bond compounds RE=X. Low coordinated double-bond compounds between group 15 and group 16 elements, dithioxo-phosphorane [RP(S)=S][43] and diselenoxo-phosphorane [RP(Se)=Se][44], have been synthesised as stable compounds, and thioxophosphines [RP=S][45] and selenoxophosphines [RP=Se][46] stabilised by the coordination of an amino group have been observed in solution by NMR spectroscopy. As for the low coordinated double-bond compounds between antimony or bismuth and group 16 elements the number of works are limited to a recent paper of Okazaki, who reported on the trapping of antimony-sulfur double-bond, Sb=S, with nitrile oxides.[47] However, systems containing localised Sb=X or Bi=X (X = gr. 16 element) bonds still remain unknown. Although many of the trivalent antimony and bismuth compounds containing bonds to group 13-16 compounds have one or more unsymmetrically substituted antimony or bismuth atoms, making these molecules chiral, the configurational stability in such systems was not investigated due to their low thermal stability and to difficulties with their handling. Suitable candidates for atomic inversion studies on chiral antimony and bismuth centres are the more stable chiral triorganostibanes and -bismuthanes, RR’R’’E (E = Sb, Bi) and the chiral halostibanes and bismuthanes RR’EX (E = Sb, Bi; X = halogen atom). While inversion at N, P and As has been well documented for many years,[48] it is only recently that Akiba reported the first examples of inversion at chiral antimony and bismuth centres.[49,50]

Aims of the present study

Important synthons for the synthesis of organoantimony and -bismuth compounds with element-element bonds are the alkyl- and aryl-substituted antimony and bismuth halides. Antimony(V) compounds with the formula R3SbX2 where R may be either an alkyl or an aryl group and where X is a halogen or another electron attracting group are well known. No authentic R3Sb(OH)X compounds have been isolated in the solid state unless sterically demanding R and X groups are present. Such compounds readily condense to binuclear (R3SbX)2O products. One aim of this study was to investigate of how the bulky CH(SiMe3)2 group influences the geometry and reactivity of trialkylantimony(V) halides. Also, attempts were to be made for the isolation and structural characterisation of stable R3Sb(OH)X compounds. Examples of symmetrically substituted organoantimony(III) and -bismuth(III) halides are well known.[1,2] In a series of papers the results of the crystal structure determinations for these compounds were described and a number of structural trends became apparent.[52,53] On the other hand, few examples of chiral organoantimony(III) and -bismuth(III) halides have been described, most of them being aryl substituted. In this work the synthesis and configurational stability of alkyl substituted chiral halostibines and -bismuthines were to be investigated in relation to earlier studies on the inversion of configuration at chiral Sb and Bi centres. The second part of this study is dedicated to the synthesis and structural characterisation of compounds with E-E bonds (E = Sb, Bi, S, Se, Te) and their use as ligands to transition metal complexes.

Due to the lower Sb-Sb bond energy catena-stibanes, catena-R’2Sb(RSb)nSbR’2, are expected to be more unstable than the analogous catena-phosphanes. However, using adequate organic substituents the isolation of stable catena-stibanes should be possible. The length of catena-stibanes, that is, the number of RSb units from its constitution, should also be influenced by the nature of the organic groups R and R’.

For example, catena-tristibane formation, catena-R’2Sb-SbR-SbR’2, is expected to be

Aims of the present study favoured by bulky organic groups at the terminal antimony atoms and sterically less demanding groups at the central antimony atom, while bulky substituents at the central antimony atom and sterically less demanding groups at the terminal antimony atoms would favour the formation of oligomers and polymers, catena-

R’2Sb(SbR)nSbR’2 n>1. However, catena-stibanes with n>1 are expected to be kinetically unstable and to decompose with formation of R’2Sb-SbR’2 and cyclo-

(SbR)n. A stabilisation of these systems should be possible by coordination to transition metal fragments. As part of these study the synthesis and coordination chemistry of catena-stibane ligands should be investigated. Complexes with catena- stibane ligands have not yet been reported.

Diorganobismuth chalcogenides, (R2Bi)2X (X = chalcogen), and cyclic organoantimony chalcogenides, cyclo-(RSbX)n (X = chalcogen), have been under investigation for a long time but little is known about their structural chemistry. The only examples of bis(diorganobismuth)chalcogenides with known crystal structures [54,55] are the mesityl derivatives (R2Bi)2E [E = O, S, Se; R = 2,4,6-(CH3)3C6H2]. Due to their low thermal stability the tellurium derivatives could not be characterised by X-ray diffraction studies. Cyclic organoantimony chalcogenides with known crystal [22] structure are the oxides cyclo-(RSbO)2 (R = 2,4,6-[(Me3Si)2CH]3C6H2) and cyclo- [42] (RSbO)4 [R = CH(SiMe3)2] . The reaction of transition metal carbonyls with cyclo-

(RSbX)n (X = chalcogen) ligands, containing antimony and chalcogen donor atoms, are of great interest since the complexes expected to form are diverse and difficult to predict. Complexes with cyclo-(RSbX)n (X = chalcogen) ligands have not yet been reported. These compounds show potential applications as precursors for a variety of important electronic materials.[56-58]

Results and Discussion

1. The trialkylantimony(V) dibromide R3SbBr2 [R = CH(SiMe3)2] and the

trialkylantimony(V) hydroxy halide R3Sb(Br)OH (R = CH2SiMe3)

1.1 Introduction

Triorganoantimony(V) dihalides, R3SbX2 (R = alkyl, aryl; X = Cl, Br, I) are important reagents in the organometallic chemistry of antimony which have been used for the synthesis of diorganoantimony(III) halides by thermal elimination of RX [59] or for hydrolytic reactions with formation of dihydroxides, or oxides, R3SbO [60] Intermediates of the hydrolyses are binuclear condensation products, (R3SbX)2O [51,61] or hydroxy halides of the type R3Sb(OH)X , which exist with bulky organic + - groups. Only one example, the ionic species [(2,6-Me2C6H3)3SbOH] I with tetrahedral geometry has been characterised by single crystal X-ray diffraction.[51] + - Also for triorganoantimony dihalides ionic structures, [R3SbX] X are possible and an early report in 1938 described the crystal structures of Me3SbX2 (X = Cl, Br, I) as partially ionic.[62] However, a recent reinvestigation revealed the highly symmetrical [63] D3h, non-ionic structure for Me3SbBr2. In order to study the influence of bulky organic groups on the structural aspects and on the reactivity of the antimony centre in trialkylantimony halides the dibromide

R3SbBr2, [R = CH(SiMe3)2] and a trialkylantimony hydroxy halide,

(Me3SiCH2)3Sb(Br)OH, were prepared.

1.2 Synthesis and characterisation of R3SbBr2 [R = CH(SiMe3)2] and of

R3Sb(Br)OH (R = CH2SiMe3)

The trialkylantimony dihalide R3SbBr2 [R = CH(SiMe3)2] (1) forms as air-stable solid in the usual way by reaction of Br2 with the corresponding tertiary stibanes. R3Sb [R

= CH(SiMe3)2] was obtained by complete alkylation of SbCl3, which is more

Results and Discussion

[64] effective than the procedure reported earlier , i.e. the alkylation of RSbCl2 with RLi

[R = CH(SiMe3)2].

+ Br 3 RLi + SbCl R Sb 2 R SbBr 3 - 3 LiCl 3 3 2

1 R = CH(SiMe ) 3 2

The NMR spectra of 1 in CDCl3 at 20 °C show the signals expected for equivalent bis(trimethylsilyl) substituents corresponding to the usual trigonal bipyramidal structures of covalent trialkylantimony dihalides with axial halogen atoms and 1 13 equatorial alkyl groups. The H and C NMR spectra of 1 in C6D6, in C6D6/CDCl3 mixtures or in C6D5CD3 are however surprisingly complex. Independent of temperature variations (+ 70 to - 70 °C) or concentration there are four singlets of almost equal intensity for the methine protons and multiplets for the Me3Si groups which become even more complex below – 20 °C. A similar pattern is also observed when the spectra of 1 in CDCl3 are recorded at low temperatures between –50 and – 70 °C.

3.0 2.0 1.0 0.0 3.0 2.0 1.0 0.0 (ppm) (ppm)

1 Figure 1 H NMR spectra of 1 measured at 20 °C in CDCl3 (left) and in C6D6 (right).

These results clearly indicate that the solid state structure of 1, where all the

(Me3Si)2CH substituents are equivalent (isomer 1a), is not completely preserved in

Results and Discussion solution. The most straightforward interpretation of the solution NMR spectra is to assume the presence of an additional isomer 1b which is derived from the solid state form 1a by a 180° rotation of one of the (Me3Si)2CH groups around the Sb-C bond. In 1b, where two of the C-H groups are directed towards each other, the methine protons are not equivalent and three singlet signals would be expected. The distribution of intensities in the CH region of the experimental spectra suggests a 1 : 3 molar ratio for 1a and 1b in benzene or toluene in the range – 70 to + 70 °C. The simplicity of the room temperature spectrum of 1 in CDCl3 (two lines in the ratio 1 : 18 of intensities) is presumably due to an accidental isochrony of the signals of 1a and 1b and not to an exclusive preference for 1a under these conditions.

H H CR2 CR2 Br Br Sb H H Sb H R2C Br CR2 R2C Br CR2 H

R = Me3Si 1a 1b

For solid 1 the trigonal bipyramidal structural type was confirmed by a single crystal X-ray diffraction study. The structure is depicted in Figure 2. Selected bond lengths and angles are given an Table 1. In the crystal the molecules of 1 form columns through intermolecular Br⋅⋅⋅Br contacts of 347.3(1) pm. A packing diagram for 1 showing the arrangement of the columns is provided in Figure 3. The inspection of the bond lengths and angles reveals that the D3h geometry is represented with only small distortions in the central skeleton of 1, with the Br-Sb-Br angle of 180°, the C- Sb-C angles of 119.92(2)° and Br-Sb-C angles between 88.4(2) and 91.6(2)°. The comparison of the bond lengths of 1 [Sb-C: 214.9(5); Sb-Br: 264.6(1), 267.2 (1) pm] [63] with Me3SbBr2 [Sb-C: 204.7(5); Sb-Br 264.9 pm] shows that the Sb-C bonds are longer in 1, whereas the Sb-Br bond lengths have similar values in both compounds.

Results and Discussion

The orientation of the alkyl group in 1 can be described as propeller-like with H-C- Sb-Br torsion angles of 46.94(1)°.

Sb(1)

Br(1a) Br(2) Br(1) Br(2a)

C(1) C(7) C(2)

Si(2) Si(1) C(4) C(5) C(6) C(3)

Figure 2 ORTEP-like representation of 1 at 50% probability showing the atomic numbering scheme, together with two Br atoms of neighbouring molecules.

The hydrolysis of 1 was carried out with a solution of potassium hydroxide in water.

Unexpectedly, not only bromine atoms but also Me3Si groups were substituted and the hydroxy bromide (Me3SiCH2)3Sb(Br)OH (2) was obtained. Hydrolytic cleavage of Me3Si-element bonds is common for many elements but is rare for Si-C(alkyl) bonds which usually occurs only under very drastic conditions. The sterically congested situation and the electron withdrawing effect of the Sb(V) centre may be responsible for the facile hydrolysis. A more rational synthesis of 2 (72 % yield) is achieved by reacting (Me3SiCH2)3SbBr2 with potassium hydroxide in water.

Et2O/H2O R3SbBr2 + KOH R3Sb(Br)OH + KBr 2 R = CH2SiMe3

Results and Discussion

c a

Figure 3 The crystal packing of 1 (down the c axis). Hydrogen atoms have been removed for clarity.

The novel hydroxy bromide is an air-stable compound with little tendency to dehydrate to an ox-bridged binuclear species. The compound remains unchanged for 12 h at 60 °C under reduced pressure. Further heating leads to decomposition. The presence of the hydroxy group in 2 is proven by the infrared spectra. In Nujol the ν(O-H) band appears as a broad signal with a maximum of intensity at 3446 cm-1. In -1 CH2Cl2 solution the ν(O-H) band is shifted to a higher frequency (3632 cm ) and becomes sharp. In contrast the frequency of the ν(Sb-O) band is lower (542 cm-1) in -1 CH2Cl2 than in Nujol (581 cm ). These shifts indicate weak hydrogen bonding in the solid state. Similar values have been observed for (C6H11)3Sb(OH)Br [in CH2Cl2, ν(O- H) = 3628, ν(Sb-O) 538 cm-1].[61]

Results and Discussion

Table 1 Selected interatomic distances (pm) and angles (°) in 1 and 2.

[(Me3Si)2CH]3SbBr2 (1) Sb(1)-Br(1) 267.20(11) Br(1)-Sb(1)-Br(2) 180.00(0) Sb(1)-Br(2) 264.57(11) Br(2)-Sb(1)-C(1) 91.3(2) Sb(1)-C(1) 214.9(5) Br(1)-Sb(1)-C(1) 88.7(2) Br⋅⋅⋅Br 347.3(1) Sb-C-Si 119.5(3)–120.7(3)

(Me3SiCH2)3Sb(Br)OH (2) Sb(1)-O(1) 196.1(9) O(1)-Sb(1)-C(3) 95.0(5) Sb(1)-C(1) 209.2(12) C(1)-Sb(1)-C(2) 120.1(5) Sb(1)-C(2) 211.1(12) C(1)-Sb(1)-C(3) 112.8(6) Sb(1)-C(3) 211.4(12) C(2)-Sb(1)-C(3) 125.1(6) Sb(1)-Br(2) 287.26(17) O-Sb(1)-Br(2) 179.3(3) O(1)⋅⋅⋅Br(2)# 346.8(46) C(1)-Sb(1)-Br(2) 85.7(3) C(2)-Sb(1)-Br(2) 84.8(3) O(1)-Sb(1)-C(1) 93.7(5) C(3)-Sb(1)-Br(2) 85.6(4) O(1)-Sb(1)-C(2) 95.2(4)

1 13 The H and C NMR spectra of 2 in C6D6 show two singlets as expected for the

Me3SiCH2 groups but no signal for the OH protons. The crystal structure of 2 is depicted in Figure 4. There is a slightly distorted trigonal bipyramidal coordination with angles Br-Sb-O 179.3(3)°, C-Sb-Br 84.8(3) - 85.7(3)° , O-Sb-C 93.7(2) - 95.2(4)°. The Sb-O(H) bond length [196.1(9) pm] lies in the usual range for covalent triorganoantimony(V) hydroxides, cf. Mes3Sb(OH)[O(O)CCHCl2], Sb-O(H), [65] [66] 197.5(3) ; Mes3Sb(OH)2, 202.7(3) pm . The Sb-Br bond in 2 [287.26(17) pm] is [63] longer than in 1 [264.4(1)-267.1(1) pm] or Me3SbBr2 (264.9 pm) . The hydrogen atom of the hydroxyl group was not localised by X ray diffraction. The closest intermolecular contacts exist between oxygen and bromine atoms of different molecules. The O⋅⋅⋅Br contact distances of 346.8(46) pm indicate weak intermolecular hydrogen bonds. The Sb-Br bond in 2 [284.41(9) pm] is longer than in

Results and Discussion

Me3SbBr2 (264.9 pm).

C(2) Br(2)

O(1) O(1) Br(2) H(1) C(1) Sb(1) H(1)

C(3)

Figure 4 ORTEP-like representation at 50% probability of 2 showing the atomic numbering scheme, together with the intermolecular O-H⋅⋅⋅Br interactions.

Results and Discussion

2. Chiral organoantimony and -bismuth compounds, RR’SbCl, RR’BiCl,

and RR’SbH; R = 2-(Me2NCH2)C6H4, R’ = CH(SiMe3)2

2.1 Introduction Atomic inversion, first suggested in 1924 by Meisenheimer and co-workers,[67] was recognised as being a common process in three-coordinate compounds having a pair of nonbonding electrons. In such a process a reversal of configuration results without bond cleavage. The vertex inversion mechanism, which has been generally accepted for trivalent group 15 compounds, involves passage through a transition state, in which the lone pair possesses pure p-character and the bonds from the central atom E to the substituents are sp2-hybridised (Scheme 1).

L2 L1 L3 L1 E EL3 E L2 L1 L3 L2 Transition State for Vertex Inversion Process Scheme 1 The vertex inversion mechanism for trivalent group 15 compounds.

Theoretical calculations predict that the energy barrier of vertex inversion increases with increasing pnictogen atomic number.[68,69] This is also supported by the fact that examples of vertex inversion in trivalent Sb and Bi compounds have not been observed.[48,70] Therefore, the isolation of three-coordinated optically active P,[71] As,[72] Sb,[73-75], and Bi [76,77] compounds is possible. In recent studies, Arduengo and Dixon have shown that inversion at pnictogen centres can proceed via an edge inversion mechanism [78-81] instead of the vertex inversion. The edge inversion process can be visualised as proceeding by movement of the edges of a tetrahedron to form a square planar transition state, where a vacant p-orbital appears. If one of the

Results and Discussion substituents of the tetrahedron is a pair of electrons, the structure of the transition state is viewed as T-shaped (Scheme 2). In the T-shaped intermediate the lone pair of electrons is considered to posses s-character and the bond from the central atom E to

L1 and L2 is three-centred four-electron and implies one of the p-orbitals of the central group 15 element.

Nu L1

E L3 E E

L1 L3 L3 L1 L2 Nu L2 L2

T-shaped Transition State for Edge Inversion Process

Scheme 2 The edge inversion mechanism for trivalent group 15 compounds.

Edge inversion for trivalent group 15 compounds predicts the following: (a) the inversion barrier decreases with increasing pnictogen atomic number, (b) σ-acceptors

(electronegative substituents) in the axial positions (L1 and L2) stabilise the T-shaped transition state, and (c) π-donors in the equatorial position (L3) or external nucleophiles which can interact with the out-of-plane empty p-orbital also stabilise the transition state.[50,80,82] Edge inversion was recently confirmed to occur in chiral bismoles {C6H4C(CF3)2O}BiX [X = Cl, CH3CO2, CF3CO2, 2-(Me2NCH2)C6H4, 2-

(MeOCMe2)C6H4, 2,6-(Me2NCH2)2C6H3] and in the chiral stibole [49,50] {C6H4C(CF3)2O}Sb{2,6-(Me2NCH2)2C6H3}. So far, no studies on the configurational stability of chiral halostibines or halobismuthines bearing alkyl groups have been reported. In fact, the literature to date contains only few reports on the synthesis of unsymmetrical organoantimony(III) halides. Examples are {p- [73] (EtO2C)C6H4}Sb(Cl)Ar [Ar = p-(Me)C6H4, p-(cyclo-C6H11)C6H4, 1-Naphtyl] , {2- [74] [83] (C12H9)}Sb(Cl){p-(Me)C6H4} , MeSb(Cl)CH2C6H5 . A search in the Cambridge Crystallographic Database confirms that no chiral diorganoantimony halides of the

Results and Discussion type RR'SbX (R ≠ R' = organic group, X = halogen atom) have been characterised by X-ray diffraction studies to date. However, some chiral halobismuthines stabilised by the intramolecular coordination of sulfonyl[84], (dimethylamino)methyl[85], (dimethylamino)ethyl [86,87] or acyl[88] groups, have been prepared and characterised by X-ray diffractometry.

2.2 Synthesis and characterisation of RR’SbCl, RR’BiCl, and RR’SbH; R = 2-

(Me2NCH2)C6H4, R’ = CH(SiMe3)2 The colourless crystalline compounds 3 and 4 were prepared in high yield (96 % 3 [89] and 91 % 4) via the salt elimination reaction of [2-(Me2NCH2)C6H4Li] with [90] [91] (Me3Si)2CHECl2 (E = Sb, Bi ) in toluene at –80 °C.

toluene 2-(Me NCH )C H Li + (Me Si) CHECl 2 2 6 4 3 2 2 -80 °C

[2-(Me2NCH2)C6H4][(Me3Si)2CH]ECl E = Sb (3), Bi (4)

Subsequent reduction of 3 with LiAlH4 in Et2O afforded the isolation of the diorganoantimony hydride 5.

Et O 3 + LiAlH 2 [2-(Me NCH )C H ][(Me Si) CH]SbH + LiCl + AlH 4 -80 °C 2 2 6 4 3 2 3 5

The halides 3 and 4 are insoluble in petroleum ether, but readily soluble in tetrahydrofuran, diethyl ether, aromatic hydrocarbons and other organic solvents. 5 is a colourless, viscous oil which is soluble in common organic solvents including petroleum ether. 3 – 5 decompose in air, they are stable only in an inert atmosphere. Solutions of 5 decompose at room temperature over a period of 2 days. At low temperature (-28 °C) in an inert atmosphere 3 - 5 could be stored for months. Characteristic mass spectra have been obtained by chemical ionisation and electron

Results and Discussion impact techniques. The composition of 3 and 4 has been proven by elemental analysis and of 5 by high-resolution mass spectrometry. An X-ray diffraction study carried out on single crystals of 3, obtained on cooling solutions of 3 in petroleum ether, revealed that it crystallises as a racemate without close intermolecular contacts. The molecular structure of the enantiomer of 3 with the absolute configuration R (in accordance with the rule introduced by Martin in the case of optically active sulfuranes)[92] is illustrated in Figure 5. Selected bond distance and angle data have been compiled in Table 2.

C(19) C(18)

N(1) C(17) C(16) Sb(1) Si(1)

C(21) C(11) Cl(1)

Si(2)

Figure 5 ORTEP-like representation at 50% probability and atom numbering scheme for the enantiomer of 3 having the absolute configuration R.

The overall geometry at the antimony centre in 3 is best described as distorted equatorially vacant trigonal bipyramidal. The equatorial plane is occupied by the two C(11) and C(21) carbon atoms and the lone pair of electrons with C(11)-Sb-C(21)

Results and Discussion angle of 104.3(3)°, while the chlorine and nitrogen atoms are in apical positions [N(1)-Sb(1)-Cl(1) 163.60(16) pm]. Closely related to 3 is the structure of the [85] chlorobismuthine [2-(Me2NCH2)C6H4][4-MeC6H4]BiCl. In 3 the distance between the nitrogen atom of the N,N-dimethylamino group and the central antimony atom is 253.3(7) pm, which is longer than the sum of the covalent radii (214.0 pm), but much shorter that the sum of the van der Waals radii of Sb and N (ca. 374.0 pm).

Table 2 Selected interatomic distances (pm) and angles (°) in 3.

Sb(1)-C(11) 214.5(8) C(21)-Sb(1)-N(1) 90.5(3) Sb(1)-C(21) 218.1(8) Cl(1)-Sb(1)-N(1) 163.60(16) Sb(1)-Cl(1) 250.0(3) C(17)-N(1)-C(18) 111.8(7) Sb(1)-N(1) 253.3(7) C(18)-N(1)-C(19) 109.7(7) N(1)-C(17) 147.1(10) C(17)-N(1)-C(19) 110.3(7) N(1)-C(18) 146.6(11) C(17)-N(1)-Sb(1) 103.2(5) N(1)-C(19) 150.2(10) C(18)-N(1)-Sb(1) 118.7(5) C(19)-N(1)-Sb(1) 102.5(5) C(11)-Sb(1)-C(21) 104.3(3) C(16)-C(11)-Sb(1) 119.1(6) C(11)-Sb(1)-Cl(1) 90.7(2) C(11)-C(16)-C(17) 118.4(8) C(21)-Sb(1)-Cl(1) 91.5(2) N(1)-C(17)-C(16) 110.9(7) C(11)-Sb(1)-N(1) 73.1(3)

Similar values were found also for the N-Sb distance in [2-(Me2NCH2)C6H4]2SbCl [93] [93] [246.3(2) pm] and [8-(Me2NCH2)C10H6]2SbCl [251.9(4) pm] . The Sb(1)-Cl(1) bond distance in 3 [250.0(3) pm] is slightly longer than that found in [94] [95] (Me3Si)2CHSbCl2 [238.8(1) and 236.9(1) pm] or [(Me3Si)2CH]2SbCl [239.79(12) pm]. These findings are consistent with the σ* orbitals bonding model in the sense that the strongly bound amine arm is trans to the Sb-Cl bond and that the shortening of the Sb-N distance leads to the elongation of the Sb-Cl bond. This is consistent with the view that the Lewis acidity of organopnictogen(III) halide compounds is associated with the E-X σ* orbitals[52] (X = halogen) and that E-X σ*

Results and Discussion orbitals are better acceptors than E-C σ* orbitals and is also in accord with previous [53,93] observations on related structures. Thus, the coordination of the NMe2 group in 3 effectively forms a hypervalent 10-Sb-4 [96] compound. The chelate five-membered ring generated by the intramolecular coordination of the amine arm is puckered along the Sb(1)-C(17) vector such that N(1) lies above the Sb(1)-C(11)-C(16)-C(17) plane, generating an angle of 38.9° between the Sb(1)-C(17)-C(16)-C(17) and Sb(1)-C(17)- N(1) planes. An interesting aspect of the structure of 3 is the presence of a weak interaction between the proton ortho to antimony and the chlorine atom [264.3 pm], which falls within the sum of the van der Waals radii of Cl and H [281 pm]. This weak H-Cl interaction was considered to be responsible for the large downfield shift observed in the aromatic region of the 1H NMR spectra of analogous bismuth compounds.[84,85] 1 The H NMR spectra of 3 and 4 measured at 20 °C in C6D6 or toluene-d8 show that the SiMe3, NMe2 and CH2 groups are diastereotopic. These and the observation of a large downfield shift for the signal of the proton ortho to antimony, respectively to bismuth suggest that at 20 °C the pseudotrigonal bipyramidal configuration found in solid 3 is preserved also in C6D6 or toluene-d8 solutions of 3 and 4. In order to study the configurational stability at the chiral antimony and bismuth centres the variable- temperature dynamic 1H NMR spectra were recorded (Figure 6). 1 In the H NMR spectra measured in C6D6 or toluene-d8, the signals of the NMe2 ‡ -1 groups show coalescence at 25 °C (∆G 25 °C = 13.6 kcal mol ) in the case of 3 and at ‡ -1 30 °C (∆G 30 °C = 13.8 kcal mol ) in the case of 4. The process observed corresponds to the dissociation of the intramolecular E-N (E = Sb, Bi) coordination bond followed by vertex inversion at the nitrogen atom and subsequent restoration of the E-N bond after rotation about the CH2-N bond of 180° (Scheme 3). The rate determining step for the coalescence should correspond to the dissociation of E-N bond because the barrier of inversion at a three-coordinate nitrogen atom is known to be small (~ 6 kcal mol-1).[48,70]

Results and Discussion

a bH a bH H a H b Me Me Meb Mea N N

E E a a Me3Si CH Me3Si CH Cl Cl b SiMe3 b SiMe3

E = Sb (3), Bi (4) Scheme 3

Coalescence of the SiMe3 peaks was not observed in C6D6 up to 80 °C or in toluene- d8 up to 125 °C by variation of the concentration, suggesting that inversion at the antimony and bismuth atoms does not occur under these conditions. In contrast, 1H

NMR measurements in DMSO-d6 resulted in a complete coalescence of the NMe2 ‡ -1 peaks even at 20 °C (∆G 20 °C = 13.3 kcal mol ) only in the case of 4, while the coalescence temperature of the NMe2 peaks of 3 remain unaffected by solvent change. The cause of the decrease in the barrier of dissociation of the Bi-N bond in nucleophilic solvents might be due to the fact that the DMSO molecules are able to coordinate with the bismuth atom in the ground state of 4 to accelerate the Bi-N dissociation. This is consistent with the higher Lewis acidity of the bismuth atom compared with antimony. Further heating of 3 and 4 in DMSO-d6 leads to the coalescence of the SiMe3 peaks at 45 °C in the case of 4, while in the case of 3 no coalescence was observed up to 160 °C, and further heating leads only to ‡ decomposition. The energy for the inversion (∆G Tc) at the bismuth and antimony -1 atoms was calculated to be 15.5 kcal mol (Tc = 45 °C) in the case of 4 and higher -1 than 20 kcal mol (Tc = 160 °C) in the case of 3, respectively. These findings are consistent with the predictions for edge inversion. Similar values for the free energies of activation were reported also for the chiral bismole and stibole

{C6H4C(CF3)2O}EX [E = Sb, Bi; X = 2-(Me2NCH2)C6H4], which were found to undergo edge inversion.[50] The higher barriers of inversion at the antimony and bismuth centres compared with those of the dissociation of the E-N (E = Sb, Bi) bond

Results and Discussion indicate that two independent processes are occurring, i.e., the reversible dissociation of the intramolecular E-N coordination (E = Sb, Bi) followed by the inversion of configuration at the chiral pnictogen centre by nucleophilic participation of the solvent. The inversion process for 4 is illustrated in Scheme 4. The dissociation of the Bi-N bond takes place before the inversion of the bismuth atom. As the compound moves toward the T-shaped transition state, the NMe2 group recombines with Bi to stabilise the vacant p-orbital which is perpendicular to the plane. Additional stabilisation of

45 °C, 80 °C, C D DMSO-d6 6 6

4 3 2 1 0 4 3 2 1 0

20 °C, DMSO-d6 25 °C, C6D6

4 3 2 1 0 4 3 2 1 0

20 °C, C6D6 20 °C, C6D6

4 3 2 1 0 4 3 2 1 0

Figure 6 Variable-temperature dynamic 1H NMR spectra of racemic 3 (left) and 4 (right). Only the highfield part of the spectra is shown.

Results and Discussion the vacant p-orbital is realised by the coordination of a DMSO molecule to form a pseudooctahedron, were a pair of stereochemically inactive electrons is involved. Then the redissociation of the Bi-N bond takes place to give a pyramidal structure with an inverted configuration in which the NMe2 group interacts with the σ*Bi-Cl orbital. The inversion at the bismuth atom in 4 cannot be rationalised by Berry pseudorotation because the lone pair electrons must be placed at an apical position in the inevitable intermediate during the pseudorotation process. The high energy required for such a pseudorotation has been previously demonstrated by the isolation [92] of the chiral 10-S-4 sulfurane {C6H4C(CF3)2O}S(Cl)Ph.

Cl Cl Cl Cl Cl R R R Me R R + Nu - Nu Nu Bi N Bi Bi Bi Bi Me - Nu + Nu Me Me CH2 Me Me N N N N Me Me Me Me CH2 CH2 CH2 CH2

R = CH(SiMe3)2

Scheme 4 Edge inversion at the chiral bismuth centre in 4 by nucleophilic participation of the solvent (DMSO).

1 In the H NMR spectra of 5 measured at 20 °C in C6D6, toluene-d8 or DMSO-d6 the signals of the SiMe3 and CH2 groups were observed to be diastereotopic, while for the

NMe2 group only a singlet signal was observed even on cooling toluene-d8 solutions of 5 until –80 °C. These results may suggest the absence of the intramolecular Sb-N coordination in the temperature range –80 to +20 °C. The coalescence of the SiMe3 peaks was not observed on heating DMSO-d6 solutions of 5 up to 100 °C, while further heating led only to decomposition. Evidence for the Sb-H bond in 5 comes from the observation in the 1H NMR spectra of two sets of doublets for the Sb-H 3 (4.34 ppm) and methine (0.1 ppm) protons due to the JHH coupling, and from the presence of a strong absorption at 1791 cm-1 in the IR spectra assigned to the νSb-H vibration.

Results and Discussion

3. Organoantimony chain compounds, catena-R2Sb(SbR)nSbR2

3.1 Introduction The chemistry of organometallic antimony chains (catena-stibanes) has been investigated for a long time,[5, 6, 97, 98] but our knowledge of this highly diverse group - of compounds is still rather limited. Only three ionic trimers, [R2Sb-Sb-SbR2] (R = [99] [100] + [101] Ph , t-Bu ) and [R2Sb-SbR2-SbR2] (R = Me) have been characterised by X- ray crystallography. Neutral catena-stibanes have been reported as tristibanes, R2Sb- [26] [26] SbR´-SbR2 (R = Me, Et, Ph ; R´= Me, Et, t-Bu, (Me3Si)2CH, Ph), a tetrastibane, [97,98] Ph2Sb-SbEt-SbEt-SbPh2 and several polymers, all with unknown crystal structures. The tri- and tetrastibanes were identified by 1H NMR and mass spectrometry as components in equilibrium mixtures with distibanes and cyclostibanes. In these mixtures the catena-tri- and tetrastibanes are by far the most abundant chain species and even under favourable conditions [excess of cyclo-

(RSb)n] the catena-tetrastibanes form only as minor components. The presence of the lone pairs on the antimony atoms offers promise for the selective extraction and stabilisation of catena-stibanes in the coordination sphere of transition metal carbonyl complexes. Complexes with homonuclear organoantimony chain ligands have not yet been reported. However complexes with phosphorus or arsenic chains have been reported previously and also a phosphorus antimony chain, Me2P-SbMe-SbMe-PMe2 was synthesised in the coordination sphere of a transition metal carbonyl complex.[32- 40]

3.2 Synthesis and characterisation of cyclo-[Cr(CO)4(R´2Sb-SbR-SbR-SbR´2)]

(R´= Ph or Me, R = Me3SiCH2), cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)],

and cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2)

[102] The trimethylsilylmethyl antimony rings, cyclo-(Me3SiCH2Sb)n (n = 4, 5) react [103] [104] instantaneously with Me4Sb2, or Ph4Sb2, in benzene with formation of the

Results and Discussion tristibanes catena-Me2Sb-SbR-SbMe2 (6) or catena-Ph2Sb-SbR-SbPh2 (7) (R =

Me3SiCH2) as major components of the equilibria mixtures.

' ' ' cy cl o - ( M e3 Si CH 2S b )n + n R 4 Sb 2 n R 2 Sb - S b R- S b R 2 n = 4 , 5 6: R ' = M e 7 : R ' = P h

R = Me 3 Si C H2

Even at low temperatures the equilibria reactions are fast and techniques allowing the isolation of 6 or 7 from the mixtures are not available. Removal of the distibanes gives the antimony rings back. 6 and 7 were identified by 1H NMR spectroscopy in 1 C6D6 and by mass spectrometry in the case of 6. A typical H NMR spectrum of the equilibrium mixture obtained by the reaction of Me4Sb2 with cyclo-(Me3SiCH2Sb)n (n

= 4, 5) in C6D6 is depicted in Figure 7.

o x x

o o o o o o o o o

1.65 1.60 1.55 1.50 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 0.20 0.15 0.10 0.05 -0. (ppm) (ppm)

Figure 7 1H NMR spectrum of the components of the equilibrium mixture containing (Me3SiCH2Sb)5 (o), - Me4Sb2 (~), and Me2Sb-SbCH2SiMe3-SbMe2, 6, (x).

Results and Discussion

The most intense signals stem from the starting materials and from the tristibane, 6, for which the singlet signals at 0.11 ppm for the SiMe3 protons, at 0.89 ppm for the methylene protons of the central Me3SiCH2Sb group and two singlet signals of equal intensity for the diastereotopic methyl substituents of the terminal SbMe2 groups are characteristic. The low intensity signals probably result from catena-Me2Sb-SbR-

SbR-SbMe2 (R = Me3SiCH2) and from longer antimony chains. They disappear with excess distibane. Estimations of the equilibrium constants for the reaction of cyclo- 1 (Me3SiCH2Sb)n with Me4Sb2 or Ph4Sb2 are based on the intensity of the H NMR signals of the most abundant components using the C6H6 peak as internal standard. 5 5 For K = [Me2SbSbRSbMe2] / [R5Sb5] [Me4Sb2] , R = Me3SiCH2, K = 26 was found. Analogous values for R = Et or n-Pr are K = 120 or K = 46.[11] For K = 5 5 [Ph2SbSbRSbPh2] / [R5Sb5] [Ph4Sb2] , R = Me3SiCH2, K = 8 was found. These data reflect a partial shift of the equilibria towards catena-stibanes when bulkier substituents at the end and less bulky groups in the centre of the antimony chains are used. A complete shift of the equilibria is achieved when antimony chains are trapped as ligands in transition metal carbonyl complexes.

The equilibrium mixtures obtained by combining solutions of Me4Sb2 or Ph4Sb2 with cyclo-(Me3SiCH2Sb)n (n = 4, 5) in toluene react with [Cr(CO)4(nbd)] (nbd = norbornadiene) to give the tetrastibane complexes cyclo-[Cr(CO)4(R´2Sb-SbR-SbR-

SbR´2)] (8: R´= Me; 9: R´= Ph, R = Me3SiCH2). Best yields (8: 69 %, 9: 62 %) are obtained when the exact stoichiometry is used. Variations of molar ratios reduce the yields of 8 and 9 but do not lead to complexes of other catena-stibanes. The highly selective formation of 8 and 9 is remarkable in view of the complexity of the initial mixture, which contains the free tetrastibane at best as a minor component. It reflects the high thermodynamic stability of five-membered ring systems and the good fit between the bite of the tetrastibane ligand and the chromium centre.

+ n/2 Cr(CO)4(nbd) cyclo-(Me3SiCH2Sb)n + n/2 R' Sb 4 2 - n/2 nbd n = 4, 5 n/2 cyclo-[Cr(CO)4(R'2Sb-SbR-SbR-SbR'2)] 8: R' = Me, 9: R' = Ph

Results and Discussion

The influence of the organic substituents from catena-tetrastibane ligands on the donor strengths towards [Cr(CO)4(nbd)] is reflected in the different reactivities of derivatives with methyl or phenyl groups in terminal positions. The former react already at room temperature, whereas for the latter high temperatures with reflux of the solvent are required. Under these conditions migration of the organic groups is also possible and cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)] (R = Me3SiCH2) (10), a complex in which a Me3SiCH2 was replaced by a phenyl group on a central antimony atom of the catena-stibane chain, forms as side product (2.3 %).

Further complexation of 8 with [W(CO)5(thf)] gives the complex cyclo-

[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) (11) in 79 % yield as orange crystals, soluble in aromatic and aliphatic solvents.

cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] + W(CO)5thf -thf

cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5]

11: R = Me3SiCH2

The complexes 8-11 are stable for a short time in air. The NMR spectra of 8 - 11 are consistent with the structures established by X-ray diffraction. They correspond also to the spectra of analogous phosphorus compounds.[32, 35, 37] 1H NMR spectra of 8 and

9 exhibit one singlet for the SiMe3 protons and two doublets (AB spin system) for the methylene groups bonded to one of the central antimony atoms, which are both chiral. The organo groups bonded to the terminal antimony atoms of the ligand are not equivalent and therefore two signals are observed for the SbMe2 groups in 8. In the case of 9 the non equivalency of the phenyl groups is best reflected in the 13C NMR spectra, which exhibit two singlet signals for each kind of carbon atoms of the phenyl rings. In 10 and 11 all the organic groups are non-equivalent. The 1H NMR spectra of 11 show two singlet signals for the SiMe3 groups, two AB spin systems for the methylene groups and four singlet signals for the SbMe2 groups. The EI mass spectra of 8 – 11 contain molecular ions at highest mass and in the case of 8 also with highest intensity. Fragmentation occurs mainly by loss of the CO groups.

Results and Discussion

The IR spectra of 8 - 11 show in the region of the CO-stretching vibrations the common pattern for complexes of the type cis-L2Cr(CO)4. In the case of 11 instead of a strong signal at 1945 – 1950 cm-1, which is common for complexes of the type -1 LW(CO)5, a shoulder was observed at 1952 cm . The composition of 8, 10 and 11 has been proven by high-resolution mass spectrometry and by elemental analyses in the case of 8, 9, 11. In an NMR-tube experiment the reactivity of 8 with tetramethyldistibane was also studied. The spectra reveal that excess distibane leads to the formation of the tristibane 6 and probably to [cis-(Me2SbSbMe2)2Cr(CO)4], a compound showing two singlet signals of equal intensity in the region of the SbMe2 protons (0.87, 1.01 ppm).

Si(2)

C(15) C(11)

C(5) Sb(3a) Sb(2) Sb(4)

Sb(3) Cr(1) Sb(1) Sb(2a) C(16)

C(7) C(6) Si(1)

Figure 8 ORTEP-like representation at 50% probability of the two possible conformers of 8 [ball-and-stick representation of Sb(2a) and Sb(3a)] and atom numbering scheme for one of the d, l forms of 8.

Single crystals for X-ray diffraction studies have been obtained by cooling solutions of 8 in petroleum ether to - 28 °C, solutions of 10 in Et2O to –3 °C, and solutions of

Results and Discussion

11 in petroleum ether/toluene (5/1) to 7 °C. The crystal structures of 8, 10 and 11 consist of five-membered CrSb4 rings in which the Me2Sb-SbR’-SbR-SbMe2 (R, R’ =

Me3SiCH2 in 8, 11; R = Me3SiCH2, R’ = Ph in 10) chain functions as a chelating bidentate four-electron donor via lone pair donation through the terminal Sb atoms. The structures of 8, 10 and 11 are depicted in the Figures 8 - 10. Selected bond distances and angle data have been compiled in Table 3. In all of these complexes the five-membered rings are non-planar, the Sb(2)-Sb(3) unit being twisted out of the Sb(1)-Cr(1)-Sb(4) plane with 22.4o in the case of 11, with 23.3° in the case of 10 and with 26.3o in the case of the main conformer of 8. The organic groups bound to Sb(2) and Sb(3) occupy trans positions. For a catena-tetrastibane the meso and d, l forms are possible, however only the d, l forms act as ligand in 8, 10 and 11.

Table 3 Selected interatomic distances (pm) and angles (°) in 8, 10, and 11. cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (8) Sb(2)-Sb(3) 281.3(5) Cr(1)-Sb(1)-Sb(2) 118.88(2) Sb(2)-Sb(1) 282.8(5) Sb(3)-Sb(2)-Sb(1) 95.805(13) Sb(4)-Sb(3) 282.2(5) Sb(2)-Sb(3)-Sb(4) 94.947(13) Sb(2a)-Sb(3a) 280.0(2) C(11)-Sb(2)-Sb(3) 98.05(16) Sb-Cr(1) 258.8(8) – 259.6(8) C(11)-Sb(2)-Sb(1) 89.14(14) Sb(1)-C 213.7(5) – 214.4(5) C(15)-Sb(4)-C(16) 97.6(3) Sb(2)-C(11) 218.9(5) C-Sb-Cr(1) 113.6(2) - 118.39(1) Sb(3)-C(7) 217.8(5) C-Sb(4)-Sb(3) 99.46(2) - 102.86(2) Sb(4)-C 2.130(6) - 2.139(6) C(6)-Sb(1)-C(5) 98.5(3) C-Sb(1)-Sb(2) 96.52(1) - 104.27(1) Sb(4)-Cr(1)-Sb(1) 92.11(3) C(7)-Sb(3)-Sb(2) 95.24(15) Cr(1)-Sb(4)-Sb(3) 121.55(2) C(7)-Sb(3)-Sb(4) 90.06(14)

cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)] (10) Sb(1)-Sb(2) 286.1(1) Sb(2)-Sb(1)-Cr(1) 120.72 Sb(2)-Sb(3) 282.0(1) Sb(3)-Sb(4)-Cr(1) 121.88

Results and Discussion

Sb(4)-Sb(3) 284.1(2) Sb(1)-Sb(2)-Sb(3) 95.17 Sb(2)⋅⋅⋅Sb(2a) 363.6 Sb(2)-Sb(3)-Sb(4) 97.18 Sb-Cr(1) 260.6(5) – 261.0(6) C-Sb(1)-Sb(2) 99.17 – 103.31 Sb(1)-C 214.6(6) – 215.3(1) C(31)-Sb(2)-Sb(1) 96.06 Sb(2)-C(31) 216.4(6) C(31)-Sb(2)-Sb(3) 93.9 Sb(3)-C(41) 218.4(2) C(41)-Sb(3)-Sb(2) 96.07 Sb(4)-C 213.8(4) – 214.8(1) C(41)-Sb(3)-Sb(4) 91.85 C-Sb(4)-Sb(3) 95.84 – 105.24 Sb(1)-Cr(1)-Sb(4) 91.60 C(51)-Sb(4)-C(61) 99.05 C(1)-Sb(1)-C(21) 96.84

cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (11) Sb(3)-Sb(2) 281.1(9) Sb(3)-Sb(2)-Sb(1) 99.17(3) Sb(3)-Sb(4) 284.5(9) W(1)-Sb(2)-Sb(1) 99.17(3) Sb(1)-Sb(2) 283.2(11) W(1)-Sb(2)-Sb(3) 118.49(3) Sb-Cr(1) 257.6(1) – 259.3(2) C(11)-Sb(2)-Sb(3) 107.7(2) Sb(2)-W(1) 279.1(6) C(11)-Sb(2)-Sb(1) 99.1(2) Sb(4)-C 214.2(1) - 214.5(1) C(11)-Sb(2)-W(1) 116.4(3) Sb(2)-C(11) 214.9(8) C(15)-Sb(1)-C(16) 100.0(5) Sb(3)-C(7) 217.7(9) C(6)-Sb(4)-C(5) 95.9(5) Sb(1)-C 213.4(1) – 215.4(1) C-Sb(1)-Cr(1) 114.9(3) - 118.5(3) C-Sb(4)-Cr(1) 114.0(4) - 117.3(3) Sb(1)-Cr(1)-Sb(4) 94.21(5) C-Sb(1)-Sb(2) 100.4(3) - 101.1(3) Cr(1)-Sb(1)-Sb(2) 118.73(4) C-Sb(4)-Sb(3) 101.5(3) - 102.9(3) Cr(1)-Sb(4)-Sb(3) 121.19(4) C(7)-Sb(3)-Sb(2) 88.6(3) Sb(2)-Sb(3)- 94.780(3) C(7)-Sb(3)-Sb(4) 95.3(3) Sb(4)

Selected geometrical parameters for compounds 8, 10 and 11 are listed in Table 3. The Sb-Cr bond lengths [259.6(8), 258.8(8) pm in 8, 261.06(5), 260.65(5) pm in 10 and 259.3(19), 257.5(15) pm in 11,] lie in the usual range for Sb-Cr distances [(cyclo-

Results and Discussion

[(Me2SbOSbMe2Cr(CO)4]2, 256.6(3), 257.3(4) pm; cis-[(Me2SbSSbMe2)2Cr(CO)4], 259.86(12), 258.38(9) pm].[105] The angles around the antimony atoms [Sb(1) 96.52(17) - 118.39(17)° in 8, 96.82(1) – 116.69(2)° in 10, and 100.0(5) – 118.73(4)° in 11; Sb(4) 97.6(3) – 121.55(2)° in 8, 95.84(1) – 116.4(1)° in 10, and 95.9(5) – 121.19(4)° in 11; Sb(2) 89.14(14) – 98.05(16)° in 8, 93.90(1) – 96.00(2)° in 10, and 99.1(2) – 118.49(3)° in 11 and Sb(3) 90.06(14) – 95.24(15)° in 8, 91.85(2) – 97.18(1) in 10, and 88.6(3) – 116.4(3)° in 11,] correspond to p3 configurations for the 3- coordinate antimony atoms and to sp3 hybridisation for the 4-coordinate antimony atoms. This view is also supported by the Sb-C bond lengths of 8, 10 and 11 [Sb(4- coordinate)-C 213.0(6) – 215.4(10) pm and Sb(3-coordinate)-C 214.9(8)-218.9(5) pm]. No significant differences were observed between the Cr-C or the C-O distances for the carbonyl groups trans to each other or trans to Sb.

Si(1)

C(41)

Sb(3) C(11) C(61) Sb(4) Sb(2)

Cr(1) Sb(1) C(21) Sb(2a) C(31) C(51)

Figure 9 ORTEP-like representation at 50% probability of 10, showing the dimer association and atom numbering scheme for one of the enantiomers of 10.

Results and Discussion

Differences in the π-acceptor strength between the antimony ligand and the carbonyl groups are not reflected in the CO distances. Additional electron densities representing approximately 1.5 electron each were found close to the Sb(2) and Sb(3) atoms of 8. These electron densities were assigned to antimony atoms from another conformation of the five-membered CrSb4 ring. The crystal of 8 contains 98% of the main conformer and 2% of the second conformer, the latter being formed by a ring inversion process. Conformational effects of this kind are not unusual for five- membered metal-containing rings.[106] The crystals of 8 and 11 (Figure 8 and 10) consist of discrete molecules, without unusually close intermolecular contacts. By contrast, in the crystal of 10 (Figure 9) molecules are associated pairwise through short intermolecular contacts (Sb…Sb 363.6 pm). This dimeric association is probably responsible for the colour shift from solid 9 (yellow) to 10 (orange).

Si(2)

C(11) C(5)

Sb(2) C(15) Sb(4) Cr(1) W(1) Sb(3) Sb(1) C(6) C(7)

C(16)

Si(1)

Figure 10 ORTEP-like representation at 25% probability of 11 and atom numbering scheme for one of the enantiomers of 11.

Results and Discussion

3.3 Synthesis and characterisation of the open-chain polystibanes, catena- t t Bu2Sb(SbCH3)nSb Bu2, catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2) and catena-

R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4]. Molecular and crystal

structures of [(CO)5Cr(Me2Sb-SbMe2)Cr(CO)5]

In an earlier attempt to stabilise a catena-tristibane in the solid state, the reactions of [26] Ph2SbM (M = Li, Na) with PhSbCl2 in liquid ammonia were accomplished. The resulting catena-tristibane, Ph2Sb-SbPh-SbPh2, was however found to decompose with formation of Ph2Sb-SbPh2 and a polymeric form of phenylantimony. This result and the inspection of the equilibrium constants calculated for the reaction of cyclostibanes with distibanes[26] indicate that catena-tristibane formation is favoured by bulky organic groups at the terminal antimony atoms and sterically less demanding groups at the central antimony atom. In order to obtain further insight into the chemistry of this organoantimony chain species, the formation and stability of some catena-stibanes was studied. [107] [108] The reduction of a mixture of (Me3SiCH2)2SbBr and CH3SbCl2 with magnesium at room temperature lead to the formation of an orange product, probably

R2Sb(SbCH3)nSbR2 (n = 1, 2; R = CH2SiMe3), which decomposes during the work-up procedures with formation of a yellow solution containing R2Sb-SbR2 (R =

CH2SiMe3) and a black polymeric form of methylantimony, (CH3Sb)x.

+ CH3SbCl2 + Mg / thf, 25 °C R2SbBr R2Sb(SbCH3)nSbR2 n = 1, 2 - MgClBr

R = CH2SiMe3

R Sb-SbR + n/x (CH Sb) x >>5 2 2 3 x

1 The identity of R2Sb-SbR2 (R = CH2SiMe3) was confirmed by comparison of its H NMR spectra with literature data.[109] The black product is insoluble in water or organic solvents and turns rapidly into a white powder when exposed to air. In the

Results and Discussion

EI mass spectra of the black product signals for oligomers of the form (CH3Sb)x (x = 3,4) were observed. A polymeric form of methylantimony,

(CH3)2Sb(CH3Sb)11Sb(CH3)2, was found to form by the elimination of [110] tetramethyldistibane from catena-(CH3)2Sb-SbCH3-Sb(CH3)2. The instability of catena-R2Sb-(SbCH3)n-SbR2 (R = CH2SiMe3) reveals that the kinetic stabilisation supplied by the trimethylsilylmethyl group is not sufficient. A more effective stabilisation of the organoantimony chain species is achieved with t t Bu groups at the terminal antimony atoms. The reduction of a mixture of Bu2SbCl [111] and CH3SbCl2 in 2 : 1 molar ratio with magnesium gave an orange oil consisting t t of the catena-tri- and tetrastibanes, catena- Bu2Sb(SbCH3)nSb Bu2 [n = 1 (12), 2 (13)].

+ CH3SbCl2 + Mg / thf, 25 °C R2SbCl R2Sb(SbCH3)nSbR2 - MgCl2 R = tBu 12: n =1; 13: n = 2

1 t In the H NMR spectra of a C6D6 solution containing 12 and 13 the two Bu groups bound to a terminal antimony atom were found to be anisochronous and hence two singlet signals were observed (Figure 11). This non-equivalence of the organic groups [26] of a peripheral R2Sb moiety is typical for catena-stibanes. There is only one pnictogen chain compound, catena-(CH3)2As-P(CF3)-As(CH3)2, where, on heating, inversion at the As-atoms occurs through an intermolecular exchange reaction.[112] The novel catena-stibanes do not take part in ring-chain equilibria but they decompose however, over 24 hours at room temperature with formation of t 1 t Bu2SbCH3. In the H NMR spectra of Bu2SbCH3 two singlets at 1.16 and 0.57 ppm t + in the intensity ratio 6 : 1 were observed. An intense signal for the Bu2SbCH3 ion was found also in the EI mass spectra of a mixture of 12 and 13 measured at elevated temperatures. Attempts to separate 12 and 13 by column chromatography, using

Al2O3 of activity level I or II as stationary phase failed.

Results and Discussion

x x

o o

x o

1.8 1.6 1.4 1.2 1.0

1 t Figure 11 H NMR spectra of a C6D6 solution containing catena- Bu2Sb-SbCH3- t t t Sb Bu2 (x), and catena- Bu2Sb(SbCH3)2Sb Bu2 (o).

The effect of terminal mesityl groups in stabilising chain compounds was also [113] [114] explored. Reaction of Mes2SbLi with PhSbCl2 at –70 °C followed by purification of the reaction products by column chromatography leads to the isolation of an orange oil consisting of a 8 : 2 mixture of catena-tri- and tetrastibanes, catena-

Mes2Sb(SbPh)nSbMes2 [n = 1 (14), 2 (15)]. Again, the separation of 14 from 15 by column chromatography was unsuccessful.

+ PhSbCl2 / thf, -70 °C Mes2SbLi Mes2Sb(SbPh)nSbMes2 - LiCl 14: n =1; 15: n = 2

The mixture of 14 and 15 is air sensitive, but it is stable in an inert atmosphere, at room temperature for several days. The 1H NMR spectra of a mixture of 14 and 15 show the expected pattern for the diastereotopic mesityl groups of the peripheral

Mes2Sb unit, i.e. three sets of two singlets for the ortho methyl protons, para methyl protons and for the meta protons (Figure 12). In the EI mass spectra the decomposition product Mes2PhSb was identified as being the ion with the highest

Results and Discussion mass. Since there is no evidence for an equilibrium process the formation of 15 can be best interpreted as being the result of an lithium-chlorine exchange [formation of

Mes2SbSb(Ph)Li from Mes2SbSb(Ph)Cl], which takes place on reacting Mes2SbLi with PhSbCl2.

x x

x x x and o o o o o x o o o

7.6 7.2 6.8 2.6 2.4 2.2 2.0

1 () () Figure 12. H NMR spectra of a C6D6 solution containing, catena-Mes2Sb-SbPh-

SbMes2 (x) and catena-Mes2Sb(SbPh)2SbMes2 (o).

[115] We found also that reaction of LiSb(SiMe3)2ּdme (dme = dimethoxyethan) with [93] [2-(Me2NCH2)C6H4]2SbCl in thf at –40 °C results in the formation of a mixture [116] containing Sb(SiMe3)3 and catena-R2Sb-(SbSiMe3)-SbR2 [R = 2- 1 (Me2NCH2)C6H4] (16). The novel catena-stibane was identified in the H NMR spectrum of a mixture of Sb(SiMe3)3 and 16 which contains the expected signals for the diastereotopic [(dimethylamino)methyl]phenyl groups of the peripheral R2Sb unit and one singlet signal for the SiMe3 group from the central antimony atom (Figure

13). Sb(SiMe3)3 is expected to form as a byproduct by the synthesis of 16 if the reaction pathway shown in Scheme 5 is considered.

Results and Discussion

LiSb(SiMe ) + R SbCl (Me Si) Sb-SbR 3 2 2 - LiCl 3 2 2 (A)

LiSb(SiMe3)2 + A Li[(Me3Si)Sb-SbR2] - Sb(SiMe3)3 (B)

R2SbCl + B R2Sb-Sb(SiMe3)-SbR2 - LiCl 16 R = 2-(Me2NCH2)C6H4 Scheme 5

c c NMe2 NMe2 f f H2C H2C # Sb

Sb SiMe3 Sb a e H CN N C H e Me Me H Me Me H d b b d b b a c b f e d

3.5 3.0 2.5 2.0 1.5 1.0 0.5 (ppm)

1 Figure 13 H NMR spectra of a C6D6 solution containing, Sb(SiMe3)3 (#) and catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4] (16). Only the high-field part of the spectra is shown.

A similar reaction pathway was also proposed for the formation of catena- triphosphanes HP[PR2M(CO)5]2 (R = Ph, Et; M = Cr, W) from the reaction of alkali metal-bis(trimethylsilyl)phosphides with pentacarbonylmetal(0)- [117] chlorodiorganophosphanes. Attempts to separate Sb(SiMe3)3 from 16 by column chromatography failed due to the low thermal stability of 16.

Results and Discussion

In an attempt to coordinate catena-Me2Sb-SbR-SbMe2 (R = CH2SiMe3) on Cr(CO)5, the equilibrium mixture obtained by combining solutions of Me2Sb-SbMe2 with cyclo-(Me3SiCH2Sb)n (n = 4, 5) was reacted with Cr(CO)5thf in thf. After complete reaction and separation of the reaction products by column chromatography the tetramethyldistibane complex, [(CO)5W(Me2Sb-SbMe2)W(CO)5] (17) as major product (60 %) and the chelate complex, cyclo-Cr(CO)4(Me2Sb-SbR-SbR-SbMe2) (R

= CH2SiMe3) as minor product (7.6 %) were isolated. This result may suggest that the coordination of catena-stibanes as open-chains on transition metal fragments is not favourable. However, examples of transition metal complexes with open-chain catena-triphosphane ligands are known.[41, 117-119] In the context of our interest in coordination compounds with organoantimony ligands we determined the X-ray crystal structure of [(CO)5W(Me2Sb- [120] SbMe2)W(CO)5] (17). A more direct synthesis of 17 was reported previously. The molecular structure of 17·C6H6 is depicted in Figure 14. It reveals the bridging bidentate coordination of the tetramethyldistibane ligand to two Cr(CO)5 centres. As expected, after complexation an increase in the angles at the antimony atoms (C-Sb-C [121] 99.2 - 100.34° in 17·C6H6 and 92.2 - 95.2° in Me2Sb-SbMe2 ; C-Sb-Sb 96.94 - [121] 102.6° in 17·C6H6 and 94.27 – 94.65° in Me2Sb-SbMe2 ) and a shortening of the [121] Sb-C bonds (214.1 pm in 17·C6H6 and 216.2 pm in Me2Sb-SbMe2 ) was observed.

The Sb-Sb (280.97 pm) and Sb-Cr (262.5 pm) distances in 17·C6H6 compare well with those found in 8 (Sb-Sb 282.1 pm and Sb-Cr 259.2 pm). Additional close

.intermolecular contacts were not found in the crystal of 17ּC6H6

In order to describe the different conformations in Me2Sb-SbMe2 and in 17·C6H6, the torsion angles lp-Sb-Sb-lp (ϕ) for the free ligand (lp is the assumed direction of the lone pair at antimony) and Cr-Sb-Sb-Cr (ϕ) for bridging bidentate coordination, is used. The molecular conformations are gauche and anti for ϕ angles of 60° and 180°.

It should be noted that the ideal anti conformation found in crystalline Me2Sb-SbMe2 [121] (ϕ = 180°) is not preserved after complexation (ϕ = 160° in the case of 17·C6H6). A significant deviation from the ideal anti conformation was also found in [122] [123] [CdI2(Et2Sb-SbEt2)]n. [Re2Br2(CO)6(Ph2Sb-SbPh2)] and

Results and Discussion

[124] [Rh2(cod)2(Ph2Sb--SbPh2)(SbPh2)2] (cod = cyclooctadiene) are the only distibane complexes with the distibane ligand adopting a syn structure, which is a consequence of the positions of the coordination sites in the bridged transition metal fragment. In comparison, all diphosphine complexes of the type [LnM(R2P-PR2)MLn] with known crystal structure adopt in the solid state the ideal anti conformation with ϕ angles of 180°.[125-130] Structural parameters of distibine complexes are summarised in Table 5.

Cr(1) C(3)

C(4) Sb(2) Sb(1)

C(2) C(1)

Cr(2)

Figure 14. ORTEP-like representation at 50 % probability of 17 showing the atomic numbering scheme.

Table 4 Selected interatomic distances (pm) and angles (°) in [(CO)5W(Me2Sb-

SbMe2)W(CO)5] (17·C6H6).

Sb(1)-Sb(2) 281.0 C(1)-Sb(1)-C(2) 99.18 Sb(1)-C(1) 213.9 C(3)-Sb(2)-C(4) 100.3 Sb(1)-C(2) 214.2 Cr(1)-Sb(1)-Sb(2) 122.4 Sb(2)-C(3) 214.4 Cr(2)-Sb(2)-Sb(1) 118.3 Sb(2)-C(4) 214.4 C-Sb(1)-Sb(2) 96.94-102.6 Sb(1)-Cr(1) 262.8 C-Sb(2)-Sb(1) 96.8-104.3 Sb(2)-Cr(2) 262.1 C-Sb-Cr 112.3-118.8

Results and Discussion

Table 5 Geometrical parameters of crystal structures for complexes with bis(stibino) donors. Sb-Sb Sb-M C-Sb-C C-Sb-M ϕa Ref.

(pm) (pm) (deg) (deg) (deg)

Me2Sb-SbMe2 286.3 93.7 180 [121]

Ph2Sb-SbPh2 283.7 94.4 180 [131]

[(CO)5Cr(Me2Sb-SbMe2)Cr(CO)5] 281.0 262.4 99.7 115.6 160 [b]

[I2Cd(Et2Sb-SbEt2)]n 278.4 282.1 103.1 112.6 153 [122]

[(CO)5Cr(Ph2Sb-SbPh2)Cr(CO)5] 286.6 262.6 101.0 116.5 180 [132]

[(CO)5W(Ph2Sb-SbPh2)W(CO)5] 286.1 274.9 100.7 116.8 180 [133]

[Rh2(cod)2(Ph2Sb-SbPh2)(SbPh2)2] 304.0 263.1 95.3 120.4 7 [124]

[Br2Re2(CO)6(Ph2Sb-SbPh2)] 282.6 272.6 102.8 120.6 0.3 [123] aϕ = (lp)M-Sb-Sb-M(lp); [b] This work.

Results and Discussion

4. Bis(diorganobismuth)chalcogenides, (R2Bi)2E [E = S, Te; R =

CH(SiMe3)2]

4.1 Introduction

The first bis(diorganobismuth)chalcogenides, (R2Bi)2E (E = O, S, Se, Te) were prepared fifteen years ago by chalcogen insertion into bismuth-bismuth bonds[134-137], later reactions between diorganobismuth halides and sodium chalcogenides were also used [54]. The only examples with known crystal structures are the mesityl derivatives [54,55] (R2Bi)2E [E = O, S, Se; R = 2,4,6-(CH3)3C6H2]. In this work the synthesis and structural characterisation of two novel bis(dialkylbismuth)chalcogenides, (R2Bi)2E [E =

S, Te; R = CH(SiMe3)2] protected by a bulky alkyl group is described. The telluride, [138] {[(Me3Si)2CH]2Bi}2Te, is a heavy atom analogue of cacodyl oxide and the first organometallic molecule with a Bi-Te bond with known crystal structure[1].

4.2 Synthesis and characterisation of {[(Me3Si)2CH]2Bi}2S and

{[(Me3Si)2CH]2Bi}2Te

The bis(dialkylbismuth) sulfide and telluride, {[(Me3Si)2CH]2Bi}2S (18) and [91] {[(Me3Si)2CH]2Bi}2Te (19), are formed by reaction of [(Me3Si)2CH]2BiCl with

Na2S in water or with Na2Te in liquid NH3, respectively.

2 R2BiCl + Na2E (R2Bi)2E + 2 NaCl

E = S (18), Te (19) R = CH(SiMe ) 3 2

18 is a yellow crystalline compound, readily soluble in organic solvents. The solid compound decomposes in air; it is stable only at low temperature in an inert atmosphere. In solution decomposition occurs with formation of R3Bi [R =

CH(SiMe3)2] and Bi2S3. A similar decomposition pathway was also reported for other

Results and Discussion

Si(3)

Si(6)

C(3) Bi(2) C(2) Bi(1) Si(8) C(4) Si(5) Si(2) Si(4) C(1) S(1) Si(7) Si(1)

Figure 15 ORTEP-like representation of 18 at 50% probability showing the atomic numbering scheme.

Si(4)

Si(6) C(2) Si(3) Si(8) Bi(1) C(4) Bi(2) Si(1) C(3) C(1)

Si(5) Si(7) Te(1) Si(2)

Figure 16 ORTEP-like representation of 19 at 50% probability showing the atomic numbering scheme.

Results and Discussion bis(diorganobismuth)sulfides[54,136]. 19 is a red-brown solid which is very unstable. Decomposition occurs in solution and in solid state even at low temperature (-30 °C). 1 The H NMR spectra of 18 and 19 measured in C6D6 at 20 °C shows two singlet signals for the trimethylsilyl groups and a singlet for the methine protons. Characteristic mass spectra have been obtained by direct chemical ionisation or electron impact techniques. To establish the solid-state structure of 18 and 19, X-ray diffraction studies were carried out on single crystals obtained by cooling concentrated solutions of 18 in petroleum ether and of 19 in tetrahydrofuran. The molecular structures are shown in Figure 15 and 16. Selected bond lengths and angles are given in Table 6.

Table 6 Selected interatomic distances (pm) and angles (°) in 18 and 19.

{[(Me3Si)2CH]2Bi}2S (18) Bi(1)-C(1) 230.7(4) C(1)-Bi(1)-C(2) 104.63(15) Bi(1)-C(2) 230.9(4) C(3)-Bi(2)-C(4) 95.74(14) Bi(2)-C(3) 230.4(4) Bi(2)-S(1)-Bi(1) 92.48(4) Bi(2)-C(4) 230.5(4) C(1)-Bi(1)-S(1) 103.19(10) Bi(1)-S(1) 257.19(12) C(2)-Bi(1)-S(1) 93.56(10) Bi(2)-S(1) 255.74(12) C(3)-Bi(2)-S(1) 101.07(11) C(4)-Bi(2)-S(1) 103.63(9)

{[(Me3Si)2CH]2Bi}2Te (19) Bi(1)-C(1) 230.6(10) C(1)-Bi(1)-C(2) 105.0(4) Bi(1)-C(2) 231.6(10) C(3)-Bi(2)-C(4) 97.7(4) Bi(2)-C(3) 231.5(10) Bi(2)-Te(1)-Bi(1) 88.00(7) Bi(2)-C(4) 231.4(10) C(1)-Bi(1)-Te(1) 103.9(3) Bi(1)-Te(1) 288.9(2) C(2)-Bi(1)-Te(1) 93.5(3) Bi(2)-Te(1) 287.2(3) C(3)-Bi(2)-Te(1) 104.6(3) C(4)-Bi(2)-Te(1) 101.3(3)

Results and Discussion

The crystals of 18 and 19 consist of discrete molecules with a pyramidal environment around the bismuth centres. The Bi2E moieties are angular. The Bi-E-Bi angle in 18 [92.48(4)°] is larger than that found in 19 [88.0(7)°]. As a general trend, the Bi-E-Bi angle becomes smaller going from the oxide to the telluride (see Table 7). The Bi-S bond lengths in 18 [255.74(12) and 257.19(12) pm] are comparable to those found in [54] (Mes2Bi)2S [252.0(7) and 254.5(6) pm] . The Bi-Te bond lengths in 19 [287.2(3) and 288.9(2) pm] are considerably shorter than the shortest Bi-Te distance found in [139] the crystal of Bi2Te3 [306.6(2) pm] . An interesting aspect of the structures of 18 and 19 is the dissimilarity of the bond angles: C-Bi-C = 95.74(14)° and 104.63(15)° in 18, 97.7(4)° and 105.0(4)° in 19; C-Bi(1)-E (E = S) 93.56(10)° and 103.19(10)° in 18, (E = Te) 93.5(3)° and 103.9(3)° in 19. This difference may be a consequence of the steric strain in the molecule, caused by the bulky CH(SiMe3)2 substituents. [140] Similar distorsions have also been observed in the structures of [(Me3Si)2CH]3Bi [91] and [(Me3Si)2CH]2BiCl . In order to describe the different conformations of bis(diorganobismuth)chalcogenides, the torsion angles ϕ, Bi-E-Bi-lp, where lp stands for the assumed direction of the lone pair at bismuth and E for the chalcogen atom, are used. With an assignment of the terms syn and anti to angles of 0° and 180°, the extreme molecular conformations are syn-syn and syn-anti.

R R R

R E R R E R = CH(SiMe3)2, mesityl Bi Bi Bi Bi E = O, S, Se, Te

R R syn-syn syn-anti

As shown in Table 7 all the bis(diorganobismuth)chalcogenides with known crystal structures including 18 and 19 adopt intermediate conformations. They are closer to syn-syn than to syn-anti (Table 7). In 18 and 19 the organic substituents exhibit a gauche orientation (Figure 17) with respect to the Bi⋅⋅⋅Bi axis.

Results and Discussion

Bi(2) Bi(1) Bi(2) Bi(1) C(2) C(2)

C(3) C(4) C(3) C(4) C(1) C(1)

S(1) Te(1) (a) (b)

Figure 17 Conformation of the C2Bi-E-BiC2 fragment in (a) 18 and (b) 19.

Table 7 Comparative dimensional parameters (interatomic distances, pm, and angles, [54,55] [54] [54] deg) for (R2Bi)2E derivatives [R = mesityl, E = O , S , Se and R =

CH(SiMe3)2, E = S, Te].

Conformation R E ϕ Bi-E-Bi-lp Bi-E-Bi C-Bi-C Bi-E Bi⋅⋅⋅Bia)

ϕ1 ϕ2 mesityl 86.51 92.99 124.6(3) 98.3(3) 2.064(7) 3.665 O 98.4(3) 2.075(8) mesityl Ob) 84.17 86.46 117.1(8) 97.4(1) 209.5(2) 359.5 98.3(1) 211.7(2) mesityl S near 19.47 26.3 98.7(3) 97.4(1) 252.0(7) 384.4 syn-syn 98.9(9) 254.5(6)

(Me3Si)2CH S near 21.39 59.12 92.48(4) 95.74(14) 255.7(12) 370.5 syn-syn 104.63(15) 257.2(12) mesityl Se near 22.14 22.14 91.2(1) 100.6(3) 265.1(1) 379.1 syn-syn

(Me3Si)2CH Te near 21.33 62.64 88.0(7) 97.69(4) 287.2(3) 400.2 syn-syn 104.96(4) 288.9(2) a) crystallised with 0.5 EtOH; b) intramolecular Bi⋅⋅⋅Bi distances

Results and Discussion

5. Transition metal complexes with cyclo-(RSbX)n [X = S, Se; R =

CH(SiMe3)2] ligands

5.1 Introduction

Organoantimony sulfides cyclo-(RSbS)n (R = alkyl, aryl) have been under investigation since the end of the 19th century [98,141] but little is known of the structural chemistry of these polymeric or cyclic compounds. The organoantimony selenides cyclo-(RSbSe)n (R

= alkyl, aryl) have received even less attention. In an earlier work on cyclo-(RSbX)n [X

= S, n = 2 - 4; X = Se, n = 2, 3; R = CH(SiMe3)2] a NMR study revealed the presence of ring-ring equilibria between dimers and trimers in chloroform solution.[142] In the case of [142] cyclo-(RSbS)n tetramers were also detected by mass spectrometry. The reaction of a ring-ring equilibrium mixture of cyclo-(RSbX)n [n = 2, 3; X = S, X = Se; R =

CH(SiMe3)2] with W(CO)5thf (thf = tetrahydrofuran) in thf results in trapping of the dimers in cyclo-(RSbX)2[W(CO)5]2 [X = S (20), X = Se (21)]. Complexes with cyclo-

(RSbX)n (R = alkyl, aryl; X = chalcogen) ligands have not been previously described. [22] Closely related compounds are cyclo-(RSbSe)3 (R = 2,4,6-[(Me3Si)2CH]3C6H2 , 2,6- [143] [22] [144] [47] [(Me3Si)2CH]2-4-[(Me3Si)3C]C6H2 ), cyclo-(RSbO)2 , cyclo-R2Sb2S4 , RSb=S , [47] cyclo-RSbSn (n = 5, 7) (R = 2,4,6-[(Me3Si)2CH]3C6H2), and complexes with cyclo- [145] t [146] (PhPS)2 or cyclo-(RESe)2 [R = Bu, E = As; R = Ph, E = P] ligands. Complexes derived from linear Sb-S ligands with known crystal structure are [(Ph2Sb- [147] [148] SPh)3Mo(CO)3], [(Ph2Sb-S-SbPh2)Cr(CO)5], cyclo-[(Me2Sb-S-SbMe2)Cr(CO)4]2 [149] and cyclo-[(Me2Sb-S-SbMe-S-SbMe2)Cr(CO)4]·[nbdCr(CO)4] .

5.2. Synthesis and characterisation of cyclo-(RSbX)2[W(CO)5]2 [X = S, Se; R =

CH(SiMe3)2]

The ring-ring equilibrium mixture of cyclo-(RSbX)n [X = S, Se; n = 2 - 3; R = [142] CH(SiMe3)2] reacts with W(CO)5thf (thf = tetrahydrofuran) to form cyclo-

(RSbX)2[W(CO)5]2 [X = S (20); X = Se (21)].

Results and Discussion

RW(CO)5 Sb 2/n cyclo-(RSbX) + 2 W(CO) thf 25 °C X X n 5 - 2 thf Sb n = 2, 3 RW(CO)5

X = S (20), Se (21) R = CH(SiMe3)2

Brown crystals of 20 (68 %) and 21 (42 %) were obtained by cooling petroleum ether solutions to –28 °C. They are slightly soluble in aromatic or aliphatic hydrocarbons and form brown solutions in tetrahydrofuran, dichloromethane or chloroform. The complexes are stable for a short time in air. Solutions of 20 under an argon atmosphere are stable for several days at room temperature. Crystals of 21 are stable at -30 °C, but slow decomposition occurs on storing solutions of 21 at room temperature. The selective formation of 20 and 21 (the smaller yield for 21 is due to partial decomposition during work-up procedures) is remarkable in view of the complexity of the initial mixture, which contains the ring-ring equilibrium mixture of cyclo-(RSbX)n

(n = 2, 3; X = S, Se). The coordination of two W(CO)5 units to the cyclo-(RSbX)n ligand increases the sterical protection at the periphery of the antimony-chalcogen ring and under these conditions the dimeric form is favoured. We have found no indication for the formation of a complex derived from coordination of the trimers cyclo-(RSbX)3 (X = S, Se) which were present in the initial mixtures. Apparently the trimers were transformed into the dimers on complexation. Both complexes were characterised by IR, 1H and 13C NMR and by mass spectrometry using DCI techniques. The NMR spectra of 20 and 21 in C6D6 are consistent with the structures established by X-ray diffraction and contain the expected singlets for equivalent Me3Si or CH groups. However, the same pattern of the spectra is also to 1 expect for the trans isomer. The H NMR spectra of cyclo-(RSbS)n [n = 2 - 3; R =

CH(SiMe3)2] and 20 are shown in Figure 18.

Results and Discussion

x ~

o o o

x o o ~

0.6 0.5 0.4 0.3 0.2 0.4 0.0 (ppm) (ppm)

1 Figure 18 H NMR spectra in C6D6 of the equilibrium mixture containing cyclo-

(RSbS)n [n = 2 - 3; R = CH(SiMe3)2] (left) and of cyclo-(RSbS)2[W(CO)5]2 (14) (right). cyclo-(RSbS)2 (x); cyclo-(RSbS)3 (o); cyclo-(RSbS)2[W(CO)5]2 (~).

The ring-ring equilibria observed for the free cyclo-(RSbX)n (X = S, Se) ligand are not retained after complexation. However, if solutions of 21 in C6D6 are exposed to sunlight beside the signals of 21 (0.23 ppm for Me3Si and 0.29 ppm for CH) two new singlet 1 signals at 0.22 (Me3Si) and 0.28 (CH) ppm appear in the H NMR spectra. They reach a maximum of intensity after 90 minutes (Figure 19). The photochemical process is reversible and the original spectrum is recovered after 12 h in the absence of light. The most straightforward interpretation for these phenomena is to assume a photochemically induced equilibrium between 21 and the monomer [(CO)5W]RSb=Se [R = CH(SiMe3)2].

(CO)5W W(CO)5 Se (CO)5W

Sb Sb 2 Sb Se

Se R R R

R = CH(SiMe3)2

Results and Discussion

However, also the formation of the trans isomer of 21 cannot be excluded. Attempts to study the photolysed solutions by mass spectroscopy using the ESI technique failed.

x x

5 min 20 min

0.4 0.3 0.2 0.1 0.0 0.4 0.3 0.2 0.1 0.0

x 45 min 90 min

0.4 0.3 0.2 0.1 0.0 0.4 0.3 0.2 0.1 0.0 1 Figure 19 H NMR spectra in C6D6 of a photolysed solutions of 21 (x).

In the case of 20 the DCI mass spectra contain molecular ions at highest mass. Fragmentation occurs mainly by loss of the groups bonded to the antimony atom. The

IR spectra of 20 and 21 show the common pattern for complexes of the type LW(CO)5. The composition of 20 has been proven by elemental analyses. The structures of 20 and 21 were determined by single crystal X-ray diffractometry. The molecular structures are shown in Figure 20 and 21. The central unit of both complexes consists of four-membered Sb2X2 (X = S, Se) rings (mean deviation from plane 9.65 Å for 20 and 12.41 pm for 21) with alternating antimony and chalcogen atoms. The dihedral angles between the Sb-X-X or X-Sb-Sb planes are 12.9° in the case of 20 and

15.7° in the case of 21. In cyclo-(RSbO)2 [R = 2, 4, 6-[(Me3Si)2CH]3C6H2], which

Results and Discussion crystallises as a trans isomer, no deviation from the planarity was observed.[22] In 20 and 21 both antimony atoms of the ring are coordinated to W(CO)5 units which occupy cis positions relative to the ring and trans positions relative to the alkyl groups.

Table 8 Selected interatomic distances (pm) and angles (°) in 20 and 21. cyclo-[(Me3Si)2CHSbS]2[W(CO)5]2 (20) Sb(1)-C(1) 214.3(4) Sb(1)-S(1)-Sb(1)* 89.67(3) Sb(1)-S(1) 242.5(1) S(1)-Sb(1)-S(1)* 89.61(3) Sb(1)-S(1)* 242.8(1) C(1)-Sb(1)-S(1) 103.8(1) W(1)-Sb(1) 273.7(7) C(1)-Sb(1)-S(1)* 99.9(1) Sb(1)…Sb(1)* 3.423(3) C(1)-Sb(1)-W(1) 128.61(10) S(1)…S(1)* 342.0(2) S(1)-Sb(1)-W(1) 112.24(3)

W(1)-Cax 199.6(4) S(1)*-Sb(1)-W(1) 115.28(3)

W(1)-Ceq 203.2(4) – 204.8(5)

cyclo-[(Me3Si)2CHSbSe]2[W(CO)5]2 (21) Sb(1)-C(1) 215.5(3) C(1)-Sb(1)-Se(1) 100.07(7) Sb(1)-Se(1) 255.86(6) C(1)-Sb(1)-Se(1)* 104.27(8) Sb(1)-Se(1)* 255.74(7) Se(1)*-Sb(1)-Se(1) 90.37(3) Se(1)-Sb(1)* 255.74(6) Sb(1)*-Se(1)-Sb(1) 88.56(3) Sb(1)-W(1) 274.91(5) Se(1)-Sb(1)-W(1) 114.493(16) Sb(1)…Sb(1)* 357.2(5) Se(1)*-Sb(1)-W(1) 111.61(2) S(1)…S(1)* 362.9(4) C(1)-Sb(1)-W(1) 128.86(8)

W(1)-Cax 200.2(3)

W(1)-Ceq 204.2(3) - 205.7(4)

The Sb-S bond lengths [242.5(1) and 242.8(1) pm] in 20 are similar to those found in other known complexes with Sb-S ligands, cyclo-[(Me2Sb-S-SbMe-S-

SbMe2)Cr(CO)4]·[nbdCr(CO)4], 243.3(9) and 241.2(8) pm; cyclo-[(Me2Sb-S- [149] SbMe2)Cr(CO)4]2, 242.4(9) and 242.1(5) pm] but shorter than in the case of the

Results and Discussion

[150] solid Me2Sb-S-SbMe2 [249.8(1) pm]. The Sb-Se bond lengths [255.74(6) and

255.86(6) pm] in 21 are similar to those found in Sb(SeMe)3 [256.8(1) – 258.8(1) pm] [151]. In both complexes the endocyclic angles on the antimony and the chalcogen atoms are close to 90° with Sb(1)-S(1)-Sb(1)* 89.67(3)°, S(1)-Sb(1)-S(1)* 89.61(3)° in 20 and Sb(1)-Se(1)-Sb(1)* 88.56(3)°, Se(1)-Sb(1)-Se(1)* 90.37(3)° in 21 and describe an almost ideal square. The Sb-W bond lengths [273.7(7) pm in 20 and 274.91(5) in 21] correspond to the sum of the van der Waals radii for Sb and W

[278.0 pm] and are similar to the values found in cyclo-[Cr(CO)4(Me2Sb-SbR-SbR- [152] SbMe2)W(CO)5] [R = Me3SiCH2 Sb-W 279.1(6) pm]. Longer Sb-W bonds were t [153] found in cyclo-[ Bu4Sb4][W(CO)5]2 [2.847(3) and 2.822(2) Å]. In both complexes the Me3Si groups of the cis alkyl substituents are directed outwards and together with the W(CO)5 groups they shield the molecules from each other. Consequently close intermolecular contacts are not observed in the crystals of 20 and 21. A similar cis orientation of the CH(SiMe3)2 groups exist also in cyclo-(RSb)3 [R = [154] CH(SiMe3)2]. The formation of 20 and 21 in the cis form does not necessarily prove a cis preference also for the free ligand cyclo-(RSbX)2.

W(1) S(1) Sb(1) Sb(1)*

S(1)* Si(1) C(1)

Si(2)

Figure 20 ORTEP-like representation of the structure of 20. Thermal ellipsoids are represented with 50% probability.

Results and Discussion

W(1)

Se(1)

Sb(1)* Sb(1)

Se(1)* Si(1) C(1)

Si(2)

Figure 21 ORTEP-like representation of the structure of 21. Thermal ellipsoids are represented with 50% probability.

Experimental section

6. Experimental Section

6.1. General Comments

All the reactions and manipulations were performed, as far as otherwise not noted, under strict air exclusion, in an inert atmosphere of dry argon. The glass equipment was heated under vacuum (1x10-3 mbar) and filled with argon. The solvents were boiled for ten hours under an argon atmosphere with the appropriate drying agent [155- 157] and freshly distilled prior to their use. As drying agent potassium (tetrahydrofuran), sodium (toluene), sodium/potassium (20 / 80 alloy) (petroleum ether), sodium wire/benzophenone (diethyl ether) and P4O10 (chloroform) were used. Tetrahydrofuran, diethyl ether and petroleum ether were initially stored over potassium hydroxide. For the UV irradiation a TQ 150 mercury lamp of the company Hanau was used. The

Al2O3 (particle size 50-200 µm) used as stationary phase for the column chromatography was heated for 48 h at ~ 300 °C in vacuo (1×10-3 mbar) and then saturated with argon. The obtained Al2O3 corresponds to Grade I on the Brockmann scale [158]. The less active grades, II and III, were obtained successively by the addition of the appropriate amount of water (II, 2 %; III, 4 %). NMR spectra were run on Bruker DPX 200 and AVANCE DRX-600 spectrometers. Chemical shifts are reported in δ units (ppm) referenced to TMS. The signals are indicated using the usual abbreviations: s (singlet), d (doublet), t (triplet), q (quartet), 1 br (broad). As internal standard C6D5H with δ = 7.15 ppm in the H and C6D6 with δ 13 1 = 128.00 ppm in the C-spectra; CHCl3 with δ = 7.25 ppm in the H and CDCl3 with 13 1 δ = 77.00 ppm in the C-spectra; or d5-DMSO with δ = 2.50 ppm in the H and d6- DMSO with δ = 39.43 ppm in the 13C-spectra were used. The programs 1D- and 2D WinNMR were used for the handling of the NMR Spectra.[159] The C, H correlation was performed by use of HSQC spectra, and to define the assignment of the signals to

Experimental section the same or to different organic groups. Mass spectra were recorded on Finnigan MAT CH7 (A) and Finnigan MAT 8222 spectrometers. The pattern of antimony- containing ions was compared with theoretical values. For simulation the program MASPEC was used.[160] For the IR spectra an Perkin Elmer FT-IR SPEKTRUM 1000 instrument was used. The samples were measured as solutions in toluene, petroleum ether, methylene chloride, or nujol, and the absorption spectra of the respective pure solvent was subtracted from the spectrum of the sample. The intensity of the bands is indicated in the usual type: vs = very strong, s = strong, m = mean, sh = shoulder. Elemental analyses were performed by Mikroanalytisches Laboratorium Beller in Göttingen. [161] [89] [90] (Me3SiCH2)3SbBr2, [(2-Me2NCH2)C6H4]Li, [(Me3Si)2CH]SbCl2, [91] [91] [142] [(Me3Si)2CH]BiCl2, [(Me3Si)2CH]2BiCl, cyclo-[(Me3Si)2CHSbS], cyclo- [142] [103] [104] [102] [162] [(Me3Si)2CHSbSe], Me4Sb2, Ph4Sb2, (Me3SiCH2Sb)5, nbdCr(CO)4, [107] [108] [114] [113] t [111] (Me3SiCH2)2SbBr, CH3SbCl2, PhSbCl2, Mes2SbLi, Bu2SbCl , [115] [93] LiSb(SiMe3)2ּdme, [2-(Me2NCH2)C6H4]2SbCl, were prepared according to the reported procedures. The data for X-ray structure analysis were collected on a Siemens P4 four-circle and a Stoe IPDS diffractometer using graphite-monochromated Mo Kα radiation (λ = 71.073 pm). For this propose the crystals were attached with Kel-F oil to a glass fibre and cooled in a nitrogen stream to 173 K. The structures were solved, after Lp correction, by direct methods. All non-hydrogen atoms were refined with anisotropic thermal parameters. The hydrogen atoms were refined with a riding model and a mutual isotropic thermal parameter. For structure solving and refinement the software package SHELX-93 or SHELX-97 [163,164] was used. The drawings were created by the Diamond program by Crystal Impact GbR.[165] Crystallographic data for the structural analysis of some of the crystal structures have been deposited with the respective Cambridge Crystallographic Data Centre CCDC number (appendix). Copies of the information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44-1223-336-033; Email: [email protected] or www: http//www.ccdc.cam.ac.uk).

Experimental section

6.2 Organoantimony- and bismuth halides

Tris[bis(trimethylsilyl)methyl]antimony, [(Me3Si)2CH]3Sb

A solution of (Me3Si)2CHCl (5.00 g, 25.7 mmol) in THF (10 mL) was added with stirring to lithium powder (0.54 g, 77.8 mmol, 50-200 µm) in boiling Et2O (30 mL). The addition was completed after 1 h and the reaction mixture was stirred for 24 h under reflux. The solution was filtered and added at room temperature to freshly sublimed SbCl3 (1.66 g, 7.26 mmol) in Et2O (25 mL). After stirring for 16 h at room temperature the solvents were removed under reduced pressure and the solid residue was extracted with petroleum ether (2 x 120 mL). Removal of the petroleum ether gave 4.26 g (98 %) of [(Me3Si)2CH]3Sb, as a yellow solid which can be purified by sublimation at 110 0C / 6·10-3 mbar. M. p. 80-82 0C. 1 H NMR (C6D6, 200 MHz): 0.31 (s, 18 H, CH3), 0.98 (s, 1H, CH). MS data as reported.[64]

Tris[bis(trimethylsilyl)methyl]antimony dibromide,

[(Me3Si)2CH]3SbBr2

0 At –20 C a solution of Br2 (52 mg, 0.32 mmol) in Et2O (20 mL) was added to

[(Me3Si)2CH]3Sb (200 mg, 0.33 mmol) in 30 mL Et2O. After the addition the mixture was allowed to warm to room temperature. Slow evaporation of the solvent yielded

210 mg (84 %) of [(Me3Si)2CH]3SbBr2 as colourless crystals melting at 174 °C.

Anal. found: C, 33.20; H, 7.55; Br, 21.00. C21H57Si3Br2Sb calc.: C, 33.20; H, 7.56; Br, 20.75 %. 1 H NMR (CDCl3, 200 MHz), 20 °C: 0.43 (s, 18 H, CH3), 2.38 (s, 1 H, CH); -70 °C:

0.28 (m, 54 H, CH3), 2.09, 2.23, 2.36, 2.57 (s, 1 H, CH).

Experimental section

1 H NMR (C6D6, 200 MHz): 0.51 (m, 54 H, CH3), 2.49, 2.60, 2.80, 2.91 (s, 1 H, CH). 13 C NMR (C6D6, 50 MHz): 5.06 (s, CH3), 5.14 (s, CH3), 5.46 (s, CH3), 5.63 (s, CH3), 36.15 (s, CH), 37.37 (s, CH), 40.43 (s, CH), 42.51 (s, CH). MS (EI, 70 eV): 745 (5) [M+ - Me], 679 (41) [M+ - Br], 599 (3) + + [[(Me3Si)2CH]2SbBr2 ], 505 (8) [[(Me3Si)2CH]2SbBr - Me], 439 (32) + + [[(Me3Si)2CH]2Sb ], 361 (16) [[(Me3Si)2CH]SbBr ], 273 (13), 207 (11) + + + [(Me3Si)CHSb ], 129 (100) [(Me3Si)2CH - 2Me], 87 (49) [Me4Si ], 73 + + (100) [Me3Si ], 59 (36) [Me2Si ].

Tris[(trimethylsilyl)methyl]antimony bromide hydroxide,

(Me3SiCH2)3Sb(OH)Br

a) by hydrolysis of [(Me3Si)2CH]3SbBr2. 35 mg (0.046 mmol)

[(Me3Si)2CH]3SbBr2 in 5 mL Et2O was added to 1 mL of a solution of KOH (1 %) in water. After stirring for 2 h the organic phase was separated and washed twice with 5 mL of diethyl ether. The organic phases were dried with Na2SO4. Crystals of

(Me3SiCH2)3Sb(OH)Br (154 mg, 70 %) were obtained by slow evaporation of the diethyl ether solution and used for X-ray diffractommetry.

b) by hydrolysis of (Me3SiCH2)3SbBr2. 6.5 mL of a solution of KOH (1 %) in water was added to a solution of (Me3SiCH2)3SbBr2 (0.63 g, 1.16 mmol) in Et2O (40 mL). After stirring for 4 h the organic phase was separated and the water phase was washed twice with 50 mL of diethyl ether. The organic phases were dried with

Na2SO4. The solvent was removed in vacuo and the remaining white solid was washed twice with 5 mL of petroleum ether. Crystals of (Me3SiCH2)3Sb(OH)Br (0.4 g , 72 %, m. p. 120-123 °C) were obtained by slow evaporation of the petroleum ether solution.

Anal. found: C, 29.88; H, 7.03. C12H34Si3BrOSb calc.: C, 30.01; H, 7.13%. 1 2 1 H NMR (C6D6, 200 MHz): 0.20 (s, 27 H, CH3, JSiH = 6.7 Hz, JCH = 117.5 Hz), 1.81

(s, 6 H, CH2).

Experimental section

1 2 1 H NMR (CDCl3, 200 MHz): 0.27 (s, 27 H, CH3, JSiH = 6.5 Hz, JCH = 119.7 Hz),

1.78 (s, 6 H, CH2). 13 C NMR (C6D6, 50 MHz): 0.88 (s, 27 H, CH3), 27.11 (s, 6 H, CH2). - - - MS (CIneg, NH3): 465 (100) [M - Me], 421 (7) [M - 4Me], 393 (43) [M - - CH2SiMe3], 319 (7) [(Me3SiCH2)2SbBr(OH) - Me3Si].

IR (CH2Cl2): 3632 sh ν(O-H), 848 vs δ(Sb-O-H), 542 m ν(Sb-O). IR (Nujol): 3446 br ν(O-H), 841 vs δ (Sb-O-H), 581 m ν(Sb-O) cm-1.

Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]stibine,

[(2-Me2NCH2)C6H4][(Me3Si)2CH]SbCl

A solution of 2-(N,N-dimethylaminomethyl)phenyllithium (1.11 g, 7.87 mmol) in toluene (40 mL) was added to a cold (-78 °C) solution of [(Me3Si)2CH]SbCl2 (2.77 g, 7.87 mmol) in toluene (30 mL) over 1 h. The reaction was stirred at this temperature for ½ h and then allowed to warm to room temperature. The solution was filtered and the solvent removed in vacuo to yield 3.39 g (96 %) of [(2-

Me2NCH2)C6H4][(Me3Si)2CH]SbCl as colourless solid. M. p.: 80 °C.

Analysis: Found: C, 41.96; H, 6.75. C16H31Si2SbClN calc.: C, 42.63; H, 6.93 %. 1 2 H NMR (C6D6, 200 MHz): -0.19 (s, 1 H, CH), 0.07 (s, 9 H, SiCH3, JSiH = 6.3 Hz), 2 0.44 (s, 9 H, SiCH3, JSiH = 6.3 Hz), 1.59 (s, 3 H, NCH3), 1.75 (s, 3 H, 2 NCH3), AB spin system with A: 2.81, B: 3.49 (2 H, CH2, JHH = 14.2 Hz), 3 6.8 (d, 1 H, C6H4, JHH = 7.4 Hz), 7.1 (m, 2 H, C6H4), 8.8 (dd, 1 H, C6H4, 3 4 JHH = 7.4 Hz, JHH = 1.2 Hz). 13 C NMR (C6D6, 50 MHz): 3.7 (s, SiCH3), 4.16 (s, SiCH3), 10.07 (s, CH), 44.46 (s,

NCH3), 45.71 (s, NCH3), 65.65 (s, CH2), 126.49 (s, C6H4), 128.30 (s,

C6H4), 128.94 (s, C6H4), 137.61 (s, C6H4), 142.90 (s, C6H4), 145.42 (s,

C6H4). + + + MS (CIpos, NH3) m/z (%): 452 (16) [M + H], 416 (100) [M - Cl], 292 (28) [RSbCl ], + 134 (8) [R ] R = C6H4CH2NMe2. - - MS (CIneg, NH3) m/z (%): 486 (100) [M + Cl], 451 (28) [M ].

Experimental section

Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]bismuthine,

[(2-Me2NCH2)C6H4][(Me3Si)2CH]BiCl

The reaction of 2.17 g (4.94 mmol) [(Me3Si)2CH]BiCl2 with 0.69 g (4.89 mmol) 2- (N,N-dimethylaminomethyl)phenyllithium in 75 mL of toluene and the work-up procedures were performed in an analogous manner to the synthesis of [(2-

Me2NCH2)C6H4][(Me3Si)2CH]SbCl. After filtration of the reaction mixture and removal of the solvent 2.42 g (91 %) of [(2-Me2NCH2)C6H4][(Me3Si)2CH]BiCl as colourless solid were obtained. 141-143 °C decomposition.

Analysis: Found: C, 36.05; H, 5.69. C16H31Si2BiClN calc.: C, 35.72; H, 5.81 %. 1 H NMR (C6D6, 200 MHz): -0.17 (s, 1 H, CH), 0.14 (s, 9 H, SiCH3), 0.39 (s, 9 H,

SiCH3), 1.55 (s, 3 H, NCH3), 1.74 (s, 3 H, NCH3), AB spin system with A: 2 3.02, B: 3.44 (2 H, CH2, JHH = 14.4 Hz), 7.16 (m, 3 H, C6H4), 9.32 (d, 1 H, 3 C6H4, JHH = 7.6 Hz). 13 C NMR (C6D6, 50 MHz): 4.26 (s, SiCH3), 5.54 (s, SiCH3), 31.58 (s, CH), 44.53 (s,

NCH3), 46.6 (s, NCH3), 68.99 (s, CH2), 128.13 (s, C6H4), 128.29 (s, C6H4),

128.94 (s, C6H4), 130.79 (s, C6H4), 140.55 (s, C6H4), 147.48 (s, C6H4). + + + MS (CIpos, NH3) m/z (%): 538 (14) [M + H], 502 (100) [M - Cl], 136 (70) [R + H]

R = C6H5CH2NMe2. - - MS (CIneg, NH3) m/z (%): 572 (92) [M + Cl], 537 (100) [M ], 403 (10) - [(Me3Si)2CHBiCl ].

[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]stiban,

[(2-Me2NCH2)C6H4][(Me3Si)2CH]SbH

A solution of 2.6 g (5.77 mmol) [(2-Me2NCH2)C6H4][(Me3Si)2CH]SbCl in Et2O (50 mL) was added drop-wise to a cold (-78 °C) suspension of LiAlH4 (0.23 g, 6.05 mmol) in Et2O (30 mL). The mixture was warmed and filtered through a D4 frit

Experimental section covered with Kieselguhr. Removal of the solvent under reduced pressure gave 2.08 g

(86.6 %) of [(2-Me2NCH2)C6H4][(Me3Si)2CH]SbH as colourless, viscous oil. 121 + HRMS (EI, 70 eV): 415.11019 (calcd 415.11116 amu, C16H32NSi2Sb , M ). 1 3 H NMR (C6D6, 200 MHz): 0.1 (d, 1 H, CH, JHH = 3.3 Hz), 0.17 (s, 9 H, SiCH3),

0.24 (s, 9 H, SiCH3), 1.92 (s, 6 H, NCH3), AB spin system with A: 3.38, B: 2 3 3.54 (2 H, CH2, JHH = 13.1 Hz), 4.34 (d, 1 H, SbH, JHH = 3.3 Hz), 6.98

(m, 3 H, C6H4), 7.75 (m, 1 H, C6H4). + + + MS (CIpos, NH3) m/z (%): 416 (100) [M + H], 256 (26) [RSbH ], 136 (40) [R + 2

H] R = C6H4CH2NMe2. - - MS (CIneg, NH3) m/z (%): 414 (100) [M ], 159 (25) [(Me3Si)2CH ]. MS (EI, 70 eV): 415 (5) [M+], 400 (5) [M+ - Me], 256 (100) [RSbH+], 134 (28) [R+]

R = C6H4CH2NMe2. -1 IR (toluene-d6): 1791 cm (ν Sb-H).

Experimental section

6.3 Organoantimony chains

Reactions of cyclo-(Me3SiCH2Sb)n (n = 4, 5) with distibanes

Solutions of distibanes (Me2SbSbMe2 and Ph2SbSbPh2) in various concentrations in

C6D6 were added at room temperature to saturated solutions of (Me3SiCH2Sb)5. The catena-stibanes were formed immediately in equilibria with the distibanes and the cyclostibane. The molar ratio of the components was determined by integration of the NMR signals.

1,1,3,3-Tetramethyl-2-(trimethylsilylmethyl)tristiban, Me2Sb-Sb(CH2SiMe3)-

SbMe2 1 2 H NMR (C6D6, 600 MHz): 0.11 (s, 9 H, (CH3)3Si, JSiH = 6.4 Hz), 0.89 (s, 2 H, CH2), 13 1.05 (s, 6 H, CH3Sb), 1.08 (s, 6 H, CH3Sb). C (C6D6, 50 MHz):-12.42

(CH2), -8.40 (CH3Sb), -8.20 (CH3Sb), 1.33 ((CH3)3Si). o + + + MS (EI, 70 eV, 44 C): 512 (2) [M ], 497 (1) [M - Me], 440 (3.4) [M - Me3Si], 425 + + + (2) [Sb3Me2 ], 409 (1.4) [Sb3Me3 ], 395 (4.4) [Sb3Me2 ], 376 (1.2) + + [Sb3Me ], 365 (1) [Sb3 ].

1,1,3,3-Tetraphenyl-2-(trimethylsilylmethyl)tristiban, Ph2Sb-Sb(CH2SiMe3)-SbPh2 1 2 1 H NMR (C6D6, 600 MHz): -0.11 (s, 9 H, (CH3)3Si, JSiH = 6.3 Hz, JCH = 115.2 Hz),

0.90 (s, 2 H, CH2), 7.06 (m, 12 H, C6H5 – m + p), 7.72 (m, 8 H, C6H5 - o). 13 C (C6D6, 50 MHz):-9.13 (CH2), 0.63 ((CH3)3Si), 128.56 (C6H5 - p), 128.72 (C6H5 -

p), 129.31 (C6H5 - m), 129.37 (C6H5 - m), 138.08 (C6H5 - o), 138.27 (C6H5 - o).

Experimental section

Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2)

A mixture of 0.99 g (0.94 mmol) of (Me3SiCH2Sb)5 and 0.72 g (2.36 mmol) of Me4Sb2 in 15 mL of toluene was added to 0.6 g (2.36 mmol) of nbdCr(CO)4 in toluene. (10 mL). The reaction mixture was stirred for 12 h at room temperature. Thereafter the solution was reduced to 10 mL, combined with Al2O3 (2 g), dried to a flowing powder under reduced pressure and placed on a chromatography column (12 x 2 cm, Al2O3, activity level II). With petroleum ether/toluene (1/1) an intense orange fraction was eluted. Removal of the solvents under reduced pressure gave 1.44 g (69 %) of cyclo-

[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2) as an orange microcrystalline solid. Crystals were grown by keeping a solution of cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-

SbMe2)] (R = Me3SiCH2) in petroleum ether for 2 days at –28 °C; m. p. 107 °C. 52 121 123 HRMS (EI, 70 eV): 885.75616 (calcd 885.75617 amu, C16H34O4Si2Cr Sb2 Sb2 , M+).

Anal. Calcd.for C16H34Si2O4Cr1Sb4 (885.57): C, 21.70; H, 3.86. Found: C, 21.71; H, 3.82. 1 1 2 H NMR (C6D6, 200 MHz): -0.04 (s, 18 H, (CH3)3Si, JCH = 136.9 Hz, JSiH = 6.1 Hz), 2 AB spin system with A: 0.11, B: 0.19 (4 H, CH2, JHH = 12.9 Hz), 1.09 (s,

6 H, CH3Sb), 1.38 (s, 6 H, CH3Sb). 13 C NMR (C6D6, 50 MHz): -9.34 (s, CH2), -2.56 (s, CH3Sb), -1.95 (s, CH3Sb), 0.62

(s, (CH3)3Si), 221.82 (s, COeq), 234.42 (s, COax). IR (toluene): 1998 s, 1988 sh, 1909 vs cm-1 (ν CO). MS (EI, 70 eV, 204 oC): 886 (100) [M+], 802 (14) [M+ - 3 CO], 774 (47) [M+ - 4 + + CO], 740 (4) [M - (SiMe3)2], 686 (14) [Sb4Me6Cr(CO)2 ], 670 (15) + + [(Me3SiCH2)4Sb3 – 3 Me], 540 (20) [Sb4Cr ], 502 (33) + + [CH2Sb2Cr2(CO)5 ], 446 (18) [(Me3SiCH2)4Sb2 – (SiMe3)2], 430 (23), 417 + + (20) [(Me3SiCH2)4Sb2 – CH2(SiMe3)2, - Me], 295 (11) [(Me3SiCH2)2Sb ], + + + 225 (5) [(Me3SiCH2)MeSb ], 139 (29) [Me3SiCH2Cr ], 73 (58) [Me3Si ], 52 (18) [Cr+].

Experimental section

Cyclo-[Cr(CO)4(Ph2Sb-SbR-SbR-SbPh2)] and cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-

SbPh2)] (R = Me3SiCH2)

The reaction of a mixture of 0.37 g (0.35 mmol) (Me3SiCH2Sb)5 and 0.49 g (0.88 mmol)

Ph4Sb2 with 0.22 g (0.88 mmol) nbdCr(CO)4 in 20 mL of toluene and the work-up procedures were performed in an analogous manner to the synthesis of cyclo-

[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2). However, after stirring for 12 h at room temperature, the reaction mixture was heated under reflux for 3 h. For the chromatography Al2O3, activity level III, 17 x 2 cm was used. Cyclo-[Cr(CO)4(Ph2Sb-

SbR-SbR-SbPh2)] (R = Me3SiCH2) was eluted with petroleum ether/toluene (19/1) as a yellow fraction. Removal of the solvent under reduced pressure gave 0.62 g (62 %) of cyclo-[Cr(CO)4(Ph2Sb-SbR-SbR-SbPh2)] (R = Me3SiCH2) as a yellow microcrystalline solid. m. p. 181 °C.

Anal. Calcd.for C36H42Si2O4Cr1Sb4 (1133.86): C, 38.13; H, 3.73. Found: C, 38.36; H, 3.82. 1 1 H NMR (C6D6, 200 MHz): -0.02 (s, 18 H, (CH3)3Si, JCH = 122.1 Hz), AB spin 2 system with A: 0.08, B: 0.47 (4 H, CH2, JHH = 12.8 Hz), 6.91 - 7.08 (m, 12 3 H, C6H5 - m + p), 7.95 (d, 4 H, C6H5 - o, JHH = 7.2 Hz), 8.10 (d, 4 H, C6H5 3 - o, JHH = 7.2 Hz). 13 C NMR (C6D6, 50 MHz): -8.45 (s, CH2), 0.23 (s, (CH3)3Si), 129.67 (s, C6H5 - m),

129.74 (s, C6H5 - p), 129.83 (s, C6H5 - m), 129.87 (s, C6H5 - p), 134.24 (s,

C6H5 - ipso), 134.70 (s, C6H5 - ipso), 136.17 (s, C6H5 - o), 136.61 (s, C6H5 -

o), 221.63 (s, COeq), 233.72 (s, COax). IR (toluene): 2003 vs, 1970 sh, 1909 vs cm-1 (ν CO). MS (EI, 70 eV, 230 oC): 1134 (22) [M+], 1022 (52) [M+ - 4 CO], 658 (14) + + [Sb3Ph(Me3SiCH2)3 - 3 Me], 648 (15) [Sb3Ph2(Me3SiCH2)2 - 3 Me], 604 + + + (38) [Ph4Sb2Cr ], 552 (20) [Ph4Sb2 ], 502 (27) [CH2Sb2Cr2(CO)5 ], 450 + + + (26) [CH2Sb2Cr(CO)5 ], 327 (29) [Ph2SbCr ], 295 (23) [(Me3SiCH2)2Sb ], + + + 285 (25) [(Me3SiCH2)SbPh ], 275 (65) [Ph2Sb ], 205 (39) [Sb(CH2Si)2 ],

Experimental section

+ + + + 154 (100) [Ph2 ], 135 (96) [PhSiMe3 ], 77 (20) [Ph ], 73 (98) [Me3Si ], 52 (34) [Cr+], 28 (9) [Si+]. With petroleum ether/toluene (3/1) an orange fraction was eluted. Removal of the solvent under reduced pressure gave 0.023 g (2.3 %) of cyclo-[Cr(CO)4(Ph2Sb-SbPh-

SbR-SbPh2)] (R = Me3SiCH2) as a yellow microcrystalline solid. m. p. 166 °C. 52 121 123 HRMS (EI, 70 eV): 1123.79599 (calcd 1123.79489 amu, C38H36O4SiCr Sb2 Sb2 , M+). 1 H NMR (C6D6, 200 MHz): -0.16 (s, 9 H, (CH3)3Si), AB spin system with A: -0.02, 2 B: 0.53 (2 H, CH2, JHH = 12.9 Hz), 6.47 – 6.63 (m, 3 H, SbC6H5 - m + p),

6.72 – 6.76 (m, 2 H, SbC6H5 - o), 6.93 – 7.09 (m, 12 H, Sb(C6H5)2 – m +

p), 7.64 – 8.10 (m, 8 H, Sb(C6H5)2 – o). 13 C NMR (C6D6, 50 MHz): -9.22 (s, CH2), 0.34 (s, (CH3)3Si), 126.3 (s, C6H5 - ipso),

129.32 – 129.79 (m, C6H5 – m + p), 134.15, 134.52, 134.74, 135.14 (s,

C6H5 - ipso), 136.16, 136.27, 136.32, 136.69, 138.40 (s, C6H5 - o), 220.40

(s, COeq), 221.39 (s, COeq), 233.98 (s, COax). IR (toluene): 2279 s, 2002 vs, 1907 vs cm-1 (ν CO). o + + + MS (EI, 70 eV, 214 C): 1124 (5) [M ], 1012 (52) [M - 4 CO], 604 (8) [Ph4Sb2Cr ], + + + 552 (38) [Ph4Sb2 ], 327 (6) [Ph2SbCr ], 275 (60) [Ph2Sb ], 154 (100) + + + + [Ph2 ], 135 (35) [PhSiMe3 ], 77 (29) [Ph ], 52 (17) [Cr ].

Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2)

0.5 g (0.56 mmol) of cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2) and

0.22 g (0.56 mmol) of W(CO)5(thf) in 150 mL of thf were stirred for 12 h at room temperature. Thereafter, the solution was reduced to 10 mL, combined with Al2O3 (1.5 g), dried to a flowing powder under reduced pressure and placed on a chromatography column (20 x 2 cm, Al2O3, activity level III). An orange fraction was eluted with petroleum ether/toluene (19/1). Removal of the solvents under reduced pressure gave

0.54 g (79 %) of cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) as an orange microcrystalline solid. Crystals were grown by storing a solution of cyclo-

Experimental section

-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) in petroleum ether/toluene (5/1) for 12 h at 7 °C; m. p. 146-147 °C. 52 121 182 HRMS (EI, 70 eV): 1203.67822 (calcd 1203.67826 amu, C21H34O9Si2Cr Sb4 W , M+).

Anal. Calcd. for C21H34Si2O9Cr1W1Sb4 (1209.47): C, 20.85; H, 2.83. Found: C, 21.10; H, 2.94. 1 H NMR (C6D6, 200 MHz): -0.06 (s, 9 H, (CH3)3Si), -0.04 (s, 9 H, (CH3)3Si), AB 2 spin system with A: 0.08, B: 0.16 (2 H, CH2, JHH = 12.7 Hz), AB spin 2 system with A: 0.70, B: 0.82 (2 H, CH2, JHH = 12.9 Hz), 1.13 (s, 3 H,

CH3Sb), 1.18 (s, 3 H, CH3Sb), 1.31 (s, 3 H, CH3Sb), 1.40 (s, 3 H, CH3Sb). 13 C NMR (C6D6, 50 MHz): -8.01 (s, CH2), -4.95 (s, CH2), -2.46 (s, CH3Sb), -1.95 (s,

CH3Sb), -1.62, (s, CH3Sb), -0.13 (s, (CH3)3Si), 0.79 (s, CH3Sb), 1.16 (s,

(CH3)3Si), 197.58, 198.47, 220.75, 232.21 (CO). IR (toluene): 2064vs, 1999 s, 1977 sh, 1952 sh, 1914 s, 1900 s cm-1 (ν CO). MS (EI, 70 eV, 237 oC): 1210(29) [M+], 1098 (26) [M+ - 4 CO], 886 (100) [M+ - + + W(CO)5], 802 (32) [M - W,- 8 CO], 774 (82) [M - W, 9 CO], 742 (16) + + [M - W(CO)5,- (SiMe3)2], 686 (29) [Sb4Me6Cr(CO)2 ], 670 (17) + + [(Me3SiCH2)4Sb3 – 3 Me], 540 (19) [Sb4Cr ], 502 (29) + + [CH2Sb2Cr2(CO)5 ], 446 (16) [(Me3SiCH2)4Sb2 – (SiMe3)2], 430 (18), 417 + + (17) [(Me3SiCH2)4Sb2 – CH2(SiMe3)2, - Me], 295 (8) [(Me3SiCH2)2Sb ], + + + 139 (19) [Me3SiCH2Cr ], 73 (56) [Me3Si ], 52 (22) [Cr ].

Reaction of CH3SbCl2 and R2SbBr with Mg (R = Me3SiCH2)

To 0.35 g (14.58 mmol) magnesium filings activated with 0.5 mL 1,2-dibromethane were added simultaneously 5.43 g (14.44 mmol) (Me3SiCH2)2SbBr in 35 mL thf and 1.5 g (7.21 mmol) CH3SbCl2 in 15 mL thf using of two dropping funnels. The reaction mixture was stirred for 2 h at room temperature until the magnesium had all reacted. The solvent was subsequently removed in vacuo and the black remaining product mixture

Experimental section was washed with 3x100 mL petroleum ether, yielding an orange solution. During the extraction from the orange petroleum ether solution a black solid product precipitate and the solution becomes yellow. 2.77 g (64.87 %) of a yellow-orange oil and 0.31 g of a black powder was obtained. 1 H NMR (C6D6, 200 MHz): [(Me3SiCH2)2Sb]2: 0.17 (s, 36 H, (CH3)3Si), AB spin 2 system with A: 0.67, B: 0.97 (8 H, CH2, JHH = 13 Hz). + + MS (EI, 70 eV, 238 °C) black product: 546 (1.75) [Me4Sb4 ], 531 (1.5) [Me3Sb4 ], + + + 501 (1.8) [MeSb4 ], 410 (100) [Me3Sb3 ], 395 (69) [Me2Sb3 ], 365 (54) + + + + [Sb3 ], 304 (62) [Me4Sb2 ], 289 (34) [Me3Sb2 ], 274 (19) [Me2Sb2 ], 259 + + + + (26) [MeSb2 ], 244 (20) [Sb2 ], 166 (11) [Me3Sb ], 151 (100) [Me2Sb ].

t t Catena- Bu2Sb(SbCH3)nSb Bu2 (n = 1, 2)

t The reaction of a mixture of 4.93 g (18.15 mmol) Bu2SbCl in 25 mL thf and 1.89 g

(9.08 mmol) CH3SbCl2 in 15 mL thf with 0.5 g (20.83 mmol) Mg and the work-up procedures were performed in an analogous manner to the syntheses described above. However, after stirring for 5 h at room temperature, and removal of the solvent in vacuo the brown remaining product mixture was washed with 4x120 mL petroleum ether, giving an orange solution. Evaporation of the solvent gave 2.56 g of a mixture of 70 mol t t t t % of catena- Bu2Sb-SbCH3-Sb Bu2 and 30 mol % of catena- Bu2Sb(SbCH3)2Sb Bu2 as an orange oil. 1 t t H NMR (C6D6, 200 MHz): catena- Bu2Sb-SbCH3-Sb Bu2: 1.05 (s, 3H, SbCH3), 1.46

(s, 18 H, (CH3)3C), 1.53 (s, 18 H, (CH3)3C). catena- t t Bu2Sb(SbCH3)2Sb Bu2: 1.35 (s, 6H, SbCH3), 1.42 (s, 18 H, (CH3)3C), 1.51

(s, 18 H, (CH3)3C). o t + t + MS (EI, 70 eV, 100 C): 550 (4) [ Bu3(CH3)Sb3 ], 472 (1) [ Bu4Sb2 ], 430 (7) t + t + t + [ Bu3(CH3)Sb2 ], 388 (1) [ Bu2(CH3)2Sb2 ], 374 (3) [ Bu2(CH3)Sb2 ], 259 (6) + t + t + + [(CH3)Sb2 ], 194 (2) [ Bu(CH3)Sb ], 179 (2) [ BuSb ], 151 (2) [(CH3)2Sb ], 57 (100) [tBu+].

Experimental section

Catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2)

A solution of 0.275 g (1.02 mmol) PhSbCl2 in 60 mL of thf was added drop-wise to a solution of 0.817 g (2.26 mmol) Mes2SbLi in 40 mL thf at –70 °C. The solution mixture was stirred for 1 h at –70 °C and than allowed to warm slowly to room temperature. Afterwards the solvent was removed in vacuo and the residue extracted with 100 mL of petroleum ether. The orange petroleum ether solution was reduced to 10 mL, combined with Al2O3 (1 g), dried to a flowing powder under reduced pressure and placed on a chromatography column (8 x 2 cm, Al2O3, activity level II). With petroleum ether/toluene (16/4) an orange broad fraction was eluted. Removal of the solvent gave

0.2 g of a mixture of 80 mol % of catena-Mes2Sb-SbPh-SbMes2 and 20 mol % of catena-Mes2Sb(SbPh)2SbMes2 as an orange oil. 1 H NMR (C6D6, 200 MHz): catena-Mes2Sb(SbPh)2SbMes2: 2.03 (s, 6H, CH3 – p),

2.12 (s, 6H, CH3 – p), 2.29 (s, 12H, CH3 – o), 2.54 (s, 12H, CH3 – o), 6.62

(s, 4H, C6H2 – m), 6.77 (s, 4H, C6H2 – m), 6.98 – 7.10 (m, 6H, SbC6H5 – m

+ p), 7.40 – 7.45 (m, 4H, SbC6H5 – o). catena-Mes2SbSbPhSbMes2: 2.06

(s, 6H, CH3 – p), 2.10 (s, 6H, CH3 – p), 2.32 (s, 12H, CH3 – o), 2.47 (s,

12H, CH3 – o), 6.65 (s, 4H, C6H2 – m), 6.73 (s, 4H, C6H2 – m), 6.98 – 7.10

(m, 3H, SbC6H5 – m + p), 7.65 – 7.70 (m, 2H, SbC6H5 – o). o + + MS (EI, 70 eV, 136 C): 436 (46) [Mes2PhSb ], 359 (10) [Mes2Sb ], 316 (58) [MesPhSb+], 195 (100) [MesSb+], 119 (66) [Mes+], 77 (16) [Ph+].

Catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4]

A solution of 1.9 g (4.46 mmol) [2-(Me2NCH2)C6H4]2SbCl in 40 mL of thf was added

.drop-wise to a solution of 1.6 g (4.38 mmol) LiSb(SiMe3)2ּdme in 10 mL thf at –40 °C The reaction mixture was stirred for 1 h at –40 °C and than allowed to warm to room temperature. Afterwards the solvent was removed in vacuo and the residue extracted with 50 mL of petroleum ether, giving an orange solution which was filtered through a

Experimental section

D4 frit covered with Kieselguhr. Removal of the solvent gave 2.4 g of an orange product. The 1H NMR spectra of the orange product indicate the presence of a 1 : 1 mixture of catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4] and Sb(SiMe3)3. 1 H NMR (C6D6, 200 MHz): catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4]:

0.35 (s, 9 H, SiCH3), 1.91 (s, 12 H, NCH3), 1.97 (s, 12 H, NCH3), AB spin 2 system with A: 3.16, B: 3.61 (4 H, CH2, JHH = 12.4 Hz), 3.22 (s, 4 H,

CH2), 6.87-7.19 (m, 16 H, C6H4). Sb(SiMe3)3: 0.41 (s, 9 H, SiCH3).

6.4 Bis(diorganobismuth) chalcogenides

Bis[bis(bis(trimethylsilyl)methyl)bismuth]sulfide, {[(Me3Si)2CH]2Bi}2S

0.22 g (0.91 mmol) Na2S·9H2O in 20 mL water were added to a solution of

[(Me3Si)2CH]2BiCl (1 g, 1.7 mmol) in 60 mL Et2O. After mixing for 1 h the yellow phase was separated and the water phase was washed twice with 50 mL of diethyl ether. The organic phases were dried on CaSO4. Removal of the solvent in vacuum gave 0.85 g (88 %) of {[(Me3Si)2CH]2Bi}2S as yellow solid. M. p.: 87 °C (dec.). 1 H NMR (C6D6, 200 MHz): 0.26 (s, 9 H, SiCH3), 0.41 (s, 9 H, SiCH3), 1.30 (s, 1 H, CH). 13 C NMR (C6D6, 50 MHz): 4.11 (s, CH3), 5.74 (s, CH3), 26.04(s, CH). + + + MS (EI, 70 eV) m/z (%): 927 (44) [M - R], 559 (6) [R2BiS ], 527 (83) [R2Bi ], 457 + + + (11) [R(MeSiCH2)BiS ], 413 (9) [R(CH)BiS ], 353 (8) [RBi - Me], 129 + + (35) [R - 2Me], 73 (92) [Me3Si ] R = CH(SiMe3)2.

Experimental section

Bis[bis(bis(trimethylsilyl)methyl)bismuth]telluride, {[(Me3Si)2CH]2Bi}2Te

1.5 g (2.66 mmol) [(Me3Si)2CH]2BiCl were added at –60 °C to Na2Te prepared from

0.06 g (2.6 mmol) Na and 0.2 g (1.5 mmol) Te in 60 mL NH3(l). The reaction mixture was stirred at –60 °C for 3 h and than the solvent (NH3) was evaporated. The residue was dissolved in petroleum ether and a red-brown solution was obtained. The solvent was removed from the petroleum ether solution and 0.84 g (53 %) of

{[(Me3Si)2CH]2Bi}2Te as a red-brown solid was obtained. M. p.: 83 °C (dec.). 1 H NMR (C6D6, 200 MHz): 0.27 (s, 9 H, SiCH3), 0.40 (s, 9 H, SiCH3), 1.44 (s, 1 H, CH).

+ + + MS (DCIpos, NH3) m/z (%): 527 (28) [R2Bi ], 449 (34) [R2Te ], 377 (26) [R2Te ·NH3, + + -SiMe4], 306 (20) [RTe ·NH3], 289 (8) [RTe ]. - - - MS (DCIneg, NH3) m/z (%): 653 (46) [R2BiTe ], 526 (100) [R2Bi ], 454 (49) [R2Bi , - - - SiMe3], 289 (82) [RTe ], 159 (30) [R ] R = CH(SiMe3)2.

6.5 Transition metal complexes with cyclo-(RSbE)n ligands

Cyclo-(RSbS)2[W(CO)5]2 [R = CH(SiMe3)2]

0.28 g (0.44 mmol) of cyclo-(RSbS)n and W(CO)5thf prepared from 0.31 g (0.88 mmol)

W(CO)6 by irradiation with an UV lamp, in 150 mL thf were stirred for 5 h at room temperature. Thereafter the solvent was removed under reduced pressure and the remaining brown product was washed twice with 50 mL of petroleum ether. 0.38 g (68

%) of brown crystals [m. p. 152 °C (dec.)] of cyclo-(RSbS)2[W(CO)5]2 [R =

CH(SiMe3)2] were obtained by cooling at –28 °C petroleum ether solutions.

Anal. Calcd.for C24H38Si4O10S2W2Sb2 (1274.22): C, 22.62; H, 3.01. Found: C, 22.77; H, 2.99.

Experimental section

1 1 2 H NMR (C6D6, 200 MHz): 0.22 (s, 18 H, (CH3)3Si, JCH = 119.2 Hz, JSiH = 6.3 Hz), 0.38 (s, 1 H, CH). 13 C NMR (C6D6, 50 MHz): 2.94 (s, (CH3)3Si), 37.51 (s, CH), 196.01 (s, COeq), + 197.69 (s, COax). MS (DCIpos, NH3) m/z (%):1291 (18) [M + NH4], 1274 + + + (13) [M ], 952 (19) [M - W(CO)5], 887 (24) [R2Sb2W(CO)5 ]. - - MS (DCIneg, NH3) m/z (%): 1115 (22) [M - R], 950 (30) [M - W(CO)5], 866 (14) - - - [M - W(CO)5, - 3 CO], 791 (46) [M - W(CO)5, - R], 680 (56) [M - - - W(CO)5, - 4 CO, - R], 638 (28) [[RSbS][W(CO)5] ], 594 (32) [R2Sb2S ], - - 582 (30) [[RSbS][W(CO)3] ], 324 (78) [W(CO)5 ] R = CH(SiMe3)2. IR (toluene): 2081vs, 2074s, 1919m cm-1 (ν CO).

Cyclo-(RSbSe)2[W(CO)5]2 [R = CH(SiMe3)2]

1.5 g of cyclo-(RSbSe)n and W(CO)5thf prepared from 1.46 g (4.14 mmol) W(CO)6 by irradiation with a UV lamp, in 150 mL of thf were stirred for 4 h at room temperature. Thereafter the solvent was removed under reduced pressure and the remaining brown product was washed twice with 100 mL of petroleum ether. 1.2 g

(42 %) of cyclo-(RSbSe)2][W(CO)5]2 [R = CH(SiMe3)2] was obtained as brown crystals (dec. 134 °C) by cooling petroleum ether solutions to –28 °C. 1 1 H NMR (C6D6, 200 MHz): 0.23 (s, 18 H, (CH3)3Si, JCH = 119.3 Hz), 0.29 (s, 1 H, CH). 13 C NMR (C6D6, 50 MHz): 2.70 (s, (CH3)3Si), 31.94 (s, CH), 196.93 (s, COeq),

197.32 (s, COax). + + MS (DCIpos, NH3) m/z (%): 843 (38) [R2Sb2SeW + NH3], 643 (100) [R2Sb2Se ]. - - MS (DCIneg, NH3) m/z (%): 1281 (5) [M - SiMe4], 1122 (8) [M - SiMe4, -R], 807 - - - (16) [RSb2SeW(CO)5 ], 721 (46) [R2Sb2Se2 ], 642 (100) [R2Sb2Se ], 324 - (52) [W(CO)5 ] R = CH(SiMe3)2. IR (petroleum ether): 2072s, 1981s, 1950s cm-1 (ν CO).

Summary

7. Summary

In an attempt to stabilise catena-stibanes, catena-R2Sb-(SbR’)n-SbR2, by the bulky bis(trimethylsilyl)methyl substituent the reduction of a mixture of R2SbCl [R =

CH(SiMe3)2] and R’SbCl2 (R = CH2SiMe3) with Mg was accomplished. The analysis of the reaction products mixture showed no evidence for catena-stibane formation, but R3Sb [R = CH(SiMe3)2], a compound formed as a result of the migration of the organic groups from antimony, was identified by 1H NMR spectroscopy and mass spectrometry. The synthesis of R3Sb [R = CH(SiMe3)2] was achieved by complete alkylation of SbCl3, which was found to be more effective than the procedure reported earlier, i.e. the alkylation of RSbCl2 with RLi [R = CH(SiMe3)2]. Reaction of

R3Sb [R = CH(SiMe3)2] with Br2 gives the trialkylantimony(V) dibromide, R3SbBr2

[R = CH(SiMe3)2]. Hydrolysis of R3SbBr2 [R = CH(SiMe3)2] was carried out with a solution of potassium hydroxide in water. Unexpectedly not only bromine atoms but also Me3Si groups were substituted and the hydroxy bromide R3Sb(Br)OH (R =

CH2SiMe3) was obtained. An effective synthesis of R3Sb(Br)OH (R = CH2SiMe3) was achieved by reacting R3SbBr2 (R = CH2SiMe3) with KOH in water.

Br R Et2O/H2O R SbBr + KOH Sb R 3 2 -KBr R

R = CH2SiMe3 OH

The crystal structures of R3SbBr2 [R = CH(SiMe3)2] and R3Sb(Br)OH (R =

CH2SiMe3) have been determined. In both compounds the geometry around the antimony atoms is trigonal bipyramidal. R3Sb(Br)OH (R = CH2SiMe3) is the only covalent hydroxy halide with a known crystal structure.

The chiral chlorostibine and chlorobismuthine, RR’ECl [R = CH(SiMe3)2, R’ = 2-

(Me2NCH2)C6H4; E = Sb, Bi] were prepared by the reaction of (Me3Si)2CHECl2 (E =

Sb, Bi) with [2-(Me2NCH2)C6H4]Li. Reduction of RR’SbCl [R = CH(SiMe3)2, R’ =

Summary

2-(Me2NCH2)C6H4] with LiAlH4 afforded the isolation of the chiral antimony hydride, RR’SbH [R = CH(SiMe3)2, R’ = 2-(Me2NCH2)C6H4]. The chlorobismuthane

RR’BiCl [R = CH(SiMe3)2, R’ = 2-(Me2NCH2)C6H4] was found to undergo edge inversion in the presence of donor solvents (dmso).

Cl Cl Cl R R Me R + Nu - Nu Bi Nu Bi N Bi Me - Nu + Nu Me CH2 Me N N Me Me CH2 CH2

R = CH(SiMe3)2

Inversion at the antimony atom in RR’SbCl and RR’SbH [R = CH(SiMe3)2, R’ = 2-

(Me2NCH2)C6H4] could not be observed in dmso-d6 up to 160 °C and 100 °C respectively, while further heating led only to decomposition.

For solid RR’SbCl [R = CH(SiMe3)2, R’ = 2-(Me2NCH2)C6H4] the pseudotrigonal bipyramidal configuration with intramolecular coordination of the NMe2 group was confirmed by an X-ray diffraction study of single crystals. 1H NMR studies at 20 °C confirm that in C6D6 or toluene-d8 solutions the chlorostibane and chlorobismuthane,

RR’SbCl and RR’BiCl [R = CH(SiMe3)2, R’ = 2-(Me2NCH2)C6H4] exist as hypervalent 10-E-4 species with intramolecular coordination of the NMe2 group. 1 However, H NMR measurements in toluene-d8 for RR’SbH [R = CH(SiMe3)2, R’ =

2-(Me2NCH2)C6H4] show no evidence for the intramolecular Sb-N coordination in the temperature range –80 to +20 °C.

The tristibanes catena-Me2Sb-SbR-SbMe2 or catena-Ph2Sb-SbR-SbPh2 (R =

Me3SiCH2) were formed as major components of the equilibria mixtures obtained on reacting the trimethylsilylmethyl antimony rings, cyclo-(Me3SiCH2Sb)n (n = 4, 5) with Me4Sb2, or Ph4Sb2 in benzene. Even at low temperatures the equilibria reactions are fast and techniques allowing the isolation of catena-Me2Sb-SbR-SbMe2 or catena--Ph2Sb-SbR-SbPh2 from the mixtures are not available.

Summary

R R R Sb Sb R' R' R' R' + 55Sb Sb Sb Sb R Sb R' R' R' Sb Sb R' R Sb R

R = CH2SiMe3; R' = CH3, Ph

A complete shift of the equilibrium to the side of the catena-stibanes was achieved through coordination to transition metal fragments. The equilibrium mixtures obtained by combining solutions of Me4Sb2 or Ph4Sb2 with cyclo-(Me3SiCH2Sb)n (n =

4, 5) react with [Cr(CO)4(nbd)] to give the tetrastibane complexes cyclo-

[Cr(CO)4(R’2Sb-SbR-SbR-SbR’2)] (R’ = Me, Ph, R = Me3SiCH2, Ph).

R' R' R Sb Sb

(CO)4Cr Sb Sb R R' R'

R' = Me, Ph R = CH SiMe , Ph 2 3

Further complexation of cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2) with [W(CO)5(thf)] gives the complex cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-

SbMe2)W(CO)5] (R = Me3SiCH2).

CH3 H3C R Sb Sb

(CO)4Cr W(CO)5 Sb Sb R H3C CH3

R = CH2SiMe3

Summary

X-ray diffraction studies on cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] and cyclo-

[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] revealed the formation of five- membered CrSb4 rings in which the Me2Sb-SbR’-SbR’-SbMe2 chain functions as a chelating bidentate four electron donor via lone pair donation through the terminal Sb atoms. t t The open-chain catena-stibanes, catena- Bu2Sb(SbMe)nSb Bu2, catena-

Mes2Sb(SbPh)nSbMes2 (n = 1, 2) and catena-R2Sb-(SbSiMe3)-SbR2 [R = 2- 1 (Me2NCH2)C6H4] were prepared and characterised by H NMR spectroscopy and mass spectrometry. The novel catena-stibanes do not take part in ring-chain equilibria but decompose, however at room temperature. In an attempt to coordinate catena-

Me2Sb-SbR-SbMe2 (R = CH2SiMe3) on Cr(CO)5, an equilibrium mixture obtained by combining solutions of Me2Sb-SbMe2 with cyclo-(Me3SiCH2Sb)n (n = 4, 5) was allowed to react with Cr(CO)5thf in thf. After the reaction and separation of the reaction products by column chromatography the tetramethyldistibane complex,

[(CO)5W(Me2Sb-SbMe2)W(CO)5] and a small yield of the chelate complex, cyclo-

Cr(CO)4(Me2Sb-SbR-SbR-SbMe2) (R = CH2SiMe3) were isolated. As expected coordination of open-chain catena-stibanes on transition metal fragments is less favourable than chelate coordination.

The bis(dialkylbismuth) sulfide and telluride, {[(Me3Si)2CH]2Bi}2S and

{[(Me3Si)2CH]2Bi}2Te were prepared by reaction of [(Me3Si)2CH]2BiCl with Na2S or

Na2Te. The X-ray diffraction studies carried out on single crystals of

{[(Me3Si)2CH]2Bi}2S and {[(Me3Si)2CH]2Bi}2Te revealed that both compounds adopt a conformation which is closer to syn-syn than to syn-anti.

R R R E R Bi Bi

R = CH(SiMe3)2 E = S, Te

The telluride, {[(Me3Si)2CH]2Bi}2Te is a heavy atom analogue of cacodyl oxide and the first organometallic molecule with Bi-Te bond with known crystal structure.

Summary

The reaction of the ring-ring equilibrium mixtures of cyclo-(RSbX)n [X = S, Se; n =

2, 3; R = CH(SiMe3)2] with [W(CO)5(thf)] resulted in trapping of the dimers in cyclo-

(RSbX)2[W(CO)5]2 (X = S, Se). A X-ray crystal structure analysis revealed that the complex contains a four membered antimony-chalcogen ring in an almost planar conformation, where the alkyl groups occupy cis positions and the W(CO)5 units are bonded trans to the alkyl groups on the antimony atoms.

(CO)5W W(CO)5 E Sb Sb E R R

R = CH(SiMe3)2 E = S, Se

The ring-ring equilibria observed for the free cyclo-(RSbX)n (X = S, Se, n = 2, 3) ligands are not retained after complexation. The 1H NMR spectra of photolysed solutions of cyclo-(RSbSe)2[W(CO)5]2 suggest the presence of an photochemically induced equilibrium between cyclo-(RSbSe)2[W(CO)5]2 and the monomer

[(CO)5W]RSb=Se [R = CH(SiMe3)2]. However, further efforts should be undertaken for the isolation of low coordinated double-bond compounds between antimony and group 16 elements. Although various double bonds of group 15-group 15 and group 14-group 15 elements have already been reported, no actual examples of compounds of the type R-Sb=X (R = organic group, X = group 16 element) containing localised multiple bonds between antimony and group 16 elements have been isolated so far.

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[127] J. A. Jarvis, R. H. B. Mais, P. G. Owston, D. T. Thompson, J. Chem. Soc. A 1968, 622. [128] R. Hoge, R. Lehrnet, K. F. Fischer, Cryst. Struct. Commun. 1977, 6, 359. [129] R. H. B. Mais, P. G. Owston, D. T. Thompson, A. M. Wood, J. Chem. Soc. A 1967, 1744. [130] J. T. Lin, A. C. Yeh, Y. C. Chou, T. Y. R. Tsai, Y. S. Wen, J. Organomet. Chem. 1995, 486, 147. [131] K. V. Deuten, D. Rehder, Cryst. Struct. Commun. 1980, 9, 167. [132] J. v. Seyer, G. Huttner, Cryst. Struct. Commun. 1980, 9, 1099. [133] H. J. Breunig, J. Pawlik, Z. anorg. allg. Chem. 1995, 621, 817. [134] M. Wieber, I. Sauer, Z. Naturforsch. 1984, 39b, 887. [135] H. J. Breunig, D. Müller, Z. Naturforsch. 1986, 41b, 1129. [136] M. Wieber, I. Sauer, Z. Naturforsch. 1987, 42b, 695. [137] F. Calderazzo, R. Poli, G. Pelizzi, J. Chem. Soc. Dalton Trans. 1984, 2365. [138] L. C. Cadet de Gassincourt, Mem. Math. Phys. Savants Etrangers 1760, 3, 363. [139] Y. Feutelais, B. Legendre, N. Rodier, V. Agafonov, Material Research Bulletin 1993, 28, 591. [140] B. Murray, J. Hvoslef, H. Hope, P. P. Power, Inorg. Chem. 1983, 22, 3421. [141] J. Hasenbäumer, Ber. Deut. Chem. Ges. 1898, 31, 2910. [142] M. A. Mohammed, K. H. Ebert, H. J. Breunig, Z. Naturforsch. 1996, 51b, 149. [143] N. Tokitoh, T. Sasamori, R. Okazaki, Chem. Lett. 1998, 725. [144] N. Tokitoh, Y. Arai, J. Harada, R. Okazaki, Chem. Lett. 1995, 959. [145] K. Merzweiler, H-J. Kersten, Z. Naturforsch. 1993, 48b, 541. [146] L-R. Frank, K. Evertz, L. Zsolnai, J. Organomet. Chem. 1987, 335, 179. [147] M. Wieber, H. Hohl, Ch. Burschka, Z. Anorg. Allg. Chem. 1990, 583, 113. [148] M. Wieber, N. Graf, Z. Anorg. Allg. Chem. 1993, 619, 1991. [149] H. J. Breunig, M. Jönsson, R. Rösler, E. Lork, Z. Naturforsch. 1999, 625, 2120. [150] H. J. Breunig, E. Lork, R. Rösler, G. Becker, O. Mundt, W. Schwarz, Z. Anorg. Allg. Chem. 2000, 626, 1595. [151] H. J. Breunig, S Güleç, B. Krebs, M. Dartmann, Z. Naturforsch. 1989, 44b, 1351.

References

[152] H. J. Breunig, I. Ghesner, E. Lork, Organometallics 2001, 20, 1360. [153] H. J. Breunig, J. Pawlik, Z. Anorg. Allg. Chem. 1995, 621, 817. [154] H. J. Breunig, R. Rösler, E. Lork, Organometallics 1998, 17, 5594. [155] D. R. Burfield, K.-H. Lee, R. H. Smithers, J. Org. Chem. 1977, 42, 3060. [156] D. R. Burfield, R. H. Smithers, J. Org. Chem. 1978, 43, 3966. [157] D. R. Burfield, R. H. Smithers, J. Org. Chem. 1983, 48, 2420. [158] H. Brockmann, H. Schodder, Ber. 1941, 74b, 73. [159] Bruker-Franzen Analytik GmbH, Win-NMR Version 6.0, 1997. [160] Mass Spectrometry Service Ltd., MASPEC Data System for Windows, 1996. [161] D. Seyfert, J. Am. Chem. Soc. 1958, 80, 1336. [162] R. B. King, in Organometallic Synthesis, R. B. King, J. J. Eisch Eds.; 1865, vol. 1, p 122. [163] G. M. Sheldrick, SHELX-93, Universität Göttingen 1993. [164] G. M. Sheldrick, SHELX-97, Universität Göttingen 1997. [165] DIAMOND-Visual Crystal Structure Information System, CRYSTAL IMPACT, P Box 1251, D-53002 Bonn.

Appendix

9. APPENDIX

9.1 Abbreviations

amu atomic mass unit ax axial tBu tertiary butyl calc. calculated

CIneg chemical ionisation, negative charged ions

CIpos chemical ionisation, positive charged ions

DCIneg direct chemical ionisation, negative charged ions

DCIpos direct chemical ionisation, positive charged ions cod cyclooctadiene dec. decomposition EI electron ionisation ESI electrospray ionisation

Et2O diethyl ether Et ethyl eq equatorial HRMS high resolution mass spectrometry IR infrared spectroscopy m meta Me methyl Mes mesityl ν stretching vibration MS mass spectrometry m.p. melting point nbd norbornadiene NMR nuclear magnetic resonance

Appendix o orto p para Ph phenyl thf tetrahydrofuran

1 [(Me3Si)2CH]3SbBr2

2 (Me3SiCH2)3Sb(Br)OH

3 [2-(Me2NCH2)C6H4][(Me3Si)2CH]SbCl

4 [2-(Me2NCH2)C6H4][(Me3Si)2CH]BiCl

5 [2-(Me2NCH2)C6H4][(Me3Si)2CH]SbH

6 catena-Me2Sb-SbCH2SiMe3-SbMe2

7 catena-Ph2Sb-SbCH2SiMe3-SbPh2

8 cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = CH2SiMe3)

9 cyclo-[Cr(CO)4(Ph2Sb-SbR-SbR-SbPh2)] (R = CH2SiMe3)

10 cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)] (R = CH2SiMe3)

11 cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5]

(R = CH2SiMe3) t t 12 catena- Bu2Sb-SbCH3-Sb Bu2 t t 13 catena- Bu2Sb(SbCH3)2Sb Bu2

14 catena-Mes2Sb-SbPh-SbMes2

15 catena-Mes2Sb(SbPh)2SbMes2

16 catena-R2Sb-SbSiMe3-SbR2 [R = 2-(Me2NCH2)C6H4]

17 [(CO)5W(Me2Sb-SbMe2)W(CO)5]

18 [(Me3Si)2CH]2Bi-S-Bi[CH(SiMe3)2]2

19 [(Me3Si)2CH]2Bi-Te-Bi[CH(SiMe3)2]2

20 cyclo-(RSbS)2[W(CO)5]2 [R = CH(SiMe3)2]

21 cyclo-(RSbSe)2[W(CO)5]2 [R = CH(SiMe3)2]

Appendix

9.2 Details of crystal structure determination

Table 9.2.1 Crystal data and structure refinement for [(Me3Si)2CH]3SbBr2

Identification code jg1a

Empirical formula C21H57Br2SbSi6 CCDC-Number 174048 Formula weight 759.78 Temperature 173(2) K Wavelength 71.073 pm Crystal system Hexagonal Space group R3c Unit cell dimensions a = 1880.0(3) pm α = 90° b = 1880.0(3) pm β= 90° c = 1757.5(4) pm γ = 120° Volume 5.3795(17) nm3 Z 6 Diffractometer Stoe IPDS

Density (calculated) 1.407 Mg/m3 Absorption coefficient 3.207 mm-1 F(000) 2328 Crystal size 0.5 x 0.2 x 0.2 mm3 Theta range for data collection 3.41 to 26.13° Index ranges -23 ≤ h ≤ 23, -23 ≤ k ≤ 23, -21 ≤ l ≤ 21 Reflections collected 19385 Independent reflections 2373 [R(int) = 0.0737] Completeness to theta = 26.13° 99.1 % Absorption correction DIFABS

Appendix

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2373 / 1 / 99 Goodness-of-fit on F2 1.164 Final R indices [I>2sigma(I)] R1 = 0.0321, wR2 = 0.0850 R indices (all data) R1 = 0.0392, wR2 = 0.1025 Absolute structure parameter 0.008(17) Largest diff. peak and hole 0.689 and -0.489 e.Å-3

Table 9.2.2 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for [(Me3Si)2CH]3SbBr2. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 10000 10000 6597(1) 40(1) Br(1) 10000 10000 8117(1) 60(1) Br(2) 10000 10000 5092(1) 55(1) C(1) 8720(4) 9083(5) 6626(5) 84(3) Si(1) 8341(1) 8133(1) 7241(1) 53(1) C(2) 7589(4) 7204(4) 6682(4) 67(2) C(3) 7783(5) 8219(5) 8091(4) 80(2) C(4) 9128(5) 7879(5) 7600(4) 72(2) Si(2) 7999(1) 9108(1) 5888(1) 50(1) C(5) 7821(5) 8415(4) 5052(4) 70(2) C(6) 8290(4) 10157(4) 5526(4) 65(2) C(7) 6997(4) 8766(5) 6380(5) 73(2)

Appendix

Table 9.2.3 Crystal data and structure refinement for (Me3SiCH2)3Sb(Br)OH

Identification code jg3i

Empirical formula C12H34BrOSbSi3 CCDC-Number 174049 Formula weight 480.32 Temperature 173(2) K Wavelength 71.073 pm Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 670.40(1) pm α = 90° b = 3145.3(6) pm β= 94.16(3)° c = 1056.6(2) pm γ = 90° Volume 2.2221(7) nm3 Z 4 Diffractometer Stoe IPDS

Density (calculated) 1.436 Mg/m3 Absorption coefficient 3.194 mm-1 F(000) 968 Crystal size 0.4 x 0.2 x 0.1 mm3 Theta range for data collection 3.11 to 23.50° Index ranges -7<=h<=7, 0<=k<=35, 0<=l<=11 Reflections collected 2241 Independent reflections 2241 [R(int) = 0.0000] Completeness to theta = 23.50° 68.1 % Absorption correction Numerical

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2241 / 0 / 172 Goodness-of-fit on F2 0.919

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0567, wR2 = 0.1330 R indices (all data) R1 = 0.0794, wR2 = 0.1401

Largest diff. peak and hole 0.821 and -0.493 e.Å-3

Table 9.2.4 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for (Me3SiCH2)3Sb(Br)OH. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 3732(1) 1371(1) 8301(1) 36(1) Br(2) 133(2) 1626(1) 9411(2) 61(1) Si(1) 1316(5) 790(1) 5891(4) 42(1) Si(2) 4847(6) 2404(1) 7734(4) 48(1) Si(3) 5135(6) 781(1) 11022(4) 47(1) O(1) 6179(13) 1200(3) 7525(10) 52(2) C(1) 1951(18) 1330(4) 6595(11) 39(3) C(2) 4850(17) 1966(4) 8950(12) 36(3) C(3) 3580(20) 818(4) 9430(16) 57(4) C(4) -280(30) 887(5) 4431(16) 69(5) C(5) -90(20) 457(5) 6988(14) 52(4) C(6) 3620(20) 508(5) 5535(16) 61(4) C(7) 6280(20) 2235(5) 6364(14) 59(4) C(8) 6080(30) 2863(5) 8500(18) 75(5) C(9) 2250(20) 2554(5) 7225(17) 65(5) C(10) 3950(30) 363(6) 11939(17) 70(5) C(11) 5090(30) 1286(6) 11914(17) 80(5) C(12) 7700(20) 628(6) 10750(17) 72(5)

Appendix

Table 9.2.5 Crystal data and structure refinement for

[2-(Me2NCH2)C6H4][(Me3Si)2CH]SbCl

Identification code jg16

Empirical formula C16H31ClNSbSi2 Formula weight 450.80 Temperature 173(2) K Wavelength 71.073 pm Crystal system Triclinic

Space group P1 Unit cell dimensions a = 724.3(4) pm α = 79.88° b = 1037.3(3) pm β= 78.27° c = 1539.6(5) pm γ = 71.48(1)° Volume 1.0662(7) nm3 Z 2 Diffractometer Siemens P4

Density (calculated) 1.404 Mg/m3 Absorption coefficient 1.527 mm-1 F(000) 460 Crystal size 0.3 x 0.2 x 0.2 mm3 Theta range for data collection 2.62 to 25.00° Index ranges -1<=h<=8, -11<=k<=12, -18<=l<=18 Reflections collected 4779 Independent reflections 3744 [R(int) = 0.0519] Completeness to theta = 25.00° 99.4 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3744 / 0 / 202 Goodness-of-fit on F2 0.985

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0614, wR2 = 0.1076 R indices (all data) R1 = 0.1197, wR2 = 0.1275 Largest diff. peak and hole 0.820 and -0.940 e.Å-3

Table 9.2.6 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for [2-(Me2NCH2)C6H4][(Me3Si)2CH]SbCl. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) -4256(1) 903(1) 3278(1) 26(1) Cl(1) -1973(4) 2355(2) 2785(2) 46(1) N(1) -6066(11) -854(7) 3368(4) 28(2) C(11) -2784(12) -332(8) 2218(5) 26(2) C(21) -6636(12) 2494(8) 2709(5) 22(2) C(12) -917(14) -394(9) 1783(6) 39(2) C(13) 38(15) -1234(10) 1124(6) 45(3) C(14) -926(17) -2056(11) 898(6) 51(3) C(15) -2783(16) -2037(10) 1325(6) 45(3) C(16) -3727(14) -1174(9) 1976(6) 33(2) C(17) -5787(15) -1107(9) 2432(6) 38(2) C(18) -8146(15) -533(10) 3779(7) 48(3) C(19) -4871(15) -2075(8) 3901(6) 44(3) Si(1) -7979(4) 3669(2) 3594(2) 29(1) Si(2) -6156(4) 3378(3) 1540(2) 33(1) C(22) -9078(15) 2676(9) 4586(5) 41(3) C(23) -10033(14) 5104(8) 3203(6) 42(3) C(24) -6296(16) 4423(9) 3972(6) 47(3) C(25) -8503(15) 3888(10) 1057(6) 49(3) C(26) -5416(16) 4953(10) 1526(7) 54(3) C(27) -4238(16) 2258(10) 747(6) 56(3)

Appendix

Table 9.2.7 Crystal data and structure refinement for

cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2)

Identification code jg5

Empirical formula C16H34CrO4Sb4Si2 Formula weight 885.61 Temperature 173(2) K Wavelength 71.073 pm Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 1585.1(1) pm α = 90° b = 1012.2(1) pm β= 110.58(1)° c = 2043.6(3) pm γ = 90° Volume 3.0696(6) nm3 Z 4 Diffractometer Siemens P4

Density (calculated) 1.916 Mg/m3 Absorption coefficient 3.911 mm-1 F(000) 1672 Crystal size 0.50 x 0.40 x 0.30 mm3 Theta range for data collection 2.75 to 27.50° Index ranges -20<=h<=1, -13<=k<=1, -26<=l<=26 Reflections collected 8799 Independent reflections 7032 [R(int) = 0.0259] Completeness to theta = 27.50° 99.7 % Absorption correction ψ-scans

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7032 / 0 / 267 Goodness-of-fit on F2 1.045

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0337, wR2 = 0.0709 R indices (all data) R1 = 0.0470, wR2 = 0.0753 Largest diff. peak and hole 0.688 and -0.638 e.Å-3

Table 9.2.8 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R =

Me3SiCH2). U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 6346(1) 7100(1) 5079(1) 28(1) Sb(2) 7173(1) 4593(1) 5413(1) 28(1) Sb(3) 8460(1) 5018(1) 4775(1) 28(1) Sb(2A) 7021(11) 4600(16) 4791(8) 34(5) Sb(3A) 8848(12) 5085(17) 5518(9) 50(5) Sb(4) 8677(1) 7733(1) 5104(1) 28(1) Cr(1) 7354(1) 9162(1) 5168(1) 31(1) O(1) 8495(3) 11540(4) 5218(3) 73(2) O(2) 5894(3) 10927(4) 5278(3) 70(1) O(3) 8100(4) 8990(5) 6756(2) 70(1) O(4) 6637(4) 9329(5) 3590(2) 70(1) Si(1) 6868(1) 4092(1) 3175(1) 34(1) Si(2) 8815(1) 4202(2) 7054(1) 46(1) C(1) 8068(4) 10614(5) 5209(3) 43(1) C(2) 6434(4) 10233(6) 5231(3) 48(1) C(3) 7814(4) 9027(5) 6152(3) 44(1) C(4) 6910(4) 9262(5) 4185(3) 44(1) C(5) 5628(4) 7019(6) 5792(3) 49(2) C(6) 5236(4) 6779(6) 4129(3) 48(1) C(7) 7480(4) 5491(5) 3750(3) 40(1)

Appendix

C(8) 5935(5) 4818(7) 2433(3) 73(2) C(9) 6376(6) 2946(7) 3648(4) 73(2) C(10) 7653(5) 3169(10) 2862(4) 95(3) C(11) 7961(4) 5333(5) 6455(3) 41(1) C(12) 8303(7) 2580(7) 7092(4) 85(3) C(13) 9773(6) 3981(9) 6736(4) 81(3) C(14) 9226(5) 4992(7) 7933(3) 61(2) C(15) 9909(4) 7786(6) 5974(3) 57(2) C(16) 9198(5) 8374(7) 4324(4) 59(2)

Table 9.2.9 Crystal data and structure refinement for

cyclo-[Cr(CO)4(Me2Sb-SbPh-SbR-SbMe2)] (R = Me3SiCH2)

Identification code jg14i

Empirical formula C38CrH36O4Sb4Si Formula weight 1123.76 Temperature 173(2) K Wavelength 71.073 pm Crystal system Triclinic

Space group P1 Unit cell dimensions a = 1127.0(2) pm α = 83.94(3)° b = 1254.9(3) pm β= 72.60(3)° c = 1529.6(3) pm γ = 81.63(3)° Volume 2.0379(7) nm3 Z 2 Diffractometer Stoe IPDS

Density (calculated) 1.831 Mg/m3 Absorption coefficient 2.940 mm-1 F(000) 1076

Appendix

Crystal size 0.50 x 0.40 x 0.30 mm3 Theta range for data collection 2.36 to 25.92° Index ranges -13<=h<=13, -15<=k<=15, -18<=l<=18 Reflections collected 29045 Independent reflections 7379 [R(int) = 0.0525] Completeness to theta = 27.50° 92.9 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7379 / 0 / 452 Goodness-of-fit on F2 0.883 Final R indices [I>2sigma(I)] R1 = 0.0337, wR2 = 0.0709 R indices (all data) R1 = 0.0470, wR2 = 0.0753 Largest diff. peak and hole 0.688 and -0.638 e.Å-3

Table 9.2.10 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for cyclo-[Cr(CO)4(Me2Sb-SbPh-SbR-SbMe2)] (R =

Me3SiCH2). U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 5844(1) 2820(1) 1488(1) 30(1) Sb(2) 4085(1) 4581(1) 1148(1) 32(1) Sb(3) 2400(1) 4442(1) 2928(1) 32(1) Sb(4) 2917(1) 2182(1) 3292(1) 31(1) Cr(1) 5083(1) 1116(1) 2522(1) 30(1) O(1) 4183(3) 291(2) 1065(2) 53(1) O(2) 6162(3) 1595(4) 4016(3) 62(1) O(3) 7534(3) -192(2) 1639(2) 56(1) O(4) 4111(3) -769(2) 3772(2) 61(1) Si(1) 3738(1) 6262(1) 3754(1) 46(1)

Appendix

C(11) 7038(3) 3702(3) 1928(3) 33(1) C(21) 7089(3) 2530(3) 142(2) 33(1) C(31) 3065(3) 3630(3) 576(3) 40(1) C(41) 3699(3) 4789(3) 3641(3) 40(1) C(51) 1338(3) 1507(3) 3174(3) 38(1) C(61) 2396(3) 2225(3) 4757(2) 35(1) C(7) 5738(3) 1468(3) 3449(3) 40(1) C(8) 4482(3) 654(3) 1611(3) 38(1) C(9) 6601(4) 328(3) 1976(2) 39(19 C(10) 4484(3) -53(3) 3287(3) 41(1) C(12) 7040(4) 4818(3) 1766(3) 49(1) C(13) 7824(4) 5337(3) 2083(3) 62(1) C(14) 8615(4) 4753(3) 2536(3) 59(1) C(15) 8640(4) 3644(3) 2678(3) 53(1) C(16) 7856(3) 3133(3) 2363(3) 43(1) C(22) 6998(3) 1641(3) -293 39(1) C(23) 7808(4) 1436(3) -1160(3) 50(1) C(24) 8720(4) 2095(3) -1581(3) 51(1) C(25) 8811(3) 2980(3) -1147(3) 47(1) C(26) 8001(3) 3196(3) -290(3) 38(1) C(32) 1772(4) 3838(3) 780(3) 48(1) C(33) 1112(4) 3275(4) 398(3) 60(1) C(34) 1751(5) 2479(4) -188(3) 59(1) C(35) 3037(4) 2267(3) -410(3) 58(1) C(36) 3690(4) 2843(3) -32(3) 49(1) C(42) 2172(5) 6843(4) 4441(4) 88(2) C(43) 4922(5) 6374(3) 4353(4) 67(1) C(44) 4160(5) 6988(3) 2602(3) 67(1) C(52) 433(4) 1159(3) 3936(3) 50(1) C(53) -546(4) 656(4) 3831(4) 65(1)

Appendix

C(54) -601(4) 511(3) 2963(4) 61(1) C(55) 281(4) 884(3) 2202(3) 56(1) C(56) 1259(4) 1381(3) 2297(3) 47(1) C(62) 1378(4) 2935(3) 5210(3) 46(1) C(63) 1068(4) 2975(3) 6155(3) 52(1) C(64) 1736(4) 2329(3) 6652(3) 50(1) C(65) 2732(4) 1618(4) 6217(3) 53(1) C(66) 3052(3) 1564(3) 5270(3) 43(1)

Table 9.2.11 Crystal data and structure refinement for

cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2)

Identification code jg6a

Empirical formula C21H34CrO9Sb4Si2W Formula weight 1209.51 Temperature 298(2) K Wavelength 71.073 pm Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 963.9(4) pm α = 90° b = 2148.4(3) pm β= 90.56(2)° c = 1841.4(2) pm γ = 90° Volume 3.8131(17) nm3 Z 4 Diffractometer Siemens P4

Density (calculated) 2.107 Mg/m3 Absorption coefficient 6.172 mm-1 F(000) 2248

Appendix

Crystal size 0.70 x 0.50 x 0.50 mm3 Theta range for data collection 2.56 to 25.00° Index ranges -11<=h<=1, -25<=k<=1, -21<=l<=21 Reflections collected 8544 Independent reflections 6654 [R(int) = 0.0198] Completeness to theta = 25.00° 99.0 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6654 / 0 / 356 Goodness-of-fit on F2 1.029 Final R indices [I>2sigma(I)] R1 = 0.0388, wR2 = 0.0894 R indices (all data) R1 = 0.0530, wR2 = 0.0942 Largest diff. peak and hole 0.975 and -0.995 e.Å-3

Table 9.2.12 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R =

Me3SiCH2). U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) W(1) 3667(1) 1131(1) 3817(1) 51(1) Sb(1) 3110(1) 3526(1) 6167(1) 59(1) Sb(2) 1539(1) 2776(1) 5187(1) 53(1) Sb(3) 3559(1) 1837(1) 5087(1) 45(1) Sb(4) 5967(1) 2569(1) 5320(1) 58(1) Cr(1) 5798(2) 3538(1) 6137(1) 68(1) Si(1) 1435(4) 3813(2) 3717(2) 85(1) Si(2) 1902(3) 988(1) 6445(1) 65(1) O(1) 8928(8) 3596(5) 6187(6) 143(4) O(2) 5656(9) 4669(4) 7087(5) 123(3)

Appendix

O(3) 5741(12) 4312(5) 4785(6) 51(1) O(4) 5806(12) 2703(5) 7470(6) 59(1) O(5) 395(8) 1186(5) 3666(5) 53(1) O(6) 4033(9) 352(4) 2404(4) 45(1) O(7) 6915(8) 1067(4) 3997(4) 51(1) O(8) 3452(10) -152(4) 4643(5) 59(1) O(9) 4005(8) 2306(3) 2788(4) 53(1) C(1) 7729(13) 3561(5) 6179(7) 68(1) C(2) 5707(11) 4239(5) 6705(6) 85(1) C(3) 5788(11) 3974(6) 5401(10) 65(1) C(4) 5821(12) 3022(6) 6969(6) 143(4) C(5) 2270(13) 3252(7) 7193(6) 123(3) C(6) 2067(12) 4406(5) 6111(6) 68(1) C(7) 2378(11) 3192(5) 4207(5) 53(1) C(8) 1730(30) 4557(7) 4191(9) 45(1) C(9) -300(20) 3659(15) 3710(15) 85(1) C(10) 2170(20) 3868(6) 2799(7) 51(1) C(11) 3563(9) 1328(4) 6092(4) 59(1) C(12) 964(14) 1591(7) 6947(8) 53(1) C(13) 2381(16) 341(6) 7053(7) 45(1) C(14) 755(12) 699(7) 5719(7) 51(1) C(15) 7393(12) 1866(5) 5698(7) 68(1) C(16) 6680(13) 2683(5) 4234(6) 85(1) C(17) 1556(12) 1165(5) 3726(5) 65(1) C(18) 3864(12) 628(5) 2922(6) 51(1) C(19) 5753(11) 1100(4) 3945(5) 59(1) C(20) 3489(11) 330(4) 4383(5) 53(1) C(21) 3850(10) 1897(4) 3174(4) 45(1)

Appendix

Table 2.9.13 Crystal data and structure refinement for

.CO)5Cr(Me2Sb-SbMe2)Cr(CO)5]ּC6H6)]

Identification code jg9i

Empirical formula C14Cr2H12O10Sb2ּC6H6 Formula weight 765.84 Temperature 173(2) K Wavelength 71.073 pm Crystal system Monoclinic

Space group P1 Unit cell dimensions a = 1523.3(3) pm α = 90° b = 1155.6(2) pm β = 107.15(3)° c = 1673.0(3) pm γ = 90° Volume 2.8141(9) nm3 Z 4 Diffractometer Stoe IPDS

Density (calculated) 1.808 Mg/m3 Absorption coefficient 2.696 mm-1 F(000) 1472 Crystal size 0.50 x 0.35 x 0.30 mm3 Theta range for data collection 2.52 to 26.08° Index ranges -18 ≤ h ≤ 18, -14 ≤ k ≤ 14, -20 ≤ l ≤ 20 Reflections collected 39116 Independent reflections 5486 [R(int) = 0.0455] Completeness to theta = 25.94° 98.2 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5486 / 0 / 343 Goodness-of-fit on F2 1.010

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0254, wR2 = 0.0669 R indices (all data) R1 = 0.0325, wR2 = 0.0690 Largest diff. peak and hole 1.051 and -0.660 e.Å-3

Table 2.9.14 Atomic coordinates (x 104) and equivalent isotropic displacement

parameters (pm2x 10-1) for [(CO)5Cr(Me2Sb-SbMe2)Cr(CO)5]ּC6H6. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 6837(1) 5585(1) -723(1) 37(1) Sb(2) 8067(1) 6609(1) 691(1) 34(1) Cr(1) 3032(1) 5135(1) 1884(1) 32(1) Cr(2) 9240(1) 5271(1) 1753(1) 33(1) O(1) 9568(2) 3871(3) 328(2) 63(1) O(2) 8961(3) 6761(3) 3159(2) 68(1) O(3) 7660(2) 3746(3) 1895(2) 70(1) O(4) 10618(2) 3777(3) 2974(2) 60(1) O(5) 10792(2) 6894(3) 1703(2) 61(1) O(6) 5328(2) 5190(3) -3112(2) 71(1) O(7) 5154(2) 8073(4) -120(2) 81(1) O(8) 6462(3) 8442(3) -2095(2) 73(1) O(9) 3611(2) 7795(3) -2660(2) 65(1) O(10) 4238(2) 4704(3) -1017(2) 70(1) C(1) 6786(3) 3838(3) -331(2) 54(1) C(2) 7804(3) 5385(4) -1426(2) 55(1) C(3) 7215(3) 7672(3) 1203(2) 49(1) C(4) 8596(3) 7879(3) 28(2) 47(1) C(5) 9428(2) 4396(3) 852(2) 44(1) C(6) 9061(3) 6196(3) 2627(2) 47(1)

Appendix

C(7) 8248(3) 4307(3) 1824(2) 48(1) C(8) 10086(3) 4344(3) 2511(2) 44(1) C(9) 10196(2) 6289(3) 1701(2) 42(1) C(10) 5334(3) 5708(3) -2530(2) 49(1) C(11) 5233(3) 7512(4) -658(2) 52(1) C(12) 6037(3) 7747(3) -1892(2) 49(1) C(13) 4246(3) 7332(4) -2248(2) 49(1) C(14) 4634(3) 5416(4) -1234(2) 50(1)

Table 2.9.15 Crystal data and structure refinement for {[(Me3Si)2CH]2Bi}2S

Identification code jg11i

Empirical formula C28H76Bi2SSi8 Formula weight 1087.63 CCDC-Number 185871 Temperature 173(2) K Wavelength 71.073 pm Crystal system Triclinic

Space group P1 Unit cell dimensions a = 1157.4(2) pm α = 104.32(3)° b = 1347.6(3) pm β = 92.65(3)° c = 1781.6(4) pm γ = 114.13(3)° Volume 2.4228(9) nm3 Z 2 Diffractometer Stoe IPDS

Density (calculated) 1.491 Mg/m3 Absorption coefficient 7.510 mm-1 F(000) 1076 Crystal size 0.40 x 0.40 x 0.30 mm3

Appendix

Theta range for data collection 1.96 to 25.94° Index ranges -14 ≤ h ≤ 14, -16 ≤ k ≤ 16, -21 ≤ l ≤ 21 Reflections collected 34531 Independent reflections 8774 [R(int) = 0.0591] Completeness to theta = 25.94° 92.7 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 8774 / 0 / 375 Goodness-of-fit on F2 0.892 Theta range for data collection 1.96 to 25.94° Final R indices [I>2sigma(I)] R1 = 0.0215, wR2 = 0.0421 R indices (all data) R1 = 0.0211, wR2 = 0.0356 Largest diff. peak and hole 0.797 and -0.754 e.Å-3

Table 2.9.16 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2x 10-1) for {[(Me3Si)2CH]2Bi}2S. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Bi(1) 2938(1) 3466(1) 2375(1) 26(1) Bi(2) 2368(1) 6018(1) 3130(1) 25(1) S(1) 3032(1) 5135(1) 1884(1) 32(1) C(1) 3316(4) 2323(4) 1314(2) 28(1) C(2) 731(4) 2673(3) 2277(2) 26(1) C(3) 4256(4) 7606(4) 3718(2) 30(1) C(4) 1341(4) 6981(3) 2711(2) 26(1) C(5) 3620(4) 3527(4) 32(3) 45(1) C(6) 5270(5) 2321(5) 160(3) 52(1)

100

Appendix

C(7) 5807(4) 4488(4) 1429(3) 45(1) C(8) 2727(5) 818(5) 2462(3) 55(1) C(9) 3615(6) 82(5) 948(3) 59(2) C(10) 5459(5) 2171(5) 2304(3) 54(1) C(11) 1592(5) 3223(5) 4084(3) 50(1) C(12) -972(5) 3050(4) 3465(3) 43(1) C(13) -488(5) 920(4) 3199(3) 55(1) C(14) -2034(4) 1357(5) 1378(3) 51(1) C(15) -274(5) 207(4) 1100(3) 50(1) C(16) 155(4) 2243(4) 494(2) 39(1) C(17) 4483(5) 8264(4) 2124(3) 49(1) C(18) 6575(5) 7841(4) 2836(3) 26(1) C(19) 6095(5) 9923(4) 3633(3) 25(1) C(20) 5444(5) 6080(4) 4143(3) 32(1) C(21) 6542(4) 8594(4) 5084(2) 28(1) C(22) 3941(4) 6938(4) 5263(2) 26(1) C(23) 1363(5) 6393(4) 899(2) 30(1) C(24) -675(4) 4731(4) 1573(3) 26(1) C(25) -701(4) 6980(4) 1519(3) 45(1) C(26) -1175(4) 6186(4) 3440(3) 52(1) C(27) 320(5) 8689(4) 3521(3) 45(1) C(28) 1343(5) 7660(5) 4526(2) 55(1) Si(1) 4488(1) 3164(1) 749(1) 59(2) Si(2) 3781(1) 1364(1) 1743(1) 54(1) Si(3) 219(1) 2452(1) 3233(1) 50(1) Si(4) -310(1) 1627(1) 1329(1) 43(1) Si(5) 5333(1) 8366(1) 3081(1) 55(1) Si(6) 5045(1) 7307(1) 4532(1) 51(1) Si(7) 348(1) 6272(1) 1692(1) 50(1) Si(8) 457(1) 7351(1) 3519(1) 39(1)

101

Appendix

Table 2.9.17 Crystal data and structure refinement for {[(Me3Si)2CH]2Bi}2Te

Identification code jg14b

Empirical formula C28H76Bi2Si8Te Formula weight 1183.17 CCDC-Number 185872 Temperature 173(2) K Wavelength 71.073 pm Crystal system Triclinic

Space group P1 Unit cell dimensions a = 1173.0(14) pm α = 75.00(3)° b = 1363.7(6) pm β = 88.17(7)° c = 1758.7(8) pm γ = 65.19(5)° Volume 2.46(1) nm3 Z 2 Diffractometer Siemens P4

Density (calculated) 1.599 Mg/m3 Absorption coefficient 7.945 mm-1 F(000) 1148 Crystal size 0.60 x 0.40 x 0.30 mm3 Theta range for data collection 2.13 to 27.54 Index ranges -15 ≤ h ≤ 1, -16 ≤ k ≤ 15, -22 ≤ l ≤ 22 Reflections collected 12768 Independent reflections 10971 [R(int) = 0.0341] Completeness to theta = 27.54° 96.9 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 10971 / 0 / 379 Goodness-of-fit on F2 1.007

102

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0550, wR2 = 0.1178 R indices (all data) R1 = 0.0980, wR2 = 0.1379 Largest diff. peak and hole 1.919 and -2.063 e.Å-3

Table 2.9.18 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2x 10-1) for {[(Me3Si)2CH]2Bi}2Te. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Bi(1) 5385(1) 6568(1) 2299(1) 33(1) Bi(2) 8691(1) 3920(1) 3096(1) 31(1) Te(1) 7037(1) 4742(1) 1681(1) 39(1) C(1) 3893(10) 7747(9) 1257(5) 35(2) C(2) 6833(10) 7322(9) 2247(5) 34(2) C(3) 10683(10) 3011(9) 2711(6) 36(2) C(4) 8402(10) 2341(9) 3737(6) 36(2) Si(1) 2540(3) 8684(3) 1719(2) 39(1) Si(2) 3476(3) 6975(3) 642(2) 39(1) Si(3) 6861(3) 8380(3) 1322(2) 41(1) Si(4) 7143(3) 7513(3) 3228(2) 39(1) Si(5) 10991(3) 3671(3) 1692(2) 38(1) Si(6) 11872(3) 2715(3) 3529(2) 41(1) Si(7) 8154(3) 1485(3) 3138(2) 48(1) Si(8) 7296(4) 2702(3) 4527(2) 56(1) C(11) 1639(11) 7908(12) 2256(7) 57(3) C(12) 3107(12) 9183(12) 2469(8) 62(4) C(13) 1476(14) 9969(12) 953(8) 71(4) C(21) 4646(12) 6643(11) -118(7) 51(3) C(22) 1881(12) 7844(12) 78(7) 61(4)

103

Appendix

C(23) 3416(12) 5678(11) 1274(8) 41(1) C(31) 8326(14) 8634(14) 1385(8) 39(1) C(32) 5492(13) 9773(10) 1124(8) 38(1) C(33) 6978(12) 7822(12) 449(7) 41(1) C(41) 6563(12) 6700(12) 4059(7) 48(1) C(42) 8919(11) 6938(12) 3434(7) 56(1) C(43) 6348(13) 8997(12) 3281(8) 57(3) C(51) 10258(12) 3392(12) 887(6) 62(4) C(52) 10393(11) 5214(10) 1539(6) 62(4) C(53) 12724(12) 3073(12) 1553(8) 71(4) C(61) 12273(13) 3923(11) 3450(8) 51(3) C(62) 13334(12) 1429(12) 3557(9) 61(4) C(63) 11283(13) 2412(15) 4532(7) 62(4) C(71) 9014(13) 1440(11) 2232(7) 71(4) C(72) 6461(14) 1949(13) 2837(9) 41(1) C(73) 8829(15) -11(12) 3749(9) 39(1) C(81) 5733(13) 3879(13) 4108(8) 38(1) C(82) 7966(13) 3146(14) 5256(7) 41(1) C(83) 7021(15) 1458(14) 5107(9) 48(1)

104

Appendix

Table 2.9.19 Crystal data and structure refinement for

cyclo-[(Me3Si)2CHSbS)]2[W(CO)5]2

Identification code jg12a

Empirical formula C24H38O10S2Sb2Si4W2 Formula weight 1274.22 Temperature 173(2) K Wavelength 71.073 pm Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 2239.6(5) pm α = 90° b = 1091.9(4) pm β= 98.08(2)° c = 1718.3(4) pm γ = 90° Volume 4.160(2) nm3 Z 4 Diffractometer Siemens P4

Density (calculated) 2.034 Mg/m3 Absorption coefficient 7.054 mm-1 F(000) 2400 Crystal size 0.60 x 0.40 x 0.40 mm3 Theta range for data collection 2.81 to 27.51° Index ranges -1<=h<=13, -15<=k<=14, -22<=l<=22 Reflections collected 10582 Independent reflections 4757 [R(int) = 0.0316] Completeness to theta = 27.51° 99.4 % Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4757 / 0 / 207 Goodness-of-fit on F2 1.133

105

Appendix

Final R indices [I>2sigma(I)] R1 = 0.0258, wR2 = 0.0621 R indices (all data) R1 = 0.0288, wR2 = 0.0632 Largest diff. peak and hole 1.160 and -1.282 e.Å-3

Table 2.9.20 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x10-1) for cyclo-[(Me3Si)2CHSbS)]2[W(CO)5]2. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) W(1) 3590(1) 6494(1) 1315(1) 23(1) Sb(1) 4322(1) 4605(1) 1900(1) 17(1) S(1) 4631(1) 4781(1) 3306(1) 22(1) C(1) 4191(2) 2676(3) 1717(2) 22(1) C(2) 2815(2) 5504(4) 1207(2) 30(1) C(3) 3478(2) 6954(5) 2437(3) 40(1) C(4) 4355(2) 7545(4) 1445(3) 37(1) C(5) 3673(2) 6078(5) 175(2) 33(1) C(6) 3075(2) 7886(4) 867(2) 31(1) C(11) 4585(2) 3223(5) 87(2) 33(1) C(12) 3268(2) 2717(6) 199(3) 44(1) C(13) 4211(2) 686(5) 453(3) 45(1) C(21) 3117(2) 3128(5) 2648(3) 38(1) C(22) 4142(2) 1430(5) 3307(3) 47(1) C(23) 3248(3) 636(6) 1942(3) 61(2) O(2) 2362(1) 4998(4) 1130(2) 48(1) O(3) 3419(2) 7243(5) 3058(2) 71(1) O(4) 4774(2) 8137(4) 1537(3) 60(1) O(5) 3691(2) 5900(5) -467(2) 58(1) O(6) 2770(2) 8650(3) 582(2) 46(1)

106

Appendix

Si(1) 4060(1) 7243(5) 1942(3) 71(1) Si(2) 3674(1) 8137(4) 1130(2) 60(1)

Table 2.9.21 Crystal data and structure refinement for

cyclo-[(Me3Si)2CHSbSe]2[W(CO)5]2

Identification code jg15i

Empirical formula C24H38O10Sb2Se2Si4W2 Formula weight 1368.02 CCDC-Number 185873 Temperature 173(2) K Wavelength 71.073 pm Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 2271.4(5) pm α = 90° b = 1093.2(2) pm β= 98.00(3)° c = 1733.5(3) pm γ = 90° Volume 4.2626(14) nm3 Z 4 Diffractometer Stoe IPDS

Density (calculated) 2.132 Mg/m3 Absorption coefficient 8.495 mm-1 F(000) 2544 Crystal size 0.5 x 0.4 x 0.3 mm3 Theta range for data collection 2.32 to 25.86° Index ranges -27<=h<=27, -12<=k<=12, -21<=l<=21 Reflections collected 29232 Independent reflections 3996 [R(int) = 0.0381] Completeness to theta = 25.86° 96.4 %

107

Appendix

Absorption correction DIFABS

Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3996 / 0 / 207 Goodness-of-fit on F2 0.986 Final R indices [I>2sigma(I)] R1 = 0.0168, wR2 = 0.0349 R indices (all data) R1 = 0.0211, wR2 = 0.0356 Largest diff. peak and hole 0.900 and -0.753 e.Å-3

Table 2.9.22 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (pm2 x 10-1) for cyclo-[(Me3Si)2CHSbSe]2[W(CO)5]2. U(eq) is defined as one third of the trace of the orthogonalised Uij tensor.

x y z U(eq) Sb(1) 4297(1) 5443(1) 1893(1) 23(1) Se(1) 5375(1) 5216(1) 1642(1) 28(1) W(1) 3560(1) 3566(1) 1314(1) 29(1) C(1) 4180(1) 7385(3) 1721(2) 29(1) C(2) 3055(1) 2162(3) 873(2) 38(1) C(3) 3645(1) 3969(4) 182(2) 42(1) C(4) 2795(1) 4574(3) 1198(2) 37(1) C(5) 3441(2) 3113(4) 2431(2) 47(1) C(6) 4314(2) 2501(4) 1451(2) 48(1) O(2) 2761(1) 1399(2) 594(2) 52(1) O(3) 3662(1) 4151(3) -457(2) 72(1) O(4) 2356(1) 5080(3) 1125(2) 55(1) O(5) 3378(1) 2858(3) 3044(2) 78(1) O(6) 4725(1) 1913(3) 1546(2) 72(1) C(11) 3265(2) 7365(4) 223(2) 50(1)

108

Appendix

C(12) 4197(2) 9404(3) 478(2) 37(1) C(13) 4556(2) 6861(4) 91(2) 47(1) C(21) 3126(1) 6931(4) 2667(2) 48(1) C(22) 3255(2) 9428(4) 1964(2) 52(1) C(23) 4145(2) 8632(4) 3302(2) 72(1) Si(1) 4044(1) 7751(1) 637(1) 55(1) Si(2) 3676(1) 8077(1) 2401(1) 78(1)

109

CURRICULUM VITAE

Personal data Family name: GHESNER First name: IOAN Date of birth: 14th of September 1975 Place of birth: Turda, Romania

Education - 1982 to 1994 primary and secondary school, in Turda, Romania 1994 to 1999 study of chemistry at the Babeş-Bolyai University, Cluj-Napoca, Romania - June 1999, M.Sc. degree - 1999 to 2002 Ph.D. student in the group of Prof. Dr. H. J. Breunig at the University of Bremen, Germany

110

Publications

1. Organoantimony ring-chain equilibria: trapping of catena-tetrastibanes in cyclo-

[Cr(CO)4(R’2Sb-SbR-SbR-SbR’2)] (R’ = Me, Ph; R = Me3SiCH2) and related complexes, Hans Joachim Breunig, Ioan Ghesner, Enno Lork, Organometallics, 20 (2001) 1360-1364.

2. Organoantimony derivatives of organophosphorus ligands containing inorganic chelate rings, Gábor Balázs, Hans Joachim Breunig, John E. Drake, Ioan Ghesner, Anca Silvestru, Phosphorus, Sulfur and Silicon, 169 (2001) 97-100.

3. Lithium tetraorganodichalcogenoimidodiphosphinates. Crystal structure of

[Li{(OPPh2)(SPMe2)N}⋅2H2O]2, a dimer formed through oxygen-bridging phosphorus ligands, Ioan Ghesner, Csaba Palotaş, Anca Silvestru, Cristian Silvestru, John E. Drake, Polyhedron, 20 (2001) 1101-1105.

4. Phenylantimony(III) derivatives of tetraphenyldichalcogenoimidodiphosphinic

acids. Crystal and molecular structure of PhSb[(XPPh2)(SPPh2)N]2 (X = O, S), Ioan Ghesner, Laura Opris, Gábor Balázs, Hans J. Breunig, John E. Drake, Anca Silvestru, Cristian Silvestru, J. Organomet. Chem., 642 (2002), 113-119.

5. Syntheses and crystal structures of a covalent trialkyl hydroxo bromide and related trialkylantimony(V) compounds, Lucia Balázs, Hans J. Breunig, Ioan Ghesner, Enno Lork,

111

Publications

J. Organomet. Chem., 648 (2002) 33.

6. A complex with the cyclo-R2Sb2S2 [R = CH(SiMe3)2] ligand, Hans Joachim Breunig, Ioan Ghesner, Enno Lork, Appl. Organometal. Chem., 16 (2002) 547.

7. Coordination Compounds with Organoantimony and Sbn Ligands, Hans Joachim Breunig, Ioan Ghesner, Adv. Organomet. Chem., in press.

112

Contributions to professional reports

Contribution to professional reports (presenter underlined)

1. Organoantimony tetraorganodichalcogenoimidodiphosphinates. Asymmetric

coordination pattern in PhSb[(OPPh2)(SPPh2)N]2, Ioan Ghesner, I. Negru-Pavel, John E. Drake, Cristian Silvestru, Ionel Haiduc, at The XVIIIth International Conference on Organometallic Chemistry (XVIIIth ICOMC), Münich (Germany),August 1998.

2. Organoantinony derivatives of organophosphorus ligands containing inorganic chelate rings, Gábor Balázs, Hans J. Breunig, John E. Drake, Ioan Ghesner, Anca Silvestru, at The IXth International Conference on Inorganic Ring Systems, Saarbrücken (Germany), July 2000.

3. Novel bis(diorganobismuth)chalcogenides; coordination chemistry of the cyclo-

RnSbnSn [R = CH(SiMe3)2] ligand, Hans J. Breunig, Ioan Ghesner, Enno Lork, at The XIVth FECHEM Conference on Organometallic Chemistry, Gdansk (Poland), September 2001.

4. Coordination chemistry of the cyclo-RnSbnSn [R = CH(SiMe3)2] ligand, Ioan Ghesner, Hans J. Breunig, at 4. Norddeutsches Doktoranden-Kolloquium, Hamburg (Germany), Oktober 2001.

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Acknowledgements

I am most grateful to Prof. Dr. Hans Joachim Breunig, my supervisor, for giving me the opportunity to develop this work, for his generous support, guidance, and encouragement. I would also like to thank Prof. Dr. Gerd-Volker Röschenthaler and Prof. Dr. Karl- Peter Wanczek for reviewing this work. Thanks to all members and former members of the research group for their good co- operation. I would like to thank to Dr. Tamara Krüger and Dr. Henrik Althaus for their friendly reception. A special thank goes to Dr. Enno Lork for introducing me X-ray crystallography and for helping me with the solution of the X-ray crystal structures. Also, I want to thank to Mr. Peter Brackmann for his patience with the selection of suitable single crystals for the X-ray diffraction studies as well as for carrying out the X-ray crystallographic measurements. Many thanks to Dr. Thomas Dülcks and Dipl. Ing. Heike Anders, who carried out the mass spectra measurements. Thanks also to Dipl. Ing. Johannes Stelten for the NMR measurements and for briefing me with the use of the DPX 200 device. I would like to thank Prof. Dr. Cristian Silvestru and Conf. Dr. Ing. Anca Silvestru from Babeş-Bolyai University for their support. For the review of the English manuscript I wish to thank to Dr. Paul G. Watson. Finally I wish to express my thanks to the University of Bremen for the financial support and to all those who made my stay at the University of Bremen, in Bremen and in Germany very pleasant.

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