Functionalized nido-C_1tn4B_1tn2, closo-C_1tn2B_1tn5 and -C_1tn2B_1tn1_1tn0 carboranes, and reactivity studies on electron-poor 2,3-dihydro-1,3-diborolyl complexes of ruthenium [Elektronische Ressource] / vorgelegt von Yong Nie

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Functionalized nido-C B , closo-C B and -C B4 2 2 5 2 10 Carboranes, and Reactivity Studies on Electron-Poor 2,3-Dihydro-1,3-diborolyl Complexes of Ruthenium INAUGURAL - DISSERTATION zur Erlangung der Doktorwürde der Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht-Karls-Universität Heidelberg Vorgelegt von Yong Nie (MSc.) aus Shandong, P. R. China 2005 INAUGURAL - DISSERTATION zur Erlangung der Doktorwürde der Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht-Karls-Universität Heidelberg Vorgelegt von Yong Nie (MSc.) aus Shandong, P. R. China Tag der mündlichen Prüfung: 11.3.2005 Functionalized nido-C B , closo-C B and -C B4 2 2 5 2 10 Carboranes, and Reactivity Studies on Electron-Poor 2,3-Dihydro-1,3-diborolyl Complexes of Ruthenium Gutachter: Prof. Dr. Walter Siebert Prof. Dr. Lutz H. Gade Many thanks to my supervisor, Prof. Dr. Walter Siebert, for his very helpful advice, stimulating ideas and fruitful discussions throughout my research in his group. Dedicated to my parents ?????????????? Part of the work described herein has been published: 1.

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Functionalized nido-C B , closo-C B and -C B4 2 2 5 2 10
Carboranes, and Reactivity Studies on Electron-Poor
2,3-Dihydro-1,3-diborolyl Complexes of Ruthenium



INAUGURAL - DISSERTATION
zur
Erlangung der Doktorwürde
der
Naturwissenschaftlich-Mathematischen
Gesamtfakultät
der
Ruprecht-Karls-Universität
Heidelberg




Vorgelegt von
Yong Nie (MSc.)
aus Shandong, P. R. China
2005




INAUGURAL - DISSERTATION
zur
Erlangung der Doktorwürde
der
Naturwissenschaftlich-Mathematischen
Gesamtfakultät
der
Ruprecht-Karls-Universität
Heidelberg









Vorgelegt von
Yong Nie (MSc.)
aus Shandong, P. R. China

Tag der mündlichen Prüfung: 11.3.2005



Functionalized nido-C B , closo-C B and -C B4 2 2 5 2 10
Carboranes, and Reactivity Studies on Electron-Poor
2,3-Dihydro-1,3-diborolyl Complexes of Ruthenium




















Gutachter: Prof. Dr. Walter Siebert
Prof. Dr. Lutz H. Gade













Many thanks to my supervisor, Prof.
Dr. Walter Siebert, for his very helpful
advice, stimulating ideas and fruitful
discussions throughout my research in
his group.

























Dedicated to my parents
??????????????
























Part of the work described herein has been published:

1. Yong Nie, Stefan Schwiegk, Hans Pritzkow, Walter Siebert,*
One-Pot Synthesis of 1,6-Diiodo-2,3,4,5-tetracarba-nido-hexaboranes(6) and
Mechanistic Studies on the Reaction System Alkynes/BI / NaK . 3 2.8
Eur. J. Inorg. Chem., 2004, 1630-1638.

2. Yong Nie, Hans Pritzkow, Walter Siebert,*
Reactivity Studies on 1,6-Diiodo-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-
hexaborane(6): Synthesis and Structures of New C B -nido-carborane 4 2
Derivatives.
Eur. J. Inorg. Chem., 2004, 2425-2433.

3. Yong Nie, Hans Pritzkow, Chunhua Hu, Thomas Oeser, Bettina Bach,
Thomas Müller, Walter Siebert,*
7 5( η -4-Borataborepine)( η -pentamethylcyclopentadienyl)ruthenium
complexes: ruthenocene analogs with a novel C B ligand. 5 2
Angew. Chem., 2005, 117, 638-640; Angew. Chem. Int. Ed., 2005, 44,
632- 634.













Table of contents
Table of contents
Summary
Zusammenfassung
1 Introduction................................................................................................. 1
1.1 Organoboranes and carboranes................................................................................... 1
1.2 Boron heterocycles as ligands to transition metals..................................................... 9
2 Objectives.................................................................................................. 10
3 Results and discussion ...............................................................................11
3.1 Synthesis and reactivity of 2,3,4,5-tetracarba-nido-hexaboranes(6)...................... 11
3.1.1 One-pot synthesis and properties of 1,6-diiodo-2,3,4,5-tetracarba-nido-
hexaboranes(6) (5a-5c) ................................................................................................. 12

3.1.2 Crystal structure of 1,6-diiodo-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexa-
borane(6) (5a) ................................................................................................................ 14

3.1.3 Formation of nido-(EtC) (BI) (4) and crystal structure of 3,4-bis(diiodoboryl)- 4 4
3-hexene (2) ................................................................................................................... 16

3.1.4 Scope and limitations of the one-pot method................................................................. 18

3.1.5 Mechanistic studies on the reaction system alkynes/BI /NaK ................................... 18 3 2.8

3.1.6 Reactivity of 1,6-diiodo-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-
hexaborane(6) (5a) ........................................................................................................ 22
3.1.6.1 Regiospecific substitution at the basal boron atom....................................................... 22
3.1.6.2 Substitution reactions involving the apical boron atom................................................ 27
3.1.6.3 Cluster linkages involving 2,3,4,5-tetracarba-nido-hexaboranes(6) ............................. 33

3.1.7 Conclusion ................................................................................................................... 37

ITable of contents
3.2 Formation and properties of 2,3-dicarba-closo-heptaboranes(7)............................. 38
3.2.1 Facile synthesis of apically halogenated 2,3-dicarba-closo-heptaboranes(7)
(19a,b) from 2,3-dicarba-nido-hexaborane(8) .............................................................. 38

3.2.2 Alkynyl-substituted 2,3-dicarba-closo-heptaboranes(7) (19c-f) via
Pd-catalyzed cross-coupling reactions .......................................................................... 39

3.2.3 Alkenyl-linked 2,3-dicarba-closo-heptaborane(7) clusters (20) .................................... 40

3.2.4 Reactions of 19c,d with cobalt complexes .................................................................... 40

3.2.4.1 Reactions of carboranylacetylenes 19c,d with Co (CO) ............................................. 40 2 8
3.2.4.2 Reactions of 19c with CpCo(C H ) : formation of 2 4 2
CpCo(dicarboranylcyclobutadiene) complex 23 .......................................................... 41

3.2.5 Conclusion..................................................................................................................... 42

3.3 C-Boryl-o-carborane compounds .............................................................................. 42
3.3.1 C-Aminoboryl-o-carborane derivatives......................................................................... 43

3.3.2 Diborane(4)-yl-o-carboranes 28 .................................................................................... 45

3.3.3 o-Carboranes with exo-cluster boron heterocycles........................................................ 47

3.3.4 Conclusion..................................................................................................................... 48

5 53.4 Reactivity of ( η -pentamethylcyclopentadienyl)( η -2,3-dihydro-1,3-diborolyl)-
ruthenium complexes .................................................................................................. 49
3.4.1 Crystal and electronic structures of Ru and Fe complexes ............................................ 50

3.4.1.1 Crystal structure of the B-trimethylsilylmethyl derivative 35b .................................... 50
3.4.1.2 Electronic structures of the model compounds of Ru (35) and Fe (36) ........................ 50

3.4.2 Insertion of alkynes into 1,3-diborolylruthenium complexes........................................ 58

3.4.2.1 Formation of novel 4-borataborepine complexes 38..................................................... 58
3.4.2.2 Attempts to prepare 4-borataborepines from 1,3-diborole 37c ..................................... 62
3.4.2.3 Formation of boratabenzene ruthenium complexes 39f,g............................................. 63

3.4.3 Formation of the triple-decker 46 with a bridging C B ligand 65 5 2


IITable of contents
53.4.4 Interactions of η -2,3-dihydro-1,3-diborole-(chloro)rhodium complexes with
RCH C H and (R P) C H (R = Ph).............................................................................. 66 2 2 2 2 2 4

3.4.5 Crystal structure of the tetradecker complex 53a.......................................................... 68

3.4.6 Reaction of 35a with allylchloride: formation of “oligodecker” 58.............................. 69

3.4.7 Conclusion..................................................................................................................... 73

3.5 Synthesis of the 1,3-diiodo-1,3-diborole 37d and formation of
+ the 2,3,4,5,6-pentacarba-nido-hexaborane(6) cation (63 ) ........................................ 74
3.6 Synthesis and properties of some aminoborane derivatives ..................................... 77
3.6.1 1,2-Dibromo-1,2-dipyrrolidinodiborane(4) (72b)......................................................... 79

3.6.2 Properties of (Me N) B [B(NMe ) ] (70) .................................................................... 84 2 2 4 2 2 2

3.6.2.1 Reactions with S and Me NO ...................................................................................... 84 8 3
3.6.2.2 Rearrangement of 70 into the cyclo-B isomer 67a ...................................................... 85 6
3.6.2.3 Reactions with isonitriles .............................................................................................. 86

3.6.3 Conclusion..................................................................................................................... 87
4 Experimental section................................................................................ 88
5 References.................................................................................................125
6 Appendices...............................................................................................139
6.1 Abbreviations and Symbols........................................................................................139
6.2 Selected NMR and MS spectra ................................................................................... 140
6.3 Crystal data and refinement details............................................................................. 146
Acknowledgement

IIISummary
Summary
The results are described in six chapters on organoborane/carborane compounds (3.1, 3.2,
3.3, 3.5), on the reactivity of 2,3-dihydro-1,3-diborolyl complexes of ruthenium (3.4), and on
aminoborane derivatives (3.6).
In Chapter 3.1, a one-pot synthesis of 1,6-diiodo-2,3,4,5-tetracarba-nido-hexaborane(6)
derivatives (5a-c) is reported, involving disubstituted alkynes and BI (in 1:1 ratio) and NaK3 2.8
at low temperature. The reaction of 3-hexyne, BI (2 equiv.) and NaK at r.t. affords a mixture 3 2.8
of 5a, nido-(EtC) (BI) (4) and closo-(EtC) (BI) (6). 4 4 2 5
II I
BEtEt BB IR R Et BC CI I
B B Et B IB I BR CC
IB EtR Et Bc5 a b
II 4R Et Me Ph 6
The alternative formation of 4 and 6 by dehalogenation of the known cis-I B(Et)C= 2
C(Et)BI (2) indicates that diborylalkenes are precursors for nido-C B carboranes. In general, 2 4 4
dehalogenation reactions proceed clean and give higher yields of carboranes at low
temperature. The nido-C B skeleton has been confirmed by an X-ray diffraction analysis of 4 2
yellow 5a. The structure of 2 exhibits a remarkable B-I-B bridge.
I2
C6C4
C5C3
C1 C2B2
C7 C9
B2 B1
C5 C11C2 C3
C1 C4 I4C8 I2 I3B1
C10
C12C6
I1 I1

5a 2
IV