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Precursors for Synthesis of the First Compounds with Metal-Silicon Triple Bonds

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Precursors for Synthesis of the First Compounds with Metal-Silicon Triple Bonds Novel Molecular Si(II) Precursors for Synthesis of the First Compounds with Metal-Silicon Triple Bonds Dissertation Submitted in fulfillment of the degree doctor rerum naturalium (Dr. rer. nat) of The Faculty of Mathematics and Natural Sciences of The Rheinische Friedrich-Wilhelms-University of Bonn by Dipl.-Chem. Oleg Chernov born in Belgorod, Russia Bonn, April 2012 Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn 1st Examiner: Prof. Dr. A. C. Filippou 2nd Examiner: Prof. Dr. J. Beck 3rd Examiner: Prof. Dr. A. Gansäuer 4th Examiner: Prof. Dr. M. Wagner Date of dissertation defense: 21. September 2012 Publication year: 2012 2 Acknowledgements First, I would like to thank Prof. Dr. Alexander C. Filippou for giving me the opportunity to work in his research group, for his guidance, helpful advices and the thorough evaluation of my thesis including various suggestions for amendments. I am obliged to many of my colleagues, without their help this dissertation would not have been possible: Dr. Gregor Schnakenburg for the X-ray diffraction measurements, quantum chemical calculations and of course for correcting the draft of the disertation. Gabriele Hofer, Katrin Puffler, Kerstin Kühnel-Lysek, Bernhard Beile and Dietmar Kühlmorgen for the synthesis of starting materials and everyday help. Dr. Jürgen Tirée for his great help in organization of the experimental work. All of my students, who contributed to my research: Volker Adam, Martin Speer, Jana Haag, Klaas Remmerssen. Dr. Nils Weidemann for his useful advices and some of precious starting materials. Dr. Sebastian Schwieger for solving some of my X-ray structures The NMR department: Karin Prochnicki, Claus Schmidt, Hannelore Spitz and Dr. Wilfried Hoffbauer. Dr. Sabine Rings and her colleagues for the elemental analysis measurements. Dr. Burhanshah Lewall for the cyclic voltammetry studies. Dr. Maurice van Gastel for the EPR measurements in the MPI Mülheim. Dr. Eckhard Bill and Bernd Mienert for the Mössbauer measurements in the MPI Mülheim. Phillip Malcho for proofreading the draft of the thesis. All the group members for the friendly atmosphere, support and help. 3 4 For the things we have to learn before we can do, we learn by doing. Aristotle 5 6 Table of Content 1 Introduction ................................................................................................................13 1.1 Silylenes............................................................................................................................................. 13 1.2 Silylidene complexes [LnM=SiR2] ................................................................................................... 23 1.3 Group 14 ylidyne complexes [LnM≡E–R] (E = Ge–Pb) ................................................................ 26 1.4 Goals and objectives of the work .................................................................................................... 31 2 Results and discussion................................................................................................32 2.1 Carbene-stabilized silylenes SiX2(NHC) and SiArCl(NHC) (NHC = N-heterocyclic carbene; X = halogen; Ar = aryl group)....................................................................................................................... 32 2.1.1 NHC-stabilized silylenes, SiX2(NHC), (X = Cl, Br, I; NHC = N-heterocyclic carbene). .............. 34 2.1.2 NHC-stabilized organochlorosilylenes, SiClAr(NHC) (Ar = m-terphenyl; NHC = N- heterocyclic carbene)................................................................................................................................... 44 2.1.3 Preliminary reactivity studies of NHC-stabilized silylenes SiX2(NHC) and SiArCl(NHC)........... 50 2.2 Access to the first silylidyne complexes. ......................................................................................... 73 2.2.1 Synthesis of zwitterionic silylidene complexes of Mo and W........................................................ 73 2.2.2 Synthesis of zwitterionic halosilylidene complexes of Cr, Mo and W........................................... 79 2.2.3 Reactions of the NHC-stabilized halosilylidyne complexes........................................................... 87 2.2.4 Synthesis of the first silylidyne complexes..................................................................................... 95 2.3 Chemistry of the silylidyne complexes.......................................................................................... 108 2.3.1 Addition of polar reagents ............................................................................................................ 108 2.3.2 Addition of nucleophiles .............................................................................................................. 117 2.3.3 Reactivity towards acetylenes....................................................................................................... 129 2.4 Metallagermylenes ......................................................................................................................... 141 2.5 Open-shell carbene complexes of iron.......................................................................................... 149 2.6 Other reactions............................................................................................................................... 157 3 Summary and Outlook.............................................................................................160 3.1 Summary......................................................................................................................................... 160 3.2 Outlook............................................................................................................................................ 166 7 4 Experimental Section................................................................................................ 169 4.1 General part.................................................................................................................................... 169 4.1.1 IR spectroscopy ............................................................................................................................ 170 4.1.2 NMR spectroscopy ....................................................................................................................... 170 4.1.3 X-ray crystallography ................................................................................................................... 171 4.1.4 Elemental analysis ........................................................................................................................ 172 4.1.5 Melting points determination........................................................................................................ 172 4.1.6 Mössbauer and EPR spectroscopy................................................................................................172 4.1.7 Cyclic voltammetry....................................................................................................................... 172 4.2 Syntheses ......................................................................................................................................... 174 4.2.1 [SiBr3(IDipp)]Br (15) ................................................................................................................... 174 4.2.2 SiBr2(IDipp) (16) .......................................................................................................................... 174 4.2.3 [SiI3(IDipp)]I (17)......................................................................................................................... 175 4.2.4 SiI2(IDipp) (18)............................................................................................................................. 176 4.2.5 [SiBr3(ISdipp)]Br (19) .................................................................................................................. 177 4.2.6 SiBr2(ISdipp) (20)......................................................................................................................... 178 4.2.7 Si2(ISdipp)2 (21) ........................................................................................................................... 179 4.2.8 SiI2(ISdipp) (22) ........................................................................................................................... 180 4.2.9 [Si(IMe4)3]I2 (23) .......................................................................................................................... 181 4.2.10 1,1-diodo-2,3,4,5-tetra(diethylamino)silole (24) .......................................................................... 181 4.2.11 SiCl(C6H3-2,6-Mes2)(IMe4) (28) .................................................................................................. 182 4.2.12 SiCl(C6H3-2,6-Trip2)(IMe4) (29) .................................................................................................. 183 4.2.13 Si(C6H3-2,6-Dipp2)HCl2 (30)........................................................................................................184 4.2.14 SiCl(C6H3-2,6-Dipp2)(IMe4) (31) ................................................................................................. 185 4.2.15 {Si(C6H3-2,6-Mes2)(IMe4)}2 (32) .................................................................................................186 4.2.16 Synthesis of 34; K2(IMe4)3[SiHR2]2;
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