Synthesis, Characterization, and Reactions of Selected Heteronuclear Diboron Ring Systems
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This dissertation has been microfilmed exactly as received 66-15,151 W E L C H , Cletus Norman, 1937- SYNTHESIS, CHARACTERIZATION, AND REACTIONS OF SELECTED HETERONUCLEAR DIBORON RING SYSTEMS, The Ohio State University, Ph.D., 1966 Chemistry, inorganic University Microfilms, Inc., Ann Arbor, Michigan SYNTHESIS, CHARACTERIZATION, AND REACTIONS OF SELECTED HETERONUCLEAR DIBORON RING SYSTEMS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Cletus Norman Welch, B.S., M.Sc, The Ohio State University 1966 Approved by Adviser Department of Chemistry ACKNOWLEDGMENTS This investigation was financially supported by a grant from the National Science Foundation. I would like to take this opportunity to express my appreciation to Dr. Sheldon G„ Shore for his continued interest and guidance throughout the duration of this investigation and in the preparation of this dissertation. A special note of thanks goes to my colleagues Mr. Russell A. Geanangel, Mr. David E. Young, and Dr. Roger K. Bunting for their generous imparting of beneficial assistance, equipment, and technical information. My wife, Delores, deserves a sincere expression of appreciation for her unselfish desires, understanding, and moral support to the completion of this investigation, 11 VITA February 2, 1937 Born— Convoy , Ohio 1 9 6 1 ............ B.S., Bowling Green State University, Bowling Green, Ohio 1961-1954. Teaching Assistant, Department of Chemistry, The Ohio State University, Columbus, Ohio 1964 ............ M. Sc., The Ohio State University, Columbus, Ohio 1964-1966. Research Fellow, Department of Chemistry, The Ohio State University, Columbus, Ohio PUBLICATIONS "New Organic Boron Heterocycles Contain Oxygen or Sulfur Atoms in the Ring," C & EN News, p. 42, April 4, 1966. FIELD OF STUDY Major Field; Inorganic Chemistry Studies in Non-Metal Chemistry. Professor Sheldon G. Shore Studies in Transition-Metal Coordination Chemistry, Professor Daryle H. Busch, Devon W, Meek, and Andrew A. Wojcicki 111 CONTENTS Page ACKN0WLEDGI4ENTS.......................................... ii VITA ......................................................... iii TABLES ...................................................... vii ILLUSTRATIONS.............................................. viii INTRODUCTION ............................................. 1 I, Background of Diboron Chemistry .............. 1 II. General Preparation of Diboron Compounds. 2 III. Tetrahalodiborons .............................. 3 IV. Tetra-(amino)-diborons......................... 16 V. Tetraalkoxydiborons ............................ 25 VI. Tetraalkyl- or Tetraaryldiborons.............. 30 VII. Tetrathiodiborons ....................... 32 VIII. Tetra-(hydrido)-diboron ....................... 32 IX. Mixed Diboron Systems .......................... 33 STATEMENT OF PROBLEM ................................... 44 DISCUSSION AND CONCLUSIONS ............................ 47 I. Syntheses ........................................ 47 XV CONTENTS - Cont'd. Page II. R e a c t i o n s ........................................... 67 III. Nuclear Magnetic Resonance. ............ 80 EXPERIMENTAL .................. 92 I. Apparatus .................................... 92 II. Starting Materials................................. 104 III. Analytical Procedures .......................... 109 IV. Synthesis and Properties of Heteronuclear Diboron Ring Compounds Considered in This Investigation ................................. 113 A. B 2 (02C2H^)2..................................... 113 B. B 2 CI 2 (O2 C 2 H 4 ) .................................. 121 C. 12 3 D. B2(02CgHg)2« .....«..•«••••Cl 127 E. Bg (S2 C 2 H 4 ) 2 12 8 F. B 2 CI 2 (S2 C 2 H 4 ) .................................. 134 G. B 2 [N(CH3 )2 ]2 (S2 C 2 H 4 ) ....................... 136 H. B 2 [(NCH3)2C2H4]2 ............................ 137 I. B 2 [(NH)2 C g H 4 ] 2 ................................ 143 J. B2(S2C2H4)2*2 NH(CH3)2 ..................... 147 CONTENTS - Cont'd. Page V. Chemistry of Diboron Compounds Synthesized in This Investigation............................ 152 A. Reactions of B 2 CI 2 (O2 C 2 H 4 ) . ....... 153 B. Reactions of B 2 CI 2 (S2 C 2 H 4 ).............. 158 C. Reactions of B 2 [N (CII3) 2 ] 2 .... 162 D. Reactions of B 2 (0 2 C 2 H 4 )2 . ........ 170 E. Reactions of B 2 (S2 C 2 H 4 ) 2 ................ 174 F. Reactions of B 2 [(NH)2 C 5 H 4 ] 2 .......... 177 SUMMARY ............................................ 179 APPENDIX................................ 183 BIBLIOGRAPHY................................................186 VI TABLES Table Page 1. X-Ray Powder Diffraction Pattern Data of B 2 (0 2 C 2 H 4 ) 2 and B 2 C l 2 (0 2 C 2 H 4 ) ............... 119 2. X-Ray Powder Diffraction Pattern Data of B2(02CeH4)2 and B 2 (0 2 C 3 H g ) 2 ..................125 3. X-Ray Powder Diffraction Pattern Data of B 2 (S2 C 2 H 4 ) 2 and B 2 CI 2 (S2 C 2 H 4 ) ............. 132 4. X-Ray Powder Diffraction Pattern Data of B 2 [N(CH3 ) 2 ] 2 (S2 C 2 H 4 ) and B 2 [ (NCH 3 )2 C 2 H 4 ] 2 . 138 5. X-Ray Powder Diffraction Pattern Data of B 2 [(NH)2 C e H 4 ] 2 and B 2 (S2 C 2 H 4 ) 2 * 2 NH(CH 3 ) 2 . 146 6 . Boron-11 N.M.R. Chemical Shift Data and Physical Properties of Synthesized Diboron Compounds .......................... .,..,149 7. Proton N.M.R. Data of Synthesized Diboron C o m p o u n d s ....................................... 151 8 . X-Ray Powder Diffraction Pattern Data of B 2 C l 4 * 2 N H ( C H 3 ) 2 and (CH3 ) 2 H 2 NCI. ..... 165 9. Boron-11 N.M.R. Chemical Shift Data of other Synthesized Boron Compounds ................ 178 V I 1 ILLUSTRATIONS Figure Page 1. Discharge Cell for the Preparation of Diboron Tetrachloride..................... 9 4 2. Schematic Diagram for Automatic Arc Dis charge System................................. 96 3. Electrical Circuit for Automatic Operation of Discharge System.......................... 97 4. Molecular Weight Cryoscopy Apparatus . 99 5. Reaction Vessels ............................. 101 6 . Vacuum Filtering Apparatus ................. 116 7. Infrared Spectrum of B 2 (0 2 C 2 H 4 ) 2 ......... 120 8 . Infrared Spectrum of B 2 CI 2 (O2 C 2 H 4 ) .... 120 9. Infrared Spectrum of B 2 (0 2 CgH 4 ) 2 ......... 126 10. Infrared Spectrum of 6 2 (0 2 0 3 1 1 5 ) 2 ........... 126 11. Apparatus for Reactions with Hydrogen C h l o r i d e .............................. 130 12. Infrared Spectrum of B 2 (B2 O 2 H 4 ) 2 ......... 133 13. Infrared Spectrum of B 2 CI 2 (S2 C 2 H 4 ) .... 133 14. Infrared Spectrum of B 2 [N(CH3 )2 )2 (S2 C 2 H 4 ) . 139 15. Infrared Spectrum of B 2 C 1 ^ * 2 NH(CH 2 )2 * • • 139 16. Infrared Spectrum of B 2 [ (NCH3 )2 0 2 6 4 )2 • • « 142 17. Infrared Spectrum of B 2 [ (NH)2O 6 H 4 ] 2 . 142 viii INTRODUCTION I. Background of Diboron Chemistry This introduction is concerned with the chemistry of (diboron compounds, those compounds with a single boron-boron bond excluding the boron hydrides. A detailed description of more than sixty diboron compounds are reported in the literature. The present treatment of diboron chemistry is not exhaustive since recent reviews appear elsewhere (1,2). Comprehensive reviews which include only boron subhalide chemistry have also been compiled (2,3). Diboron chemistry had its origin with Stock's original preparation of diboron tetrachloride in 1925 (4). For the next several years, very little research was initiated with diboron tetrachloride due largely to its difficulty in synthesizing. In 1948, Professor Schlesinger and associates undertook a systematic study of the prep aration and reactions of diboron tetrachloride (5). Prior to 1960, diboron chemistry was limited to diboron tetrachloride and its derivatives. At this time, two independent groups developed the techniques for the preparation of tetrakis-(dialkylamino)-diboron compounds in macro quantities using large bench-scale equipment (6,7,1), With this development, an increase in interest and diversification in diboron chemistry resulted. II. General Preparation of Diboron Compounds The preparation of diboron compounds can be grouped under three general headings; (a) the electric discharge of a simple borane such as boron trihalides to yield diboron tetrahalides, (b) the coupling of bis-substituted- haloboranes with an active metal such as the reaction of bis-(dimethylamino)-chloroborane with sodium, and (c) the reaction of a boron-boron bond compound with the appropriate reagent to yield the desired product. Exam ples of this type are diboron tetrachloride or tetrakis- (dimethylamino)-diboron reacting with amines and alcohols. Of these, the latter two methods are less specific and most applicable to the preparation and study of diboron compounds. Further considerations of each method will be given later. III. Tetrahalodiborons Diboron tetrafluoride,-tetrachloride,-tetrabromide and -tetraiodide have been known for some time. Of these, diboron tetrachloride was first prepared and its chemistry has been more completely elucidated. A. Diboron tetrachloride 1. Properties and structure Diboron tetrachloride is a colorless liquid at room temperature, which ignites in dry air with the emission of light and undergoes partial decomposition at 0°C or above (8,9,10). The decomposition products are mainly BCI 3 , B^Cl^, and B]_2 Cli]_ (11,12). Interest in B 2 CI 4 is created by its extremely high reactivity toward Lewis bases and rr-electron systems. The possibil ity exists for participation in both addition and