DOCSLIB.ORG

[2.2.2] Propellane

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
[2.2.2] Propellane City University of New York (CUNY) CUNY Academic Works Dissertations, Theses, and Capstone Projects CUNY Graduate Center 1983 The Theory and Synthesis of [2.2.2] Propellane Theodore Mark Prociv The Graduate Center, City University of New York How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_etds/4125 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1. The sign or “target” for pages apparently lacking from the document photographed is “Missing Page(s)”. If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed. For blurred pages, a good image of the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photographed, a definite method of “sectioning” the material has been followed. It is customary to begin filming at the upper left hand corner of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete. 4. For illustrations that cannot be satisfactorily reproduced by xerographic means, photographic prints can be purchased at additional cost and inserted into your xerographic copy. These prints are available upon request from the Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases the best available copy has been filmed. University M odfilm s International 300 N. Zeeb Road Ann Arbor, Ml 48106 8312365 Prociv, Theodore Mark THE THEORY AND SYNTHESIS OF (2.2.2) PROPELLANE City University of New York Ph.D. 1983 University Microfilms International300 N. Zeeb Road, Ann Arbor, MI 48106 Copyright 1982 by Prociv, Theodore Mark All Rights Reserved PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V . 1. Glossy photographs or pages ______ 2. Colored illustrations, paper or print ______ 3. Photographs with dark background ______ 4. Illustrations are poor copy ______ 5. Pages with black marks, not original copy ______ 6. Print shows through as there is text on both sides of page ______ 7. Indistinct, broken or small print on several pages 8. Print exceeds margin requirements ______ 9. Tightly bound copy with print lost in spine ______ 10. Computer printout pages with indistinct print _____ 11. Page{s)____________lacking when material received, and not available from school or author. 12. Page{s)____________seem to be missing in numbering only as text follows. 13. Two pages num bered ___________, Text follows. 14. Curling and wrinkled pages ______ 15. Other_______________________________________________________________ University Microfilms International THE THEORY AND SYNTHESIS OF [2.2.2] PROPELLANE BY THEODORE M. PROCIV A dissertation submitted to the Graduate Faculty in Chemistry in partial fulfillment of the require­ ments for the degree of Doctor of Philosophy, The City University of New York. 1982 9 COPYRIGHT BY THEODORE M. PROCIV 1982 ii This manuscript has been read and accepted for the Graduate Faculty in Chemistry in satisfaction of the dissertation requirement for the degree of Doctor of Philosophy. [Signature] so P^/rs-2- date Chaimapr of Examining Committe [Signature] date Executive Officer [Signature] [Signature] Supervisory Committee The City University of New York iii Abstract THE THEORY AND SYNTHESIS OF [2.2.2] PROPELLANE by Theodore M. Prociv Advisor: Professor Joseph J. Dannenberg INDO calculations indicated that the triplet state of dimethylene cyclohexane could rearrange to gometrically relaxed triplets which should collapse pref­ erentially to the ground state [2.2.2] Propellane. A mercury sensitized photolysis of the dimethylene cyclohexane did in fact result in detectable quantities of the propellane, trapped as 1,4 dibromobioyolo octane. Synthesis of 1,4 dibromobioyolo ootane and 1,1,6,6 tetradeuterodimethylene-cyclohexane are presented in the dissertation. Included in the dissertation are the results of INDO calculations of various propellane isomers having nitrogens and borons in the bridgehead positions. iv TABLE OP CONTENTS Page CHAPTER I. THEORETICAL APPROACH TO THE SYNTHESIS OF [2.2.2] PROPELLANE ................................................ 1 Introduction .............................. 1 Description of Project .................................. 3 Experimental History Related to the Propellanes ........... 5 Theoretioal History Related to Propellanes ................. 12 EH Calculation ..................................... 12 Ab-Initio SCF/CI ....................................... 16 Geometrical Strain Consideration .................... 16 Competition With the Cope Rearrangement ................. 16 Summary and Justification .................................. 22 II. MOLECULAR ORBITAL TREATMENT OF [2.2.2] PROPELLANE ENERGY SURFACE .............................................. 24 Method of Calculation of this Thesis ................. 24 Selection of Method ............................... 24 INDO Method ............................................ 25 Theoretioal Approach .................................. 26 Results: Optimization of Geometries ......................... 28 Disoussion of Calculations ....................... 32 Singlet State Isomers ...................................... 32 The Triplet State .......................... 35 Suggested Experimental Approaoh ................... 35 III. SYNTHESIS OF [2.2.2] PROPELLANE ............................ 40 An Approaoh to the Synthesis of 2 40 Choice of Starting Material .................. 41 Dibromo Derivative of 2 42 v TABLE OF CONTENTS (Continued) Page Experimental Approaches .................. 44 A. Photolysis of 1,4-Dimethyleneoyolohexane Cuprous Chloride Complex .......................... 44 B. Triplet Sensitization ......................... 46 C. Meroury Sensitization ............................ 47 Results of Syntheses ....... 47 A. Results of CuCl Complex Irradiation ............... 47 B. Results of Aoetone Sensitization Experiments ...... 50 C. Results of Meroury Sensitization Experiments ...... 50 Discussion ..................................... 62 Conclusion ............................................ 64 Experimental ....................................... 65 Apparatus ........ 65 A. Irradiation of 24 66 B. Aoetone Sensitization ............................ 68 C. Meroury Sensitized Photolysis of 4 68 D. Preparation of 1,4-Dibromoblcyclooctane, 22 70 1.4-Dicarbethoxy-2.5 Diketobicyolo[2.2.2]octane, 2J ............................................... 70 Bis-(trimethylene)meroaptol of Dioarbethoxy- 2.5 Dike to Bioyolo[2.2.2]ootane, 28 72 Diethyl Bicyolo[2.2.2]octane-1,4-Dioarboxylate, 29 72 Bicyclo[2.2.2]octane-l,4-Dicarboxylic Acid, _30 ....... 73 1.4-Dibromobioyolo[2.2.2] ootane, 22 73 IV. SYNTHESIS AND REACTION OF 2,2,3,3-TETRADEUTERO [2.2.2] PROPELLANE ........................................ 75 Experimental Design ................... 75 Descriptions of Experiments ............................. 77 Synthesis of £2 by Wittig Reaction .................... 77 Reverse Deuteration of 4, ............................. 77 An Alternative Synthesis of 32 79 Irradiation of 32 79 vi TABLE OF CONTENTS (Continued) Page Results ............................................. 79 Synthesis of 22 79 Irradiation of 32 31 Experimental .................................... 84 di| 1,4-Diemthylene Cyclohexane, £2 84 A. Triphenylmethylphosphonium Iodide ......... 84 B. 1,4-Dimethylene Cyclohexane 32 in DMSO/NaH .... 84 C. £2 in KtBuO/KtBuOH ............................ 85 Alternative Synthesis for 32 86 1.4-Dimethanol Cyolohexane (dij), 38 86 1.4-Cyelohexane Dimethanol Tosyl Ester (djj), 40 87 1.4-Cyolohexane Dimethyl Iodide (di|), 4J[ ......... 87 1.4-Dimethylene Cyolohexane (dij), £2 88 Irradiation of £2, Meroury Sensitized ................. 88 CHAPTER V. THEORETICAL TREATMENT OF ISOSTRUCTURAL ISOMERS ............. 90 Introduction ............... 90 Theoretioal Approach ...................... 92 Results ....................... 94 Discussion ........................... 124 The rj | Bond Distance ................................. 124 C+2 Dictation .............................. 126 DABCO and Isomers ........................... 129 BO isomers ..................................... 132 44 Eleotron System ....................... 135 VI. CONCLUSIONS ..............................................
Load more

Recommended publications
  • Cycloalkanes, Cycloalkenes, and Cycloalkynes
    CYCLOALKANES, CYCLOALKENES, AND CYCLOALKYNES any important hydrocarbons, known as cycloalkanes, contain rings of carbon atoms linked together by single bonds. The simple cycloalkanes of formula (CH,), make up a particularly important homologous series in which the chemical properties change in a much more dramatic way with increasing n than do those of the acyclic hydrocarbons CH,(CH,),,-,H. The cyclo- alkanes with small rings (n = 3-6) are of special interest in exhibiting chemical properties intermediate between those of alkanes and alkenes. In this chapter we will show how this behavior can be explained in terms of angle strain and steric hindrance, concepts that have been introduced previously and will be used with increasing frequency as we proceed further. We also discuss the conformations of cycloalkanes, especially cyclo- hexane, in detail because of their importance to the chemistry of many kinds of naturally occurring organic compounds. Some attention also will be paid to polycyclic compounds, substances with more than one ring, and to cyclo- alkenes and cycloalkynes. 12-1 NOMENCLATURE AND PHYSICAL PROPERTIES OF CYCLOALKANES The IUPAC system for naming cycloalkanes and cycloalkenes was presented in some detail in Sections 3-2 and 3-3, and you may wish to review that ma- terial before proceeding further. Additional procedures are required for naming 446 12 Cycloalkanes, Cycloalkenes, and Cycloalkynes Table 12-1 Physical Properties of Alkanes and Cycloalkanes Density, Compounds Bp, "C Mp, "C diO,g ml-' propane cyclopropane butane cyclobutane pentane cyclopentane hexane cyclohexane heptane cycloheptane octane cyclooctane nonane cyclononane "At -40". bUnder pressure. polycyclic compounds, which have rings with common carbons, and these will be discussed later in this chapter.
    [Show full text]
  • Inverted Geometries at Carbon
    Acc. Chem. Res. 1984,17, 379-386 379 Inverted Geometries at Carbon KENNETHB. WIBERG Department of Chemistry, Yale University, New Haven, Connecticut 06511 Received March 3, 1984 (Revised Manuscript Received June 25, 1984) One of the main structural elements in organic Scheme I chemistry is the tetrahedral geometry of a four-coor- dinate carbon. Distortions from a perfect tetrahedron are common, but they are generally fairly small. It is, + HOAc - however, possible to "invert" the normal geometry via OAc a C3" or "umbrella" motion leading to a set of com- pounds having all of the groups attached to some car- bon lying on one side of a plane.'J Preparative Methods A number of compounds that are constrained to have The first of these compounds to be prepared is 6 that this type of structure have now been prepared. The is readily obtained from bicyclo[3.2.0]hex-l(5)-ene17via methods of preparation and their reactions and prop- cycloaddition reactions.lJ4 The structure of the di- erties will be described belowq3 It should be noted that (1) K. B. Wiberg, J. E. Hiatt, and G. J. Burgmaier, Tetrahedron Lett., inverted geometries may in some cases be found in the 5855 (1968). absence of structural constraint. Bicyclo[ l.l.0]butane4 (2)'K. B. Wiberg, G. B. Ellison, and J. J. Wendoloski, J. Am. Chem. and its derivatives5 are notable examples, and the re- SOC.,98, 1212 (1976). (3) For a review of earlier work on 'propellanes" see D. Ginsberg, lationship between the geometry at the bridgehead and "Propellanes", Verlag Chemie, Weinheim, 1975, and reference 8.
    [Show full text]
  • The Synthesis and Reactivity Of
    THE SYNTHESIS AND REACTIVITY OF 3,7 1,3 TETRACYCLO ^3.3.1.1 .0 J DECANE by EDWARD JOHN THORPE B.Sc. (Hons.) University of British Columbia, 1965 M.Sc. University of British Columbia, I968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF' THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Chemistry We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA August, 1975 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver 8. Canada Date it, H-u^jf IVi I - ii - ABSTRACT Supervisor: Dr. R. E. Pincock The structures and some properties of adamantane (lb), strained cyclopropanes (23), and certain small ring propeller• like molecules (28) are reviewed. The synthesis of a new type of compound containing a combination of such structures and properties is presented. This compound tetracyclo more simply 1,3-dehydroadamantane (DHA) contains a very strained cyclopropyl group within an adamantane skeleton and was produced by bonding two bridge• head (tertiary) carbons together across the normally extremely rigid structure of adamantane. (This new compound, DHA, is shown below.) In the synthesis of DHA using alkali metal (or alloys) with 1,3-dibromoadamantane (37)> the reaction times and relative yields of adamantane and DHA were extremely variable.
    [Show full text]
  • Propellane ⇑ Robynne Kirkpatrick A, Tony Masiello B, Matthew Martin A, Joseph W
    Journal of Molecular Spectroscopy 281 (2012) 51–62 Contents lists available at SciVerse ScienceDirect Journal of Molecular Spectroscopy journal homepage: www.elsevier.com/locate/jms High-resolution infrared studies of the m10, m11, m14, and m18 levels of [1.1.1]propellane ⇑ Robynne Kirkpatrick a, Tony Masiello b, Matthew Martin a, Joseph W. Nibler a, , Arthur Maki c, Alfons Weber d, Thomas A. Blake e a Department of Chemistry, Oregon State University, Corvallis, OR 97332-4003, USA b Department of Chemistry and Biochemistry, California State University, East Bay, Hayward, CA 94542, USA c 15012 24th Ave., Mill Creek, WA 98012, USA d Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA e Pacific Northwest National Laboratory, P.O. Box 999, Mail Stop K8-88, Richland, WA 99352, USA article info abstract Article history: This paper is a continuation of earlier work in which the high resolution infrared spectrum of [1.1.1]pro- Received 27 July 2012 pellane was measured and its k and l structure resolved for the first time. Here we present results from an In revised form 3 September 2012 0 0 0 0 analysis of more than 16000 transitions involving three fundamental bands m10 ðE À A1Þ; m11ðE À A1Þ, m14 Available online 15 September 2012 00 0 0 00 0 00 ðA2 À A1Þ and two difference bands (m10–m18)(E ÀE ) and (m11 À m18)(E À E ). Additional information 0 00 about m18 was also obtained from the difference band (m15 + m18) À m18 (E À E ) and the binary combina- Keywords: 0 0 tion band (m15 + m18) ðE À A Þ.
    [Show full text]
  • Hyper-Structural Ethers
    J. Eur. Soc. Math. Chem. | 2019 1(1): 6 Hyper-structural Ethers Mircea V. Diudea Department of Chemistry, Faculty of Chemistry and Chemical Engineering Arany Janos Str. 11, 400028, “Babes-Bolyai” University,Cluj, Romania [email protected] Abstract. Rhombellanes represent a new structural class, of which functionalized derivatives may be synthesized as real molecules. Several hypothetical structures/molecules were proposed: their topology, energetics, and pharmaceutic properties have been computed. Drug-like properties of some of the proposed molecular structures were compared with existing nano-molecules. Among the designed polymeric networks, the etheric ones represent a promise for the material science and technology. Keywords: cube, rhombellane, rank, rod-like polymer, triple periodic polymer, ether. 1. Introduction Crystal engineering and self-assembly processes have recently promoted new classes of finite and/or periodic nanostructures, with promising applications in material science and biosciences [1–7]. Several nano-sized spheroid architectures, based on Platonic and Archimedean solids have been synthesized. A variety of appropriate (as angles and bond length) ligands have been used in such syntheses. As metals to join the ligands, the most used was Pd2+ [3–6], then Zn2+ [7] or Cu2+ [8]. The single-shell spherical structures, possessing large hollows, could be functionalized, both endo– and/or exohedrally. A self‐assembled double-shell structure, a sphere‐in‐sphere, molecular “Russian doll”, was also reported [9]. Rhombellanes are structures with all strong rings rhombs/squares, some of them forming local propellane substructures; they have been proposed by Diudea in 2017 [10]. Propellane is an organic molecule, first synthesized in 1982 [11]; by IUPAC nomenclature, it is named tricyclo[1.1.1.01,3]pentane, a hydrocarbon with formula C5H6.
    [Show full text]
  • A Procedure for Computing Hydrocarbon Strain Energies Using Computational Group Equivalents, † with Application to 66 Molecules
    Article A Procedure for Computing Hydrocarbon Strain Energies Using Computational Group Equivalents, y with Application to 66 Molecules Paul R. Rablen Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, USA; [email protected] Dedication: This paper is dedicated to Professor Bernd Giese on the occasion of his 80th birthday. It was a y pleasure and an honor to work with you on the question of electron conduction in peptides a few years ago. Received: 4 April 2020; Accepted: 27 April 2020; Published: 30 April 2020 Abstract: A method is presented for the direct computation of hydrocarbon strain energies using computational group equivalents. Parameters are provided at several high levels of electronic structure theory: W1BD, G-4, CBS-APNO, CBS-QB3, and M062X/6-31+G(2df,p). As an illustration of the procedure, strain energies are computed for 66 hydrocarbons, most of them highly strained. Keywords: strain; strain energy; group equivalents; strained hydrocarbons; calculated strain; quadricyclane; cubane; prismane; fenestranes; propellanes; spiroalkanes 1. Introduction The concept of strain has long held interest for organic chemists, going back all the way to Baeyer [1–5]. Strain refers to the amount by which the energy of a molecule exceeds that which one would expect if all bond lengths, bond angles, and dihedral angles could simultaneously hold their ideal values, and if no repulsive nonbonded interactions (steric repulsions) were present. As such, strain is generally assumed to be absent in molecules such as straight-chain alkanes in which the bond lengths, angles, and dihedral angles are not geometrically constrained, and in which the extended conformation avoids repulsive nonbonded interactions.
    [Show full text]
  • Spartanmodel an Electronic Model Kit Organic Chemistry Problems by Topic
    SpartanModel An Electronic Model Kit Organic Chemistry Problems by Topic SpartanModel An Electronic Model Kit Organic Chemistry Problems by Topic Copyright © 2010 by Wavefunction, Inc. All rights reserved in all countries. No part of this book may be reproduced in any form or by any electronic or mechanical means including information storage and retrieval systems without permission in writing from the Wavefunction, Inc., except by a reviewer who may quote brief passages in a review. Table of Contents Section I INTRODUCTION………………………………. 1 Section II Getting Started with SpartanModel……………. 3 Section III Organic Chemistry Problems …….……………. 6 Structure and Bonding ...……………………………… 6 Polar and Non-polar Molecules……………………….. 10 Alkanes and Cycloalkanes…………………………….. 16 Properties of Haloalkanes……………………………... 18 Reactions of Alkanes…………………………………… 19 Stereochemistry………………………………………… 21 Alcohols…………………………………………………. 24 Ethers……………………………………………………. 26 NMR…………………………………………………….. 28 Alkenes and IR Spectroscopy………………………….. 30 Reactions of Alkenes……………………………………. 37 Alkynes…………………………………………………… 41 Dienes, Higher Polyenes and UV Spectroscopy……….. 43 Aromaticity……………………………………………… 50 Regiochemistry in Electrophilic Aromatic Substitution. 57 Aldehydes and Ketones………………………………….. 60 Enols and Enolates………………………………………. 64 Carboxylic Acids………………………………………… 67 Amines and Amine Derivatives…………………………. 70 Chemistry of Substituents on Benzene…………………. 75 Carbohydrates…………………………………………… 80 Heterocycles…………………………………………….... 82 Amino Acids and Proteins………………………………. 88 Reactions………………………………………………….
    [Show full text]
  • Division of Organic Chemistry
    ORGN DIVISION OF ORGANIC CHEMISTRY S. Silverman and E. McLaughlin, Program Chairs SUNDAY MORNING Section A Pennsylvania Convention Center 116 New Reactions & Methodology S. M. Silverman, Organizer 8:00 1. Copper catalyzed reductive carbonylation of alkyl iodides. S. Zhao, N.P. Mankad 8:20 2. Sulfenate-anion-catalyzed diastereoselective aziridination of imines. Z. Zheng, P.J. Walsh 8:40 3. Cyanoalkylcopper species in carbon-carbon bond forming reactions. D.L. Silverio 9:00 4. New reactivity enabled by cation-π interactions. P.J. Walsh 9:20 5. Dipolar alkynyl-prins (DAP) cyclization for the rapid construction of complex polycycles. S. Abdul-Rashed, G. Alachouzos, A. Frontier 9:40 6. Subphthalocyanines and perylene-diimide derivatives in organic photovoltaics. L. Chockalingam Kasi Viswanath 10:00 7. Silylated α-aminonitriles for late-stage functionalization. T. Mathew, T. Yamato, S.G. Prakash 10:20 8. Synthesis of differentially substituted diynes via tandem nucleophilic addition/fragmentation pathways. A. Tavakoli, G.B. Dudley 10:40 9. Analogues of Bestmann’s ylide, Ph3P=C=C=O: Syntheses, structures and Lewis acid catalyzed cyclizations with organic substrates. C. Krempner 11:00 10. Diastereoselective alkynylations of β-(Bromo)iminium ions via copper(I) catalysis. S.O. Santana, W. Guan, M.P. Watson 11:20 11. Modular three-component difunctionalization of aryl/cyclohexenyl triflates via arynes and cyclohexynes. S. Cho, Q. Wang 11:40 12. 1,2-aminocyanation of alkenes via distal migration. Y. Kwon, Q. Wang Section B Pennsylvania Convention Center 117 Heterocycles & Aromatics S. M. Silverman, Organizer 8:00 13. Formal [4+2] cycloaddition between alkynes and allene-ynes to generate functionalized toluenes.
    [Show full text]
  • [1.1.1]Propellane with Alkynes: Synthesis of Exocyclic Allenic Cyclobutanes Danieĺ Lasanyí and Gergely L
    This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Letter Cite This: Org. Lett. 2019, 21, 10057−10062 pubs.acs.org/OrgLett Copper-Catalyzed Ring Opening of [1.1.1]Propellane with Alkynes: Synthesis of Exocyclic Allenic Cyclobutanes Danieĺ Lasanyí and Gergely L. Tolnai* Institute of Chemistry, Eotvos Lorand University, Pazmany P. setany. 1/a, 1117 Budapest, Hungary *S Supporting Information ABSTRACT: Despite the long history and interesting properties of propellanes, these compounds still have tremendous potential to be exploited in synthetic organic chemistry. Herein we disclose an experimentally simple procedure to achieve cyclobutane-containing allenes and alkynes through a copper-catalyzed ring opening of [1.1.1]propellane and subsequent reaction with ethynes. ropellanes are fascinating molecules.1 The unique of the most comprehensive early studies on the reactions of P structure and behavior of these molecules have captivated [1.1.1]propellane briefly mentions these kinds of reactions.11 the imagination of chemists from the time they were predicted Wiberg and Waddel found analytical evidence that 1 in the to exist to the present day.2 Their most interesting properties presence of transition metals is prone to undergo dimerization include high ring strain and the “inverted” charge-shift type and trimerization (Scheme 2). This might happen through a central C−C bond.3 This property can be used to open up [1.1.1]propellane (1) in various interesting ways. Owing to the Scheme 2.
    [Show full text]
  • Tetrahedral Units: Fordodecahedral Super-Structures Y. Ortiz A,B, D. J. Kleina, & J. F. Liebmanc a MARS, Texas A&M Unive
    Tetrahedral Units: forDodecahedral Super-Structures Y. Ortiz a,b, D. J. Kleina, & J. F. Liebmanc a MARS, Texas A&M University at Galveston, Galveston, 200 Seawolf Pkwy, Galveston, TX 77554 bInstituto de CienciasFísicas, Universidad NacionalAutónoma de México, Avenida Universidad s/n, 62210 Cuernavaca, México; cDept of Chemistry & Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 Abstract Different novel organic-chemical possibilities for tetrahedral building units are considered, with attention to their utility in constructing different super-structures. As a representative construction we consider the useof sets of 20 such identical tetrahedral units to form a super-dodecahedron. Introduction Recently Minyaevet al [1] proposed a dodecahedral-symmetry molecule comprised of tetrahedral submolecular building blocks placed at the corners of a large dodecahedron with the tetrahedral units interconnected via covalent bonds. The tetrahedral units in isolation are of the form TH4 with the 4 H atoms bonded covalently to the central tetrahedral core T. Then taking 20 of these tetrahedral building blocks, one deletes 3 H atoms from each, and reconnects the consequent dangling bonds of each resultant TH to 3 of these equivalent neighboring TH units, to obtain (TH)20– as indicated in Fig.1.The prototype for this construction may be viewed to be Paquetteet al’s[2]dodecahedrane, (CH)20, with T being just a single C atom. The tetrahedral units considered by Minyaevet al[1] aretetrahedra where T is taken as a (hydrogen- deleted) cage: B4, or C4, or Al4. In fact, there are many more (hydrogenated) tetrahedral cages TH4 possible which may be utilized in such a construction of a “super-dodecahedron”.
    [Show full text]
  • What Is Ring Strain?
    Strain-Promoted Reactivity in Organic Synthesis Steph McCabe Frontiers of Chemistry 08/19/2017 Wipf Group 1 Steph McCabe @Wipf Group Page 1 of 30 09/02/2017 2/10/2011 4.4 Conformations of Cycloalkanes Cyclopropane • Most strained of all the rings • Angle strain – caused by 60º C-C-C bond angles • Torsional strain – caused by the eclipsed C-H bonds on neighboring carbon atoms a) Structure of cyclopropane showing the eclipsing of neighboring C- H bonds giving rise to torsional strain b) Newman projection along a C-C bond of cyclopropane Conformations of Cycloalkanes • Bent C-C bonds • Orbitals can’t point directly toward each other • Orbitals overlap at a slight angle • Bonds are weaker and more reactive than typical alkane bonds 2/10/20112/10/2011 • C-C bond: 4.4 Conformations255 kJ/mol (61 kcal/mol) of Cycloalkanes for cyclopropane What 4.4is ConformationsRing355 kJ/mol Strain? (85 ofkcal/mol) Cycloalkanes for open-chain propane Cyclopropane Cyclopropane• Most strained of all the rings Ring Strain Theory: Adolf von Baeyer• • (NobelMostAngle strained strain Prize of – allcaused in the Chemistry rings by 60º C-C- C1905) bond angles 1. Angle Strain: Expansion/compression• • AngleTorsional of strain ideal strain– caused(tetrahedral) – caused by 60 ºby C -the Cbond-C eclipsed bond angle angles C-H bonds on neighboring • Torsionalcarbon strainatoms – caused by the eclipsed C-H bonds on neighboring 2. Torsional Strain: Rotational strain e.g.carbon a)eclipsingStructure atoms bonds of cyclopropane on neighboring showing the eclipsing atoms of
    [Show full text]
  • MINKIN Pages 869..892
    Russian Chemical Reviews 71 (11) 869 ± 892 (2002) # 2002 Russian Academy of Sciences and Turpion Ltd DOI 10/1070.RC2002v071n11ABEH000729 Non-classical structures of organic compounds: unusual stereochemistry and hypercoordination V I Minkin, R M Minyaev, R Hoffmann Contents I. Introduction 869 II. Tetracoordinate carbon atom with a planar configuration of bonds in the molecules and ions of organic 870 and organoelement compounds: stereoelectronic strategies of stabilisation III. The mechanism of intramolecular inversion of the tetrahedral configuration of bonds at the carbon atom 875 IV. Structures with a pyramidal configuration of bonds at a tetracoordinate carbon atom 876 V. Tetracoordinate carbon atom with a bisphenoidal configuration of bonds and inverted tetracoordinate carbon atom 879 VI. Carbonium ions with penta-, hexa- and heptacoordinate carbon atoms 881 VII. Planar hexacoordinate carbon atom inside a cyclic borocarbon cage 887 VIII. Molecules and ions containing planar penta-, hepta- and octacoordinate carbon atoms or atoms of other 889 non-transition elements IX. Conclusion 890 Abstract. Non-classical structures of organic compounds are defined as molecules containing non-tetrahedral tetracoordinate and/or hypercoordinate carbon atoms. The evolution of the views on this subject is considered and the accumulated theoretical and experimental data on the structures and dynamic transformations of non-classical organic compounds are systematised. It is shown that computational analysis using the methods and the software potential of modern quantum chemistry has now acquired high predictive capacity and is the most important source of data on the structures of non-classical compounds. The bibliography includes 227 references. I. Introduction Molecular structure is a key concept of theoretical organic chemistry.
    [Show full text]