Fulleranes: The Hydrogenated Fullerenes (Carbon Materials: Chemistry and Physics Book 2)

Fulleranes are a special class of carbon molecules derived from fullerenes whose double bonds are partially or at least theoretically fully saturated by hydrogen. The hydrogenation changes the chemical properties of fullerenes which can become susceptible to substitution reactions as opposed to addition reactions to the double bonds (present in common fullerenes). One of the most intriguing aspects of fulleranes is the fact that they have been thought to exist in the interstellar medium or even in certain circumstellar media. The reasoning is quite simple: if fullerenes can be formed in the interstellar or better in the circumstellar medium, then they should undergo a simple hydrogenation reaction because of the ubiquitous presence of hydrogen in the universe. There is therefore a need not only to synthesize fulleranes in order to study their properties but also to study their infrared and electronic absorption spectra. Such spectra are used in the search for these molecules in the interstellar medium and around certain promising carbon-rich stars. Many efforts have been made by chemists and chemical physicists to synthesize these molecules at different degrees of hydrogenation and to record their spectra. Thus, __Fulleranes:____The Hydrogenated Fullerenes__ presents the state of the art research, synthesis and properties of these molecules; astrophysicists and astrochemists detail their expectations regarding the presence of these molecules in space. __Fulleranes: The Hydrogenated Fullerenes__ is written for researchers, postgraduates, and advanced undergraduates in organic synthetic chemistry, physical chemistry, and astrophysics. Cover 1 CARBON MATERIALS: CHEMISTRY AND PHYSICS Volume 2 3 Fulleranes: The Hydrogenated Fullerenes 4 Copyright 5 9781402098864 5 Foreword 6 Preface 10 Contents 14 Fulleranes and Carbon Nanostructures in the Interstellar Medium 16 1.1 Introduction 17 1.2 General Properties of Fullerenes 18 1.2.1 Icosahedric Fullerenes 18 1.2.1.1 Photoabsorption Spectra 18 1.2.2 Fullerenes with Multiple Spheric Layers: Buckyonions 20 1.2.3 Fulleranes: Hydrogenated Fullerenes 22 1.3 Formation of Fullerenes and Fulleranes in Astrophysical Environments 22 1.3.1 Meteorites 22 1.3.2 Carbon Stars and Planetary Nebulae 23 1.3.3 Formation of Fullerenes and Buckyonions 24 1.4 Fullerenes in the Interstellar Medium 25 1.4.1 Interstellar Extintion and the UV Bump 25 1.4.2 Theoretical Spectra and the 2,175 Å Band 26 1.4.3 Carbon Fraction in Fullerenes and Buckyonions 27 1.4.4 Diffuse Interstellar Bands 28 1.4.5 The Hydrogenation of Fullerenes in the Interstellar Medium 32 1.5 Anomalous Microwave Emission and Hydrogenated Fullerenes 33 1.5.1 Electric Dipole and Inertia Moment of Fulleranes 33 1.5.2 Rotation and Electric Dipole Emisivity from Fulleranes 34 1.5.3 Electric Dipole Emissivity from Fulleranes 36 1.6 Conclusions 38 References 38 Infrared and Ultraviolet Spectra of Fulleranes: HREELS Studies and Implications for the Interstellar Medium 42 2.1 Introduction 42 2.2 The Unidentified Infrared Emission Problem 43 2.3 The Ultraviolet Extinction Curve 44 2.4 Experimental Procedures 44 2.5 Results 45 2.5.1 Infrared Spectra 45 2.5.2 Ultraviolet Spectra 47 2.6 Conclusions 51 References 51 The Potential Role Played by the Fullerene-Like Structures of Interstellar Carbon Dust in the Formation of Molecular Hydrogen 54 3.1 General Aspects About Molecular Hydrogen Formation in the Interstellar Medium 54 3.2 Surfaces Involved in the Synthesis of Molecular Hydrogen in the Interstellar Medium 56 3.3 Carbon Surfaces and Molecular Hydrogen Formation 58 3.4 Fullerene-Like Structures on Carbon Dust of the Interstellar Medium: Their Role in Molecular Hydrogen Formation 59 3.5 On the Reversibility of Hydrogen Chemisorption and Release from Fulleranes 64 3.6 Thermal Decomposition of C70H38 and Formation of C70 65 3.7 Conclusions 67 References 67 Thermodynamic Properties of Fullerene Hydrides C60H2n and Equilibria of Their Reactions 70 4.1 Introduction 70 4.2 Isomerism of C60H2n Fullerene Hydrides 72 4.2.1 Isomeric Composition of C60H2 72 4.2.2 Isomeric Composition of C60 H4 72 4.2.3 Isomeric Composition of C60 H6 73 4.2.4 Isomeric Composition of C60 H18 74 4.2.5 Isomeric Composition of C60 H36 75 4.2.6 Isomeric Composition of C60 H60 76 4.3 Experimental Investigation of Thermodynamic Properties for C60H2n 77 4.4 Thermodynamic Properties of C60H2n in the Ideal-Gas State 78 4.4.1 Quantum-Chemical Calculations of Molecular Parameters for C60 H2n 79 4.4.2 Thermodynamic Properties of C60H2n in the Ideal-Gas State 82 4.4.3 Calculation of �f Hom for C60H2n in the Ideal-Gas State 82 4.4.4 Thermodynamics of Hydrogenation Reactions for Hydrocarbons and Fullerene C60 in the Gas State 85 4.5 Thermodynamic Properties of C60H2n Crystals 86 4.5.1 Heat Capacity and Derived Thermodynamic Properties of C60 H2n Crystals 86 4.5.2 Formation and Sublimation Enthalpies for C60H2n Crystals 89 4.6 Equilibria of Reactions of C60H2n Hydrides 90 4.6.1 Gas-Phase Hydrogenation C60 + nH2 = C60H2n 90 4.6.2 Hydrogenation C60(cr)+ nH2(g) = C60H2n(cr) 91 4.6.3 Hydrogenation with DHA 94 4.6.4 Is It Possible to Synthesize C60 H60? 95 4.7 Conclusion 96 References 97 Fulleranes by Direct Reaction with Hydrogen Gas at Elevated Conditions 100 5.1 Introduction 100 5.2 Hydrogenation of Fullerenes by Hydrogen Gas: Conditions and Characterization of Products 102 5.3 Mass Spectrometric Characterization of Complex Fullerane Mixtures 108 5.4 High Pressure (GPa) Methods of Fullerane Synthesis 111 5.5 Future Outlook 114 5.5.1 Fulleranes with Composition C60Hx and Number of Hydrogen atoms X Below 60 114 5.5.2 Fragmented Fullerenes, e.g. C59Hx, C58Hx etc. 115 5.5.3 Fullerene Fragments 115 5.5.4 Hydrogenation of Peapods 115 References 116 Chemical Methods to Prepare [60]Fulleranes 120 6.1 Introduction 121 6.2 C60H2 121 6.3 [60]Fulleranes with More Than 2 But Less Than 18 Hydrogens: C60H2