Octaazacubane
Encyclopedia
Octaazacubane is a hypothetical allotrope of nitrogen
, whose molecule
s have eight atom
s arranged into a cube
. (By comparison, nitrogen usually occurs as the diatomic molecule N2.) It can be regarded as a derivative of cubane
, where all eight carbon
atoms (and their corresponding hydrogen
atoms) have been replaced with a nitrogen atom. It is predicted to be a metastable molecule, in which despite the thermodynamic
instability caused by bond strain
, and the high energy of the N-N single bonds
, the molecule remains kinetically
stable for reasons of orbital symmetry.
(assuming decomposition into N2) of 22.9 MJ / kg
, which is over 5 times the standard value
of TNT. It has therefore been proposed (along with other exotic nitrogen allotropes) as an explosive, and as a component of high performance rocket fuel. Its velocity of detonation is predicted to be 15,000 m/s, much (50%) more than any known nonnuclear explosive.
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, whose molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s have eight atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s arranged into a cube
Cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and...
. (By comparison, nitrogen usually occurs as the diatomic molecule N2.) It can be regarded as a derivative of cubane
Cubane
Cubane is a synthetic hydrocarbon molecule that consists of eight carbon atoms arranged at the corners of a cube, with one hydrogen atom attached to each carbon atom. A solid crystalline substance, cubane is one of the Platonic hydrocarbons. It was first synthesized in 1964 by Philip Eaton, a...
, where all eight carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atoms (and their corresponding hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
atoms) have been replaced with a nitrogen atom. It is predicted to be a metastable molecule, in which despite the thermodynamic
Chemical thermodynamics
Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics...
instability caused by bond strain
Strain (chemistry)
In chemistry, a molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound. The internal energy of a molecule consists of all the energy stored within it. A strained molecule has an additional...
, and the high energy of the N-N single bonds
Bond order
Bond order is the number of chemical bonds between a pair of atoms. For example, in diatomic nitrogen N≡N the bond order is 3, while in acetylene H−C≡C−H the bond order between the two carbon atoms is also 3, and the C−H bond order is 1. Bond order gives an indication to the stability of a bond....
, the molecule remains kinetically
Chemical kinetics
Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition...
stable for reasons of orbital symmetry.
Explosive and fuel
Octaazacubane is predicted to have an energy densityEnergy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...
(assuming decomposition into N2) of 22.9 MJ / kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
, which is over 5 times the standard value
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
of TNT. It has therefore been proposed (along with other exotic nitrogen allotropes) as an explosive, and as a component of high performance rocket fuel. Its velocity of detonation is predicted to be 15,000 m/s, much (50%) more than any known nonnuclear explosive.
See also
- TetranitrogenTetranitrogenAs reported in the January 18, 2002 edition of Science at the Sapienza University of Rome, Fulvio Cacace and his colleagues created a new nitrogen molecule known as tetranitrogen, with the structure N4...
(Nitrogen allotrope with formula N4) - HexazineHexazineHexazine is a hypothetical allotrope of nitrogen composed of 6 nitrogen atoms arranged in a ring-like structure analogous to that of benzene. It would be the final member of the azabenzene series, having all of the methylidyne groups of the benzene molecule replaced with nitrogen atoms...
(Nitrogen allotrope with formula N6) - OctanitrocubaneOctanitrocubaneOctanitrocubane is a high explosive that, like TNT, is shock-insensitive , not detonating even when struck by a hammer...