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Novel Fulleranes and Carbons

V Novel fulleranes
V Novel carbons

Novel fulleranes

A number of cyclic alkanes have been synthesized that correspond to the water clustering in the icosahedral water clusters.

 

Poly cyclic alkanes

 

poly cyclic alkanes

a) C8H14, bicyclo[2,2,2]octane; b) C10H16 adamantane (tricyclo[3.3.1.13,7]decane); c) C12H18, iceane (wurtzitane, tetracyclo[5.3.1.12,604,9] dodecane) [1843]; d) C20H20, dodecahedrane (fullerane-C20-Ih, undecacyclo[9.9.0.02,9.03,7.04,20.05,18.06,16.08,15.010,14.012,19.013,17] icosane) [1844].

 

 

C280H120 structure

 

c280h120 structure

 

Dodecahedrane

 

Dodecahedrane

The basic expanded network structure of the icosahedral water cluster is mechanically strong, having close to tetrahedrally-positioned bonds, and the central dodecahedron as an alkane (see left) has been synthesized. The complete cluster could be found in the, as yet unsynthesized, alkane C280H120; made up of twenty C14 tetrahedral sub-structures. Such molecules are also known as 'nanodiamonds'. The stability and electronic spectra of the icosahedral carbon nanoparticles C20H20, C100H60 and C280H120 have been calculated [1845]. It was calculated that hydrogenation stabilized the structures that otherwise preferred an 'onion' like (Russian doll) layered carbon shell structure [1846]. The first discussion of similar icosahedral carbon clusters was in 1993 [1847].

 

Using the AMBER force-field, the average C-C and C-H bond lengths and bond angles for C280H120were 1.533 Å (SD 0.014 Å), 1.091 Å (SD 0.0001 Å) and 109.46° (SD 1.47°) respectively.

 

Interactive structures are given (Jmol).

C70H60 structure

 

C70H60 structure

 

There could also be the quarter-structure C70H60 (Jmol), shown left made up of five C14 tetrahedral sub-structures (the dihedral angle at each edge of a tetrahedron is 70.529°, leaving this structure just 7.356° (2%) short of that required for perfect tetrahedra forming a  circle). Using the AMBER force-field, the average C-C and C-H bond lengths and bond angles of C70H60 were 1.534 Å (SD 0.0026 Å), 1.091 Å (SD 0.0002 Å) and 109.47° (SD 0.68°) respectively.

 

Other derivative fulleranes are also possible such as (from the left below) C100H60 (20 ˣ C5H3 units) based on the inner cluster with a central carbon dodecahedron, C120H72 (24 ˣ C5H3 units) based on the inner cluster with a central carbon  tetrakaidecahedron (51262) and C336H144 (24 ˣ C14H6 units) based on the complete tetrakaidecahedron cluster.

 

C100H60, C120H72 and C336H144 alternative fulleranes

C100H60, C120H72 and C336H144 alternative fulleranes

 

C14 cluster as part of the structure of diamond

 

C14 cluster as part of the structure of diamond

Novel carbons

Carbon-only structures with the same topologies as the oxygen atoms in the water ices are also possible. Thus, diamond (see right) has the same topology as cubic ice (and the tetrahedral water cluster as part of ((H2O)14)20, consisting of 14 water molecules). Other carbons with topologies similar to the oxygen nets of crystalline ice phases have been predicted, including some with a density greater than diamond that may exist at high pressure [2261].

 

 

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This page was established in 2002 and last updated by Martin Chaplin on 5 November, 2017