Novel carbons

Some cyclic alkanes have been synthesized that correspond to the water clustering in the icosahedral water clusters.

Polycyclic alkanes

a) C_{8}H_{14}, bicyclo[2,2,2]octane; b) C_{10}H_{16} adamantane (tricyclo[3.3.1.1^{3,7}]decane); c) C_{12}H_{18}, iceane (wurtzitane, tetracyclo[5.3.1.1^{2,6}0^{4,9}] dodecane) [1843]; d) C_{20}H_{20}, dodecahedrane (fullerane-C_{20}-I_{h,} undecacyclo[9.9.0.0^{2,9}.0^{3,7}.0^{4,20}.0^{5,18}.0^{6,16}.0^{8,15}.0^{10,14}.0^{12,19}.0^{13,17}] icosane) [1844].

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
C_{280}H_{120}; made up of twenty C_{14} tetrahedral sub-structures. Such molecules are also known as 'nanodiamonds'. The stability and electronic spectra of the icosahedral carbon nanoparticles C_{20}H_{20}, C_{100}H_{60} and C_{280}H_{120 }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
C_{280}H_{120}were 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).

There could also be the quarter-structure C_{70}H_{60} (Jmol), shown left made up
of five C_{14} 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 C_{70}H_{60} 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) C_{100}H_{60} (20 ˣ C_{5}H_{3} units) based on the inner cluster with a central carbon dodecahedron,
C_{120}H_{72} (24 ˣ C_{5}H_{3} units)
based on the inner cluster with a central carbon tetrakaidecahedron
(5^{12}6^{2})
and C_{336}H_{144} (24 ˣ C_{14}H_{6} units) based on the complete tetrakaidecahedron cluster.

C_{100}H_{60}, C_{120}H_{72} and C_{336}H_{144} alternative fulleranes

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This page was established in 2002 and last updated by Martin Chaplin on 19 March, 2020