Diamond and Its Structure

In diamond, each carbon atom has four immediate neighbors situated at the corners of a tetrahedron that is circumscribed to the atom in question. All carbon atoms are sp -hybridized, and the bond length uniformly is 154.45 pm. 

The unit cell contains four atoms, and the lattice parameters are Oo = 252 pm and Co = 412 pm. 

As a visualization, starting from hexagonal graphite, one may fancy the freely mobile rr-electrons alternately to form upward and downward o-bonds with the respective atoms of adjacent layers. This causes a formal compression and undulation of the lattice (change of hybridization), but conserves the AB AB stacking of the imaginary planes. For the formation of cubic diamond, on the other hand, a slight 

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Let us describe some frequently encountered polycyclic structures. Bicyclo[2.2.1] heptane, also known as norbomane, is the basic structure of a series of natural products. The tricyclic compound adamantane (tricyclo[3.3.1.L ]decane) is in principle the smallest structural fragment of diamond and its structure appears on the list of pharmaceutically important products. Adamantane was synthesized for the first time in 1941 at the University of Zagreb by Vladimir Prelog. 

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