Refinement of the structure of chrysene

The co-ordinates of the carbon and hydrogen atoms and the anisotropic thermal vibrations of the carbon atoms of chrysene have been determined by three-dimensional least-squares refinement and by three-dimensional Fourier, and difference Fourier, syntheses. The value of $R = \frac{\Sigma||F_o| - |F_c||}{\Sigma|F_o|}$ for over 1000 planes observed with CuK$\alpha$ radiation is 0.076. The standard deviations of the carbon atom co-ordinates are less than 0.0033 $^\overset\circ{A}$. One C-C bond is significantly longer than the mean and longer than would be expected by any theoretical consideration. The value 1.465 $^\overset\circ{A}$ can be explained by overcrowding of the hydrogen atoms attached to the carbon atoms concerned. The `K' bond of the phenanthrene nucleus has a length of 1.365 $^\overset\circ{A}$ and this is in the same benzene ring and diametrically opposite to the very long bond mentioned above. It is shown that the thermal vibrations obtained for the individual carbon atoms can be well represented by considering the molecule to vibrate as a rigid body.