Synthesis, < sup> 1 H NMR, single crystal X-ray determined and ab-initio molecular structural analyses on 1-(isopropylideneaminomethyl)pyrene

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A previously unobserved crystalline precipitate in an extract of crude 1-(aminomethyl) pyrene was shown to be 1-(isopropylideneaminomethyl)pyrene. The identity of this compound was established by a single crystal X-ray determination that revealed an overall planar arrangement for the non-hydrogen atoms. The molecule crystallized in the monoclinic space group P21/c, with the following unit cell dimensions: a = 11.6650(10) Å, b = 8.2850(9) Å, c = 16.0220(9) Å, β = 108.297(6)°, V = 1470(2) Å3, and Z = 4. The structure was refined to R = 0.059 (Rw = 0.150) for 2576 data points with Fo2 > 2σ(Fo2). The results of ab-initio-calculations at the STO-3G level suggest that the difference in rotational conformer energy for rotation about the C-N single bond varied by less than 1 kcal/mol between the maximum (-30°) and minimum (90°) values. Packing forces in the solid state arrangement are believed to be responsible for the difference between this result and experiment, since an AM1 calculation with 1 constrained between two molecules of 1 at the experimental distances led to the planar structure as the one with lowest energy. © 2001 Elsevier Science B.V.

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Journal of Molecular Structure