A stable argon compound HArF

Up to the year of 2000, no compound of helium, neon, or argon was known. However, that did not discourage theoretical chemists from nominating candidate compounds to the synthetic community. In a conference in London in August 2000, there were two poster papers with the following intriguing titles Prediction of a stable helium compound HHeF by M. W. Wong and Will 

Let us now consider the calculated results. The calculated bond lengths of HArF are summarized in Table 5.8.1, while the calculated vibrational frequencies, along with the experimental data, are listed in Table 5.8.2. 

Examining the results given in these two tables, it is seen that, for this small molecule, very advanced calculations can be carried out. In the tables, all the methods employed have been introduced in the previous sections. For the basis sets, aug-cc-pVnZ stands for augmented correlation consistent polarized valence n zeta, with n = 2-5 referring to double, triple, quadruple, and quintuple, respectively. Clearly, these basis functions are specially designed for 

To conclude, HArF represents one of those rare examples for which calculations preceded experiment. In addition, it nicely demonstrates that computational results can play an indispensable role in the characterization and understanding of small molecules. 

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