Knowledge Bank

Following studies of the nature of covalent and recoupled pair bonding in PF($n$=1$-$5),SF$_n$($\mathit{n}$=1$-$6),andClF$_n$($\mathit{n}$=1$-$7),wehaveusedtherecoupledpairbondingmodeltoinvestigatetheClF$_n^{+/-}$($\mathit{n}$=1$-$5)ions.ThebehaviorofthecationseriesparallelstheSF$_n$ series to great extent, while the behavior of the anion series would parallel that of ArF if those species were bound. In the present research, we predict experimentally measurable properties, such as the electron affinities (EA) and ionization energies (IE) of the associated neutral ClF species. The optimized ground state structures, bond energies, and spectral properties of ClF were obtained by employing high level {\em ab initio} calculations (MRCI, CCSD(T)) with correlation consistent basis sets. Our predictions agree well with the structures of experimentally observed species, including ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">+</mrow>}$, ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">-</mrow>}$, ClF$\mathrm{4<mrow\; data-mjx-texclass="ORD">+</mrow>}$, and ClF$\mathrm{4<mrow\; data-mjx-texclass="ORD">-</mrow>}$. Low-lying excited states of ClF$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$($4\Sigma -$) and ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">+</mrow>}$($\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}B1$), were also identified. We found the excited $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}B1$ state of ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">+</mrow>}$ is bent with an angle of 154.8$^irc\}$ and a bond length of 1.596 $\backslash AA$ at the RCCSD(T)/AVQZ level. We also found a major difference between SF$2$ and ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">+</mrow>}$: the $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}A2$ state of SF$2$ is bound while the same state of ClF$\mathrm{2<mrow\; data-mjx-texclass="ORD">+</mrow>}$ is repulsive. Second, we systematically explored the bond formation processes, adding F atoms one at a time to the optimized ClF(1$\le$$n$$\leq$5)ions.WefoundtheionizationenergiesandtheelectronicaffinitiesbothexhibitanoscillatingtrendasseeninthebondenergiesoftheneutralClF$_n$ species. The structural and energetic data obtained by our calculations might help spectroscopists to identify new ClF species or to detect new electronic states of known species.