C2: More complicated than it sounds

Abstract

<p>The present work is another contribution to a better understanding of the chemical bond in C<sub>2</sub>. A density functional approach is employed, and the obtained results (bond distance and bond dissociation energy) agrees very well with the previously [2-4] valence bond results. The obtained results also points to a bond order of four, reinforcing previously obtained data [3]. Furthermore, based on the calculated IR and Raman spectra, is proposed that C<sub>2</sub> exhibits, at an electronic level, an asymmetry, and that such molecule has not, in fact, a centre of inversion. </p>

C2: An Asymmetric Specie ?

“…Based on the results obtained here, as well as literature data [1][2][3][4][5][6][7][8][9], some conclusion can be pointed out:…”

“…In a previous work [2], C 2 was modelled by using a density functional approach, and it was verified that the calculated bond distance and bond dissociation energies were in very good agreement with the previously [3][4][5][6] valence bond results. Furthermore, the obtained results also points to a bond order of four, reinforcing previously obtained data [5,6].…”

“…As can be verified form Table 1 data, the DF-ωB97X-D/6-31+G* theoretical approach provides a bond dissociation energy (kJ mol -1 ) calculated value of 593.40, only 3.2% below the available experimental value of 613.08 ± 0.25 [2]. Such fact, as well a bond order close to four, in agreement with previous calculated data, reinforced the hypothesis of a quadruple bond in C 2 [2,5,6].…”

“…As a preliminary finding, I can say that my previous study [2] Another "safe territory" is the bond lengths: C-C, 153 pm; C=C 134 pm and C≡C 120 pm [10]. Once again, can be concluded that the carbon-carbon bond in C 2 is about "two and half".…”

“…The present work is another contribution to a better understanding of the chemical bond in C 2 and expands the previous one [2]. Its main goal is to verify if the hypothesis of an electronic asymmetry in C 2 could be proved.…”