The electronic and vibrational structures of the vis–UV transitions in the 1,3-dicyanomethylene croconate anion in terms of CASSCF and DFT theory. The Franck–Condon analysis of 12B1→12A2 and 12B1→22A2 transitions

✍ Scribed by Marcin Makowski; Marek T. Pawlikowski

• Book ID: 104108327
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 201 KB
• Volume: 376
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/s0009-2614(03)01039-x

✦ Synopsis

The visible and near UV absorption spectra of the 1,3-dicyanomethylene croconate anion radical are discussed in terms of density functional theory (DFT) and the complete active space (CASSCF) method employed with augmented cc-pVDZ basis set. It is shown that the three transitions 1 2 B 1 ! 2 2 A 2 , 1 2 B 1 ! 2 2 B 1 and 1 2 B 1 ! 3 2 B 1 shape the absorption in the near UV region. The FC activity in the most intense 1 2 B 1 ! 2 2 A 2 near UV transition was shown to be quite modest. On the other hand the near visible absorption of the croconate derivative is shown to be due to 1 2 B 1 ! 1 2 A 2 transition accompanied by a short progression of v 5 ða 1 Þ ¼ 1567 cm À1 mode.