IR Spectroscopic and DFT Studies on the Reactions of Laser-Ablated Nb Atoms with Carbon Dioxide

Abstract

Reactions of laser-ablated Nb atoms with CO 2 give insertion products ONbCO and O 2 Nb(CO) 2 and the negative species O 2 Nb(CO) 2 -, which have been identified by matrix isolation FTIR method and DFT calculations. Two ONbCO structural products (I and II) were observed with infrared absorptions at 1902.6/960.1 and 1821.3/915.6 cm -1 , respectively. UV light irradiation destroyed the O 2 Nb(CO) 2anion completely, while the intensities of ONbCO(II) and O 2 NbCO were enhanced markedly. Sample annealing led to the obvious increase of ONbCO(II), while the ONbCO(I) can further combine with CO 2 to form O 2 Nb(CO) 2 .

Photoionization of Nb3CO and Nb3(CO)2: Is CO Molecularly or Dissociatively Adsorbed on Niobium?

“…For the analogous reaction, Nb + CO 2 f ONbCO, insertion of Nb into the CO bond is predicted to occur spontaneously. 27 That is, the transition state to the insertion lies lower in energy than the Nb + CO 2 reagents. By analogy, it is likely…”

“…This result is consistent with the barrierless reaction path predicted for the analogous insertion reaction Nb + CO 2 f ONbCO. 27 The experimental results can be summarized as follows. From analysis of the mass spectra, it is clear that a single form of Nb 3 -CO, either dissociatively or molecularly adsorbed, is present in the experiment.…”

Theoretical study on the reactions of Nb and Nb+ with CO2 in gas phase

“…Qin and coworkers [17] reported an IR study on the reaction of laser-ablated Nb atom with CO 2 , they also carried out a DFT calculation on the observed products ONbCO and ONb(g 2 CO). Compared with our calculation results, the discrepancies on geometry also exist because of adopting different basis set for Nb, but the bond discrepancies are less than 0.005 Å .…”

“…From their work, one can see that the CO 2 activation mediated by Nb þ cation is an exothermic spin-forbidden process, which resulted from a crossing between quintet and triplet energetic profiles, but they didn't locate the exact region of curve-crossing. Qin and coworkers [17] reported an IR study on the reaction of laser-ablated Nb atom with CO 2 , and they carried out a density functional theory (DFT) calculation on the observed products ONbCO and ONb(g 2 CO). But detailed information for the potential energy surfaces of reaction Nb þ CO 2 is still scarce.…”

“…To explain this phenomenon, we analyze the frontier molecular orbital of insertion species. Here, we take example for Using the Lanl2DZ basis sets, Qin and coworkers [17] has performed DFT calculations on the structures and energies of the CAO bond activation species, IM3. As both the doublet and quartet ONbCO have very close energy and CO stretching fundamental, it is difficult to determine, which one is the ground state.…”