Structural and bonding properties of AlnC4-/0 (n=2-4) clusters: Anion photoelectron spectroscopy and theoretical calculations

We measured the photoelectron spectra of AlnC4- (n=2-4) clusters by using size-selected anion photoelectron spectroscopy. The structures of AlnC4-/0 (n = 2-4) clusters were explored with quantum chemistry calculations and were determined by comparing the theoretical results with the experimental spectra. It is found that the most stable structure of Al2C4- anion is a C-2v symmetry planar structure with two Al atoms interacting with two C-2 units. In addition, Al2C4- anion also has a D-infinity h symmetry linear structure with two Al atoms located at the two ends of a C-4 chain, which is slightly higher in energy than the planar structure. The most stable structure of neutral Al2C4 has a D-infinity h symmetry linear structure. The most stable structure of Al3C4- anion is a planar structure with three Al atoms interacting with two C-2 units. Whereas neutral Al3C4 cluster has a C-2v symmetric V-shaped bent structure. The global minima structures of both Al4C4- and neutral Al4C4 are C-2h symmetry planar structures with four Al atoms interacting with the ends of two C-2 units. Adaptive natural density partitioning analyses of AlnC4- (n=2-4) clusters show that the interactions between the Al atoms and C-2 units have both sigma and pi characters.

Automated summary

In this study, the structures of AlnC4- (n=2-4) clusters were investigated using size-selected anion photoelectron spectroscopy and quantum chemistry calculations. The most stable structures were identified through comparisons of theoretical and experimental data, revealing differences in stability between different structural forms.