With the PACIS source (pulsed arc cluster ion source, figure below) it is possible to synthesize new cluster compounds. In the source the material of the cathode is vaporized in an electric arc (e.g., zinc). This takes place in a carrier gas atmosphere. Reactive gases, such as hydrogen, methane, or H2S, can be mixed with the carrier gas. In the arc the carrier gas and the reactive gas are ionized, and molecules, such as H2S, are fractionally dissociated to radicals. The gas stream carries the mixture of radicals, ions, and evaporated electrode material to the extender, a channel about 15 cm long and 4 mm in diameter. There the mixture is cooled, and a multitude of new materials are formed that cannot be produced with conventional chemical reactions. With this source, which was built in Konstanz and is now located in the laboratory in Baltimore, many new cluster compounds were synthesized and characterized over the last years.
An example, which should be highlighted, are aluminum hydrides (Science 315, 356 (2007)). Aluminum was evaporated and mixed with hydrogen as carrier gas. Hydrogen is dissociated in the arc and reacts exceptionally vigorously with aluminum. So far unknown compounds were formed from numerous aluminum and hydrogen atoms (figure below). The novel cluster compounds are similar to boron hydride, which have been known for decades. Aluminum is found in the periodic table below boron, and maybe such compounds have been expected to exist but so far these aluminum hydrides were unknown
Another example is the novel compound ZnPtH5-. The five hydrogen atoms form a ring around the platinum atom. The sigma binding to the H-atoms are delocalized, i.e., aromatic. This is an example of sigma-aromaticity.
Latest Publicationen (from 1.1.2014):
- Allyson Buytendyk, Jacob Graham, Haopeng Wang, Xinxing Zhang, Evan Collins, Y.-J. Ko, Gerd Gantefoer, Bryan Eichhorn, Anushoba Regmi, Kiran Boggavarapu, and Kit H. Bowen, "Photoelectron Spectra of the MgH- and MgD- Anions", Int. J. Mass Spectr. (2014), accepted.
- Haopeng Wang, Xinxing Zhang, Yeon Jae Ko, Andrej Grubisic, Xiang Li, Gerd Gantefoer, Hansgeorg Schnoeckel, Bryan W. Eichhorn, Mal-Soon Lee, P. Jena, Anil K. Kandalam, Boggavarapu Kiran, and Kit H. Bowen, "Aluminum Zintl Anion Moieties within Sodium Aluminum Clusters", J. Chem. Phys. 140, 054301 (2014). doi: 10.1063/1.4862989.
- Haopeng Wang, Yeon Jae Ko, Xinxing Zhang, Gerd Gantefoer, Hansgeorg Schnoeckel, Bryan W. Eichhorn, Puru Jena, Boggavarapu Kiran, Anil K. Kandalam, and Kit H. Bowen, Jr., "The Viability of Aluminum Zintl Anion Moieties within Magnesium-Aluminum Clusters", J. Chem. Phys. (2014), in press.
- Xinxing Zhang, Gerd Gantefoer, Kit H. Bowen, Anastassia N. Alexandrova, "The PtAl- and PtAl2- Anions: Theoretical and Photoelectron Spectroscopic Characterization", J. Chem. Phys. 140, 164316 (2014).
- J. D. Graham, A. M. Buytendyk, X. Zhang, E. L. Collins, B. Kiran, G. Gantefoer, B. W. Eichhorn, G. L. Gutsev, S. Behera, P. Jena, and K. H. Bowen, "The Alanate Anion, AlH4-: Photoelectron Spectrum and Computations", Journal of Physical Chemistry, in press (2014).
- Xinxing Zhang, Gaoxiang Liu, Gerd Ganteför, Kit H. Bowen, and Anastassia N. Alexandrova, "ZnPtH5-, A σ-Aromatic Cluster", J. Phys. Chem. Lett., J. Phys. Chem. Lett. 2014, 5, 1596−1601. Highlighted in Chemistry World 28. April 2014.
- Haopeng Wang, Xinxing Zhang, Yeon Jae Ko, Gerd Gantefoer, Kit H. Bowen*, Xiang Li, Boggavarapu Kiran, Anil K. Kandalam*, "Photoelectron Spectroscopy of Boron Aluminum Hydride Cluster Anions", submitted to J. Chem. Physics, 14. Feb. 2014.