pubs.acs.org/Organometallics Published on Web 07/09/2009 r 2009 American Chemical Society 4308 Organometallics 2009, 28, 4308–4315 DOI: 10.1021/om9003253 Multidecker Sandwiches of Silicon-Carbon Clusters E. N. Koukaras and A. D. Zdetsis* Department of Physics, University of Patras, GR-26500 Patras, Greece Received April 27, 2009 It is shown by ab initio density functional theory calculations that hydrogenated silicon-carbon clusters, in particular of the form Si 3 C 2 H 2 , can generate stable organometallic multidecker sandwiches in which transition metal centers, such as Co and Fe, bridge Si 3 C 2 H 2 rings. These multidecker sandwiches are fully homologous and isolobal to the well-known similar metalocarbor- ane sandwiches. This is in full agreement with the isolobal analogy between Si n-2 C 2 H 2 clusters and the corresponding isovalent carboranes C 2 B n-2 H n , n g 3, known as the “boron connection”. The interplanar binding energy of these sandwiches between successive decks increases as the number of decks increases, suggesting that even larger multideckers will also be very stable. Such organometallic species could be proven very important for chemical and technological applications, which could be integrated with current semiconductor technologies. With this perspective it is furthermore illu- strated that by modifying the bridging transition metal or the multidecker linking method, such multidecker sandwiches could be tuned to exhibit specific electronic, optical, and magnetic proper- ties. In addition, due to the chemical similarity provided by the “boron connection”, it would be expected that most of the vital properties, capacities, and applications of the organometallic carboranes, metallaboranes, and metallacarboranes, in particular as building blocks (synthons) of more complex systems, could be transferable to the corresponding isolobal metal-silicon-carbon structures. 1. Introduction Silicon, carbon, and silicon-carbon clusters, cluster as- sembled materials, and nanostructures in addition to their fundamental significance for chemistry, physics, and materi- als science are also of vital importance for technological and chemical applications in nanotechnology, biotechnology, and ceramics industry (this is particularly true for SiC). Composite metal-silicon clusters are widely known, espe- cially as (transition) metal-embedded or (transition) metal- adsorbed silicon clusters. 1-5 Although small silicon carbon clusters have been well studied for several years, 6-8 metallic- SiC (and metallic-C) clusters are only known recently 9 mainly as models or subunits of larger systems, through their role in the production of carbon and silicon-carbon nanotubes, nanorods, and nanowires. 9,10 For instance, Zhao et al. 9 have examined silicon carbide nanotubes functiona- lized by transition metal atoms, while Terrones et al. 10 prepared SiC nanofibers by chemical vapor deposition (CVD), using carbon and silicon powders and hydrogen as a reactant gas with transition metal catalysts (Fe, Cr, or Ni). As we can see, transition metals are instrumental for such complex systems, 1-5,9,10 and so is hydrogen. Another parallel and equally successful direction and ap- proach for developing building blocks of functionalized and “functionalizable” complex systems (as, for instance, double- and multidecker metal-semiconductor sandwiches 11-13 ) is through the methods and techniques of organometallic chemistry. 14 Silicon has long held a privileged status in organic synthesis. Organosilicon chemistry has matured substantially over the course of the past decade, and new methods have been developed for both the introduction of silicon groups and for chemical manipulation of those groups. 14 Organosilicon chemistry is an area of rapid expansion, 14 of almost comparable growth and importance to organoboron chemistry. These two fields are not totally *Corresponding author. E-mail: zdetsis@upatras.gr. (1) Beck, S. M. J. Chem. Phys. 1987, 87, 4233. Beck, S. M. J. Chem. Phys. 1989, 90, 6306. (2) Hiura, H.; Miyazaki, T.; Kanayama, T. Phys. Rev. Lett. 2001, 86, 1733. (3) Kumar, V.; Kawazoe, Y. Phys. Rev. Lett. 2001, 87, 045503. (4) Kumar, V. Comput. Mater. Sci. 2006, 36, 1. (5) Koukaras, E. N.; Garoufalis, C. S.; Zdetsis, A. D. Phys. Rev. B 2006, 73, 235417. Zdetsis, A. D. Phys. Rev. B 2007, 75, 085409. (6) M€ uhlh€ auser, M.; Froudakis, G. E.; Zdetsis, A. D.; Peyerimhoff, S. D. Chem. Phys. Lett. 1993, 204, 617. Froudakis, G. E.; Zdetsis, A. D.; M€ uhlh€ auser, M.; Engels, B.; Peyerimhoff, S. D. J. Chem. Phys. 1994, 101, 6790. (7) Zdetsis, A. D.; Engels, B.; Hanrath, M.; Peyerimhoff, S. D. Chem. Phys. Lett. 1999, 302, 288. (8) Zhao, J.; Ding, Y. J. Phys. Chem. C 2008, 112, 2558–2564. (9) Terrones, M.; Grobert, N.; Olivares, J. Nature 1997, 388, 52. (10) Stephan, M.; M€ uller, P.; Zenneck, U.; Pritzkow, H.; Siebert, W.; Grimes, R. N. Inorg. Chem. 1995, 34, 2058. (11) Bluhm, M.; Pritzkow, H.; Siebert, W.; Grimes, R. N. Angew. Chem., Int. Ed. 2000, 39, 4562. (12) Edwin, J.; Whiteley, M. W.; Herter and, W.; Siebert, W. J. Organomet. Chem. 1990, 394, 329. (13) Fessenbecker, A.; Attwood, M. D.; Bryan, R. F.; Grimes, R. N.; Woode, M. K.; Stephan, M.; Zenneck, U.; Siebert, W. Inorg. Chem. 1990, 29, 5157. (14) Brook, M. A. Silicon in Organic, Organometallic, and Polymer Chemistry; John Wiley & Sons: New York, 2000.