Does the 18-Electron Rule Apply to CrSi12?
Understanding the bonding between silicon and transition metals is valuable for devising strategies for incorporating magnetic species into silicon. CrSi12 is the standard example of a cluster whose apparent high stability has been explained by the 18-electron rule. We critically examine the bonding and nature of stability of CrSi12 and show that its electronic structure does not conform to the 18-electron rule. Through theoretical studies, we find that CrSi12 has 16 effective valence electrons assigned to the Cr atom and an unoccupied 3dz(2) orbital. We demonstrate that the cluster's apparent stability is rooted in a crystal field-like splitting of the 3d orbitals analogous to that of square planar complexes. CrSi14 is shown to follow the 18-electron rule and exhibits all conventional markers characteristic of a magic cluster.
Department of Physics, Virginia Commonwealth University, 1020 West Main Street, Richmond, Virginia 23284-2000, United States.
Marissa Baddick
MB
Abreu
Department of Physics, Virginia Commonwealth University, 1020 West Main Street, Richmond, Virginia 23284-2000, United States.
Arthur C
AC
Reber
Department of Physics, Virginia Commonwealth University, 1020 West Main Street, Richmond, Virginia 23284-2000, United States.
Shiv N
SN
Khanna
18-electron rule; magic clusters; silicon clusters; silicon encapsulated transition-metal clusters