title: A deeper insight into strain for the sila-bi[6]prismane ( Si18H12) cluster with its endohedrally trapped silicon atom, Si19H12.
abstract: A new family of over-coordinated hydrogenated silicon nanoclusters with outstanding optical and mechanical properties has recently been proposed. For one member of this family, namely the highly symmetric Si19 H12 nanocrystal, strain calculations have been presented with the goal to question its thermal stability and the underlying mechanism of ultrastability and electron-deficiency aromaticity. Here, the invalidity of these strain energy (SE) calculations is demonstrated mainly based on a fundamentally wrong usage of homodesmotic reactions, the miscounting of atomic bonds, and arithmetic errors. Since the article in question is entirely anchored on those erroneous SE values, all of its conclusions and predictions become without meaning. We provide evidence here that the nanocrystal in question suffers from such low levels of strain that its thermodynamical stability should be largely sufficient for device fabrication in a realistic plasma reactor. Most remarkably, the two "alternative," irregular isomers explicitly proposed in the aforementioned article are also electron-deficient, nontetrahedral, ultrastable, and aromatic nicely underlining the universality of the ultrastability concept for nanometric hydrogenated silicon clusters.
authors.affiliation: CNRS-LPICM, Ecole Polytechnique, 91128, Palaiseau, France.
authors.forename: Holger
authors.initials: H
authors.lastname: Vach
authors.affiliation: Department of Chemistry, Marquette University, Milwaukee, Wisconsin, 53201.
authors.forename: Lena V
authors.initials: LV
authors.lastname: Ivanova
authors.affiliation: Department of Chemistry, Marquette University, Milwaukee, Wisconsin, 53201.
authors.forename: Qadir K
authors.initials: QK
authors.lastname: Timerghazin
authors.affiliation: CNRS-LPICM, Ecole Polytechnique, 91128, Palaiseau, France.
authors.forename: Fatme
authors.initials: F
authors.lastname: Jardali
authors.affiliation: CNRS-LPICM, Ecole Polytechnique, 91128, Palaiseau, France.
authors.forename: Ha-Linh Thi
authors.initials: HL
authors.lastname: Le
keywords: aromaticity; electron delocalization; electron-deficient bonds; hydrogenated silicon nanoclusters; ultrastability