The structure and energy of SiH+5. comparisons with CH+5 and BH5

✍ Scribed by Paul von Ragué Schleyer; Yitzhak Apeloig; Dorit Arad; Brian T. Luke; John A. Pople

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 517 KB
• Volume: 95
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(83)80336-4

✦ Synopsis

Diiicrences between SiHS and CH; are more significant than the similarities. The proton affinity of Sib exceeds that of CH4 by ~25 kcal/mol. but the heat of hydrogenation of SiH; is smaller than that of CH: by nearly the mrne amount. Like CH:, the Cs structures of SiH: are preferred, but SiH: is best regarded as a weaker SiH~-H2 complex. Dsh, C,,. and CG~ forms arc much higher in energy and SiHz should nor undergo hydrogen scrambliq (pseudorotation) readily, as does CH$ The neutral BH5 is only weakly bound towards loss of Hz. and the D3h. C,,, and Cav forms are also high in energy. The central-atom electronegativities. c' > B > Sl". control this behavior. The clectroncgativitics also dcterntinc Ihc ability to bear positive chages. Thermodynamically, Sii; and SiH; are more stable than CH; and CH;. respectively: h\*dride trausfcr occurs from SiH, to CH; and proton transfer from CH; to SiH4_ little-known species. The CHC ion, readily formed in pure gaseous methane by reaction of CHZ with CH,, plays an important role in ion-molecule processes