Mass spectrometric and theoretical studies on the fragmentation mechanism of protonated molecules and molecular radical cations of organometallic compounds with Si-C, Si-Si, Ge-C and Ge-Ge bonds

摘要

Protonated hexamethyldigermane [HMDG]H+ and protonated hexamethyldisilane [HMDS]H+ were generated in the gas phase by nanoelectrospray ionization (nano-ESI) and atmospheric pressure chemical ionization (APCI). The fragmentation mechanisms of [HMDG]H+ and [HMDS]H+ were investigated by analyzing the collision-induced dissociation (CID). In CID spectra of [HMDG]H+, the fragment ions due to a CH4 elimination from the protonated hexamethyldigermane were observed. The potential energy curves were calculated using the ab initio method (B3LYP/6-31G(2df,p)). The calculated optimal geometries of [HMDG]H+ and [HMDS]H+ were the proton-bound structures and the ion-neutral complexes. The results of ab initio calculations showed that C2H4 elimination occurred more easily than C2H6 elimination in both (CH3)(3)Ge+ and (CH3)(3)Si+. This was consistent with the experimental results of the CID spectrum of (CH3)(3)Si+. Copyright (C) 2006 John Wiley & Sons, Ltd.