Sequential IRMPD of XGe(OEt) 4− ions: Gas-phase synthesis of novel oxy-germanium anions

Abstract

The gas-phase ion/molecule reactions of F − and EtO − with Ge(OEt) 4 yield readily and exclusively pentacoordinated complexes XGe(OEt) 4 − (X = F, EtO) at pressures in the 10 −8 T range as observed by FT-ICR techniques. These hypervalent species are prone to undergo sequential fragmentations induced by infrared multiphoton excitation that lead to a variety of germyl and germanate anions. In the case of FGe(OEt) 4 −, three primary competitive channels are observed in the IRMPD process that can be identified as (EtO) 3GeO −, F(EtO) 2GeO − and (EtO) 3Ge −. Ab initio calculations have been carried out to characterize the primary fragmentation paths induced by IRMPD and the most favorable structure of the resulting anions. The gas-phase acidity of a number of these germanium-containing ions have been estimated by bracketing experiments and by theoretical calculations. Germanate anions such as (EtO) 3GeO − undergo some interesting reactions with H 2S to give rise to anions such as (EtO) 3GeS − and (EtO) 2Ge(OH)S −.