Acid–Base Properties of Monomethylgermanium(IV) in Aqueous Solutions
Abstract
Monomethylgermanium (MMGe), the dominant organogermanium species in aquatic systems, exists predominantly as the neutral mononuclear species (CH₃)Ge(OH)₃ under environmentally relevant conditions. MMGe displays conservative behavior in freshwater and marine environments, an observation consistent with high chemical stability, yet its fundamental acid–base properties remain poorly characterized. To address this gap, we investigated the protolytic properties of (CH₃)Ge(OH)₃ at 298.2(2) K across a range of ionic strengths (0.1–1.0 mol·L −1 ) and five supporting electrolytes (LiCl, NaCl, KCl, CsCl, TMACl) by glass-electrode potentiometry. The first deprotonation constant (p K a = –log K 1 ) of (CH₃)Ge(OH)₃ was consistently determined across experimental conditions with values ranging from 11.07(4) to 11.22(3), except in 1 mol·L −1 TMACl, where an anomalously high value (11.62(5)) was attributed to specific ion effects. ¹H and ¹³C NMR titrations in 1 mol·L −1 KCl confirmed a single protonation equilibrium with p K a = 11.22(1), in excellent agreement with the potentiometric results. No evidence was found for the formation of a doubly deprotonated species under the investigated p[H] range (< 13). These findings contribute fundamental thermodynamic data for MMGe and enhance our understanding of its chemical behavior in natural waters.
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BibTeX
@article{biver2026acidbase,
title = {{Acid–Base Properties of Monomethylgermanium(IV) in Aqueous Solutions}},
author = {Marc Biver and Lucas Vachey and Marie-José Penouilh and Michel Meyer and Montserrat Filella},
journal = {Journal of Solution Chemistry},
year = {2026},
month = aug,
doi = {10.1007/s10953-026-01640-x},
url = {https://hal.science/hal-05761444v2},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Acid–Base Properties of Monomethylgermanium(IV) in Aqueous Solutions
AU - Marc Biver
AU - Lucas Vachey
AU - Marie-José Penouilh
AU - Michel Meyer
AU - Montserrat Filella
PY - 2026
DA - 2026/08/03
JO - Journal of Solution Chemistry
DO - 10.1007/s10953-026-01640-x
UR - https://hal.science/hal-05761444v2
AB - Monomethylgermanium (MMGe), the dominant organogermanium species in aquatic systems, exists predominantly as the neutral mononuclear species (CH₃)Ge(OH)₃ under environmentally relevant conditions. MMGe displays conservative behavior in freshwater and marine environments, an observation consistent with high chemical stability, yet its fundamental acid–base properties remain poorly characterized. To address this gap, we investigated the protolytic properties of (CH₃)Ge(OH)₃ at 298.2(2) K across a range of ionic strengths (0.1–1.0 mol·L −1 ) and five supporting electrolytes (LiCl, NaCl, KCl, CsCl, TMACl) by glass-electrode potentiometry. The first deprotonation constant (p K a = –log K 1 ) of (CH₃)Ge(OH)₃ was consistently determined across experimental conditions with values ranging from 11.07(4) to 11.22(3), except in 1 mol·L −1 TMACl, where an anomalously high value (11.62(5)) was attributed to specific ion effects. ¹H and ¹³C NMR titrations in 1 mol·L −1 KCl confirmed a single protonation equilibrium with p K a = 11.22(1), in excellent agreement with the potentiometric results. No evidence was found for the formation of a doubly deprotonated species under the investigated p[H] range (< 13). These findings contribute fundamental thermodynamic data for MMGe and enhance our understanding of its chemical behavior in natural waters.
SN - 0095-9782
SN - 1572-8927
ER -