M-Ge-Si thermolytic molecular precursors and models for germanium-doped transition metal sites on silica

James P Dombrowski; Vidmantas Kalendra; Micah S Ziegler; K V Lakshmi; Alexis T Bell; T Don Tilley

doi:10.1039/d4dt00644e

M-Ge-Si thermolytic molecular precursors and models for germanium-doped transition metal sites on silica

Dalton Trans. 2024 Apr 30;53(17):7340-7349. doi: 10.1039/d4dt00644e.

Authors

James P Dombrowski^{1

2}, Vidmantas Kalendra³, Micah S Ziegler^{1

2}, K V Lakshmi³, Alexis T Bell^{2

4}, T Don Tilley^{1

2}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA. tdtilley@berkeley.edu.
² Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, USA.
³ Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
⁴ Department of Chemical and Biomolecular Engineering, University of California, Berkeley, 201 Gilman Hall, Berkeley, CA, USA.

PMID: 38602311
DOI: 10.1039/d4dt00644e

Abstract

The synthesis, thermolysis, and surface organometallic chemistry of thermolytic molecular precursors based on a new germanosilicate ligand platform, -OGe[OSi(O^tBu)₃]₃, is described. Use of this ligand is demonstrated with preparation of complexes containing the first-row transition metals Cr, Mn, and Fe. The thermolysis and grafting behavior of the synthesized complexes, Fe{OGe[OSi(O^tBu)₃]₃}₂ (FeGe), Mn{OGe[OSi(O^tBu)₃]₃}₂(THF)₂ (MnGe) and Cr{OGe[OSi(O^tBu)₃]₃}₂(THF)₂ (CrGe), was evaluated using a combination of thermogravimetric analysis; nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis), and electron paramagnetic resonance (EPR) spectroscopies; and single-crystal X-ray diffraction (XRD). Grafting of the precursors onto SBA-15 mesoporous silica and subsequent calcination in air led to substantial changes in transition metal coordination environments and oxidation states, the implications of which are discussed in the context of low-coordinate and low oxidation state thermolytic molecular precursors.