1. Access to metastable [GeH2]n materials via a molecular 'bottom-up' approach
- Author
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Makoto Yasuda, Anagha Kiran, Kwami Aku-Dominguez, Jocelyn Sinclair, William Medroa del Pino, Yohei Minami, Eric Rivard, and Michael J. Ferguson
- Subjects
Materials science ,010405 organic chemistry ,Band gap ,Hydride ,chemistry.chemical_element ,Germanium ,010402 general chemistry ,Metathesis ,01 natural sciences ,Borylation ,0104 chemical sciences ,Amorphous solid ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Physical chemistry ,Thin film ,Catecholborane - Abstract
We describe the application of a mild, molecular-based, hydride metathesis protocol for the preparation of metastable germanium(II) dihydrides with compositions approaching [GeH2]n. The common starting material for this work [Ge(OtBu)2] was prepared in a high yield and shown to undergo OtBu/H exchange at Ge with the hydride sources pinacolborane (HBpin), catecholborane (HBcat), and diisobutylaluminum hydride (DIBAL-H) to give the [GeH2]n materials as yellow to orange solids. Heating one of these [GeH2]n materials to 200 °C affords a narrowing of the optical band gap (from 2.5 eV) and the generation of amorphous Ge. Reaction of [Ge(OtBu)2] with excess H3B·SMe2 in toluene at 70 °C provides a convenient route to thin films of amorphous Ge, including its deposition onto soft substrates, such as polyethyleneterephthalate (PET). Accompanying computations give insight into the energetics of OtBu/H exchange at Ge, and reveal a general thermodynamic preference for branched structures of [GeH2]n oligomers over linear forms as the Ge chain becomes longer. We also show that [Ge(OtBu)2] is a suitable pre-catalyst for the borylation of aldehydes.
- Published
- 2021