Silyl- and Germyl-Substituted Boranes: Synthesis and Investigation as Potential Atomic Layer Deposition Precursors
Bibliographic record
Abstract
Boranes featuring bulky hypersilyl or supersilyl groups and/or sterically unencumbered trimethylgermyl substituents were synthesized for investigation as potential precursors for atomic layer deposition (ALD) of elemental boron. The envisaged ALD process would employ a boron trihalide coreactant, exploiting the formation of strong silicon-halogen and germanium-halogen bonds as a driving force. The alkali metal silyl and germyl compounds hypersilyl lithium, {(Me 3 Si) 3 Si}Li(THF) 3 ( 1 ), supersilyl sodium, ( t Bu 3 Si)Na(THF) n ( 2, n = 2–3), and trimethylgermyl lithium, {Me 3 GeLi(THF) 2 } 2 ( 3 ), were used for the synthesis of the silyl- and germyl-substituted boranes in this work. Compounds 1 and 2 were synthesized as previously reported, and compound 3 was isolated from the reaction of trimethylgermane with tert -butyl lithium. Compounds 2 and 3 were crystallographically characterized. Reaction of B(NMe 2 )Cl 2 with 2 equiv of 1 afforded previously reported {(Me 3 Si) 3 Si} 2 B(NMe 2 ) ( 4 ), whereas reactions of B(NMe 2 )Cl 2 or {B(NMe 2 )F 2 } 2 with excess 2 only afforded the monosilyl boranes ( t Bu 3 Si)B(NMe 2 )X {X = Cl ( 5 ) and F ( 6 )}. Reaction of 5 with 0.5 equiv of {Me 3 GeLi(THF) 2 } 2 ( 3 ) provided the first example of a mixed silyl/germyl-substituted borane, ( t Bu 3 Si)(Me 3 Ge)B(NMe 2 ) ( 7 ). Attempts to synthesize (Me 3 Ge) 2 B(NMe 2 ) from the 1:1 reaction of B(NMe 2 )Cl 2 with {Me 3 GeLi(THF) 2 } 2 afforded a mixture of two major products, one of which was identified as the tri(germyl)(amido)borate {(Me 3 Ge) 3 B(NMe 2 )}Li(THF) 2 ( 8 ); compound 8 was isolated from the 1:1.5 reaction. Reaction of more sterically encumbered B(TMP)Cl 2 with 1 equiv of {Me 3 GeLi(THF) 2 } 2 afforded the di(germyl)(amido)borane (Me 3 Ge) 2 B(TMP) ( 9 ). Boranes 4, 7, and 9 and borate 8 were crystallographically characterized. The thermal stability and volatility of boranes 4, 7, and 9 was evaluated, the solution reactivity of 4 and 7 with boron trihalides was assessed, and ALD was attempted using 4 in combination with BCl 3 and BBr 3 at 150 and 300 °C.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".