Majeda Al Hareri, Patricio Romero, James F. Britten, David J. H. Emslie
{"title":"Silyl- and Germyl-Substituted Boranes: Synthesis and Investigation as Potential Atomic Layer Deposition Precursors","authors":"Majeda Al Hareri, Patricio Romero, James F. Britten, David J. H. Emslie","doi":"10.1021/acs.inorgchem.4c03416","DOIUrl":null,"url":null,"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<sub>3</sub>Si)<sub>3</sub>Si}Li(THF)<sub>3</sub> (<b>1</b>), supersilyl sodium, (<sup><i>t</i></sup>Bu<sub>3</sub>Si)Na(THF)<sub><i>n</i></sub> (<b>2</b>, <i>n</i> = 2–3), and trimethylgermyl lithium, {Me<sub>3</sub>GeLi(THF)<sub>2</sub>}<sub>2</sub> (<b>3</b>), were used for the synthesis of the silyl- and germyl-substituted boranes in this work. Compounds <b>1</b> and <b>2</b> were synthesized as previously reported, and compound <b>3</b> was isolated from the reaction of trimethylgermane with <i>tert</i>-butyl lithium. Compounds <b>2</b> and <b>3</b> were crystallographically characterized. Reaction of B(NMe<sub>2</sub>)Cl<sub>2</sub> with 2 equiv of <b>1</b> afforded previously reported {(Me<sub>3</sub>Si)<sub>3</sub>Si}<sub>2</sub>B(NMe<sub>2</sub>) (<b>4</b>), whereas reactions of B(NMe<sub>2</sub>)Cl<sub>2</sub> or {B(NMe<sub>2</sub>)F<sub>2</sub>}<sub>2</sub> with excess <b>2</b> only afforded the monosilyl boranes (<sup><i>t</i></sup>Bu<sub>3</sub>Si)B(NMe<sub>2</sub>)X {X = Cl (<b>5</b>) and F (<b>6</b>)}. Reaction of <b>5</b> with 0.5 equiv of {Me<sub>3</sub>GeLi(THF)<sub>2</sub>}<sub>2</sub> (<b>3</b>) provided the first example of a mixed silyl/germyl-substituted borane, (<sup><i>t</i></sup>Bu<sub>3</sub>Si)(Me<sub>3</sub>Ge)B(NMe<sub>2</sub>) (<b>7</b>). Attempts to synthesize (Me<sub>3</sub>Ge)<sub>2</sub>B(NMe<sub>2</sub>) from the 1:1 reaction of B(NMe<sub>2</sub>)Cl<sub>2</sub> with {Me<sub>3</sub>GeLi(THF)<sub>2</sub>}<sub>2</sub> afforded a mixture of two major products, one of which was identified as the tri(germyl)(amido)borate {(Me<sub>3</sub>Ge)<sub>3</sub>B(NMe<sub>2</sub>)}Li(THF)<sub>2</sub> (<b>8</b>); compound <b>8</b> was isolated from the 1:1.5 reaction. Reaction of more sterically encumbered B(TMP)Cl<sub>2</sub> with 1 equiv of {Me<sub>3</sub>GeLi(THF)<sub>2</sub>}<sub>2</sub> afforded the di(germyl)(amido)borane (Me<sub>3</sub>Ge)<sub>2</sub>B(TMP) (<b>9</b>). Boranes <b>4</b>, <b>7</b>, and <b>9</b> and borate <b>8</b> were crystallographically characterized. The thermal stability and volatility of boranes <b>4</b>, <b>7</b>, and <b>9</b> was evaluated, the solution reactivity of <b>4</b> and <b>7</b> with boron trihalides was assessed, and ALD was attempted using <b>4</b> in combination with BCl<sub>3</sub> and BBr<sub>3</sub> at 150 and 300 °C.","PeriodicalId":40,"journal":{"name":"Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":4.3000,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Inorganic Chemistry","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.inorgchem.4c03416","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, INORGANIC & NUCLEAR","Score":null,"Total":0}
引用次数: 0
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, {(Me3Si)3Si}Li(THF)3 (1), supersilyl sodium, (tBu3Si)Na(THF)n (2, n = 2–3), and trimethylgermyl lithium, {Me3GeLi(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(NMe2)Cl2 with 2 equiv of 1 afforded previously reported {(Me3Si)3Si}2B(NMe2) (4), whereas reactions of B(NMe2)Cl2 or {B(NMe2)F2}2 with excess 2 only afforded the monosilyl boranes (tBu3Si)B(NMe2)X {X = Cl (5) and F (6)}. Reaction of 5 with 0.5 equiv of {Me3GeLi(THF)2}2 (3) provided the first example of a mixed silyl/germyl-substituted borane, (tBu3Si)(Me3Ge)B(NMe2) (7). Attempts to synthesize (Me3Ge)2B(NMe2) from the 1:1 reaction of B(NMe2)Cl2 with {Me3GeLi(THF)2}2 afforded a mixture of two major products, one of which was identified as the tri(germyl)(amido)borate {(Me3Ge)3B(NMe2)}Li(THF)2 (8); compound 8 was isolated from the 1:1.5 reaction. Reaction of more sterically encumbered B(TMP)Cl2 with 1 equiv of {Me3GeLi(THF)2}2 afforded the di(germyl)(amido)borane (Me3Ge)2B(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 BCl3 and BBr3 at 150 and 300 °C.
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Inorganic Chemistry publishes fundamental studies in all phases of inorganic chemistry. Coverage includes experimental and theoretical reports on quantitative studies of structure and thermodynamics, kinetics, mechanisms of inorganic reactions, bioinorganic chemistry, and relevant aspects of organometallic chemistry, solid-state phenomena, and chemical bonding theory. Emphasis is placed on the synthesis, structure, thermodynamics, reactivity, spectroscopy, and bonding properties of significant new and known compounds.
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