Search

Methyl magnesium bromide is a precatalyst for the dehydrocoupling of silanes and amines to produce aminosilane products under mild conditions. As a commercially available Grignard reagent, this precatalyst represents a simplification over previous magnesium-containing catalysts for Si–N bond formation while displaying similar activity to other magnesium-based catalysts. This observation is consistent with the hypothesis that competitive Schlenk equilibrium can be addressed by not using an ancillary ligand. While the activity of MeMgBr is lower than some reported catalysts, including other commercially available precatalysts, unique selectivity was observed for MeMgBr that may allow for directed synthesis of aminosilane products. This work continues to increase the accessibility of Si–N heterodehydrocoupling through a growing family of commercially available precatalysts that balance activity and selectivity. [ABSTRACT FROM AUTHOR]

Group I alkoxides are highly active precatalysts in the heterodehydrocoupling of silanes and amines to afford aminosilane products. The broadly soluble and commercially available KOtAmyl was utilized as the benchmark precatalyst for this transformation. Challenging substrates such as anilines were found to readily couple primary, secondary, and tertiary silanes in high conversions (>90 %) after only 2 h at 40 °C. Traditionally challenging silanes such as Ph3SiH were also easily coupled to simple primary and secondary amines under mild conditions, with reactivity that rivals many rare earth and transition‐metal catalysts for this transformation. Preliminary evidence suggests the formation of hypercoordinated intermediates, but radicals were detected under catalytic conditions, indicating a mechanism that is rare for Si−N bond formation. [ABSTRACT FROM AUTHOR]

A family of commercially available organolithium compounds were found to effectively catalyze the heterodehydrocoupling of silanes and amines under ambient conditions. Ubiquitous nBuLi (1) was utilized as the benchmark catalyst, where an array of primary, secondary, and tertiary arylsilanes were coupled to electron-donating amines, affording aminosilanes in high conversions with short reaction times. Preliminary mechanistic analysis is consistent with a nucleophilic-type system that involves the formation of a hypervalent silicon intermediate. This work underscores the accessibility of Si-N heterodehydrocoupling, with organolithium reagents emerging as some of the most straightforward and cost-effective precatalysts for this transformation. [ABSTRACT FROM AUTHOR]

An examination of several catalytic reactions among the group 15 elements is presented. The connections between the chemistry of the pnictogens can sometimes be challenging, but aspects of metal–pnictogen reactivity are the key. The connecting reactivity comes from metal-catalyzed transformations such as dehydrocoupling and hydrofunctionalization. Pivotal mechanistic insights from E–N heterodehydrocoupling have informed the development of highly active catalysts for these reactions. Metal–amido nucleophilicity is often at the core of this reactivity, which diverges from phosphine and arsine dehydrocoupling. Nucleophilicity connects to the earliest understanding of hydrophosphination catalysis, but more recent catalysts are leveraging enhanced insertion activity through photolysis. This photocatalysis extends to hydroarsination, which may also have more metal–arsenido nucleophilicity than anticipated. However, metal-catalyzed arsinidene chemistry foreshadowed related phosphinidene chemistry by years. This examination shows the potential for greater influence of individual discoveries and understanding to leverage new advances between these elements, and it also suggests that the chemistry of heavier elements may have more influence on what is possible with lighter elements. [ABSTRACT FROM AUTHOR]

Silicon–nitrogen bond formation is an important subfield in main group chemistry, and catalysis is an attractive route for efficient, selective formation of these bonds. Indeed, heterodehydrocoupling and N‐silylation offer facile methods for the synthesis of small molecules through the coupling of primary, secondary, and tertiary silanes with N‐containing substrates such as amines, carbazoles, indoles, and pyrroles. However, the reactivity of these catalytic systems is far from uniform, and critical issues are often encountered with product selectivity, conversions, substrate scope, catalyst activation, and in some instances, competing side reactions. Herein, a catalogue of catalysts and their reactivity for Si−N heterodehydrocoupling and N‐silylation are reported. [ABSTRACT FROM AUTHOR]

Silicon–oxygen and silicon–nitrogen heterodehydrocoupling catalyzed by the commercially available cyclopentadienyl dicarbonyl iron dimer [CpFe(CO)2]2 (1) under photochemical conditions is reported. Reactions between alcohols and PhSiH3 with catalytic 1 under visible-light irradiation produced silyl ethers quantitively. Reactions between either secondary or tertiary silanes and alcohols also produced silyl ethers, however, these reactions were marked by their longer reaction times and lower conversions. Reactions of either primary or secondary amines and silanes with catalytic 1 demonstrated mixed efficiency, featuring conversions of 20–100%. Mechanistic study indicates that an iron silyl compound is unimportant in the bond-formation step and argues for either a nucleophilic alkoxide or amide intermediate. Most important, mechanistic study reveals that the most immediate hurdle in the catalysis is the poor activation of 1, demonstrating the necessity to fully activate the catalyst to realize the potential of iron in this reactivity. [ABSTRACT FROM AUTHOR]

Keywords: amines; alkoxides; amylates; heterodehydrocoupling; silanesThe activity of potassium alkoxides salts in N−Si dehydrocoupling catalysis is out of this world! For the first time, aniline derivatives are now accessible substrates in N−Si dehydrocoupling catalysis, and relative rates of reactions for benchmark substrate are substantially greater for KOtAmyl than reported catalysts. More information can be found in the Research Article by R. Waterman and co‐workers (DOI: 10.1002/chem.202302618)...By Matthew B. Reuter; Diego R. Javier‐Jiménez; Claire E. Bushey and Rory WatermanReported by Author; Author; Author; Author [Extracted from the article]

Chromium-bearing tourmalines are rare. Chromium-rich tourmaline from the northwestern part of the Adirondack Mountains in the Adirondack Lowlands is among the most chromium-rich tourmalines found to date. The mineral, with >21.0 wt. % Cr2O3, is from the marble-hosted talc–tremolite–cummingtonite schist in the #1 mine in Balmat, St. Lawrence County, New York. The atomic arrangement of the sample (a = 16.0242(3) Å, c = 7.3002(2) Å) was refined to R1 = 0.0139. The composition, from chemical analyses and optimization of the formula, is X(Ca0.22Na0.69K0.01) Y(Cr3+1.68Mg0.80Ti0.13V0.06Mn0.02Fe0.02Li0.29) Z(Al3.11Cr3+1.18Mg1.70Fe0.01) T(Si5.93Al0.07) B3O27 OH3.99 F0.01. There has been extensive debate over the ordering of Cr3+ between the tourmaline Y and Z octahedral sites. Recent work has suggested that, at low concentrations (<~1.03 apfu), the substituent Cr3+ is ordered into the Y-site, whereas, at greater concentrations, the substituent is disordered over both octahedral sites. An analysis of nine recently published, high-precision structures of chromium-bearing tourmaline, in combination with the Adirondack tourmaline, suggests that structural changes to the Y-site at low concentrations of Cr3+ induce changes in the Z-site that make it more amenable to incorporation of the Cr3+ substituents by increasing . The bond lengths change to lower the bond-valence sum of Cr3+ in the Z-site of the chromium-dravite, making that site more amenable to the substituent. Calculations suggest that the Z-site begins to accept substituent Cr3+ when the bond valence sum of that ion in Z reduces to a value of ~3.36 valence units. [ABSTRACT FROM AUTHOR]

Methyl magnesium bromide is a precatalyst for the dehydrocoupling of silanes and amines to produce aminosilane products under mild conditions. As a commercially available Grignard reagent, this precatalyst represents a simplification over previous magnesium-containing catalysts for Si-N bond formation while displaying similar activity to other magnesium-based catalysts. This observation is consistent with the hypothesis that competitive Schlenk equilibrium can be addressed by not using an ancillary ligand. While the activity of MeMgBr is lower than some reported catalysts, including other commercially available precatalysts, unique selectivity was observed for MeMgBr that may allow for directed synthesis of aminosilane products. This work continues to increase the accessibility of Si-N heterodehydrocoupling through a growing family of commercially available precatalysts that balance activity and selectivity.