Hydrosilylation of alkenes and alkynes with silsesquioxane (HSiMe2O)(i-Bu)7Si8O12 catalyzed by Pt supported on a styrene-divinylbenzene copolymer

Preparation of T8 and double-decker silsesquioxane-based Janus-type molecules: molecular modeling and DFT insights

We present a methodology for the synthesis of inorganic-organic Janus-type molecules based on mono-T8 and difunctionalized double-decker silsesquioxanes (DDSQs) via hydrosilylation reactions, achieving exceptionally high yields and selectivities. The synthesized compounds were extensively characterized using various spectroscopic techniques, and their sizes and spatial arrangements were predicted through molecular modelling and density functional theory (DFT) calculations. Quantum chemical calculations were employed to examine the interactions among four molecules of the synthesized compounds. These computational results allowed us to determine the propensity for molecular aggregation, identify the functional groups involved in these interactions, and understand the changes in interatomic distances during aggregation. Understanding the aggregation behaviour of silsesquioxane molecules is crucial for tailoring their properties for specific applications, such as nanocomposites, surface coatings, drug delivery systems, and catalysts. Through a combination of experimental and computational approaches, this study provides valuable insights into the design and optimization of silsesquioxane-based Janus-type molecules for enhanced performance across various fields.

Pt(PPh3)4 and Pt(PPh3)4@IL catalyzed hydroboration of ketones

An efficient method for the reduction of various ketones via [Pt(PPh3)4]-catalyzed hydroboration with HBpin has been successfully developed for the first time. The protocol is suitable for symmetrical and unsymmetrical derivatives possessing electron donating or withdrawing functional groups. O-borylated products were easily converted to 2° alcohols via hydrolysis with high isolated yields. According to the low-temperature NMR spectroscopy, a reaction mechanism was proposed. Additionally, effective immobilization of the catalyst in the ionic liquid [BMIM][NTf2] was applied to increase the productivity of the process by carrying out reactions under the repetitive batch mode, obtaining higher TON values and limiting the amount of expensive Pt used. The catalyst stability and almost neglectable leaching were confirmed by ICP-MS analysis of the extracted mixture. A simple separation method via extraction with n-heptane, efficient catalyst immobilization, and the commercial availability of the Pt complex, make this protocol an attractive method for the hydroboration of ketones.

Functionalization of octaspherosilicate (HSiMe2O)8Si8O12 with buta-1,3-diynes by hydrosilylation

Hydrosilylation with octaspherosilicate (HSiMe2O)8Si8O12 (1) has provided hundreds of molecular and macromolecular systems so far, making this method the most popular in the synthesis of siloxane-based, nanometric, cubic, and reactive building blocks. However, there are no reports on its selective reaction with 1,3-diynes, which allows for the formation of new products with unique properties. Therefore, herein we present an efficient protocol for monohydrosilylation of symmetrically and non-symmetrically 1,4-disubstituted buta-1,3-diynes with 1. The compounds obtained bear double and triple bonds and other functionalities (e.g., Br, F, OH, SiR3), making them highly desirable, giant building blocks in organic synthesis and material chemistry. These compounds were fully characterized by 1H, 13C, 29Si, 1D NOE, 1H-13C HSQC NMR, FT-IR, and MALDI TOF MS, EA, UV-Vis, and TGA analysis. The TGA proved their high thermal stability up to 427 ℃ (Td10%) for compound 3j.

Synthesis of unsymmetrically and symmetrically functionalized disiloxanes via subsequent hydrosilylation of C≡C bonds

A selective synthesis of unsymmetrically functionalized disiloxanes via the subsequent hydrosilylation of internal alkynes in the first step, and alkynes (terminal or internal) or 1,3-diynes in the second, with 1,1,3,3-tetramethyldisiloxane (1) is presented for the first time. Using developed approaches performed in a stepwise or one-pot manner a new family of disubstituted disiloxanes was obtained which had previously been inaccessible by other synthetic methods. Moreover, symmetrically functionalized disiloxanes were obtained by direct hydrosilylation of 2 equivalents of terminal or internal alkynes with 1, showing the unique versatility of the hydrosilylation process. Three examples of symmetric disiloxanes were characterized by single crystal X-ray diffraction for the first time. As a result, a wide group of new compounds which can find potential applications as building blocks or coupling agents was obtained and characterized.

Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium-Catalyzed Carbene Insertion into Si-H bonds

We report carbene insertion into Si-H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl-diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight Si-H bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron-dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)-functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki-Miyaura cross-coupling.

Formation of Bifunctional Octasilsesquioxanes via Silylative Coupling and Cross-Metathesis Reaction

Bifunctional silsesquioxanes create an attractive group of compounds with a wide range of potential applications, and recently they have gained much interest. They are known to be obtained mainly via hydrosilylation, but we disclose novel synthetic protocols based on different but complementary reactions, i.e., cross-metathesis (CM) and silylative coupling (SC). A series of cubic T₈ type silsesquioxane derivatives with a broad scope of styryl substituents were synthesized in a one-pot procedure and characterized by spectroscopic and spectrometric methods. All of the new compounds can be obtained in a one-pot manner, which has an attractive impact on the synthetic procedure, as it is economic in terms of the isolation of intermediate products. Additionally, the methodology disclosed here enables the (E)-stereoselective introduction of styrenes derivative to the cubic T₈ type core. The presented compounds can be interesting precursors for a further functionalization that may significantly increase the possibility of their application in the design and synthesis of new functional materials.

Dialkenylgermanes as Precursors of Silsesquioxane-based Macromolecular Structures

Herein we report a study of highly efficient platinum-catalyzed hydrosilylation of dialkenylgermanes with silsesquioxanes and spherosilicates. The use of divinyl- and diallylgermanes allowed the synthesis of new classes of compounds, i. e., dumbbell-type systems, silsesquioxanes with alkenyl pendant group, and oligomeric derivatives. The results are supported by detailed data from in situ FT-IR and NMR measurements, enabling precise monitoring of the reaction progress and determination of regioselectivity of the formed products.

The effect of organosilicon modifier structure on the efficiency of the polybutadiene hydrosilylation process

Real-time FT-IR spectroscopy permitted us to determine the influence of steoelectronic properties of functional groups on hydrosilylation. This allowed the synthesis of polybutadienes equipped with attractive silicon-based functional groups.

Introduction of organogermyl functionalities to cage silsesquioxanes

In this work, we present the first example of highly efficient platinum-catalyzed hydrosilylation of vinyl- and allylgermanes with different types of silsesquioxanes and spherosilicates. This protocol allows the straightforward introduction of organogermyl functionalities with alkyl chains linked to the silsesquioxane core with good yields and excellent selectivity. These derivatives may be applied as precursors for the development of advanced hybrid materials in the future. In addition, a comparison made between vinylsilanes and vinylgermanes showed a higher reactivity of germanium compounds in the hydrosilylation reaction. To the best of our knowledge, this is the first literature example of the functionalization of silsesquioxanes and spherosilicates with these types of germanium derivatives. The reaction parameters and kinetics were determined by in situ FT-IR. In addition, our research is supported by extensive data obtained from NMR measurements.

Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors

Over the past two decades, organic optoelectronic materials have been considered very promising. The attractiveness of this group of compounds, regardless of their undisputable application potential, lies in the possibility of their use in the construction of organic–inorganic hybrid materials. This class of frameworks also considers nanostructural polyhedral oligomeric silsesquioxanes (POSSs) with “organic coronae” and precisely defined organic architectures between dispersed rigid silica cores. A significant number of papers on the design and development of POSS-based organic optoelectronic as well as photoluminescent (PL) materials have been published recently. In view of the scientific literature abounding with numerous examples of their application (i.e., as OLEDs), the aim of this review is to present efficient synthetic pathways leading to the formation of nanocomposite materials based on silsesquioxane systems that contain organic chromophores of complex nature. A summary of stoichiometric and predominantly catalytic methods for these silsesquioxane-based systems to be applied in the construction of photoactive materials or their precursors is given.

Platinum on 2-aminoethanethiol functionalized MIL-101 as a catalyst for alkene hydrosilylation

Hydrosilylation is one of the largest-scale applications for homogeneous catalysis and is widely used to enable the commercial manufacture of silicon products. In this paper, a bifunctional heterogeneous catalyst, Pt^δ+/AET-MIL-101 (AET = 2-aminoethanethiol) with a partially positively charged Pt^δ+ electronic structure is reported, which was successfully prepared using post-synthesis modification with AET and a platinum precursor. The catalysts were characterized using X-ray diffraction (XRD), nitrogen (N₂) adsorption–desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques which showed that the synergy of AET-MIL-101 provides a good dispersion of Pt^δ+ in the channels, which can efficiently catalyze the hydrosilylation reaction with almost complete conversion and produce a unique adduct. In addition, the synthetic heterogeneous catalyst Pt^δ+/AET-MIL-101 achieves reasonable use of Pt in terms of number cycles and atomic utilization efficiency, indicating the potential to achieve a green hydrosilylation industry.

Pt^δ+ was uniformly dispersed in AET-MIL-101 as a highly efficient catalyst for a catalytic hydrosilylation reaction.

A facile approach for the synthesis of novel silsesquioxanes with mixed functional groups

An efficient pathway for the synthesis of novel organofunctional silsesquioxanes with varied functional groups.

A magnetically recyclable superparamagnetic silica supported Pt nanocatalyst through a multi-carboxyl linker: synthesis, characterization, and applications in alkene hydrosilylation

To simplify separation procedures, improve the reusability and decrease the loss of Pt, two Pt catalysts anchored on superparamagnetic silica (Fe₃O₄@SiO₂-EDTA@Pt and Fe₃O₄@SiO₂-DTPA@Pt) were prepared for the first time. The stable magnetic properties made them easily recyclable using a magnet rather than filtration, decantation or centrifugation. After 12 catalytic runs for both 30–50 nm Pt catalysts, the yield of 1-heptylmethyldichlorosilane was still up to 90%. The average loss of Pt in each reaction was only 0.87% for Fe₃O₄@SiO₂-EDTA@Pt and 0.66% for Fe₃O₄@SiO₂-DTPA@Pt owing to the strong interaction between Pt and carboxyl. The unprecedented activity and selectivity of the two Pt nanoparticle catalysts were observed in the hydrosilylation of alkenes. The turnover number in the reaction between 1-hexene and methyldichlorosilane using 5 × 10⁻⁸ mol of the Pt approached 662 733 for Fe₃O₄@SiO₂-EDTA@Pt and 579 947 for Fe₃O₄@SiO₂-DTPA@Pt over 12 h. The corresponding hydrosilylation products in excellent yields were obtained when we employed a broad range of alkenes as substrates, including 5 isomerous hexenes and 14 important industry raw materials. Fe₃O₄@SiO₂-DTPA@Pt showed a better activity. They have potential for catalyzing more reactions and replacing the current homogeneous Pt catalysts in industry.

To simplify separation procedures, improve the reusability and decrease the loss of Pt, two Pt catalysts anchored on superparamagnetic silica (Fe₃O₄@SiO₂-EDTA@Pt and Fe₃O₄@SiO₂-DTPA@Pt) were prepared for the first time.