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Eight rhodium complexes-including four new compounds-with the generic formula [RhCl(cod)(NHC)] (cod is 1,3-cyclooctadiene) differing by the size of their N-heterocyclic carbene (NHC) ligand were prepared, characterized, and found to be catalytically active in the hydrothiolation of terminal alkynes with aliphatic or aromatic thiols. The steric bulk of the carbene was found to markedly influence the reaction rate and selectivity. In particular, superbulky NHCs led to the almost quantitative formation of the sole α-vinyl sulfide products. The experimental conditions were optimized to allow the straightforward synthesis of a broad range of mono- and disubstituted α-adducts starting from terminal alkynes (18 examples) and thiols (5 examples). Altogether, the procedure devised in this study provides an easy access to α-vinyl sulfides with full atom economy and a low catalyst loading.

For the first time, the synthesis of thioesters starting from enals and thiols has been performed in the presence of a bulky N-heterocyclic carbene (NHC) as a catalyst.

A new cobalt complex bearing a bulky N-heterocyclic carbene (NHC) ligand is described as a pre-catalyst for alkyne hydroboration. The proposed catalytic system, synthesized using easily accessible reagents, allowed obtaining a series of mono- and dialkenylboranes in solvent-free conditions with excellent efficiency and selectivity. The results have been compared to those obtained in the presence of the same cobalt complex containing smaller NHC ligands and those achieved for the catalytic system based on a CoCl

The first metal-free protocol for efficient synthesis of unsymmetric bis(thioesters) via functionalization of dithiols with two different α,β-unsaturated aldehydes is presented.

The efficient and straightforward syntheses of silylthioethers and disulfides are presented. The synthetic methodologies are based on new rhodium complexes containing bulky N-heterocyclic carbene (NHC) ligands that turned out to be efficient catalysts in thiol and thiol–silane coupling reactions. These green protocols, which use easily accessible reagents, allow obtaining compounds containing S–Si and S–S bonds in solvent-free conditions. Additionally, preliminary tests on coupling of mono- and octahydro-substituted spherosilicates with selected thiols have proved to be very promising and showed that these catalytic systems can be used for the synthesis of a novel class of functionalized silsesquioxane derivatives., Two novel rhodium complexes bearing bulky N-heterocyclic carbene ligands have been synthesized and isolated. Both compounds enable efficient and selective formation of silylthioethers and disulfides in solvent-free conditions. A comparison between bulky NHC−rhodium complexes and their smaller derivatives shows that the steric hindrance around the metal center is crucial for effective formation of a product in both catalytic reactions. It has also been proved that the catalysts can be reused several times without loss of activity.

A facile and efficient Pd-based Suzuki–Miyaura coupling reaction leading to mixed chromophores with styryl fragments, enabling their further application, is presented. We also disclose their use in the formation of monofunctionalized silsesquioxanes with a chromophore group covalently bound to a T8 core that have been prepared via a cross-metathesis reaction. These new materials were studied in terms of their photophysical and also thermal properties.

In the view of the fact that catalytic routes to design functionalized silsesquioxanes are currently of high importance, herein we report the effective functionalization procedure to obtain mono-, ...

A new platinum complex bearing bulky N-heterocyclic carbene ligand of the general formula [Pt(IPr*Ph)(dvtms)] (where IPr*Ph = 1,3-bis{2,4,6-tris(diphenylmethyl)phenyl}imidazol-2-ylidene, dvtms = divinyltetramethyldisiloxane) exhibits a high catalytic activity towards E-selective dimerization of ethynyl substituted siloxysilsesquioxanes. This process leads to a novel class of functionalized silsesquioxane derivatives, resembling their dumbbell-shaped silsesquioxane analogues.

Herein, a facile and efficient synthetic route to unique hybrid materials containing polysiloxanes and mono(alkyl)silsesquioxanes as their pendant modifiers (T8@PS) was demonstrated. The idea of this work was to apply the hydrosilylation reaction as a tool for the efficient and selective attachment of mono(alkenyl)substituted silsesquioxanes (differing in the alkenyl chain length, from -vinyl to -dec-9-enyl and types of inert groups iBu, Ph at the inorganic core) onto two polysiloxanes containing various amount of Si-H units. The synthetic protocol, determined and confirmed by FT-IR in situ and NMR analyses, was optimized to ensure complete Si-H consumption along with the avoidance of side-products. A series of 20 new compounds with high yields and complete &beta, addition selectivity was obtained and characterized by spectroscopic methods.

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.

New dimeric palladium 1,2,3-triazol-5-ylidene complexes of the general formula [{Pd(μ-Cl)Cl(tzNHC)}2] (tzNHC = 1-mesityl-3-methyl-4-phenyl-1H-1,2,3-triazol-5-ylidene; 1-hexyl-3-methyl-4-phenyl-1H-1,2,3-triazol-5-ylidene and 1-butyl-3-methyl-4-phenyl-1H-1,2,3-triazol-5-ylidene) were synthesized and characterized by spectroscopic methods, X-ray analysis and DFT calculations. For the mesityl substituted complex, the crystallographic structures of both the cisoidal and transoidal isomer were obtained. In the presence of an excess of 4-tolylboronic acid, the loss of the tzNHC ligand from the palladium coordination sphere as a 5-tolyltriazolium salt was observed. The complexes are precursors of palladium species catalytically active in the coupling of arylboronic acids with aryl bromides.

Ruthenium-N-heterocyclic carbene complexes with the generic formula [RuHCl(CO)(NHC)(PCy3)] exhibit a high catalytic activity toward the (E)-selective silylative coupling of divinyl-substituted double-decker silsesquioxanes with two distinctly substituted styrenes. This process leads to a novel class of unsymmetrically functionalized silsesquioxane derivatives.

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.

For the first time, olefin cross metathesis has been developed for vinylgermanium compounds. This paper also marks the first case of transition metal-catalyzed functionalization of heterosilsesquioxanes, which in our case are cubic vinylgermasilsesquioxanes and newly synthesized di(vinylgermyl)substituted double-decker silsesquioxane. These processes lead to a series of new molecular, unsaturated mono- and divinyl-substituted germasilsesquioxanes, which can be potentially applied as precursors for optoelectronics and for the synthesis of new advanced materials. Additionally, preliminary tests of metathetic copolymerization of divinylsubstituted double-decker digermasilsesquioxanes (DDSQ-2ViGe) with selected diolefins proved to be very promising and resulted in the synthesis of novel stereoregular trans-germasilsesquioxyl-vinylene-phenylene macromolecular derivatives. All newly obtained compounds were isolated and characterized by mass and spectroscopic methods.

The regioselectivity of metathesis reactions of trisubstituted vinylsilanes H2C═CHSiR3 (SiR3 = SiCl3, SiCl2Me, SiClMe2, SiMe3, Si(OEt)3) with the second-generation ruthenium alkylidene complex has been studied theoretically, by density functional theory (DFT), and experimentally. The DFT results indicate that cycloreversion is the rate-determining step and the formation of a thermodynamically stable ruthenium methylidene complex and PhCH═CHSiR3 is generally preferred. However, the regioselectivity of the process can be also governed by the relative stabilities of the ruthenacyclobutane intermediates, which depend on the electronic and steric properties of the SiR3 substituent. Higher stability of α,β-disubstituted ruthenacyclobutanes in comparison to α,α-disubstituted ruthenacyclobutanes is predicted, in contrast to the corresponding intermediates formed during metathesis of common α-olefins. The stabilizing Ru–Cβ interaction in the ring is strengthened by the electron-donor SiR3 substituent at Cβ. The ex...

Synthesis and characterization of new, molecular DDSQ-based compounds functionalized by substituted styrenes (also with heteroatoms) in a stereoselective manner is presented. Additionally, a novel class of vinylene-arylene linear copolymers with double-decker silsesquioxane fragments in the main chain is developed. These molecular and macromolecular compounds were synthesized via efficient and highly stereoselective silylative coupling (and copolycondensation) and cross-metathesis (and ADMET) reactions.

Platinum complexes bearing bulky N-heterocyclic carbene (NHC) ligands, i.e., [Pt(IPr*)(dvtms)] (where, IPr* = 1,3-bis{2,6-bis(diphenylmethyl)-4-methylphenyl}imidazol-2-ylidene) and [Pt(IPr*OMe)(dvtms)] (where, IPr*OMe = 1,3-bis{2,6-bis(diphenylmethyl)-4-methoxyphenyl}imidazol-2-ylidene, dvtms = divinyltetramethyldisiloxane) catalyse nearly quantitatively and highly or completely the selective hydrosilylation of terminal olefins as well as terminal or internal acetylenes.

A synthesis of a new macromolecular class of vinylene-arylene copolymers with double-decker silsesquioxane in the main chain is presented. Two transition-metal-catalyzed processes, which is silylative-coupling copolycondensation (SCC) and ADMET copolymerization of divinyl-substituted double-decker silsesquioxanes (DDSQ-2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ-silylene-vinylene-arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1044–1055

New vinylgermanium cubic derivatives of silsesquioxanes (i.e., monovinylhepta(alkyl, phenyl)germasilsesqiuoxanes and (dimethylvinylgermoxy)heptaisobutylsilsesquioxanes) were synthesized and characterized by spectroscopic methods. The first ruthenium–germasilsesquioxyl complexes were also prepared via stoichiometric reaction of RuHCl(CO)(PPh3)3 with the above-mentioned vinylgermanium derivatives of silsesquioxanes, and their structures were determined by spectroscopic and X-ray analyses. The initial ruthenium complex as well as the above-mentioned Ge–Ru complexes were tested as catalysts, in the germylative coupling with olefins, and proved to be active in the case of (dimethylvinyl)germoxyheptaisobutylsilsesquioxane but showed no activity toward vinylgermasilsesquioxanes. A general mechanism for the germylative coupling of the two vinylgermanium derivatives of silsesquioxanes is presented.

Second generation Grubbs catalyst [RuCl2(H2IMes)(PCy3)( CHPh)] initiates regio- and stereoselective cross-metathesis of silylacetylenes with 1-alkenes and α,ω-dienes leading to the formation of E-2-silyl-1,3-dienes and E-2-silyl-1,3,n-trienes, respectively. Efficient progress of the reaction is achieved by using 5–8 mol% of the benzylidene initiator and twofold excess of olefin (with respect to silylacetylene) as well as ethereal solution of HCl (10–20 mol% with respect to the catalyst) as an activator. The reaction is proposed to be catalysed by alkylidene complex [RuCl2(H2IMes)(PCy3)( CHR)] (where R = alkyl, n-alkenyl) generated from the benzylidene initiator, and proceed via initial interaction of a metal alkylidene with a triple bond.

Amidobenzylidene ruthenium chelates – latent catalysts of olefin metathesis can be easily activated by the addition of Bronsted or Lewis acids. Their activation in the presence of hydrogen chloride involves the formation of catalytically active trans-dichloro carbamatobenzylidene ruthenium chelates.

New aryloxybenzylidene ruthenium chelates behave like a promising latent catalyst of olefin metathesis. The catalysts are characterised by substantial stability and catalytic inactivity in their dormant forms and a dramatic increase in activity after addition of a solution of HCl in ether. The mechanism of activation involves protonation of the phenoxide and the formation of a highly catalytically active hydroxybenzylidene ruthenium chelate.

Polyhedral oligomeric silsesquioxanes with a rigid inorganic Si–O–Si core and flexible, reactive, and/or inert organic coronae have attracted much attention. Their unique structures, in addition to their physical properties made them important due to their possible use as precursors and components of versatile inorganic/organic hybrid materials. This chapter presents a short overview of selected procedures to obtain functionalized silsesquioxanes.

A series of ruthenium complexes (RuCl 3 × 3H 2 O, [C 5 H 5 Ru(CH 3 CN) 3 ] + [PF 6 ] − , [RuCl 2 (PPh 3 ) 3 ], [RuHCl(CO)(PPh 3 ) 3 ], [RuHCl(CO)(PCy 3 ) 2 ]) immobilized in [bmim][Tf 2 N] were tested in homocoupling of vinylsilanes (H 2 C CHSi(OEt) 3 , H 2 C CHSi(O i Pr) 3 , H 2 C CHSi(OSiMe 3 ) 3 , H 2 C CHSiMe(OSiMe 3 ) 2 , and H 2 C CHSiPh(OSiMe 3 ) 2 ) performed in a biphasic system. The highest catalytic activity and selectivity of homocoupling product was observed for [RuHCl(CO)(PCy 3 ) 2 ]. The complex [RuHCl(CO)(PCy 3 ) 2 ] immobilized in a variety ionic liquids ([bmim][PF 6 ], [bmim][BF 4 ], [bmim][Tf 2 N], [bmim][TfO], [bmim][HSO 4 ], [bmim][Cl], [trimim][MeSO 4 ], [NBu 3 Me][MeSO 4 ], [PBu 4 ][Cl], [bpy][PF 6 ], [bpy][BF 4 ], [bpy][Cl]) exhibits high catalytic activity in homocoupling of H 2 C CHSiMe 2 Ph, H 2 C CHSi(OEt) 3 and H 2 C CHSiMe(OSiMe 3 ) 2 and enables high-yield stereoselective synthesis of the corresponding E -1,2-bis(silyl)ethenes. The immobilized complex can be easily recycled up to 12 times in the homocoupling of H 2 C CHSiMe 2 Ph and up to 10 times in the homocoupling of H 2 C CHSiMe(OSiMe 3 ) 2 without a significant drop in activity and selectivity. Results of a split test indicate that the source of catalytic activity is the catalyst immobilized in ionic liquid phase.

A series of functionalised cubic monovinylheptaisobutylsilsesquioxanes and octavinylsilsesquioxanes were obtained via efficient and highly stereoselective cross-metathesis and silylative coupling with substituted styrenes.

Monovinylheptaisobutylsilsesquioxane undergoes efficient cross-metathesis and silylative coupling with styrenes. Allyl derivatives were successfully tested in cross-metathesis in the presence of first generation Grubbs' catalyst, while heteroatom-substituted vinyl derivatives (vinyl ethers, 9-vinylcarbazole) efficiently undergo silylative coupling catalysed by ruthenium hydride complexes. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. Only when vinyl ethers are used does the reaction lead to a mixture of stereoisomers. Atmospheric pressure photoionisation has been successfully used for recording mass spectra of the functionalised silsesquioxanes.

Efficient silylative coupling of linear vinyl-substituted oligo- and polysiloxanes with styrene in the presence of [RuHCl(CO)(PPh 3 ) 3 ] ( 1 ) and particularly [RuHCl(CO)(PCy 3 ) 2 ] ( 2 ) combined with copper(I) chloride is described. Treatment of styrene, with terminal or side vinyl group at siloxane skeleton catalyzed by [RuHCl(CO)(PCy 3 ) 2 ]/CuCl results in the quantitative and selective formation of respective silylative coupling products.

Efficient cross-metathesis (CM) of linear and cyclic vinyl-substituted oligosiloxanes with selected olefins in the presence of Grubbs type ruthenium alkylidene complexes is described. Treatment of styrene or 4-substituted styrenes with vinyl group at siloxane skeleton results in the formation of respective cross-metathesis products with good yields and selectivities.

The first ruthenium-silsesquioxyl complexes have been synthesised and characterized via spectroscopic and X-ray methods. Mechanistic studies were performed and the complexes obtained were proved to be intermediates in the catalytic cycle of silylative coupling of olefins with vinylsilsesquioxane. Moreover, a mechanism for silylative coupling of styrene with vinylsilsesquioxanes was proposed.

A series of functionalized dialkenylsilsesquioxanes were obtained by efficient and highly stereoselective silylative coupling and cross-metathesis of divinylsubstituted double-decker silsesquioxanes (DDSQ-2SiVi) with substituted styrenes and other olefins. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. The optimized reaction conditions for styrene were adopted for successful silylative coupling polycondensation of DDSQ-2SiVi with 1,4-divinylbenzene yielding stereoregular cooligomer containing double-decker (silsesquioxyl-silylene)-vinylene-phenylene units.