Mariusz Majchrzak

Competitive silylation of olefins with vinylsilanes and hydrosilanes photocatalyzed by iron carbonyl complexes

Abstract Fe(CO) 5 appeared to be a good catalyst for competitive silylation of olefins (vinylsilanes, styrene) by vinylsilanes and hydrosilane (e.g. Et 3 SiH). The catalytic measurements for Fe(CO) 5 + Et 3 SiH system and a stoichiometric study on the insertion of olefin into Fe–Si bond in CpFe(CO)SiMe 3 confirm the mechanism of catalysis involving the first reported β -silyl transfer (from carbon of β -silylethyliron) to iron atom accompanied by dehydrogenative silylation of the olefin.

Highly stereo- and regioselective synthesis of a phenylene-silylene-vinylene polymer via ruthenium-catalyzed polycondensation

[RuCl2(CO)3]2 catalyzed cross-coupling polycondensation of 1,4-bis(vinyldimethylsilyl)benzene (A) appears to be a new, very efficient, method for highly stereo- and regioselective synthesis of phenylene‐ silylene‐vinylene polymers (B).

Synthesis and structural characterization of trans-tactic siloxylene-vinylene-p-phenylene polymers via ADMET copolymerization and silylative coupling(SC) polycondensation

Abstract The first trans -tactic stereo-regular vinylene-siloxylene- p -phenylene copolymer 1 with perfect vinylsiloxane linkage was obtained via acyclic diene metathesis copolymerization of divinyltetraethoxydisiloxane with 1,4-divinylbenzene (DVB) in the presence of Grubbs catalyst. The similar trans -tactic copolymers 2 and 3 but with no consecutive vinylsiloxane linkage was also prepared by silylative coupling copolycondensation of DVB with divinyltetra(methyl,ethoxy)disiloxane catalyzed by [Ru(H)(Cl)(CO)(PCy 3 ) 2 ].

Synthesis of new styrylarenes via Suzuki–Miyaura coupling catalysed by highly active, well-defined palladium catalysts

An efficient synthetic route for well-defined palladium(0) complexes [Pd(η(2)-dba)(PPh3)2] (2), [Pd(η(2)-dba)(PCy3)2] (3) and their crystallographic structures is reported. This is the first crystallographic characterization of palladium complexes coordinated with one dibenzylideneacetone and two phosphines. A highly effective, fully controlled method for selective synthesis of mono- (5-9) and distyrylarenes (10-15) via Suzuki-Miyaura coupling is described.

Synthesis and characterization of functionalized molecular and macromolecular double-decker silsesquioxane systems

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.

Synthesis of Phenylene-Silylene-Vinylene Polymer and Copolymer by Ruthenium-Catalyzed Silylative Cross-Coupling Reaction

RuH(OAc)(CO)(PPh 3 ) 2 catalyzed silylative croos-coupling polycondensation of 4-(dimethylvinylsilyl)styrene (2) and copolycondensation of 1,4-divinylbenzene (4) with 1,4-bis(dimethylvinylsilyl)benzene (5) appeared to be a novel synthetic route for highly stereo- and regioselective synthesis of phenylene(arylene)-silylene-vinylene polymers.

Thermal stability of hybrid materials based on epoxy functional (poly)siloxanes

Epoxy functional (poly)siloxanes are one of the most important classes of modified silicones. Due to high reactivity of epoxy group and specific features of siloxane chain, they can make an excellent raw material for synthesis of hybrid materials. Results obtained in this study have shown that both the modification of epoxy resins with epoxy functional disiloxanes as well as the application of polysiloxanes with long polysiloxane chains and a specified content of epoxy groups makes it possible to produce hybrid materials of very good thermal stability. Crosslinking reactions were carried out with use of four diamines of which the best one appeared to be 4,4′-diaminodiphenylmethane. The highest thermal stability was found in the case of hybrid materials obtained from epoxy functional polysiloxanes.

Unusual cis and trans architecture of dihydrofunctional double-decker shaped silsesquioxane and synthesis of its ethyl bridged π-conjugated arene derivatives

Double-decker silsesquioxanes have gained a high reputation in many branches of chemistry and process development. In particular, catalytic processes that convert double-decker silsesquioxanes into important functional classes of fine chemicals are a central topic of contemporary organosilicon chemistry. Although the 9,19-di(hydro)octaphenyl double-decker silsesquioxane (DDSQ-2SiH) is known, we report its cis and trans structure and X-ray structure for the first time. The combination of DDSQ-2SiH in a known hydrosilylation reaction protocol with precise reaction time control (FT-IR in situ apparatus) allowed us to selectively assemble a series of previously unreported molecular double-decker silsesquioxanes with ethyl bridged π-conjugated arenes. These compounds were used as a molecular model to obtain their respective macromolecular hybrid analogues. The obtained compounds were characterized spectroscopically and their thermal parameters were also verified.

Intramolecular charge transfer photoemission of a silicon-based copolymer containing carbazole and divinylbenzene chromophores. Electron transfer across silicon bridges.

A new copolymer consisting of N-isopropylcarbazole/dimethylsilylene bridge/divinylbenzene units was synthesized and characterized. Dual fluorescence was observed in this copolymer in polar solvents. The absence of the second band at the lower transition energy of the two emission maxima in nonpolar solvents and the quantitative correlation of the lower-energy emission band maxima with solvent polarity indicate that the lower-energy emission band arises from an intramolecular charge transfer (ICT) state. A series of model compounds was synthesized to investigate the source of the charge transfer. It was found that the Si-bridged dyad with a single N-isopropylcarbazole and a single divinylbenzene was the minimum structure necessary to observe dual luminescence. The lack of dual luminescence in low-temperature glasses indicates that the ICT requires a conformation change in the copolymer. Analogous behavior in the Si-bridged dyad suggests that the ICT in the copolymer is across the silicon bridge. Results from time-resolved luminescence measurements with picosecond and subnanosecond excitation were used to support the thesis that twisted charge-transfer states are the likely source of the observed dual luminescence.

New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP

Summary New phenoxybenzylidene ruthenium chelates were synthesised from the second generation Grubbs catalysts bearing a triphenylphosphine ligand (or its para-substituted analogues) by metathesis exchange with substituted 2-vinylphenols. The complexes behave like a latent catalyst and are characterized by an improved catalytic behaviour as compared to that of the known analogues, i.e., they exhibit high catalytic inactivity in their dormant forms and a profound increase in activity after activation with HCl. The strong electronic influence of substituents in the chelating ligand on the catalytic activity was demonstrated. The catalytic properties were tested in ROMP of cyclooctadien (COD) and a single selected norbornene derivative.