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A family of the C,N-cyclometalated species [Pt(ppy)Cl(PPh3)], [Pt(ppy)Cl(CNCy)], [Pt(ppy)(CNCy)(PPh3)](OTf), and [Pt(ppy)(CNCy)2](BF4) (ppy = 2-phenylpyridinato-C2,N; Cy = cyclohexyl) was generated...

C,N-Chelate deprotonated diaminocarbene platinum(II) complexes were synthesized by coupling coordinated isocyanides and azinyl-substituted ureas. The complexes act as catalysts of α,ω-divinylpolydimethylsiloxane and poly(dimethylsiloxane-co-methylhydrosiloxane) hydrosilylation cross-linking. Silicone rubbers obtained with (aminoisoquinoline)-containing complex 3d exhibit temperature-responsive luminescence. Their emission changes irreversibly when heated from 80–100 °C (green radiation) to 120 °C or more (blue radiation).

Acetylacetonate and 4-arylimino-2-pentanonate carbonyl complexes of rhodium(I) [Rh(RC(O)C(R')C(O)R“)(CO)2] (1: R = Me, R' = H, R'' = Me; 2: R = Me, R' = Cl, R'' = Me; 3: R = Me, R' = H, R'' = CO2Me; 4: R = Ph, R' = H, R'' = Me; 5: R = Ph, R' = H, R'' = Ph) and [Rh(MeC(NR''')CHC(O)Me)(CO)2] (6: R''' = Ph; 7: R''' = 2,6-Me2C6H3) were examined as hydrosilylation cross-linking catalysts at RT for the reaction of poly(dimethylsiloxane-co-ethylhydrosiloxane) copolymer with vinyl terminated poly(dimethylsiloxane) or vinyl terminated poly(dimethylsiloxane-co-styrene) copolymer. All complexes allow cross-linking of vinyl- and hydride-containing polysiloxanes and copolymers at RT without inhibitor addition. Complexes 1–7 possess catalytic activity comparable to the industrially used complex of Pt0 and divinyltetramethyldisiloxane (Karstedt’s catalyst). 1 is the most active among the studied rhodium complexes at 1.0 × 10−4 mol⋅L−1 and 1.0 × 10−5 mol⋅L−1. Silicone rubbers obtained with the rhodium catalysts compared to Karstedt’s catalyst possess no visible defects (bubbles or cracks), and differed by improved elastic properties (the elongation at break increased from 160 to 255%) The activity and improved silicone rubber properties using 1 renders it one of the suitable alternatives to Karstedt’s catalyst.

A new method was developed for the metal-free cross-linking of silicone rubbers. This process uses azobisisobutyronitrile (AIBN) to selectively react with Si-H and vinyl groups as a free-radical initiator for the thermal curing of polymethylhydrosiloxane (PMHS) and polymethylvinylsiloxane (PMVS). The AIBN-initiated curing reaction between the Si-H groups of PMHS generated Si-O-Si and Si-Si cross-links. In contrast, PMVS was cured via the formation of C-C bonds through "methyl-vinyl" and "vinyl-vinyl" mechanisms. Curing reactions were performed at 80-120 °C in air and confirmed by 13C and 29Si solid state NMR analyses and swelling trials.

The platinum-catalyzed self-cross-linking of polymethylhydrosiloxane at RT in air was performed for the first time and proved by 1H, 13C, and 29Si SSNMR and swelling measurements. Quantum chemical modeling of possible structures was investigated. Platinum (0) and (ii) complexes were used as catalysts between the Si-H groups of polymethylhydrosiloxane. Karstedt's catalyst leads to Si-O-Si and Si-Si bond formation, but cis-[PtCl2(BnCN)2] generates predominantly Si-O-Si cross-links. cis-[PtCl2(BnCN)2] allows creating high-quality silicone rubbers without visible mechanical defects. This cross-linking approach can be used to obtain new Si-H-containing silicone materials.

This study focuses on the synthesis of hybrid luminescent polysiloxanes and silicone rubbers grafted by organometallic rhenium(I) complexes using Cu(I)-catalyzed azido-alkyne cycloaddition (CuAAC). The design of the rhenium(I) complexes includes using a diimine ligand to create an MLCT luminescent center and the introduction of a triple C≡C bond on the periphery of the ligand environment to provide click-reaction capability. Poly(3-azidopropylmethylsiloxane-co-dimethylsiloxane) (N3-PDMS) was synthesized for incorporation of azide function in polysiloxane chain. [Re(CO)3(MeCN)(5-(4-ethynylphenyl)-2,2′-bipyridine)]OTf (Re1) luminescent complex was used to prepare a luminescent copolymer with N3-PDMS (Re1-PDMS), while [Re(CO)3Cl(5,5′-diethynyl-2,2′-bipyridine)] (Re2) was used as a luminescent cross-linking agent of N3-PDMS to obtain luminescent silicone rubber (Re2-PDMS). The examination of photophysical properties of the hybrid polymer materials obtained show that emission profile of Re(I) moiety remains unchanged and metallocenter allows to control the creation of polysiloxane-based materials with specified properties.

Cyclic organosilicon triperoxides were found to be vinyl-selective free-radical initiators for thermal curing at 100–180 °C of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated polymethylhydrosiloxane producing homogeneous transparent silicone rubbers with antibacterial properties. The usage of the cyclic organosilicon triperoxides as the curing agents does not require free radical inhibitors in comparison with diacyl- and dialkyl peroxides. Among the tested compounds, the peroxide with the Me–Si–Me fragment and two cyclohexane rings is a much more active curing agent (180 °C, c = 0.22 M, τcuring = 45 min) than other organosilicon peroxides. Cured silicone samples from mixtures with vinyl-terminated polysiloxane and silicone hydride have improved mechanical properties: peroxides provide more than 200% elongation, and compression sets of the samples are less than 1%. The prepared silicone rubbers showed pronounced antibacterial activity.

Hydrosilylation catalyzed by the rhodium(I) complex [Rh(acac)(CO)2] or platinum(0)-based Karstedt's catalyst was employed to combine hydrophilic propargylated hydroxyethyl cellulose and hydrophobic hydride-terminated polydimethylsiloxane to give polymer hybrid structures. The final polymers were characterized by FTIR, solid state 1H, 13C and 29Si NMR, contact angle, microcalorimetry and thermogravimetry measurements. The grafting degree was controlled by the catalyst choice and by the reagent load variations; an increase of the polysiloxane load and a change from Karstedt's to the rhodium catalyst led to a higher (from 2 to 7%) silicon content in the glycosilicones. The glycosilicones were insoluble in water, but swelled in organic solvents (DMSO, DMF, and chloroform). The hydrophilicity of the glycosilicones decreased with incrementing silicon content: the contact angles increased from 30 (cellulose) to 103-131° in the hybrids. The glycosilicones obtained via the hydrosilylation are less toxic toward algae Chlorella vulgaris and infusoria Paramecium caudatum than those obtained with CuAAC.

The reaction of 3,4-diaryl-1H-pyrrol-2,5-diimines with cis-dichlorobis(isonitrile)platinum(II) affords the C,N-chelated diaminocarbene platinum(II) complexes, which have been fully characterized including molecular spectroscopy, single crystal X-ray diffraction and DFT calculations. The obtained platinum(II) complexes are effective catalysts for the hydrosilylation of alkynes and alkenes. Thus, the reaction of phenylacetylene with triethoxysilane leads to the formation of α- and β-(E)-vinylsilanes, generating TON's in the range of 103 to 104 and TOF's in the range of 102 to 103 h−1. Also, the cross-linked silicones, possessing the luminescence properties, were obtained by the hydrosilylation reaction of vinyl- and hydride-containing polysiloxanes. Additionally, the efficiency of diaminocarbene platinum(II) complexes against CH1/PA-1, SW480, and A549 cancer cell lines has been demonstrated by in vitro cytotoxicity studies.

Experimental data on the application of metal complexes in radical polymerization of vinyl monomers collected over the recent 15 years have been analyzed and generalized. Special attention has been given to (un)substituted ferrocenes, macrocyclic (clathro)chelates, and iron porphyrinates as well as to the approaches to enhance their catalytic activity in controlled synthesis of macromolecules. The mentioned systems have been compared with each other as well as with selected complexes of other transition metals. It has been shown that the electronic and spatial structures of the metal complexes are related to their efficiency in the radical polymerization reactions.

The effect of the binary catalytic systems [the Karstedt catalyst–platinum(II) isocyanide complex] of the cure of vinyl-containing polydimethylsiloxane and hydride-containing siloxane oligomer via the hydrosilylation reaction has been studied.

Cyclometallated iridium(III) complexes with 2-phenylpyridine [Ir(ppy)2(CNR)Cl] (ppy = (2-phenylpyridinato-C2,N), R = Xyl, Mes), [Ir(ppy)2(CNR)2](OTf) (R = Xyl, Mes), and fac-[Ir(ppy)3] catalyse the cross-linking of polysiloxanes exclusively at temperatures above 100 °C leading to luminescent rubbers.

Cyclic peroxides as initiators for the radical polymerization of methyl methacrylate were proposed. The initial rates, initiation rates, and effective activation energies of polymerization initiated by cyclic peroxides and cyclic peroxide-1-pyridyl-2-ferrocene systems were determined. The radical yields to the volume upon the thermal decomposition of cyclic peroxides and their catalytic decomposition in the presence of 1-pyridyl-2-ferrocene were determined. In combination with 1-pyridyl-2-ferrocene cyclic peroxides form efficient initiating systems favoring an increase in the polymerization rate, a decrease in the molecular weights, and an increase in syndiotacticity of the synthesized poly(methyl methacrylate). © 2013 Springer Science+Business Media New York.

The effect of initiating systems based on substituted and unsubstituted metallocenes; polynuclear macrocyclic semi- and clathrochelates of Fe(II); and metal complexes of Ti(IV), Zr(IV), Fe(III), and Co(III) porphyrins on the free-radical polymerization of MMA and styrene is analyzed. Experimental data are systematized, general relationships are ascertained, and specific features of the process related to the structure of metal-complex compounds and the nature of initiators and monomers are revealed.

200 The use of metal complex compounds in radical polymerization of vinyl monomers is one of the most successful and promising ways of development of tai lor made synthesis of polymers on their basis [1, 2]. It has been shown [3–6] that iron(II) semi and clathro chelates in combination with traditional initiators of radical polymerization (in particular, diacyl perox ides) form high performance initiating systems. Such systems have a favorable effect on both the kinetic parameters of the process (increase the initiation rate; under certain conditions, mitigate the detrimental gel effect; reduce the effective activation energy of poly merization; etc.) and the physicochemical character istics of the resulting polymers (variation of the molec ular weight from 300 thousand daltons to 4 million daltons, the increase in stereoregularity and thermal stability). In this context, the use of new types of clath rochelates, in particular, macrobicyclic cobalt(II) tris(α dioximate)s (Scheme 1, compounds 1–3), as modifying additives in the radical polymerization of methyl methacrylate (MMA) initiated by benzoyl per oxide seems to be promising. All these compounds dif fer from the previously studied cage iron(II) com plexes [3–6] in the nature of both the encapsulated metal ion and the apical and edge substituents.

Recently, controlled radical polymerization has become one of the most important methods for producing synthetic vinyl polymers. At the moment several techniques enabling such polymerizations exist, of which ATRP (atom transfer radical polymerization) and RATRP (reverse atom transfer radical polymerization) are the most commonly used ones. [1] The significant advantages of these polymerization techniques include the ability to polymerize polymers with controlled density and chain length, and narrow molecular weight distribution (MWD) in a controlled manner. A wide range of compounds as alkoxyamines, dithioesters, trithiocarbonates, xanthates and others were proposed as propagation regulators. Metalloorganic compounds of general formula MtnYL, where Mt transition metal (Cu, Fe, Ru, Re, Ni and others); Y – halogen anion (mainly chlorine or bromine); L – organic ligand (mostly 2,2’-bipyridine, 4,4’-bi-(5-nonyl)-2,2’-pyridine, triphenylphosphine) are of great interests also. The use of metal complexes of porphyrins in controlled radical polymerization could be very promising.[2-6] Thus, catalytic chain transfer to the monomer and catalytic inhibition were discovered in the polymerization of methacrylates carried out in the presence of cobalt porphyrins.[2-5] It was found by B.B. Wayland and M. Fryd that cobalt complex of tetramesitylporphyrin initiates polymerization of acrylates leading to the formation of homopolymers and block copolymers.[7-9] However, only few metal porphyrins, which are well-soluble in organic media, mainly, cobalt, rhodium, aluminum complexes, allowing the radical polymerization of vinyl monomers under controlled mode, have been studied by now.[7-11] The goal of this work was the study of radical polymerization of vinyl monomers (by the example of methyl methacrylate (MMA) and styrene) initiated by azo-bis-isobutironitrile (AIBN) or benzoyl peroxide (BP) in the presence of various porphyrins and their metal complexes.

Influence of 1-[pyridyl-2]-, 1-[quinolin-2-yl]-, 1-[acridin-9-yl]-, 1-[pyrazin-2-yl]-, and 1-[pyrimid-4-yl]ferrocenes on heat and thermomechanical properties of the produced poly(methyl methacrylate) has been studied.

The free-radical bulk homopolymerization of methyl methacrylate and styrene initiated by benzoyl peroxide or AIBN in the presence of heterocyclic derivatives of ferrocene is studied. It is shown that, in the case of the peroxide initiator, ferrocene derivatives form highly efficient initiation systems, which make it possible to polymerize methyl methacrylate at a high rate, to reduce the molecular mass of polymers, and to synthesize polymers with a high content of syndiotactic triads, while in the case of AIBN, such systems are not formed.

The effect of ferrocenyl-containing semi- and clathrochelates on radical polymerization of methyl methacrylate, initiated by benzoyl peroxide, and on molecular characteristics of the polymer formed was examined.

Benzoyl peroxide-, lauryl peroxide-, and AIBN-initiated free-radical polymerization of methyl methacrylate has been studied in bulk and solution in the presence of macrobicyclic iron(II) bis(ferrocenyl borate) tris(nioximate). It has been found that the ferrocenyl-containing iron(II) clathrochelate forms efficient initiating systems with peroxides, whereas, in the case of AIBN, its presence has no effect on the kinetic parameters of the process and the properties of the resulting polymer. The use of clathrochelate complex-peroxide initiator systems accelerates the polymerization of methyl methacrylate and decreases the molecular mass of the polymer. The kinetic parameters of the process have been determined.

Radical polymerization of methyl methacrylate initiated by the benzoyl peroxide — macrobicyclic bis-ferrocenylboron-capped iron(ii) tris-1,2-cyclohexanedione dioximate system was studied. The ferrocenyl-containing macrobicyclic complex and benzoyl peroxide forms an efficient initiating system that allows one to perform the polymerization process at a high rate with substantially reduced amounts of the initiator and the metal complex component at 30–75 °C and to influence the molecular-weight characteristics of poly(methyl methacrylate) produced.

The free-radical polymerization of methyl methacrylate in the presence of chlorine-containing complexes of Fe(III) with 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)porphyrin and 5,10,15,20-tetrakis(3′-butoxyphenyl)porphyrin, as well as in the presence of the acetate complex of Co(III) 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)porphyrin, has been investigated. The kinetic features of the process and the molecular mass characteristics of polymers are studied, and a feasible polymerization mechanism is proposed.

Radical polymerization of methyl methacrylate and styrene initiated by azo-bis-isobutironitrile or benzoyl peroxide in the presence of chlorine-containing complexes of FeIII with 5,10,15,20-tetrakis-(3’,5’-di-tert-butylphenyl)porphyrin, 5,10,15,20-tetrakis-(3’-butoxyphenyl)porphyrin or 5,15-bis(4’-tert-butylphenyl)-2,8,12,18-tetra(n-butyl)-3,7,13,17tetramethylporphyrin and acetate complexes of CoIII with 5,10,15,20-tetrakis-(3’,5’-di-tert-butylphenyl)porphyrin or 5,10,15,20-tetrakis-(3’-butoxyphenyl)porphyrin and complex of CoII with 5,15-bis(4’-tert-butylphenyl)-2,8,12,18tetra(n-butyl)-3,7,13,17-tetramethylporphyrin were investigated. The kinetic features of the process and molecular mass characteristics of polymers were studied. Feasible polymerization scheme was proposed.

The free-radical polymerization of methyl methacrylate initiated by the three-component system ferrocene-zirconocene dichloride-benzoyl peroxide has been studied. The kinetic features of the process, the interaction between components of the initiation system, and the molecular characteristics of the polymers have been investigated. In the case of the three-component initiation system, the content of syndiotactic fragments grows and the thermal stability of the polymers is improved compared to the products of polymerization carried out in the presence of solely a peroxide initiator.

The direct template macrocyclization of 2,3-butanedione monooxime hydrazone (HDXO) with ferrocenylboronic acid on the iron(ii) ion matrix afforded the ferrocenylboron-capped semiclathrochelate iron(ii) oximehydrazonate. The H+ ion-catalyzed macrocyclization of this precursor with an excess of triethyl orthoformate gave the clathrochelate complex with syn,syn,syn-orientation of the ethoxy substituents relative to the 1,3,5-triazacyclohexane ring. The complexes synthesized were characterized using elemental analysis, IR and UV—Vis spectroscopies, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR, 57Fe Mossbauer spectroscopies, and X-ray diffraction analysis.

The effect of ternary initiating systems benzoyl peroxide-ferrocene-3,6-bis(o-carboxybenzoyl)-N-isopropylcarbazole and benzoyl peroxide-di-η5-indenylzirconium dichloride-3,6-bis(o-carboxybenzoyl)-N-isopropylcarbazole on the radical polymerization of methyl methacrylate and on the heat resistance and microstructure of the resulting polymers was examined.

The effect of zirconocene dichloride and its indene-containing derivative on the radical polymerization of methyl methacrylate initiated by benzoyl peroxide has been studied. The influence of the metallocenes on the kinetic parameters of the process and the average degree of polymerization has been established. Concentration and temperature dependences have been measured for the initial rate of reaction and the average degree of polymerization in relation to the content of the components in the systems. The microstructure of poly(methylmethacrylate) prepared in the presence of the used initiation systems has been determined.

The effect of a benzoyl peroxide-ferrocene-3,6-bis(o-carboxybenzoyl)-N-isopropylcarbazole three-component initiating system on the free-radical polymerization of methyl methacrylate has been investigated. For this process, concentration and temperature dependences of the initial rate of reaction and the average degree of polymerization have been measured. It has been established that, when the process is carried out in the presence of both ferrocene and a carbazole derivative, the former compound predominantly affects the kinetic parameters and the average degree of polymerization. The effect of the nitrogen-containing compound comes into play as the temperature of polymerization is lowered. Poly(methyl methacrylate) prepared in the presence of the ternary system is distinguished by an increased content of syndiotactic units and by the presence of isotactic structures, thus suggesting the complex-radical mechanism of polymerization.

The radical copolymerization of methyl pheophorbide A with styrene or methyl methacrylate in bulk or in benzene solution initiated by azobisisobutyronitrile at 60–90 °C was performed and kinetically characterized.

The role of the ferrocenium radical cation and Cp2Fe+–O radical in the initiation of methyl methacrylate polymerization in the absence and presence of oxygen was demonstrated.

The pivalate complexes of metals used in the radical polymerization of methyl methacrylate increase rate of process initiated by both benzoyl peroxide and azobisisobutyronitrile and decrease the molecular weight of the resulting polymethyl methacrylate.

Controlled radical polymerization of methyl methacrylate and styrene initiated by azobisisobutironitrile or benzoyl peroxide in the presence of a chlorine-containing complex of Fe III with 5,15-bis(4 ’ - tert -butylphenyl)-2,8,12,18-tetra( n -butyl)-3,7,13,17-tetramethylporphyrin was investigated.

cis- and trans-Isomers of the platinum(II) nitrile complexes [PtCl2(NCR)2] (R = NMe2, N(C₅H10), Ph, CH2Ph) were examined as catalysts for hydrosilylation cross-linking of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) producing high quality silicone rubbers. Among the tested platinum species the cis-complexes are much more active catalysts than their trans-congeners and for all studied platinum complexes cis-[PtCl2(NCCH2Ph)2] exhibits the best catalytic activity (room temperature, c = 1.0 × 10(-4) mol/L, τpot-life 60 min, τcuring 6 h). Although cis-[PtCl₂(NCCH2Ph)2] is less active than the widely used Karstedt's catalyst, its application for the cross-linking can be performed not only at room temperature (c = 1.0 × 10(-4) mol/L), but also, more efficiently, at 80 °C (c = 1.0 × 10(-4)-1.0 × 10(-5) mol/L) and it prevents adherence of the formed silicone rubbers to equipment. The usage of the cis- and trans-[PtCl2(NCR)2] complexes as the hydrosilylation catalysts do not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl terminated polysiloxanes are shelf-stable in air. Tested catalysts do not form colloid platinum particles after the cross-linking.

The controlled radical polymerization of methyl methacrylate initiated by the ferrocene–zirconocene dichloride–benzoyl peroxide system was found to occur as a living radical process with an increased concentration of sindio-triads in the resulting poly(methyl methacrylate).