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The chemistry of organo-functionalized silsesquioxanes has emerged as a fascinating new fi eld of modern nanotechnology [1]. Nanostructured polyhedral oligomeric silsesquioxanes (POS) compounds have been used to design novel hybrid nanocomposites now used in a variety of applications [2-5]. Polyhedral oligomeric silsesquioxanes remain well-defi ned, three-dimensional nanobuilding blocks that can create unique hybrid materials, where a precise control of nanostructure and properties is needed [6-10].

During the last decade or so, the emergence of the metathesis reaction in organic synthesis has revolutionised the strategies used for the construction of complex molecular structures. Olefin metathesis is indeed particularly suited for the construction of small open-chain molecules and macrocycles using crossmetathesis and ring-closing metathesis, respectively. These reactions serve, inter alia, as key steps in the synthesis of various agrochemicals and pharmaceuticals such as macrocyclic peptides, cyclic sulfonamides, novel macrolides, or insect pheromones. The present chapter is aiming at illustrating the great synthetic potential of metathesis reactions. Shortcomings, such as the control of olefin geometry and the unpredictable effect of substituents on the reacting olefins, will also be addressed. Examples to be presented include epothilones, amphidinolides, spirofungin A, and archazolid. Synthetic approaches involving silicon-tethered ring-closing metathesis, relay ring-closing metathesis, sequential reactions, domino as well as tandem metathesis reactions will also be illustrated.

Heterogeneous catalysts for olefin metathesis using different types of (i) siliceous mesoporous molecular sieves, and (ii) organized mesoporous alumina as supports are reported. The catalysts were prepared either by spreading of transition metal oxidic phase on the support surface or by immobilizing transition metal compounds (mostly organometallic) on the support. The activity of these catalysts in various types of metathesis reactions (i.e. alkene and diene metathesis, metathesis of unsaturated esters and ethers, RCM, ROMP and metathesis polymerization of alkynes) was described. The main advantages of these catalysts consist generally in their high activity and selectivity, easy separation of catalysts from reaction products and the preparation of products free of catalyst residue. The examples of pore size influence on the selectivity in metathesis reactions are also given.

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared to conventional heating methods. The present contribution aims at illustrating the advantages of this technology in olefin metathesis and, when data are available, at comparing microwave-heated and conventionally heated experiments

A new heterogeneous catalyst for ring opening metathesis polymerization (ROMP) has been prepared by immobilization of [RuCl2(p-cymene)]2 on siliceous mesoporous molecular sieves SBA-15. Activity of the catalyst was tested in ROMP of norbornene. Filtration test proved that the catalytic activity is bound to the solid phase. Catalyst could be easily separated from reaction mixture in contrast to the corresponding homogeneous system and therefore polymer with reduced amounts of catalyst residues was obtained.

A range of imidazol(in)ium-2-carboxylates and -dithiocarboxylates bearing alkyl or aryl groups on their nitrogen atoms were prepared by reacting the corresponding N-heterocyclic carbenes (NHCs) with either carbon dioxide or carbon disulfide. All the zwitterionic products were characterized by various analytical techniques, including thermogravimetric analysis (TGA). Their ability to act as NHC ligand precursors for in situ catalytic applications was investigated in the ruthenium-promoted ring-opening metathesis polymerization (ROMP) of cyclo-octene. Upon exposure to the [RuCl2(p-cymene)]2 dimer, the NHC CO2 adducts readily dissociated to generate [RuCl2(p-cymene)(NHC)] complexes that were highly active catalyst precursors for olefin metathesis. Conversely, the NHC CS2 betaines retained their zwitterionic nature and led to new cationic complexes of the [RuCl(p-cymene)(NHC CS2)]+PF6 − type that were devoid of any significant catalytic activity in the reaction under consideration

Olefin metathesis is now a synthetic tool found ubiquitously in various fields involving synthesis. Of its many variations, three are prominently used: (1) catalytic ring closing metathesis (RCM) is an extremely powerful method for the construction of carbon-carbon double bonds in organic chemistry; (2) ring opening metathesis polymerisation (ROMP) where polymers are formed by use of the energy released from cyclic strain; and (3) cross metathesis (CM) where non-cyclic partners are coupled through C–C double bond formation. These important transformations and variations on these themes mediated by second generation ruthenium complexes bearing a NHC ligand will be presented in the following sections.

Polar olefin metathesis catalysts, bearing an ammonium group are presented. The electron withdrawing ammonium group not only activates the catalysts electronically, but at the same time makes the catalysts more hydrophilic. Catalysts can be therefore efficiently used not only in traditional media, such as methylene chloride and toluene, but also in technical-grade alcohols, alcohol— water mixtures and in neat water. Finally, in this overview the influence of the anionic counter-ion on the activity of ammonium substituted Hoveyda-type olefin metathesis catalysts in aqueous media is presented.

The present research focuses on the impact of power ultrasound on the synthesis of the tungsten-based metathesis catalytic system WCl6/Me4Sn and its activity in ring-opening metathesis polymerization of cyclooctene and cyclododecene. As compared to corresponding silent ROMP reactions with this mild catalytic system, altered reaction kinetics and different product selectivity have been found. Rate acceleration and an enhancement of oligomer formation have been clearly evidenced. The demonstrated possibility of employing technical grade solvents in ROMP induced by WCl6/Me4Sn is a further gain of the ultrasound strategy. Under the right conditions, ultrasound may thus promote greener, more cost effective and sustainable metathetic procedures.

This review article is devoted to recent advances in the design and application of so-called “dormant” or “latent” ruthenium olefin metathesis catalysts bearing S-chelating alkylidene ligands. Selected ruthenium complexes containing S-donor ligands, which possess controllable initiation behaviour are presented. Applications of these complexes in olefin metathesis are described.

The chemistry of metathesis polymerization-derived monolithic supports is summarized. Since ring-opening metathesis polymerization (ROMP) triggered by well-defined transition metal alkylidenes is a living polymerization method, it allows for the controlled and highly reproducible synthesis of stationary phases in terms of both the nature and total content of the functional group(s) of interest. In addition, the high functionality tolerance of ROMP allows for creating monolithic supports with an unprecedented diversity in terms of functional groups that may be introduced. Applications in various areas of chemistry such as separation science heterogeneous catalysis and tissue engineering are summarized.

The recent advances in olefin metathesis highlight the impact of Ring Opening Metathesis Polymerisation (ROMP) as a powerful technique for macromolecular engineering and synthesis of smart materials with well-defined structures. ROMP has attracted a considerable research attention recently particularly by industry largely due to the development of well-defined metal complexes as initiators and also because of the award of the Noble Prize for Chemistry in 2005 to three scientists (Chauvin, Grubbs, Schrock) for their contributions in this area. This chapter discusses several interesting examples in order to demonstrate that ROMP is a power tool in macromolecular engineering and that it allows the design and synthesis of polymers with novel topologies.

In this chapter, the synthesis and catalytic activity towards olefin meta- thesis of homobimetallic ruthenium (Ru)-alkylidene, -cyclodiene or -arene complexes bearing phosphine or N-heterocyclic carbene (NHC) ligands are reviewed. Emphasis is placed on the last category of bimetallic compounds. Three representatives of this new type of molecular scaffold were investigated. Thus, ((p-cymene)Ru(m-Cl)3RuCl (h 2 -C2H4)(L)) complexes with L = PCy3 (15a), IMes (16a), or IMesCl2 (16b) were prepared. They served as catalyst precursors for cross-metathesis (CM) of various styrene derivatives. These experiments revealed the outstanding aptitude of complex 16a (and to a lesser extent of 16b) to catalyze olefin metathesis reactions. Contrary to monometallic Ru-arene complexes of the (RuCl2(p-cymene)(L)) type, the new homobimetallic species did not require the addition of a diazo compound nor visible light illumination to initiate the ring-opening metathesis of norbornene or cyclo- octene. When diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were exposed

The reactions of Cl-2-Ru-(3-phenylindenylidene) complexes with excess pyridine lead to new ruthenium (Ru)-based bis(pyridine) adducts in good yield. These thermally robust catalysts have been tested in ring-closing metathesis (RCM). In spite of promising initiation rates, only moderate to good activities have been observed in kinetic studies on several substrates.

In this chapter, we summarize the main results of our investigations on the ring-opening metathesis polymerization (ROMP) of cyclooctene catalyzed by various ruthenium (Ru)-arene complexes bearing imidazolin-2-ylidene, imida- zolidin-2-ylidene, or triazolin-5-ylidene ligands. Three major findings emerged from this study. First, we underscored the intervention of a photochemical activation step due to visible light illumination. Second, we established that the presence of an endocyclic double bond in the carbene ligand central heterocycle was not crucial to achieve high catalytic efficiencies. Third, we demonstrated that ortho-metallation of the N-heterocyclic carbene (NHC) ligand by the Ru center led to inactive catalysts.

Olefin metathesis has found a tremendous number of application in the past 25 years. Immobilisation of olefin metathesis (pre)catalysts in room temperature ionic liquids (RTILs) offers the opportunity to recover and reuse the catalyst and also to reduce the level of ruthenium (Ru) contaminants in the products.

1: Initiating Systems for Specialty Chemical Synthesis.- The Alkene Metathesis Ruthenium Catalyst Saga.- Ruthenium Carbenes as Catalysts for Alkene Metathesis.- Metathetical Conversion and Silylative Coupling of Alkadienes and Cycloalkenes with mono- and di-Vinylsilicon Compounds.- Synthesis of Organosilicon Reagents of Vinylsilicon Functionality via Cross-Metathesis and Silylation of Alkenes.- Catalytic Properties and Chemical Transformations of cis-W(CO)4(C5H5N)2 Initiator in Ring Opening Metathesis Polymerization.- The Impact of Weil-Defined Transition Metal Initiators on ROMP.- Dual Activity of Ruthenium Catalysts in Controlled Radical Reactions and Olefin Metathesis.- O, N- Bidentate Ligands Co-Ordinated on Ru-Based Olefin Metathesis Catalysts.- Catalytic Activity of W-Sn and Mo-Sn Bimetallic Compounds in Metathesis and Related Reactions.- Polymerizations Catalyzed with Rhodium Complexes.- Mesoporous Molecular Sieves Immobilized Catalysts for Polymerization of Phenylacetylene and its Derivatives.- Study of the Stability and Activity of Electrochemically Produced Tungsten-Based Metathesis Catalyst with Symmetrical Alkenes.- Immobilized Tungsten-Containing Catalysts for the Metathesis of Linear and Functionalized Olefins.- 2: The Range of Topics Covered Ii Material Science.- The Incorporation of Amino Acids into Polymers via ADMET.- Graft Copolymers Attained by ATRP and ADMET.- Synthesis, Conformation, and Functions of Helical Poly(N-Propargylamides):.- Synthesis of Block Copolymers and Star Polymers through Living Polymerization of Substituted Acetylenes.- Weil-Defined Linear and Crosslinked Materials via ROMP and RTM Processing.- Ring Opening Metathesis Polymerisation (ROMP) of Cyclooctene and Substituted Norbornene Derivatives Using a Ruthenium Catalyst Containing a Triazol-5-Ylidene Ligand.- Acyclic Diene Metathesis (ADMET) Polymerization by Electrochemically Generated Tungsten-Based Active Catalyst System: Optimization of Reaction Conditions.- Probing the Tacticity of Ring-Opened Metathesis Polymers of Norbornene and Norbornadiene Diesters by NMR Spectroscopy.- Metathesis and Polyolefin Growth on Cadmium Selenide Surfaces Using Ruthenium-Based Catalysts.- Acyclic Diene Metathesis Condensation (ADMET) of 1,2-Divinylferrocene (DVFC).- Acyclic Diyne Metathesis Condensation of 3-Alkyl-2,5-di(l-propynyl)-thiophenes.- Ring Closing Versus Cyclic Isomerization of 1,6-Dienes by Ruthenium Allenylidene Complexes.- Application of Uniform-Macroporous Polystyrene Particles as Support In W(CO)6/CC14/hv Photocatalytic Olefin Metathesis System.- Reactions of Atomic Carbon with 2-Norbornene.- Intramolecular Trapping of Strained Bicyclic Allene in Carbon Atom Reactions.- 3: Indusrial Aspects.- Industrial Applications of Olefin Metathesis.- Synthesis of Cyclobutane Hydrocarbons by Combination of (2+2)?-Cycloaddition and Olefin Metathesis. Their Abilities as Effective Propellants.- Directional Synthesis of Membrane Materials by ROMP of Silyl-Substituted Norbornadienes and Norbornenes.

The formation of carbon-carbon bonds using free radicals is of utmost importance both in synthetic organic chemistry and in polymer chemistry [1]. The developments that took place during the last decade have considerably modified the view that free radical reactions are commonly uncontrollable. Catalytic systems are now available, that allow radical reactions to be carried out in a precise and controlled manner. In particular, the past few years have witnessed a rapid growth in the development and understanding of controlled radical reactions based on the combination of suitable radical initiators and of transition-metal complexes. For instance, the addition of a polyhalogenated alkane to an olefin, also known as the Kharasch reaction [2], has largely benefited from the replacement of classical radical initiators such as peroxides or UV light by transition- metal complexes that promote a single-electron transfer or a redox-based chain reaction. The latter process is usually referred to as an Atom Transfer Radical Addition (ATRA). In the presence of a high ratio of olefin compared to the halogen derivative, successive insertions of the unsaturated monomer lead to a macromolecular chain, and the net process is known as an Atom Transfer Radical Polymerization (ATRP) (Scheme 1). Among the metals used for promoting ATRP, copper, nickel, iron, and ruthenium tend to display the highest activities, but complexes of rhenium, rhodium, and palladium have also been employed [[3],[4]].

The olefin metathesis reaction has been carried out with many olefins of different types over various kinds of both homogeneous and heteregeneous catalysts [1, 2, 3]. The activity of a particular catalyst system depends on a number of factors, such as proportions of the components, the order in which the components are mixed, pretreatment procedures and reaction time [4]. Optimization of a given catalyst system by adjustment of the various parameters inturn can be quite a lengthy procedure.

The six-coordinate W0 complex cis- W(CO)4(C5H5N)2 has been found to be active in the in situ formation of a carbene species from norbomene generating a typical ring opening metathesis product of the substrate. A mechanism of initiation is proposed illustrating the reaction follows the course of a 1,2-hydrogen shift in the coordinated norbornene (η2→η1). The initiating carbenoid group is identified from the products of the spontaneous carbene-CO coupling and Wittig reactions test. Formation of W(CO)5(C5H5N) and W(CO)3(η6-C6H5CH3) is blamed for catalyst deactivation.

The history of the alkene metathesis ruthenium catalyst discovery is presented and illustrated with catalyst precursor preparation methods and with references to applications in fine chemistry and polymerisation. These precursors involve well-defined and in situ prepared rutheniumalkylidenes, -vinylidenes and -allenylidenes containing bulky electronrich phosphine or imidazolylidene and imidazolinylidene ligands.

The ring opening metathesis polymerisation (ROMP) of cyclooctene and substituted Znorbornene derivatives is performed in the presence of the Ru-alkylidene (4) bearing a triaol-5-ylidene ligand (2). Analysis of the formed polymers clearly indicates the low initiation efficiency of 4. Only a small amount of the added Ru-alkylidene reacts with the monomer to generate the propagating species.

Two families of ruthenium-based olefin metathesis catalysts and their use in organic and polymer synthesis are presented. Ruthenium-allenylidene complexes [Ru=C=C=CR2(C1)(PR3)(arene)]+ X- are efficient pre-catalysts for the Ring Closure of dienes and enynes but they are also able to polymerise strained and unstrained cyclic olefins under mild conditions. These complexes have also shown interesting recycling capacity in ionic liquid solvents. The in-situ generated catalysts readily prepared from easily available reagents: a ruthenium complex, an imidazolium salt and a base promote alkene and enyne metathesis. A two-component system for the polymerization of norbornene and cyclooctene is also presented.

Dienes can undergo olefin metathesis reactions of two types: (i) intermolecular, and (ii) intramolecular. Intramolecular metathesis (RCM) reactions occur with great readiness henever the product is a 6-membered ring. They are also often favoured for the production of 5-, 7-, and 8-membered rings, depending on the nature, number and location of any substituents. Intermolecular metathesis reactions lead eventually to high polymers and proceed very cleanly when initiated by metal carbene complexes; these are known as ADMET (acyclic diene metathesis) polymerizations (Figure 1). This class of polymerization reactions has been well established and comprehensively studied by Wagener and his group [1–6]. ADMET polymerization has been also a convenient route to linear polymers containing inorganic elements and functional groups for the preparation of new materials [7].

Substituted polyacetylenes attract attention as materials with potential applications in micro- and optoelectronics and non-linear optics [1, 2]. The unique properties of these polymers, such as photoconductivity, photo- and electroluminescence and non-linear optical effects, are a function of their molecular architecture and can be tuned through both the main-chain microstructure (cis-trans and head-to-tail isomerism) and character of pendant groups. Using chain coordination polymerization of corresponding acetylenes for polyacetylenes synthesis, the main-chain polymer microstructure is primarily controlled by the catalyst and surroundings used, whereas the character of pendants is predetermined by a choice of monomer. Monomers of interest provide pendant groups that show (i) electron-donating or electron-withdrawing effects with respect to the main chain, (ii) high yield of luminescence, or (iii) ability to change properties due to changes in the oxidation state (organometallic groups). In addition to the functional effects, the pendant groups should also contribute to the sufficient polymer stability and convenient processability (especially polymer solubility). For the polymerization, either in metathesis or in insertion mode, transition metal catalysts are applied. Efficient polymerization of unconventional monomers requires always a proper selection of catalyst. All kinds of interactions of catalyst with monomer substituents leading to the substituent transformations and/or catalyst deactivation must be avoided or at least minimized. Moreover, for monomers with several multiple bonds the selectivity in opening (polymerization) the desired triple bond is very important. The controlled character of polymerization (at least partly) with respect to the molecular weight and microstructure characteristics of polymers formed is also highly desirable.

Material properties of olefin metathesis polymers made by thermal (ROMP) or photoinduced (PROMP) polymerization with ruthenium (II)-salts and the later developed ruthenium-phosphines as catalysts are described. The low oxidative stability was improved by copolymerization with so-called “build-in” antioxidants (AOs), i.e. hindered phenols or aromatic amines bearing 2-norbornene units.

Conventional monomers are known to afford upon polymerization random coils with no precise shape or topological features. On the other hand, there is a growing demand for architectures that are shape-persistent and also molecularly well-defined and these are the reasons why designing architectures that exhibit minimal fluctuations in size, composition and shape from common monomers is a major challenge in polymer chemistry. Methods of macromolecular engineering have therefore been developed with the purpose of lowering the conformational entropy of the objects formed. This could be achieved upon engineering structures of enhanced connectivity and precisely designed topology. Non-linear architectures whose branching points are topologically controlled can indeed be shaped in particular forms such as spheres, bottle-brushes, unimolecular micelles, Janus-type spheres, etc… Copolymers with non-linear -and for some of them asymmetric- structures also attract much interest because features like their phase diagram and the morphology of their mesophases totally differ from those encountered with linear copolymers.

Attempt to understand how metal complexes mediate the formation of carbon-carbon bonds is a major theme in organometallic chemistry. A much studied example among the carboncarbon bond-forming reactions is that of metal carbene bonds with olefins, a reaction leading to different products, depending on the metal, its oxidation state and its ancillary ligands [1]. On the other hand, radical methods are maybe the most powerful tools for carbon-carbon bond formation. Radical polymerisation [2] is one of the most important methods for synthesising polymers with nearly 50 % of synthetic polymers prepared through radical processes [3]. In pharmaceutical and fine organic synthesis free radical reactions, particularly cyclisations, have been extensively studied over the past twenty years. In recent years, transition metal mediated free radical processes have gained in importance. In particular the Kharasch addition to olefins such as atom transfer radical addition (ATRA) and atom transfer radical cyclisation (ATRC) and its extension to olefin polymerisation known as atom transfer radical polymerisation (ATRP) have been reported with a wide range of metal catalysts.

Thanks to recent advances in the chemistry of preparing polymers, an increasing number of tools are at our disposal for the design of polymer materials. The design level ranges from monomer synthesis, controlled stepwise or chainwise polymerisation, block copolymer synthesis, branching and crosslinking reactions. Depending on the structure of the individual polymer chains formed, these will be organised in the bulk to give specific properties. Hence, this gives us two architectural levels: the structure of individual macromolecules and the microstructure of the material produced. The synthesis of properly tailored macromolecular architectures [1] can be achieved by using living/controlled polymerisation processes such as anionic [2], cationic [3], radical [4] or group transfer polymerisation [5], ring-opening polymerisation of lactones and lactides [6], ring-opening metathesis polymerisation (ROMP) of cyclic olefins [7-9], and co-ordination polymerisation [10]. Of particular interest today is the combination of two of these processes. The present chapter aims at reviewing the synthetic routes developed recently for building up novel (co)polymer structures based on ROMP and atom transfer radical polymerisation (ATRP), with a special emphasis on the combination of two living/controlled polymerisation techniques.

Dicyclopentadiene, DCPD, is cheap and can be polymerised by ring opening metathesis polymerisation (ROMP), which yields a crosslinked polymer. This polymerisation process can be tailored to have the characteristics which make it readily adaptable to either reaction injection moulding (RIM) or resin transfer moulding (RTM). The production of large moulded objects from DCPD-based feeds using RIM technology was developed mainly in the USA by BF Goodrich under the trade name of TELENE and by Hercules under the trade name METTON [1-11]. The catalysts used in METTON process is based on a combination of WCl6/WOCl4 and nonylphenol with Et2AlCl. In the TELENE process the preferred catalyst is a trialkylammonium molybdates. Up to 10% trimer of cyclopentadiene is added to the monomer, not only to decrease the melting point of DCPD, but also to increase crosslinking in the polymer.

Ring-opening metathesis polymerization (ROMP), ring-closing metathesis (RCM) and ring-opening cross metathesis (RO/CM) are interesting methods to synthesize polymers with attractive mechanical and electrical properties, and specialty chemicals. Ruthenium and osmium based catalysts are water stable and possess a remarkable tolerance towards most functional groups. Whereas the first generation of well defined ruthenium based ROMP catalysts, cationic complexes like Ru(H2O)6tos2 (tos=toluene-4-sulfonate) and Ru(arene)2tos2 (activated by UV-irradiation) showed much lower reactivities as compared to “activated” early transition metal catalysts, Ru-phosphine complexes like RuCl2(p-MeC6H4CHMe2)(PCy3) (1, Cy=cyclohexyl) developed by Ciba SC and later Ru-phoshine-carbenes, developed by Grubbs et al. and Ciba SC are able to polymerize a large range of cycloolefins including DCPD (in technical quality and in mixtures with additives and fillers) very efficiently. The new classes of ruthenium carbene complexes are accessible by a novel synthesis which avoids the use of hydrogen gas and is therefore easy to scale up. Catalyst reactivities in ROMP of different monomers (characterized in terms of their turn-over frequencies (TOF) and compared with other catalysts for olefin polymerization), in RCM and RO/CM are very much dependent on the ligand sphere and the type of monomer used. Polymerizations were conducted in bulk, solution and dispersion with a large range of non-functionalized and functionalized 2-norbornene derivatives to obtain linear and crosslinked homo- and copolymers (block and random) which may find useful applications in the near future.

The industrial applications of the olefin metathesis reaction are relatively recent although this reaction was observed about 50 years ago. Streck described in details the historical development of this reaction in his review in a book of the same series [1]. He gave also interesting data on the industrial processes in refs. [2] and [3]. More recently, Ivin and Mol, in their classical book on olefin metathesis, have also developped this field in a special chapter [4]. The idea of olefin disproportionation was first proposed by Robert Banks at Phillips [5], who had observed traces of pentenes and propene in the reaction mixture after passing isobutane and butenes through a bed filled with molybdenum carbonyl supported on alumina. The Ring Opening Metathesis Polymerization was found by the Natta group at Montedison [6, 7]. Many groups studied this reaction and its mechanism was proposed by Chauvin

This review summarises the most interesting approaches in the polymerisation of alkynes and the ring opening metathesis polymerisation of cyclic olefins catalysed by seven-coordinate tungsten(II) and molybdenum(II) compounds. Special attention is given to the catalytically active intermediate compound formed in the reaction of the metal complex and the organic substrate (alkyne or cyclic olefin) and to the reaction mechanism.

Over the past decade, olefin metathesis has emerged as a powerful method for the formation of carbon-carbon double bonds [1]. In particular, two ruthenium-based catalysts- (PCy3)2(Cl)2Ru=CHPh (1)

Recent developments in the synthesis of ring opening metathesis polymerization- (ROMP-) based heterogeneous catalytic supports are reported. In combination with grafting and precipitation polymerization techniques, ROMP has been applied to the synthesis of surfacefunctionalized inorganic and organic supports. Selected applications of these well-defined heterogeneous catalytic supports in C-C coupling reactions (Heck couplings), C-N coupling reactions (aminations) as well as in atom-transfer radical polymerization are reported.

The Schrock type tungsten carbyne complexes Np3W=CtBu, (tBuO)3W=CtBu and Cl3(dme)W=CtBu catalyze the polymerization of 1-alkynes. The polymerization of disubstituted alkynes was only successful with Cl3(dme)W=CtBu as catalyst. The Acyclic Diyne Metathesis Condensation (ADIMET) of conjugated or non conjugated diynes is catalyzed by the carbyne tungsten(VI) complex (tBuO)3W=CtBu or W2(tBuO)6. Without or with small amounts of solvent high molecular weighted polyalkynameres were formed. Predominantly mixtures of oligomeres or cycloalkynes were produced, by using higher amounts of solvent.

The stereochemistry of the olefin metathesis has been the subject of numerous publications which tried to rationalize the behaviour of various catalysts with acyclic olefins [1-5]. It had been noticed during these studies that a cis olefin gave preferentially a cis olefin and that a trans olefin led essentially to a trans olefin. This was explained in terms of stability of the metallacyclobutanes involved in the catalytic cycle (Scheme 1): the most favoured metallacyclobutanes are those where the substituents in positions 1 and 3 are equatorial. This simple rule allowed the explanation of most experimental results and the configuration retention.

Part I: Metathesis Polymerization of Olefins: Romp and Admet. Ring-Opening Metathesis Polymerization by Molybdenum Imido Alkylidene Complexes R.R. Schrock. Metathesis of Low-Strain Olefins and Functionalized Olefins with New Ruthenium-Based Catalyst Systems A.F. Noels, A. Demonceau. Synthesis of Aryloxide Tungsten (VI) Complexes and Their Application in Olefin Metathesis F. Lefebvre, et al. Novel Catalysts for Addition Polymerization of Norbornene and its Derivatives K.L. Makovetsky, et al. The Use of Non-Traditional Catalysts in the ROMP of Cycloolefins K.L. Makovetsky. Correlation between Catalyst Nature and Polymer Selectivity in ROMP of Cycloolefins with WCl6-Based Catalytic Systems V. Dragutan, et al. Ring-Opening Metathesis Polymerization of Cycloolefins Using Tungsten-Tetraphenylporphyrinate Catalysts V. Dragutan, et al. Metathesis Ring-Chain Equilibrium in Cyclobutene and 1-Methylcyclobutene Systems E. Thorn- Csanyi. Olefin Cyclopropanation or Olefin Metathesis with Late Transition Metal Complexes? A.F. Noels, A. Demonceau. Initiation, Propagation and Termination of Olefin Metathesis Reactions L. Bencze, et al. Synthesis of Membrane Materials by ROMP of Norbornenes E.Sh. Finkelshtein, et al. Olefin Metathesis in Organosilicon Chemistry E.Sh. Finkelshtein. Side Chain Liquid Crystalline Polymers via ROMP. Influence of Content of Mesogenic Groups and Tacticity on the LC Behaviour M. Ungerank, et al. Optically Active Polymers via ROMP of Enantiomerically Pure Monomers F. Stelzer, et al. Synthesis of Well-Defined Graft Copolymers via Coupled Living Anionic and Living Ring Opening Metathesis Polymerisation E. Khosravi. Recent Developments in the Synthesis of Fluorinated Homopolymers and Block Copolymers via Living Ring Opening Metathesis Polymerisation E. Khosravi. Formation of Hydrocarbon and Functionalized Polymers by Acyclic Diene Metathesis (ADMET) Polymerization K.B. Wagener, P.S. Wolfe. A New Synthetic Route to Soluble Conjugated Polymers with Valuable Optical Properties P. Kraxner, E. Thorn-Csanyi. Metathesis Depolymerization Chemistry as a Means of Recycling Polymers to Telechelics and Fine Organic Chemicals K.B. Wagener, et al. Quantitative Determination of the Microstructure and Composition of Crosslinked Rubber Blends H.-D. Luginsland, E. Thorn-Csanyi. Industrial Applications of the Olefin Metathesis Reaction F. Lefebvre, J.-M. Basset. Part II: Alkyne Polymerization. Living Polymerization of Alkynes by Molybdenum Imido Alkylidene Complexes R.R. Schrock. Catalytic Transformation of Alkenes and Alkynes in the Presence of Group 6 Metal Carbonyls T. Szymaska-Buzar. Part III: Molecular Modeling and Alkene Polymerization. Derivatives of Chromocene in Ethylene Polymerisation B.R. Messere, et al. A Possible Mechanism of Polymer Formation from a,b-Unsaturated Carbonyl Compounds under the Influence of Metathesis Catalytic Systems Ch. Jossifov.

Ring-opening metathesis polymerisation of cycloolefins (e.g. cyclopentene, cyclooctene, cyclododecene, dicyclopentadiene) has been investigated in the presence of recently reported catalytic systems consisting of tungsten-tetraphenylporphyrinate and aluminoxane, under inert atmosphere at room temperature, in aromatic solvents. The catalyst precursor was prepared by interaction of WCl6 with free tetraphenylporphyrin in carbon tetrachloride and characterised by spectroscopic methods. Physical-chemical studies on the interaction between the catalytic components and with the monomer, as well as kinetic results indicated a high stability and efficiency of the catalytic system employed. It is of interest that the polyalkenamers displayed a high trans stereoconfiguration and a block or alternate distribution of the carbon-carbon double bonds dyads. These catalytic systems behaved as “living” ones and allowed polyalkenamers with monomodal and narrow molecular weight distribution to be produced. Block copolymers starting from dicyclopentadiene in conjunction with cyclopentene and cyclooctene have also been obtained. Data recorded under the above conditions gave information concerning the structure of the active species, the nature of the initiation and propagation steps, reaction mechanism and stereochemistry.

Unsaturated organosilicon compounds form an original field in organic and elementoorganic chemistry prospective both in theoretical and applied aspects. Their chemical properties are often determined by the presence of silicon atom and its influence on neighbouring atoms and groups.

Olefin metathesis has come a long way since its early days in the sixties. Yet, many problems remain-practically unsolved, not the least of which is the metathesis of olefins bearing polar substituents. This point is of particular importance when it is recognized that the metathesis of functionally substituted alkenes could give a ready access to a variety of valuable organic compounds difficult to synthesize by other methods.

A wide range of fluorinated norbornenes and norbornadienes are subjected to ROMP using well-defined Schrock initiator based on Mo(CH-t-Bu)(NAr)(O-t-Bu)2. All of the polymerisations show characteristics of well-ordered living systems; e.g. (a) the persistence of propagating alkylidenes in the polymerisation mixtures as observed by 1H nmr spectroscopy, (b) narrow molecular weight distributions of the resultants polymers and (c) the synthesis of diblock copolymers.