Copolymers carbonyl complexes

A half-metallocene iron iodide carbonyl complex Fe(Cp)I(CO)2 was found to induce the living radical polymerization of methyl acrylate and f-bulyl acrylate with an iodide initiator (CH3)2C(C02Et)I and Al(Oi- Pr)3 to provide controlled molecular weights and rather low molecular weight distributions (Mw/Mn < 1.2) [79]. The living character of the polymerization was further tested with the synthesis of the PMA-fc-PS and PtBuA-fi-PS block copolymers. The procedure efficiently provided the desired block copolymers, albeit with low molecular weights. 

Support-bound transition metal complexes have mainly been prepared as insoluble catalysts. Table 4.1 lists representative examples of such polymer-bound complexes. Polystyrene-bound molybdenum carbonyl complexes have been prepared for the study of ligand substitution reactions and oxidative eliminations [51], Moreover, well-defined molybdenum, rhodium, and iridium phosphine complexes have been prepared on copolymers of PEG and silica [52]. Several reviews have covered the preparation and application of support-bound reagents, including transition metal complexes [53-59]. Examples of the preparation and uses of organomercury and organo-zinc compounds are discussed in Section 4.1. 

Recently, block copolymers micelles filled with MoS nanoparticles (well miscible with mineral oil) were synthesized in heptane using interaction of Mo(CO)e with polystyrene-fc/ock-polybutadiene (PS-fc-PB) and polystyrene-i /ock-polyisobutylene (PS-fc-PIB) followed by H2S treatment [39]. To position MoS c nanoparticles in the PS core, the reaction between Mo(CO)e and block copolymer should be carried out in argon atmosphere. This yields arene Mo tricarbonyl complexes while olefin Mo carbonyl complexes do not form. By contrast, to place MoS nanoparticles in the PB corona, complexation with Mo(CO)e should be carried out in the CO atmosphere. This suppresses forma-... 

There are a number of different types of polymers that contain metal carbonyl complexes attached to polymer backbones and side chains. In the 1970s, Pittman and coworkers reported the synthesis and polymerization of a wide range of vinyl monomers containing transition-metal-coordinated cyclopentadienyl rings. Polymer 21 is an example of a copolymer containing chromium and manganese complexes in the side chain. Another class... 

A characteristic feature is that the same type of carbonyl complexes bound with aUyl fragments in the polymer chains were detected on immobilization of Co2(CO)g or Fe3(CO)i2 within polystyrene-polydiene block-copolymers. The thermal decomposition of these Jt-allyl complexes results in nanoparticles. The Cr(CO)3 fragments in polystyrene are bound via Ti -complexed benzene rings. 

A considerable viscosity increase in copolymers of tributylstannyl methacrylate with methyl methacrylate, butyl acrylate and styrene upon prolongated storage has been observed and special agents to eliminate this effect have been proposed 108). It is likely that the destruction of intermolecular coordination complexes formed by involvement of tin and carbonyl groups in comonomer units takes place in this case. 

The factors that control the strictly alternating copolymer chain with no detectable errors (e. g., microstructures involving double insertion of ethene) have been the object of detailed studies since the discovery of the first Pd" catalysts for the alternating alkene/CO copolymerisation [11]. Sen was the first to demonstrate that double carbonylation is thermodynamically unfavorable and to suggest that the higher binding affinity of Pd" for CO relative to ethene inhibits multiple ethene insertions, even in the presence of very low concentrations of CO [12]. Therefore, once a palladium alkyl is formed, CO coordination ensures that the next monomer will be a CO molecule to generate the acyl complex. 

Synthesis of carboorganosiloxane copolymers and polymers is based on hydride polyaddition of organohydrosiloxanes to organoalkenyl silanes [69], Recently, this reaction is of great interest in the field of obtaining complex monomers [70], as well as in the field of study of addition mechanisms on various Pt, Pd, Co and metal carbonyl catalysts [71-74] and specificity of actions of one or other catalytic systems [75], Besides carboorganosiloxane oligomers and linear polymers, other compo-unds were also synthesized by this method [76 -78],... 

The IR spectra of an AES film recorded in the hydroxyl vibration region during the first 38 h of irradiation showed an increase in a broad absorption band centered around 3450 cm-1 attributed to hydroperoxides. The development of a complex band with a maximum at 1713 cm-1 and shoulders around 1690, 1730 and 1770 cm-1 was observed in the carbonyl vibrations region (Figure 30.6). These maxima correspond to carbonylated photoproducts that have been previously identified during photooxidation of EPDM [17] and ethylene-propylene copolymer [18]. The bands at 1713, 1730 and 1770cm-1 correspond, respectively, to the absorption of saturated acids (dimer form) and ketones, esters and lactones or peresters the absorption around 1690 cm-1 is related to the presence of unsaturated carbonyl species. 

A bimetallic titanium complex of BINOL derivative can be used to catalyze the asymmetric carbonyl-ene reaction [46]. Insoluble polymeric catalyst 74 was prepared from a self-assembly of Ti(OiPr)4 and non-crosshnked copolymers with (R)-binaphthol pendant groups (Scheme 3.22) [47]. The self-assembled polymeric Ti complex is insoluble in organic solvent and catalyzed the carbonyl-ene reaction of glyoxylate 75 and a-methylstyrene 76. When the reaction of 75 and 76 was carried out with 20mol% of 74 in Gl pCf at room temperature, an 85% yield of the product with 88% ee was obtained. Following its recovery by filtration, this catalyst was reused five times with full retenhon of its activity and enantioselectivity, without further treatment... 

In the last year some attention has been paid to the electropolymerizations in which the electrodic depolarizer is a complex between the monomer and some Lewis acids (see Ref. 7, p. 650). These researches, pioneered by Funt, were oriented towards the formation of alternating copolymers, in reactions in which the Lewis acid gives a monomer pair charge transfer complex. This research is connected to the discovery that certain polar monomers, containing nitrile or carbonyl groups, (A), can complex with Lewis acids such as zinc halides. These complexes I can undergo a thermal homopolymerization by themselves, or can react with some electron donor monomers (D), giving rise to complexes like II,... 

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