Poly , metalation

Pt and Pt-group metals (poly- and single crystals) have long been among the most intensively studied systems in electrochemistry6 8,io,ii,i4,25,140,186,188,206,412,752-7%. nevertheless reliable ff=0 values... 

Metal-acetylide complexes have been used as a unit of organometallic polymers that have metallic species in the main chain [20]. Representative examples are metal-poly(yne) polymers (19) of group 10 metals depicted in Scheme 5. These polymers are easily prepared from M(PR3)2Cl2 (M=Pt, Pd) and dialkynyl compounds catalyzed by Cu(I) salts in amine. Recently, this synthetic method was successfully applied to the construction of metal-acetylide dendrimers. 

Metal-acetylide complexes including metal-poly(yne) polymers often show unique properties [21-23]. Thus, metal-acetylide dendrimers are of interest because amplification of the functionality due to metal-acetylide units based on three-dimensional assembly with a regular dendritic structure is expected. 

The exact nature of metal-poly(phosphonic acid) interaction is unknown (Ellis, 1989) although a number of structures can be drawn (Figure 8.3). 

Photolysis of Transition-Metal Poly hydride Complexes 363... 

Gollier, P.-A. and Bertrand, P. (2002). Cyclic oligomer segregation at the metallized poly(ethylene terephthalate) surface, J. Adhesion Sci. TechnoL, 16, 1, 1-13. 

As was the case for metals, poly crystalline ceramics show a dependence of mechanical properties on grain size, as given earlier by the Hall-Petch relation in Eq. (5.22), which in this case applies to fracture strength, ay ... 

The oxidations by [Ni,ll([9]aneN3)2]3+ and [Nim([10]aneN3)2]3+, of a series of metal poly(pyridine) complexes, have been investigated (107, 146, 149). A typical reaction of this type is seen in Eq. (9), where... 

Fell also described the hydroformylation of fatty acids with heterogenized cobalt carbonyl and rhodium carbonyl catalysts [37]. The products of the reaction with polyunsaturated fatty acids were, depending on the catalyst metal, poly- or monoformyl products. The catalyst carrier was a silicate matrix with tertiary phosphine ligands and cobalt or rhodium carbonyl precursors on the surface. The cobalt catalyst was applied at 160-180°C and gave mostly monofunctionalized fatty acid chains. With linoleic acid mixtures, the corresponding rhodium catalyst gave mono- and diformyl derivatives. Therefore, the rhodium catalyst was more feasible for polyfunctionalized oleocompounds. The reaction was completed in a batch experiment over 10 h at 100 bar and 140°C rhodium leaching was lower than 1 ppm. 

Figure 4.15 Schematic representation of the sequential steps taken for the formation of multilayers based on electrostatic self-assembly using cationic polymers and anionic a-ZrP sheets (see text for further details). Reprinted from Coord. Chem. Rev., 185-186, D.M. Kaschak, S.A. Johnson, C.C. Waraksa,J. Pogue and T.E. Mallouk, Artificial photosynthesis in lamellar assemblies of metal poly(pyridyl) complexes and metalloporphyrins, 403-416, Copyright (1999), with permission from Elsevier Science...

B. POTASSIUM HYDROTRIS(1 -PYRAZOLYL)BORATE— ALKALI METAL POLY(l-PYRAZOLYL)BORATES... 

Silver sulphide, Ag2S.—The sulphide occurs in nature as argentite, and also in combination with many other sulphides. It is formed by direct synthesis from its elements at ordinary temperatures,7 and also by immersion of the metal in solutions of alkali-metal poly sulphides. It can be prepared in cubic crystals by passing sulphur-vapour over heated silver, or by the action of hydrogen trisulphide, H2S3, on silver oxide. It is the only definite compound produced by fusion of mixtures of silver and sulphur in different proportions.9 The black, amorphous form is precipitated by the action of hydrogen sulphide or a soluble sulphide on a solution of a silver salt. It is also produced by the action of hydrogen sulphide on metallic silver, a reversible reaction.10... 

Table 3. Spectral data of metal-poly-yne polymers and monomer complexes Polymers" IRb UVC P-NMR"...

Design of the polymer structure and control of the molecular weight of the metal-poly-yne polymers will be required for studying the potential catalytic activity and physical property. 

The synthesis of the metal-poly-yne polymers with the desired molecular weight and structure may be accomplished without any difficulties. The following four cases will be discussed. 

It should be noted that the metal-poly-yne polymers except Pt-D -D1 are soluble in a variety of organic solvents such as benzene, toluene, tetrahydrofuran, and methylene chloride in spite of the fact that they contain a heavy metal in the backbone, whereas polymers containing conjugated unsaturation such as polyacetylene and poly(p-dieth-ynylbenzene) are practically insoluble in orgnaic solvents. Even a high molecular weight sample (Mw = 105) of Pt-D1 polymer dissolves in trichloroethylene at least up to a concentration of 50wt-%. 

Considerations based on the Stuart model of Pt-D1 polymer (Fig. 4) along with structure40) of the model complex imply that the high solubility of the metal-poly-yne polymers may be attributed to bulky substituents on phosphorus which efficiently cover the polymer backbone and decrease intermolecular interactions between polymer molecules. This is supported by the fact that 1) the solubility of the polymers decreases in the order... 

In spite of the presence of metal-carbon o-bonds and carbon-carbon triple bonds in the backbone, the metal-poly-yne polymers are fairly stable to air in the solid state and show considerably good thermal stability (Table 6). The platinum-containing... 

Table 6. Thermal stability of metal-poly-yne polymers (measured by thermogravimetric analysis at heating rate of 5 °Omin)...

It is well recognized experimentally and theoretically that stiff polymers exhibit characteristic properties in dilute and concentrated solutions. In this section the structure of the metal-poly-yne polymers will be discussed in terms of their solution properties. 

Metal-poly-yne polymers other than Pt-D1 polymer also form liquid crystals. They may be the first example of lyotropic liquid-crystalline materials having transition metals. 

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