Metal poly-yne polymers

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. 

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. 

Takahashi, S. Murata, E. Kariya, M. Sonogashira, K. Hagihara, N. A new liquid-crystalline material. Transition metal-poly(yne) polymers. Macromolecules 1979, 72(5), 1016-1018. 

Polymerised phosphines are frequently made by placing side groups on pre-formed polymers. Such derivatives can form metal-phosphine complexes which are of importance as catalysts [22]. Metal poly-yne polymers with phosphine side groups are known (8.163). 

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