Bridging ligands doubly bridged polymers

In general, the linear coordination polymers mentioned above are poorly soluble in solvents and poorly characterized in terms of molecular weight, structure and purity. These polymers have been currently studied from the viewpoint of the development of new functional polymers. Although there are soluble coordination polymers doubly or triply bridged by monochelating ligands, they are still not hilly characterized because of polydissociation of the ligands. 

The two doubly bridged oligomers 81 and 82 and the very insoluble polymer 83 were obtained using the bridging ligand dpa.93 These materials were characterized by H, 31P, and 19F NMR. The trans-conformation for 83 was established on the basis of IR findings (argument based on the number of bands). 

In an attempt to use dicopper(I) complex unit as building block for synthesis of metal-containing polymers, Kitagawa reported his interesting results in synthesis and structural characterization of an infinite stair-type chain compound (235). The complex of thiochrome (L88) [C CLae KClO was prepared by reduction of copper(II) perchlorate followed by reaction with the ligand. The structure contains a di-nuclear cationic unit in which the two T-shaped metal ions are doubly bridged by two thiochrome molecules with extremely short Cu Cu... 

Another class of doubly bridged metal phosphinate polymers are those possessing coordinated water and hydroxide ion in place of the organic bident-ate ligand (/2,13,116,118, 720). The synthesis ofthis class ofpolymer is shown in Eq. (lX-43). 

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