Metallic moieties chain incorporation

II. METALLIC MOIETIES IN THE POLYMER BACKBONE A. Metals Directly Incorporated into the Polymer Chain... 

Prior to the development of polymerisation catalysts based on the bis(imino)pyridine framework, the bis(imino)pyridine moiety was widely incorporated into macrocycles [163, 164], As an extension of this design strategy to polymerisation applications, several groups have been attempting to incorporate sterically bulky bis(arylimino) pyridine units into macrocycles. In a similar fashion, the introduction of the bis(imino)pyridine unit into polymeric chains in which polymerisation-active metal centres are bound has been the subject of study. 

Once an alkyne moiety is introduced into a peptide, e.g., as propargyl glycine (Pgl) in place of a simple glycine in Enk, it can of course be used directly for complexation to a metal complex. Along those lines, we have reacted Co2(CO)g with the peptide Ac-Tyr-Gly-Pgl-Phe-Leu-NH2, to yield the Co2(CO)6 complexed to the Pgl alkyne side chain [32]. In a real SPPS scheme with a pre-formed metal-alkyne complex, the amino acid building block [Tp WI(CO)(ri2-Fmoc-Pgl-OH)] was incorporated to yield the side-chain substituted Enk derivative H-Tyr-Gly-[Tp W(I)(CO)(r 2-Pgl)]-Phe-Leu-OH (Tp tris(3,5-dimethylpyrazolyl)-borate) [44]. 

In the next two sections are grouped complexes which contain metal cluster moieties at each end of the carbon chain. In general, these are attached via p-rj C (O) or -p1 p2-C2 units (P) (Chart 5). Other complexes in which C2 fragments are incorporated either partly (peripheral) or completely within metal clusters are considered in Section IX. 

Since these studies, many other rotaxanes incorporating cyclodextrins or their substituted derivatives have been reported, including other metal-containing systems. The latter include a series of a-cyclodextrin rotaxanes formed by the reaction of labile [Fe(CN)50H2J ions with pre-threaded l,l"-(a,(o-alkanediyl)-bis(4,4 -bipyridinium) dicationic moieties (incorporating methylene chains between 8- and 12-members long). " ... 

Recently, an extension of the dehydrohalogenation process to the synthesis of a new class of heterobimetallic polyyne materials 174 which contain mixed metals with alternating Ru(dppe)2 and Pd(P Bu3)2 moieties (dppe = bis(diphenylphosphino)ethane) in the polymer backbone has been reported (Equation (67)), with 71/ =14,000 (by GPC measurements). The incorporation of ferrocene units into the polymer main chain and alternation between either Ni(PBu3)2 175 or Pd(PBu3)2 1 6 moieties has also been achieved (Equation (68)) and the molecular weights of the resulting polymers were 71/ = 26,100 and 21,400, respectively. 

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