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13.6.5: Carbon Wires- Polyyne and Polyene Bridges

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    385593
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    Organic molecules with conjugated \(\pi\) systems are known to have interesting optical and electronic properties. When ligands with conjugated \(\pi\) systems are used to bridge two metal centers, the two metals can behave in a cooperative way because the electronic state of one metal ion is conjugated to the other. The most intensely investigated complexes are bimetallic metal complexes (two metal ions) that are bridged by long carbon chains with alternating single and double bonds. Some examples are given below. (This topic is reviewed in Aguirre-Etcheverry D. O’Hare, Chem. Rev., 2010, 110, 4839, doi: 10.1021/cr9003852)

    Polyene

    Polyenes are organic molecules with alternating double and single bonds. In other words, they contain a series of consecutive \(\ce{(-C= C-)_{n)}\) with \(n >1\). Aromatic and cyclic polyenes were discussed in a previous section. One of the longest ligands reported as of 2010 was a \(\ce{Ru-(CH)14-Ru}\) complex (shown in Figure \(\PageIndex{1}\)).

    clipboard_e51291195b3645d70cd93828d6978941c.png
    Figure \(\PageIndex{1}\): Structure of linear polyene complex of Ru with and 14-carbon polyene. (CC-BY-SA; Kathryn Haas)

    Source: Aguirre-Etcheverry D. O’Hare, Chem. Rev., 2010, 110, 4839, doi: 10.1021/cr9003852

    Polyyne ligands

    Polyynes are organic molecules with alternating single and double bonds. In other words, they contain a series of consecutive \(\ce{(-C \bond{#} C-)_n}\) with \(n >1\).

    Organometallic polyynes capped with metal complexes are well characterized. As of the mid-2010s, the most intense research had concerned rhenium (ReCnRe, n=6-20), ruthenium (RuRuCnRuRu, n = 8–20), iron (FeC12CFe), platinum (PtCnPt, n = 16–28), palladium (ArCnPd, n = 6–10), and cobalt (Co3CnCo3, n = 14–26) complexes (Figure \(\PageIndex{1}\)).

    clipboard_e63d4c52c654186e91de7ee79a48ec149.png
    Figure \(\PageIndex{1}\): Examples of known polyyne organometallic complexes. (Pigulski, Organometallic polyynes, CC BY-SA 4.0)

    Source: https://en.Wikipedia.org/wiki/Polyyne


    This page titled 13.6.5: Carbon Wires- Polyyne and Polyene Bridges is shared under a not declared license and was authored, remixed, and/or curated by Kathryn Haas.

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