A New Generation of All-Carbon Bridged Bimetallic Complexes featuring Redox-Active, Group 6 Metal End-Caps.

金属稳定的碳链[M-（CC）x-M]n+在过去的10年里引起了越来越多的关注，主要是由于伴随化合物形式氧化态变化的电子结构的显着变化。虽然这项工作的大部分集中在同双金属的例子，最近的合成进展使异金属的例子。本工作的目的是合成和研究一系列[M-（CC）x-M ′] n+型化合物的电子性质，其中连接基团Cx是一个含有四个或更多碳原子的不饱和碳链，金属末端为-（C1-C2）-（C2-C3）-（C3-C3帽M和M'是氧化还原活性的有机金属中心。一系列的氧化态（n = 0-4）是可获得的，其中一些是稳定的，可分离的系统。这类迷人的配合物的电子结构强烈依赖于M和M '的身份。然而，以前的工作基本上局限于铁、钌和铼的第7族和第8族过渡金属中心的封端，其中3d金属中心Fe比Ru和Re的4d/5d中心的贡献强得多。这项工作的创新之处在于包括一种有机金属封端，其特征在于第6族金属钼，它既具有强电子供体又基于4d中心-这提供了一个独特的机会来描绘封端电子供体容量与金属过渡系列对电子结构的影响。通过引入Mo基封端基团可以享有的其他优点是高分辨光谱手柄（EPR）的可用性，利用该高分辨光谱手柄（EPR）通过直接实验探针研究电子结构，以及控制混合的第6族/第8族异双金属化合物[M-（CC）x-M '] n+的氧化形式的电子结构的潜力。通过控制分子构型。这项工作是重要的，因为它将导致对不饱和全碳桥的电子结构的进一步理解，以及如何将其作为金属的函数进行控制，支持配体和碳片段的长度。尽管许多人谈到需要在未来基于分子的电子器件的分子组件的设计中进行这种详细的理解，但我们的目标是完全理解这些金属稳定的碳片段中的潜在化学，而不受依赖于一个签名金属端帽的限制。

Metal-stabilised carbon chains [M-(CC)x-M]n+ have attracted increasing interest over the last 10 years, mainly due to the remarkable changes in electronic structure which accompany changes in the formal oxidation state of the compounds. While much of this work has focussed on homobimetallic examples, recent synthetic advances make heterometallic examples accessible. This is a particularly exciting development as much of the work with homometallic polycarbon complexes has shown that distinctly different properties are imposed by different supporting metal fragments.The objective of this work is to synthesise and investigate the electronic properties of a series of compounds of the type [M-(CC)x-M']n+ in which the linking group Cx is an unsaturated carbon chain of four or more carbons and the metal end-caps M and M' are redox active, organometallic centres. A range of oxidation states (n = 0-4) is accessible of which some are stable, isolable systems. The electronic structures of this fascinating class of complexes are strongly dependent upon the identity of M and M'. However previous work has been restricted essentially to end-caps of group 7 and 8 transition metal centres of iron, ruthenium and rhenium in which the 3d metal centre Fe is much more strongly donating than the 4d/5d centres of Ru and Re. The innovation in this work is to include an organometallic end-cap featuring the group 6 metal molybdenum which is both strongly electron donating and based upon a 4d centre - this provides a unique opportunity to delineate the effect of end-cap electron donor capacity vs. metal transition series upon electronic structure. Further advantages that can be enjoyed through the introduction of Mo based end-cap group are the availability of a highly resolved spectroscopic handle (EPR) with which to investigate electronic structure by a direct experimental probe and the potential to control electronic structure in oxidised forms of the mixed group 6/group 8 heterobimetallics [M-(CC)x-M']n+ by control of molecular configuration.The work is of importance because it will lead to an enhanced understanding of the electronic structure of the unsaturated all-carbon bridge, and how this can be controlled as a function of the metal, the supporting ligands and the length of the carbon fragment. Although many talk of the need for such detailed understanding in the design of molecular components for future molecular based electronics, our goal is to arrive at a full understanding of the underlying chemistry in these metal-stabilised carbon fragments, free of the restrictions imposed by the reliance on one signature metal end-cap.