Transition metal complexes, iron synthesis

Since the pioneering work by Sarel and co-workers on the iron carbonyl promoted transformation of vinylcyclopropanes and related compounds [1], a variety of transition metal complexes have been examined to achieve effective activation of the vinylcyclopropane-cyclopentene rearrangement which usually requires pyrolytic conditions. These reactions have been applied to natural product synthesis in some cases and have already been reviewed in several excellent articles [2-4]. 

In 1951, ferrocene was synthesized by Pauson [17] and Miller [18]. Soon after this synthesis, two groups led by Wilkinson and Fischer, independently reported that ferrocene has a stable carbon-iron 7r-bond [19]. This was the first example of a true organotransition metal complex containing a carbon-metal bond. Since then, numerous organotransition metal complexes have been prepared. The importance of these complexes as intermediates of many synthetic reactions has been discovered. More importantly, some transition metal complexes were found to behave as precursors of active catalysts. 

Abstract The transition metal complexes of the non-innocent, electron-rich corrole macrocycle are discussed. A detailed summary of the investigations to determine the physical oxidation states of formally iron(IV) and cobalt(IV) corroles as well as formally copper(III) corroles is presented. Electronic structures and reactivity of other metallocorroles are also discussed, and comparisons between corrole and porphyrin complexes are made where data are available. The growing assortment of second-row corrole complexes is discussed and compared to first-row analogs, and work describing the synthesis and characterization of third-row corroles is summarized. Emphasis is placed on the role of spectroscopic and computational studies in elucidating oxidation states and electronic configurations. 

During ATRP, alkyl halides function as initiators while transition metal complexes (ruthenium, osmium, iron, copper and so on) act as the catalyst. Metal complexes are used to generate radicals (such as peroxide) via a one electron transfer process and during this process the transition metal becomes oxidised. Thus, ATRP is a reversible-deactivation radical polymerisation and can be employed to prepare polymers with similar molecular weight (MW) and low MW distribution. Advantages of ATRP are the ease of preparation, use of commercially available and inexpensive catalysts and initiators [14, 15]. The synthesis and process development of ATRP, as well as some new hybrid materials made of amphiphilic polymers, have been reported in the literature (Figure 2.3) [16, 17]. 

The work described herein is directed towards the synthesis of alkylidyne complexes of the later transition metals, specifically iron. Two approaches present themselves for the synthesis of alkylidyne complexes which might otherwise be unstable, viz steric or electronic stabilisation. The first approach involves the accumulation of steric bulk in the vicinity of the metal-carbon multiple bond, an effect easily acheived for... 

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