Building Organometallic Complexes

Eighty percent of the periodic table is made up of metals. Generally speaking, metals are electron deficient, and the properties of metal compounds are a consequence of delocalized bonding of the electrons around the metal. 

In organometallic (OM) chemistry, metals that are electron deficient try to grab electrons from organic (carbon-containing) molecules so that they can 

Before you learn about how ligands bond to organometallic complexes, you need to understand the various electron rules that chemists use to predict the characteristics and behavior of metals when forming bonds. 

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The alkynyl-metal (metal-acetyhde) complex is one of the best building blocks for organometallic dendrimers, since it has some advantages compared to other organometallic complexes [18]. Most of the metal-acetylide complexes are thermally robust and stable, even when exposed to air and moisture. Metal-acetylide complexes are fairly accessible in high yields by well-established synthetic methodology [19]. These features are essential to the construction of dendrimers. 

In fact, as coordination and organometallic complexes may possess intense, low-energy MLCT, ligand-to-metal CT (LMCT), or intraligand CT (ILCT) excitations, the metal can effectively act as the donor, the acceptor, or the polarizable bridge of a donor-acceptor network. Finally, metal ions are well suited to build molecular structures based on octupolar coordination of organic ligands with D2 or D3 symmetry. 

All these results underlined the remarkable, nearly perfect fit of the natural product into a naturally unrelated biological target, and directed most of the synthetic efforts towards partial or total synthesis of paclitaxel rather than of its structural congeners. In the following three sections, the specific achievements of the three reactions catalyzed by organometallic complexes are presented, showing the key transformations that provide the key building blocks for paclitaxel. 

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