Ligand chemistry

Sone, T., Iwata, M., Kasuga, N. and Komiya, S. (1991) Drmethylgod(III) aryloxides and alkoxides having a triphenylphosphrne ligand. Chemistry Letters, 20, 1949. 

The catalysts used in hydroformylation are typically organometallic complexes. Cobalt-based catalysts dominated hydroformylation until 1970s thereafter rhodium-based catalysts were commerciahzed. Synthesized aldehydes are typical intermediates for chemical industry [5]. A typical hydroformylation catalyst is modified with a ligand, e.g., tiiphenylphoshine. In recent years, a lot of effort has been put on the ligand chemistry in order to find new ligands for tailored processes [7-9]. In the present study, phosphine-based rhodium catalysts were used for hydroformylation of 1-butene. Despite intensive research on hydroformylation in the last 50 years, both the reaction mechanisms and kinetics are not in the most cases clear. Both associative and dissociative mechanisms have been proposed [5-6]. The discrepancies in mechanistic speculations have also led to a variety of rate equations for hydroformylation processes. 

Small-molecule isocyanides possess a ligand chemistry which is only slightly less well-developed (5). 

Berger, I., Hanif, M., Nazarov, A. A., Hartinger, C. G., John, R. O. Kuznetsov, M. L. et al. In Vitro Anticancer Activity and Biologically Relevant Metabolization of Organometallic Ruthenium Complexes with Carbohydrate-Based Ligands. Chemistry Europ. Journal 14, 9046-9057 (2008). 

Apart from this one-reaction type, the routine use of metal template procedures for obtaining a wide range of macrocyclic systems stems from 1960 when Curtis discovered a template reaction for obtaining an isomeric pair of Ni(n) macrocyclic complexes (Curtis, 1960). Details of this reaction are discussed later in this chapter. The template synthesis of these complexes marked the beginning of renewed interest in macrocyclic ligand chemistry which continues to the present day. 

Resulting from the widespread interest in macrocyclic ligand chemistry, an impressive array of synthetic procedures for macrocyclic systems has been developed. In spite of this, the synthesis of a new ring system frequently turns out to be far from trivial. Indeed, synthetic macrocyclic chemistry is often very challenging and, as well as a thorough knowledge of any metal-ion chemistry involved, skill in the subtle art of organic synthesis is also a valuable asset for those involved in the preparation of new cyclic systems. 

Binding to Via functional groups following Via ligand chemistry, only few... 

Hydroformylation is an addition reaction of a hydrogen atom and a formyl group to an olefin to form two isomeric aldehyde products (Equation (1)). Both the aldehyde products are important chemicals //or///< /-aldehydes are industrially important because they are widely used for detergents and plasticizers the /i-o-aldehydes can be important intermediates for production of fine chemicals and drugs once the chiral center at the a-carbon to aldehyde is controlled. Progress in hydroformylation exactly traces that in the phosphine ligand chemistry and valuable aldehyde products have become available on an industrial scale. 

Although the preparations of transition metal complexes with tellurium ligands often involve similar methods to those used for the synthesis of analogous selenium compounds, the ligand chemistry of tellurium has by no means achieved the scope of that now known for selenium. 

The ligand chemistry of heterocyclic tellurium compounds has been examined over several years.85 86-92 104-106 The study105 of the monomeric (6) and dimeric (7) complexes, which were obtained from the reaction of Na2PdCl4 and tellurophene and separated by their solubility differences in acetone and chloroform, is illustrative of the preparative chemistry and characterization techniques used in this area of chemistry. 

Over recent years there has been a trend in super- and supramolecular chemistry towards the synthesis of extended molecular entities that are multi-component in nature. Such a trend has also occurred in macrocyclic ligand chemistry. 

---