Ligand choice

The reduction potentials are dependent upon ligation of the gold species. Stabilization of either gold oxidation state can occur with suitable ligand choice [8, 9] (CyS is cysteinato) ... 

In homogeneous catalysis ligands play a related role with respect to selectivity. Many different complexes may be formed in a solution the desired reaction occurs only on a particular one. Ligand choice determines the particular complex formed that results in the desired product. 

Shao, N., Jin, J., Wang, G, et al. (2008) Europium(lll) complex-based luminescent sensing probes for multi-phosphate anions modulating selectivity by ligand choice. Chemical Communications, 1127-1129. 

The recommendations for ligand choice as a function of alkene substitution can be summarized as follows (The structures of the ligands are given in Table 5). 

This catalysis nicely displays the way in which the electronic and steric properties of the organometallic catalytic complexes contain the three-dimensional prescription code for the precise assembly of product molecules from substrate molecules. The results are another demonstration of the importance of ligand choice in homogeneous catalysis. In this particular instance, the choice of neutral... 

Ligand attachment to DNA carriers may not only affect cellular uptake but may also have important implications on their intracellular trafficking [181]. Ligand choice should, therefore, consider intracellular trafficking in addition to target cell specificity and increased uptake. 

Ruthenium complexes used to lead research in photochemistry of metal compounds, but rhodium complexes have recently overtaken them as the key target compounds due to their applications in OLEDs. This is a lively and ever-changing field for example, over 90% of luminescent iridum(III) complexes have been reported only in the six years to the beginning of 2009. With their luminescence tuneable through ligand choice, iridium complexes are firm candidates for optical display applications. 

This ligand class is quite useful for the synthesis of unsymmetrical alkyl diaryl amines.39 Typically, a primary aliphatic amine is first arylated using the Pd/BINAP catalyst system. The second arylation is then carried out with L6, Xantphos, or PPF-OMe (with CS2CO3 if a base sensitive aryl bromide). Ligand choice for the second arylation depends upon the electronic nature of the N-alkylaniline and Ar2Br as outlined in the table. They were unable to couple 2-bromobenzaldehyde, 4-(4 -bromophenyl)-2-butanone, or 4 -bromoacetophenone with N-alkylanilines (alkyl > Me). 

In comparison, group 9 metals can generate either the linear or the branched isomer, depending on the nature of the ancillary ligands and are thought to proceed by oxidative addition/syn-insertion/reductive elimination. Reactions of alkane thiols were achieved for the first time with Rh and later with Pd and actinides. Depending on the metal and ligand choice, either the branched or linear product can... 

Steric saturation, not electron count, decides structure, so steric considerations dominate ligand choices. 

Metal exchange reactions have been used in the preparation of heavy alkali organometallics by reaction of alkali metal alkoxide or aryloxide with an organolithium reagent under precipitation of lithium alkoxide/aryloxide. For these reactions, careful ligand choice enables the separation of the two solid reaction products. Two variants of this reaction for alkaline-earth metal organometallics... 

---