Amino ligands

In addition, highly enantioselective nitroaldol reactions were performed by Bandini et al. by using a new class of C2-symmetric oligothiophene ligands, in 2007. Thus, associated to copper, these C2-symmetric bis(amino) ligands allowed the synthesis of a wide range of enantiomerically enriched nitroalcohols... 

Organozinc Compounds Bearing Chelating Amido/Amino Ligands 352... 

MYKONOS wind-mills (see below) the first figure refers to the munt r of atoms within the phosphazenic ring (6 = N3P3, 8 = N P ) and the second figure is connected with the number of atoms within the cyclic amino ligand (3 = Az, 5 = Pyrro). 

Although complexes with these ligands are common in palladium(II) chemistry, their occurrence is more scarce in platinum(II) compounds. Nevertheless these complexes can be prepared, examples being platinum(II) complexes of the optically active quadridentate Schiff base of salicylaldehyde and (R)-l, 2-diamines.1212 An alternative synthesis involves formation of the Schiff base by reaction of a complexed amino ligand on platinum(II) with amide acetates (equation 372).1213... 

Two recent reviews have appeared on the tridentate amino ligands.10,17 These amino acids will now be considered individually. 

In this article we describe the syntheses, structures, and physical properties of metal alkyls or aryls that have a further chelating amino ligand attached to the metallic center. These substances have been mainly developed in our laboratories in order to accomplish the following objectives ... 

The heteroaurate(I) [Au 2,6-(CH2NMe3)2C6H3 I]I is obtained in a different transfer reaction, a methyl group is transferred from Mel to the nitrogen atom of the ortho amino ligand, at the same time the quantitative precipitation... 

Burger et al. have shown that the presence of amino ligands at the metal enhances the thermal stability of primary, secondary and tertiary alkyl as well as allyl and vinyl titanium compounds dramatically 39). For example, n-propyltitanium tris(di-ethylamide) 16 can be isolated in pure form by sublimation at 60 °C/10-3 torr (68 %)39b>. 

Since substituted allyl titanium derivatives (e.g., crotyl) with amino ligands are sterically more demanding than the parent compound, they should display lower degrees of ketone-selectivity. However, this turned out not to be the case. The... 

If carbanions are to be titanated, alkoxy or amino ligands at titanium are most likely to ensure success. Sulfur or phosphorus ligands have not been tested. In rare cases electrontransfer instead of titanation sets in, forming Ti(III) species which are generally unsuitable for useful chemistry. This is most likely to occur if the carbanion is very electron rich, e.g., in case of dianions or extended anionic K-systems. We have noticed that this undesired property decreases in going from chloro to alkoxy and finally to amino ligands at titanium. For example, dianions derived from carboxylic acids reduce chlorotitanium triisopropoxide 3 to some extent, whereas quantitative double titanation occurs with chloro- or bromotitanium tris(diethylamide) 15 77>. Addition of amines to the reaction mixture has similar effects 77). 

The use of different triprotic acids or more sophysticated bidentate amino-ligands as well as the functionalization of preformed cages has increasingly lengthened the list of metal-azacage complexes available today [37]. 

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