Bis amide ligand

Figure 2.13 Selected examples of gold(lll) complexes containing chelating bis(amidate) ligands.

Kilpin, K.J., Henderson, W. and Nicholson, B.K. (2007) Organogold(III) complexes containing chelating bis (amidate) ligands Synthesis, characterisation and biological activity. Polyhedron, 26, 434. 

Dianionic bis(amide) ligands bearing additional donor atoms have been described by several researchers. High activities for ethylene polymerization are observed for pyridyldiamido zirconium complexes such as (42) (1,500gmmol-1 bar-1 h-1),145 although the corresponding titanium complex is much less active.146... 

Amine—bis(amide) ligands, in chromium(III) models, 5, 376 Amine 7V-oxide promoters, in Pauson—Khand reaction with dicobalt octacarbonyl, 11, 337 Amines... 

Fig. 23. ORTEP plot of the R form of Irans-dioxoosmium(VI) of the binaphthyl bis( amide) ligand. From Ref. (227).

Relaxivity and other studies on other Gd DTPAbis(amide) complexes have been reported Dissociation kinetics of Ce and Gd complexes of bis(amide) ligands derived from DTPA have been studied. Complexes of a new octadentate ligand H5BOPTA (23) similar to DTPA have been made. 

An early example of amidate ligands being utilized with early transition metals was reported in 2001 by Giesbrecht et al. [10a] A tethered bis(amidate) ligand was used to prepare a dimeric species (Figure 14), which was tested for ethylene polymerization. In the presence of 500 equiv. of MAO at 1 atm ethylene gas only modest catalytic activity was observed. [10a]... 

Ph2CHNH2,2 TMSCN, Na2S04, DCE chiral bis(amide) ligand, 10 h, -20°C... 

J ,J )-configured ligand also attacks the enolate from its 5i-face as well. The cartoons shown in Scheme 5.42 may serve to illustrate why opposite enantiomers of the palladium catalyst both lead to (/ )-allyl tetralone 15. It seems that the t-butyl-PHOX ligand is too sluggish to react with cyclic ally substrates like 127. Therefore, it remains open whether Trost s proof of the outer-sphere mechanism is restricted to the C2-symmetric bis-amide ligands. Despite the discrepancy in the stereochemistry of the mechanism, the asymmetric decarboxylative allylic alkylation enjoyed manifold applications in total synthesis [62]. 

Bis(phenolate) ligands are also present in two new lanthanide guanidinate complexes shown in Scheme 60, which were prepared by insertion of diisopropylcarbodiimide into the Ln-N bonds of appropriate neutral lanthanide amide precursors. ... 

Following the general trend of this account, monodentate phosphinous amide ligands and bidentate AT-phosphino phosphinous amides or bis(amino-phosphanes) are included in the following discussion, but not other bidentate ligands bearing additional, different phosphorus functionalities, as for instance phosphinous amide-phosphane bidentate ligands. 

Scheme 10.81 Y-catalysed hydroaminations of 2-amino-5-hexene with bis(thiopho-sphonic amidates) ligands.

Scheme 10.82 Y-catalysed hydroamination of 1-amino-2,2-dimethyl-4-pentene with bis(thiophosphonic amidates) ligand.

Zirconium bis(amides) such as (35) and (36) display moderate ethylene polymerization activities.133,134 Complex (37) containing a chelating diamide ligand has been shown to initiate the living polymerization of a-olefins such as 1-hexene (Mw/Mn= 1.05-1.08) with activities up to 750gmmol-1 h-1.135-137 The living polymerization of propylene using this system activated with... 

Pritchett et al.119 found that Ti(OPr )4 did not react with the bis(sulfon-amide) ligand itself, so they postulated that a chiral ligand initially reacted with the diethylzinc and was subsequently transferred to the titanium in the next step. Based on this assumption, they presented an improved procedure for the asymmetric alkylation of aldehyde to overcome the poor solubility of the li-... 

Enantiomeric excesses of up to 76% have been obtained for alkyllithium-aldehyde condensations using 3-aminopyrrolidine lithium amides as chiral auxiliaries. Addition of organolithiums to imines has been achieved with up to 89% ee, in the presence of C2-symmetric bis(aziridine) ligands. ... 

Fig. 16. Prototropic exchange rates at the coordinated water molecule in Gd complexes of a series of bis-amide DTPA ligands 173).

A recent report on bimetallic ytterbium bis(amides) 116 and 117 stabilized by a flexible bridged bis(phenolato) ligand claimed a straightforward polymerization of L-lactide. The conversion is characterized by short reaction times (30 min to 2 h) and PLAs displaying broad PDls (1.71-2.24). The reason for the apparent enhancement of the activity found in the bimetallic lanthanide amides is tentatively explained by cooperative effects within these bimetallic systems [114]. 

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