Nitrogen-containing phosphine ligands

A common procedure for quaternization of an amine is the use of Meerwein s salt or Mel (excess). In the alkylation of amine-containing phosphine ligand, the nucleophilic P-atom could potentially compete with N-alkylation and therefore precomplexation with the 

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Figure 7. Nitrogen-containing phosphine ligands (continued)...

The majority of nickel(I) complexes contain phosphine ligands, or closely related ones, and have tetrahedral or tbp structures. They are paramagnetic as expected for d9 configurations. The tetrahedral compounds NiX(PPh3)3 (X = Q, Br, and I) were among the first of this sort to be isolated they decompose only slowly in air and are stable for long periods of time under nitrogen. Electrolytic reductions of... 

Nitrogen-containing phosphines (Figure 15) remain in the center of ligand synthesis. One reason for this may be in the solubility of the (unprotonated) amines in common organic solvents which allows the use of the methods of conventional organic synthesis. An additional aspect is in that amines can be further functionalized by several ways, for example as seen in 2.6 above. Another example is the reaction of 160 (diam-BINAP) with 2,6-tolylene diisocyanate affording an enantiopure polymeric... 

Synthetic procedures for the preparation of nitrogen-containing tertiaiy phosphines comprise the methods described in some detail in the preceeding sections L2 and L3. Representative examples of these ligands are shown in Figures 6 and 7. Several of these compounds are nowadays available commercially. A detailed review on pyridylphosphines [59] appeared in 1993. 

The complexes [lr(COD)(NCMe)(PR3)]BF4 (PR3 = P Pr3, PMe3), which are closely related to Crabtree s catalyst, also contain mixed ligands, very basic phosphines, P Pr3 or PMe3, and a nitrogen donor ligand, acetonitrile. These mixed-ligand pair combinations have been shown to be very useful for spectroscopic observations and have provided detailed information on the mechanism of reactions performed by those complexes [9, 10]. 

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