Cyclometallated palladium

The reversible reaction of tri-n-butylstannylfuran with the cyclometallated palladium complex 24 yields the ti C) coordinated 2-furyl complex 25 (98JA11016). 

The cyclometallated palladium and platinum derivatives of trimesityl phosphine or arsine react with pyrazole or 3,5-dimethylpyrazole to form metal chelates 243 (E = P, As M = Pd, Pt R = H, Me) having the trans configuration (81TMC24). 

P-chiral dibenzophosphole oxide (52a) (Scheme 14) shows liquid crystalline behaviour [52], a property that is of interest in the area of electro-optical displays [53]. Chiral resolution of (52a) was achieved by column chromatographic separation of the diastereoisomers obtained following coordination of the o -benzophosphole (52b) to chiral cyclometallated palladium(II) complexes [52]. Notably, the presence of a stereogenic P-centre is sufficient to generate a chiral cholesteric phase. 

Cyclometallated iridium complexes, for OLEDs, 12, 145 Cyclometallated palladium(II) complexes from amines and pyridines, 8, 280 with C,C-chelating ligands, 8, 291 enantioselective synthesis, 8, 296 ferrocene-based palladacycles, 8, 292 four-membered palladacycles, 8, 297 imine- and oxime-based complexes, 8, 285 with N-N and N=N bonds, 8, 288 palladacycle catalysis, 8, 297... 

Many of the reactions outlined in Section 4 for Pd-C bonds occur in cyclometalated complexes. However, the existence of the Pd-C bond in a chelate ring imposes some kinetic stability on the bond. In general, mild acids and bases and oxygen are unreactive with cyclometalated palladium complexes. More vigorous reagents will lead to useful reactions, however. 

The formation of hydridopalladium complexes free of phosphine ligands (Figure 4) were observed when cyclometalated palladium chloride complexes were subjected to hydrogenolysis in DMF solutionsJ ... 

Ort/ o-cyclometallated palladium complexes discussed in Section 2.2.2 have found another very important application as chiral templates that promote Diels-Alder and other reactions. This chemistry has been developed by Leung and co-workers and has allowed the synthesis of an impressing number of mono- and diphosphines bearing P-stereogenic atoms with peculiar scaffolds... 

These alkenylations using five-membered ring compounds are widely employed in synthetic organic chemistry. The reaction of alkyl or aryl vinyl ketones with a cyclometalated palladium compound is shown as an example of alkenylation in Eq. (7.15) [72]. 

Table 8.3 Molecular weight, molecular weight distribution, and melting temperature of polyethylene obtained by using the imine cyclometalated palladium catalysts 8.94b and 8.94c [139]...

With respect to medical applications of cyclopalladation compounds, Ryabov [70] reported in 2008 that the first systematic study on the cytotoxicity of cyclometalated palladium compounds was undertaken by Higgins ni et al. [71], The compounds were saeened for cytotoxicity against a panel of seven human tumor cell lines, as shown in Table 9.1. 

Palladium(ii) carbonyls can also be prepared via bridge-splitting coordination of GO to halide-bridged dimers, such as shown in Scheme 4, to prepare cyclometallated palladium carbonyls 15 and... 

Dinuclear cyclometallated palladium(ii) complexes 81 have been obtained from Schiff base ligands. Cyclopalladated complexes of oximes 82 and 83 and their ligand-exchange reactions have been studied. Ketoximes form palladacycle dimers such as 84. " ... 

---