Tridentate ligands, palladium complex

Figure 40 A conjugated homobimetallic palladium(II) complex, formed by one-pot oxidative complexation of 1,4-phenylenediamine with a palladium(II) complex bearing the tridentate ligand.

Tire early-late transition metal complex of Raymond et al. is interesting in that it requires both metal atoms to form the basic C3 structure (ideally D i, may form). Titanium complexation to three catechol units leads to a tridentate ligand, and, only when palladium bromide is added, trans coordination to palladium gives the agglomerate 31 [78]. 

A facile intramolecular hydroamination of unactivated alkenes (58), catalysed by the palladium complex (60), has been reported to take place at room temperature. The formation of hydroamination products (59) rather than oxidative amination products is believed to be due to the use of a tridentate ligand, which effectively inhibits -hydride elimination.78... 

The tetrahedral [160-163] and cis-planar [100,134,164-167] structures are characteristic for chelates of type 874 with coordination units NiN4 and MN2S2, respectively, as well as chelates 868 discussed above. Original polyhedral forms were discovered by x-ray diffraction for nickel and palladium ICC of the discussed type 874. It is accepted that, in case of a nickel complex, the compound with a carbon-carbon bond 875 is formed [165,166] formation of palladium chelates is accompanied by the cyclometallation reaction leading to tetranuclear clusters 876, where the tridentate ligand behaves as C,N,S-donor [168]. 

A fluorous palladium pincer complex for use in Heck reactions was reported by Curran (Reaction Scheme 11). The tridentate ligand ensnred stability under the high temperatures (140 °C) needed for the reaction to go to completion. The complex was recovered and rensed three times without any sign of lowered catalytic activity. 

Palladium complexes 31-32 with the tridentate chelate SCS ligands bound to poly(ethylene glycol) of a weight of 5000 was active in Heck reactions in DMFA solution in air. These catalysts were also separated by precipitation with ether and reused without loss of activity [67]. 

Tridentate nitrogen ligands have also been used, and an exceptional T -allyl palladium complex containing terpy (2,2 6, 2"-terpyridine) has been obtained as a result of the strong tendency of terpy to maintain tridentate coordination.t " ... 

Loch, J.A., Albrecht, M., Peris, E. et al. (2002) Palladium complexes with tridentate pincer bis-carbene ligands as efficient catalysts for C-C coupling. Organometallics, 21, 700-6. 

Figure 8 Coordination driven assembly to discrete structures (a) Fujita group s assembly with four tridentate ligands and six palladium atoms forms a tetrameric cage (b) Guanine derivatives assemble into planar tetramers that can use a metal coordinate to stack into more complex structures. ...

Some complexes of bidentate N-ligands are also treated here because of their similar synthesis or direct connection with chemistry of palladium(iv) complexes with tridentate ligands. 

A case where this may well be evident is in the square planar complex formed between the tridentate ligand diethylenetriamine, NH2-CH2-CH2-NH-CH2-CH2-NH2, dien, and palladium(II), [Pd(dien)(SeCN)]. In this complex the SeCN" anion is coordinated through Se and is bent. When the terminal... 

Chen and coworkers have synthesized a hybrid NHC-l,2,3-triazole tridentate ligand and its Ag(I), Pd(II), and Pt(II) complexes. Crystallography confirmed the tridentate coordination mode with the triazole unit bound through the N3 nitrogen. The palladium complex, 87, was found to be a highly active catalyst for the... 

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