Palladium bridging ligand

The new arsino(phosphino)methanes with bulky substituents at the two donor centers can behave both as chelating and bridging ligands toward palladium(II). Besides neutral and mono- as well as di-nuclear cationic compounds, in which these ligands are bonded in a chelating fashion, a di-nuclear complex of the A-frame type could also be generated (see Scheme 5).396... 

Figure 86 Compound containing a full M2L4 helical cage that has each square-planar palladium atom coordinated to the four bridging ligands and within which resides a well-ordered PF6 ion.

Reactions and Structures of Palladium Complexes Containing Bis(diphenylphosphino)methane as a Bridging Ligand... 

The Pd—Pd bond length lies between 2.61 A (for 84) and 2.72 A (for 57), varying surprisingly little for the different types of bridging ligands. This relatively short distance, comparable with the interatomic distance in metallic palladium (2.74 A), points to the existence of a direct metal-metal bond. 

Simons et al. [487] used these pincer carbene ligands in the synthesis of silver(I), palladium(II) and rhodium(l) pincer carbene complexes (see Figure 3.167). Similar to the Anker-free pincer carbene ligands, [Rh(cod)Cl]2 proved to be an unsuitable starting material to synthesise a rhodium(l) pincer carbene complex [462]. The ligand acted as bridging ligand to two [Rh(cod)Cl] units instead. 

Monodentate bridging ligands snch as SO2, PPh2, and CO usually lead to nuclearities higher than two. Several examples of homo- and heteronuclear, three or four-member palladium clusters that adopt a variety of geometries are known. 

Dipalladium(II) complexes with N,0-bridging ligands, mhp and chp, were prepared by reaction of palladium(II) acetate with Na(mhp) or Na(chp) in dichloromethane (82, 82). Recrystallization of the former from methanol gives the fnms-isomer exclusively. However, recrystallization from chloroform gives a sample containing the cis-isomer. 

A related series of palladium(II) azobenzene complexes with halogen bridging ligands has been prepared by Ghedini, in which the chirality was present in one of... 

To examine the relationship between the low-energy luminescence and intramolecular metal-metal distances, a series of [Pt2(CANAN)2(/U-L)]n+ (HCANAN=4-(aryl)-6-phenyl-2,2 -bipyridine) derivatives supported by different bridging ligands (L) have been prepared by Che and coworkers [17]. Subsequent spectroscopic assignments of cyclometalated platinum(II) or palladium(II) derivatives were made by comparing their emission energies with those of the [Pt2(CANAN)2(//-L)]n+ complexes. 

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