Palladium complexes tetranuclear

A number of Pd-Go carbonyl dimers and clusters have been prepared, either by reacting neutral cobalt carbonyl clusters or by anionic cobalt carbonyl metallates with palladium complexes. Treatment of either Pd4(/x-Gl)3-(/i3-GH)(PBu 3)4 or Pd2(/i-X)2(PBu 3)2 with Go2(GO)8 gives the tetranuclear cluster GoPd3(/X3-X)(/x-GO)3-(/X3-G0)(G0)(PBT3)3 48 (X = G1, Br, The M4 core is intermediate between a distorted tetrahedron and a... 

Biimidazole and bibenzimidazole with [(ri -2-RC3H )Pd(p-Cl)]2 (R = H, Me) taken in the 2 1 molar ratio in the presence of methanolic potassium hydroxide give complexes of the type 146 (83JCS(D)1729) and with [(ti -2-RC3H ) Pd(Mc2C0) ](C10 ) - 147. When the ratio of 2,2 -biimidazole or 2,2 -bibenz-imidazole and [(Ti -2-RC3H )Pd(p-Cl)]2 (R = H, Me) is 1 1, the homo-tetranuclear species 148 result. Heterotetranuclear palladium(II)-rhodium(I) complexes 149 (L2 = cod) follow from [(TiLcod)Rh(Hbim)] and [(ri -2-R-C3H )Pd(acac)]. They are readily carbonylated with complete substitution of... 

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]. 

The lanthanide metals, with their larger coordination numbers, invariably have the ligand coordinated in either a trismonodentate or a tetrakismonodentate fashion (42, 55, 57) (see Figs. 10 and 11). Thus, the ligand apparently tends toward the maximization of its coordinating capacity where circumstances allow, giving rise in many cases to the formation of sheet or cage structures. Limited chain formation was observed in the platinum, palladium, and rhodium complexes described, while the molybdenum complexes described by Hilbers et al. consist of dinuclear and tetranuclear units. 

Stang and Cao have reported the novel preparation and characterization of platinum- and palladium-based cationic, tetranuclear, macrocyclic complexes... 

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