Dinuclear palladium(ii) complexes with bridging amidate ligands

New homonuclear dimeric Pd(ii) complexes have been synthesized by the reaction of Pd(en)(2+) or Pd(bipy)(2+) (where en = ethylenediamine and bipy = 2,2'-bipyridine) units with acetamide or by the Pd(ii) mediated hydrolysis of CH(3)CN. In these dimers the two metal centers are bridged by either two amidates or by the combination of one hydroxo group and one amidate ligand. The crystal structures of complexes {Pd(bipy)](2)(micro-1,3-CH(3)CONH)(2)}(NO(3))(2).H(2)O.1/2(CH(3))(2)CO.1/2CH(3)CN () and {Pd(bipy)](2)(micro-1,3-CH(3)CONH)(2)}(OTf)(2) () showed intrametallic Pd-Pd distances of 2.8480(8) A () and 2.8384(7) A (), respectively, in accordance with the accepted values for a strong Pd-Pd interaction. The presence of pidot dot dot]pi interactions between the bipyridine ligands on the di-micro-amidate complexes of Pd(bipy)(2+) shortens the distance between the two Pd centers and allows the formation of the metal-metal interaction. By contrast, the crystal structure of complex {Pd(en)](2)(micro-1,3-CH(3)CONH)(2)}(OTf)(2).H(2)O (), (where OTf = triflate) where there is no pidot dot dot]pi interaction between the ligands on the metal centers, is also reported, and no Pd-Pd interaction is observed. Additionally, one of the complexes, {Pd(en)](2)(micro-OH)(micro-CH(3)CONH)}(NO(3))(2) (), presents an interesting hydrogen bonded 3-D network formed by nitrate ions and water molecules. All complexes have been characterized by infrared and (1)H NMR spectroscopy.