Chemistry of palladium(II) with bis(3-amidopyridine) ligands

• The coordination chemistry of ligands Ar(CONR-3-C5H4N)2 with Pd(II) is reported.
• When Ar = 2,6-C5H3N and R = H, helical bridged complexes are obtained.
• When Ar = 1,3-C6H4 and R = H, eclipsed bridged complexes are obtained.
• When Ar = 1,3-C6H4 or 2,5-C4H2S and R = Me, chelate complexes are obtained.
• The bridged complexes can accommodate guest molecules.

The coordination chemistry of palladium(II) with bis(3-amidopyridine) ligands [LL = 2,6-C5H3N(CONH-3-C5H4N)2, 1; 1,3-C6H4(CONH-3-C5H4N)2, 2; 1,3-C6H4(CONMe-3-C5H4N)2, 3; 2,5-C4H2S(CONMe-3-C5H4N)2, 4] has been investigated. Neutral binuclear macrocyclic complexes trans,trans-[Pd2X4(μ-LL)2] have been characterized with X = Cl or Br and LL = 1. Cationic complexes have been characterized as mononuclear bis(chelate) derivatives [Pd(LL)2]2+, when LL = 3 or 4, but a lantern complex [Pd2(μ-LL)4]4+, when LL = 2. The tendency for chelation versus bridging coordination of the flexible ligands 1–4 is analyzed in terms of substituent effects on the preferred ligand conformations. In the dipalladium complexes, the macrocycle or lantern structure can accommodate guest molecules.

The ligands LL = 2,6-C5H3N(CONH-3-C5H4N)2, 1; 1,3-C6H4(CONH-3-C5H4N)2, 2; 1,3-C6H4(CONMe-3-C5H4N)2, 3; 2,5-C4H2S(CONMe-3-C5H4N)2, 4] have given neutral binuclear macrocyclic complexes trans,trans-[Pd2X4(μ-LL)2], X = Cl or Br and LL = 1, and cationic complexes [Pd(LL)2]2+, when LL = 3 or 4, and a lantern complex [Pd2(μ-LL)4]4+, when LL = 2. The macrocyclic and lantern structures can accommodate guest molecules.Figure optionsDownload as PowerPoint slide