Inter- and intra-molecular condensation patterns of (en)PdII with trans-[a2PtL2]2+(a = am(m)ine, L = 2-aminopyridine): PtPd3 and Pt2Pd4 species with multiple amide bridges. Unexpected trapping of a pair of nitrate ions by a Pt2Pd4 double cone

Reaction of trans-[a2Pt(Hampy)2]X2(a = NH3, 2; a = MeNH2, 3; Hampy = 2-aminopyridine; X = NO3 or ClO4) with an excess of [(en)Pd (H2O)2]2+ in aqueous solution leads to two types of condensation products: (i) tetranuclear PtPd3 species, in which the deprotonated "a" ligands ((mu)-NH2, (mu)-MeNH) and the deprotonated amino group of the 2-aminopyridine (ampy) ligands are chelated by two (en) PdII entities and in addition a single PdII ion (without en) cross-links the amido functions of ampy in a nearly linear fashion. The four metal ions thus form a diamond arrangement with a short (<2.5 (angstrom) ) Pt(righr arrow)Pd dative bond. (ii) Hexanuclear Pt2Pd4 species, in which (en)PdII moieties bridge exclusively amido groups of four ampy ligands in such a way that an open rectangular box (or double cone) is formed. This allows two nitrate counter ions to become inserted in the cavity of the +8 charged cation. Thus in both cases the ampy ligand acts as a (mu)3-ligand, either in an intramolecular or an intermolecular fashion.