X-ray evidence of the metal ion tyrosine aromatic ring interaction in bis(L-tyrosinato)palladium(II)

Bis(hydrogenL-glutamato)palladium(II)

“…The maximum deviation from the least squares plane through the atoms Pd, N1, N2, O1 and O5 is 0.026 Å for N2. The distances Pd-O (1.976 (8), 2.024 (7) Å) and Pd -N (2.005 (11), 2.072 (9) Å) are in agreement with the values observed for other Pd(II) amino acid derivatives, like cisbis(L-tyrosinato)-palladium(II) hemihydrate (Jarzab et al, 1973), bis(L-tyrosinato)-palladium(II) (Sabat et al, 1979), bis-(L-valinato)-palladium(II) monohydrate (Pletnev et al, 1992); Hao et al, 2007), cis-bis(L-aspartato-N,O)-palladium(II) (Gao et al, 2008) or bis(L-serinato)-palladium(II) (Vagg, 1979). For both the hydrogen glutatmate ligands, the five membered PdNC 2 O chelate rings adopt envelope conformations with a nearly coplanar arrangement of the Pd, O, C and N atoms at the flap positions.…”

“…For the synthesis of the title compound, see: Spacu & Scherzer (1962). For the structures of related palladium complexes with amino acid ligands, see: Vagg (1979); Jarzab et al (1973); Sabat et al (1979); Pletnev et al (1992); Hao et al (2007); Gao et al (2008). Selected bond lengths (Å ).…”

Synthesis, Structure, and Catalytic Reactivity of Pd(II) Complexes of Proline and Proline Homologs

“…The benzyl groups on the ligands are oriented up and away from the proline ring, with one of the benzyl groups laying over the square plane. This is the same arrangement reported by Sabat [75] for the palladium(II)-tyrosine complex; however, in the case of 5 the second benzyl group does not lie over an adjacent metal center, but rather in the lattice space between complex molecules. This arrangement does suggest that there is a π-d interaction occurring between the metal and the aromatic ring of the ligand.…”

On the Involvement of Palladium Nanoparticles in the Heck and Suzuki Reactions

“…The appearance of the nanoparticles also did not change when the aqueous solvent was replaced by an organic medium (heptane, benzene, toluene, mesitylene). However, when the entrapped palladium acetate (1) was replaced by sol-gel entrapped Z-bis(-prolinato)palladium(II) (2), [6] Z-bis(-tyrosinato)palladium(II) (3), [7] or Z-bis(-alaninato)palladium(II) (4), [8] the catalyst did not form nanoparticles in detectable amounts during their entrapment within the ceramic matrix or during the coupling process (see Experimental Section). Unlike the reactions by Pd(OAc) 2 that could be performed in an aqueous medium under microemulsion/sol-gel transport (EST) conditions, [4] the coupling by the palladium derivatives of the amino acids had to be conducted in benzene (or in other hydrocarbons), because the immobilized palladium compounds leach readily into water.…”

“…Data analysis was performed with Vision processing data reduction software (Kratos Analytical Ltd.) and CasaXPS (Casa Software Ltd.). [4] 4-chloro-1,1Ј-biphenyl, [4] Z-bis(-prolinato)palladium, [6] Z-bis(-tyrosinato)palladium, [7] and Z-(-alaninato)palladium [8] were prepared according to literature procedures.…”