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Synthesis and structural characterization of a novel palladium Pd(II) complex with the amino acid L-citrulline (Cit, C6H13N3O3) are presented in this paper. Elemental analysis indicates a 1:2 metal/ligand molar composition for the complex, with the molecular formula PdC12H24N6O6. The compound was also characterized by infrared (IR) spectroscopic measurements and the crystal structure has been solved by powder X-ray diffraction data with simulated annealing strategy in real space. The Pd(II) complex crystallizes in the triclinic system with space group P-1 and cell parameters a = 4.6493(4) Å, b = 5.222(4) Å, c = 18.040(2) Å, α = 77.41(6)°, β = 94.72(7),° and γ = 101.45(7)°. The crystal structure confirms the presence of Pd(II) ions in a nearly square planar environment and the molecular formula with deprotonated citrulline as proposed by analytical and spectroscopic data.

Powder X-ray diffraction studies of a lithium salt of thiazolidine-4-carboxylic acid (Li-TC4) of composition LiC4H6NSO2 are presented in this paper. Analysis of the synchrotron powder X-ray diffraction data showed that the complex has an orthorhombic symmetry with space group P212121. Unit cell parameters after the refinement using the Pawley method are: a=19.4931(3) Å, b=4.947 77(6) Å, c=6.201 64(8) Å, and V=598.051 Å3.

Powder X-ray diffraction data for a new palladium(II) amino acid complex, of composition PdC12H20N2O4S2, are presented in this paper. Orthorhombic cell parameters are: a=10.740 Å, b=19.999 Å, and c=5.2470 Å. © 2004 International Centre for Diffraction Data.

Powder X-ray diffraction data for methionine sulfoxide, C5H11NO3S, obtained from the commercial amino acid, are presented in this work. Monoclinic cell parameters are: a=15.500 Å; b=3.820 Å; c=13.490 Å; β=97.300 °.

Djenkolic acid (C7H14N2C)4S2-.!>,S''-methylenebiscysteine, Figure 1) is an amino acid of vegetal origin which is contained in the seeds of Acacia species and in djenkol beans (Pithecolobium lobatum). Besides the two pairs of carboxylic and amino groups, it also contains two sulfur atoms connecting the methylene groups in a way similar to that of thioeters, but different from a typical sulfur present in other natural amino acids. A recent reference (Dictionary of Natural Products, 1997) mentions the structure determination of djenkolic acid as an accomplished fact. However, closer examination surprisingly shows that the crystal structure has actually been determined only for its derivative (Bigoli et al., 1982), S,S'-methylenebiscysteine monohydrochloride. The only data available on djenkolic acid itself is a private communication by Eli Lilly & Co reporting a set of relative intensities (IIIo) and interplanar distances (d) for a sample of unknown origin and characteristics (Powder Diffraction File, 1994). Djenkolic acid is known to possess a net biological activity, but its effects are quite unpredictable, varying from nervous reactions to serious toxic complications and even anaphylaxy (Jarusiripipat et al., 1988). It seems rather peculiar that a substance which is part of nutrients and has the ability to trap free radicals might be so toxic. Pharmacologically speaking, we may be dealing with a system with another component that is responsible for "switching on or off" the cited reactions and consequent clinical manifestations. Several well-known examples are calcium ions and blood coagulation system factors; potassium and digitalic alkaloids; and so forth.