CRYSTAL-STRUCTURE OF BIS(ETHYLENEDIPHOSPHINETETRAACETIC ACID)PALLADIUM(II) ROGENETHYLENEDIPHOSPHINETETRAACETATO)PALLADATE(II) TETRAHYDRATE HYDROBROMIDE (1 1) - AN UNUSUAL CASE OF BROMIDE UNCOORDINATED TO PALLADIUM(II)/

Synthesis, crystal and molecular structure of the title compound as a representative of the complexes of phosphineacetic acids with soft met al ions is described. Crystal data: triclinic, P1BAR, a = 10.809(1), b = 14.922(1), c = 10.617(1) angstrom, alpha = 108.871(7), beta = 102.7 73(9), gamma = 102.970(7) degrees, Z = 1, R = 0.031 for 4 545 observed reflections. The structure is built of layers composed of hydrogen-bo nded ligands; the layers are joined, in alternate manner, by Pd(II) io ns, water molecules and bromide anions. As an average, one proton of t he tetraprotonated ligand is released during complexation even in prot ic solvent (aqueous acetic acid), resulting in the given ionic composi tion with non-equivalent Pd(II) centers. The carboxyl groups and, surp risingly, even the bromide ion are not coordinated to Pd. The proton a ssigned formally to hydrobromic acid was not located and is possibly d isordered.