Complexes of palladium(II) chloride with 3-(pyrazol-1-yl)propanamide (PPA) and related ligands

Abstract

Four new derivatives of the versatile polyfunctional ligands 3-(pyrazol-1-yl)propanamide (1, = PPA) and 3-(3,5-dimethylpyrazol-1-yl)-propanamide (2, = Me2PPA) have been prepared, in which one of the amide hydrogens on 1 and 2 is formally replaced by alkyl residues. X-Ray diffraction studies revealed that, in contrast to 1 and 2, the N-isopropyl substituted derivatives 3 and 4 form supramolecular hydrogen-bonded chains rather than two-dimensional arrays, and the N-(2-methyl-4-oxypentan-2-yl) (=MOP) substituted compounds 5 and 6 exist as cyclic dimers in the solid state. Reactions of PdCl2(COD) (COD = 1,5-cyclooctadiene) with 2 equiv. of the corresponding ligands 1–6 in all cases afforded trans-PdCl2(L)2 complexes (7–12). X-ray crystal structure determinations of 8, and 10–12 revealed κN-monodentate coordination of the PPA-type ligands.