Synthesis of binuclear complexes of PdCl2 with chiral ethylenediamine dioxime (H2L1), piperazine dioxime (H2L2), and propylenediamine dioxime (H2L3), the derivatives of the natural monoterpenoid (R)-(+)-limonene. The crystal structures of [Pd2(H2L1)Cl4] and [Pd2(H2L2)Cl4]

The diamagnetic complexes [Pd-2(H2L1)Cl-4] (I), [Pd-2(H2L2)Cl-4] (II), and Pd-2(H2L3)Cl-4(III) with chiral ligands derived from the natural monoterpenoid (R)-(+)-limonene are obtained (H-2 L-1 is ethylenediamine dioxime, H2L2 is piperazine dioxime, and H2L3 is propylenediamine dioxime). According to X-ray diffraction data, the crystal structures of complexes I and II are composed of binuclear acentric molecules. The coordination polyhedra PdN2Cl2 are trapeziums (squares distorted in a tetrahedral manner) made up of two N atoms of the tetradentate bridging cyclic ligands H2L1 and H2L2 and two Cl atoms. The fragments PdCl2 are trans in the complexes. The C-13 and H-1 NMR spectra of complexes I and II in CDCl3 also suggest their binuclear structures.