Palladium(II) complexes of tridentate chalcogenated Schiff bases and related ligands of (S, N, S/Se/Te) type: Synthesis and structural chemistry

The reactions in CH3CN between PdCl2 and Schiff base ligands, 2-MeSC6H4–CHNCH2CH2E–C6H4–4-R (L1–L3) (E = S or Se, R = H; E = Te, R = OCH3) and their reduced derivatives 2-MeSC6H4CH2–NHCH2CH2E–C6H4–4-R (L4–L6) followed by treatment with AgPF6 or AgClO4 have resulted in complexes [PdCl(L)][X] (1–6; L = L1–L6; X = PF6 or ClO4) which have been characterized by IR, 1H, 13C{1H}, 77Se{1H} and 125Te{1H} NMR spectroscopy. Single crystal structures of complexes 1–6 reveal nearly square planar geometry around palladium in all of them (Pd–Se = 2.4045(16)–2.4065(6) Å; Pd–Te = 2.5052(9)–2.5307(13) Å). The various non-covalent interactions in the crystals result in the formation of chains, rings and caging of anions between cations.

Ligands 2-MeSC6H4CHNCH2–CH2E–C6H4–4-R (L1–L3) and 2-MeSC6H4CH2–NHCH2CH2E–C6H4–4-R (L4–L6) (E = S/Se, R = H; E = Te, R = OCH3) form complexes [PdCl(L)][X] (1–6; L = L1–L6; X = PF6 or ClO4), characterized by multinuclei NMR, IR and X-ray crystallography. Pd–Se/Pd–Te = 2.4045(16)–2.4065(6)/2.5052(9)–2.5307(13) Å. Secondary interactions in the crystals result in chains or rings.Figure optionsDownload as PowerPoint slideHighlights
► Pd(II) complexes of 2-MeSC6H4CHNCH2CH2EAr (E = S, Se, Te) and their reduced forms were synthesized.
► Signals in 125Te and 77Se NMR are deshielded significantly on complex formation.
► Single crystal structures showed square planar geometry of Pd in all complexes.
► Non-covalent interactions resulted chains/rings.