The influence of the intramolecular hydrogen bond on the 1,3-N,S- and 1,5-O,S-coordination of N-phosphoryl-N′-(R)-thioureas with Ni(ii) and Pd(ii)

Abstract

Reaction of the potassium salts of N-phosphorylated thioureas of common formula R¹–N(H)–C(S)–N(H)–P(O)(OiPr)₂ (HA) with Ni^II and Pd^II cations leads to [MA₂] chelate complexes (M = Ni^II, R¹ = p-MeOC₆H₄, p-BrC₆H₄, t-Bu, c-Hex; M = Pd^II, R = iPr). In both the Ni^II and Pd^II complexes, the metal center is found in a square-planar N₂S₂ environment formed by the CS sulfur atoms and the P–N nitrogen atoms of two deprotonated ligands A⁻. The Pd^II atoms in [PdB₂] complexes with deprotonated thioureas of common formula R²–C(S)–N(H)–P(O)(OiPr)₂ (HB) (R² = Et₂N, morpholine-N-yl) are coordinated in a square-planar fashion by the CS sulfur atoms and the PO oxygen atoms of two anionic ligands. Molecular structures of four complexes [M(A-N,S)₂] (M = Ni^II, R¹ = p-MeOC₆H₄, p-BrC₆H₄, t-Bu; M = Pd^II, R¹ = iPr) and the palladium(II) 1,5-O,S-chelate of formula [Pd(B-O,S)₂] (R² = morpholine-N-yl) were elucidated by X-ray diffraction.