Antitumour copper(II) salicylaldehyde benzoylhydrazone (H2sb) complexes: Physicochemical properties and the single-crystal X-ray structures of [{Cu(H2sb)(CCl3CO2)2}2] and [{Cu(Hsb)(ClO4)(C2H5OH)}2].

Article abstract of DOI:10.1016/s0020-1693(97)05548-5

Copper(II) complexes of the antitumour ligand salicylaldehyde benzoylhydrazone (H₂sb) have been prepared. In the presence of strong acids, complexes of the neutral ligand were isolated: [{Cu(H₂sb)X₂}₂]·nH₂O (X = Br, n = 1; X = CCl₃CO₂, n = 0) and [Cu(H₂sb)Cl₂(H₂O)]. In weakly acid or neutral media, monoanionic compounds separated: [{Cu(Hsb)X}₂·nH₂O] (X = Cl, Br, NO₃, 0.5SO₄, n = 0; X = ClO₄, n = 1). With base, only the highly insoluble dianionic complex [{Cu(sb)}₂] was isolated. Also prepared was the related anionic ligand complex [Cu(Hsa)Cl(H₂O)]·H₂O (H₂sa = salicylaldehyde acetylhydrazone). The complexes have been characterised by a range of physicochemical techniques and the crystal and molecular structures of [{Cu(H₂sb)(CCl₃CO₂)₂}₂], [{Cu(Hsb)ClO₄(C₂H₅OH)}₂] and [Cu(Hsa)Cl(H₂O)]·H₂O, determined by single-crystal X-ray diffraction studies. Crystals of [{Cu(H₂sb)(CCl₃CO₂)₂}₂] are triclinic, space group P1, with a = 10.130(2), c = 11.660(2), c = 11.876(2) A?, α = 67.07(2), β = 109.09(2), γ = 107.84(2)° and Z = 2. The complex is a centrosymmetric dimer, the monomeric units being bridged through the phenol oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate 'ONO' donor ligand and the symmetry-related phenol oxygen. The more weakly bound axial donor oxygens are from the coordinated trichloroacetates. Crystals of [{Cu(Hsb)ClO₄(C₂H₅OH)}₂] are monoclinic, space group P2₁/c, with a = 11.2281(8), b = 7.9129(4), c = 21.043(1) A?, β = 98.560(6)° and Z = 4. This complex is also a centrosymmetric dimer, the monomeric units being bridged through the phenoxy oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate 'ONO' ligand and the symmetry related phenoxy oxygen. The more weakly bound axial donor oxygens are supplied by the ethanol and perchlorato moieties. Crystals of [Cu(Hsa)Cl(H₂O)]·H₂O are monoclinic, space group P2₁/c, with a = 7.4877(4), b = 15.5806(7), c = 10.5208(3) A?, β = 103.56(4)° and Z = 4. The complex is monomeric with the copper(II) adopting a square-pyramidal coordination. The four in-plane donors are provided by the tridentate 'ONO' donor Hsa and an oxygen from a coordinated water molecule; the axial site is occupied by the chloride ion. Most of the complexes have low magnetic moments and are assigned dimeric side-by-side structures. Powder ESR spectra have g∥ and g⊥ resolved often with ΔM_S = 2 transitions present.