Synthesis and crystal structure of the novel chiral o-hydroxyphenyloxazoline metal complexes

The chiral o-hydroxyphenyloxazoline ligands were synthesized and their metal complexes with Cu, Ni and Ti were prepared. The crystal structure of complex 2a formed by ligand 1a with Cu (molar ratio 2:1) was determined by single-crystal X-ray diffraction analysis, and it belongs to monoclinic, space group P2₁ with a = 11.679(2), b = 17.681(4), c = 12.838(3) Å, β = 106.50(3)°, C₂₆H₃₂N₂O₄Cu, M_r = 500.08, V= 2541.8(9) ų, Z = 4, F(000) = 1052, D_c = 1.307 g/cm³, μ = 0.892 mm^-1, the final R = 0.0448 and wR = 0.0930 (I > 2σ-(I)). In the asymmetric unit of complex 2a, there exist two types of molecules which are self-associated by intermolecular O⋯Cu interactions, and "dimeric complex" is thus formed. The distances of the Cu and O atoms of a pair of intermolecular coordinated molecules are 2.828 Å for Cu(1)⋯O(21) and 2.776 Å for Cu(2)⋯ O(13), respectively. The coordination N and O atoms and the central Cu are slightly deviated from coplanarity.