Copper(II) and Nickel(II) Complexes of Unsymmetrical Tetradentate Schiff Base Ligands

A systematic synthesis is described for new types of unsymmetrical tetradentate Schiff base ligands, from the condensation of different aldehydes and ketones with the two amino groups of 1,2-diaminobenzene. 5-Chloro-2-hydroxybenzophenone (HCBP), dissolved in methanol, reacts with one amino group of 1,2-diaminobenzene to form a tridentate Schiff base ligand (HCBP-PHEN). The free amino group of this ligand can then be reacted with a series of substituted salicylaldehydes (XSALH) to form unsymmetrical tetradentate Schiff base ligands (HCBP-PHEN-XSALH). These ligands react with copper(II) and nickel(II) acetates to form complexes of the type M(CBP-PHEN-XSAL). The physicochemical properties of a series of these complexes have been measured. The crystal structures of three of the copper complexes have been determined. Crystal data for [Cu(CBP-PHEN-SAL)]·CH 3OH: space group P1, Z = 2, a = 8.666 (4) Å, b = 10.061 (4) Å, c = 14.104 (8) Å, α = 103.01 (3)°, β = 104.38 (4)°, γ = 93.07 (2)°, V = 1153 Å 3, R = 5.5% for 2259 reflections. Crystal data for [Cu(CBP-PHEN-5-ClSAL)]·H 2O: space group P2 1/c, Z = 4, a = 15.296 (6) Å, b = 7.166 (2) Å, c = 25.288 (6) Å, β = 107.68 (3)°, V = 2641 Å 3, R = 6.9% for 1220 reflections. Crystal data for [Cu(CBP-PHEN-5-OCH 3SAL)]·CH 3OH: space group P1, Z = 2, a = 8.973 (3) Å, b = 10.148 (9) Å, c = 15.836 (5) Å, α = 98.80 (4)°, β = 118.35 (3)°, γ = 95.18 (5)°, V = 1232 Å 3, R = 6.4% for 1875 reflections. A 2-mol portion of 5-chloro-2-hydroxybenzophenone, in the absence of solvent, reacts, on refluxing, with 1 mol of 1,2-diaminobenzene to form the symmetrical tetradentate Schiff base ligand HCBP-PHEN-HCBP. The nickel(II) complex of this ligand has been prepared and its crystal structure determined. Crystal data for [Ni(CBP-PHEN-CBP)]: space group P1, Z = 2, a = 8.516 (3) Å, b = 10.783 (3) Å, c = 13.057 (3) Å, α = 78.82 (4)°, β = 80.40 (4)°, γ = 86.28 (2)°, V = 1295 Å 3, R = 5.6% for 2510 rejections. [Cu(CBP-PHEN-Im)] differs from its analogue in that it is hindered from forming the CuO 2Cu bridge with metal salts and hexafluoroacetylacetonate (hfa) complexes. However, it can still form adducts via imidazole bridging, and its adducts with Cu(hfa) 2 and Co(hfa) 2 were formed to demonstrate this. © 1985 American Chemical Society