Monoprotic Tetradentate N(3)O-Donor Ligands and Their Cu(II) and Ni(II) Complexes

A convenient four-step procedure was developed to prepare the novel monoprotic tetradentate ligands N-(2-hydroxy)benzyl-N-methyl-N'-(2-pyridyl)methyl-1,3-propanediamine (Hpamap) and N-(2-hydroxy)benzyl-N'-methyl-N'-(2-pyridyl)methyl-1,3-propanediamine (Hpmaap), which provide an N(3)O metal coordination sphere. A mononuclear copper(II) complex, [Cu(pamap)Cl] (A), was obtained by reaction of Hpamap with CuCl(2).2H(2)O. The binuclear copper(II) complexes [Cu(pamap)](2)(BF(4))(2) (B) and [Cu(pmaap)](2)(BF(4))(2) (C) were obtained when these ligands were reacted with Cu(II) in the presence of the noncoordinating BF(4)(-) anion. Reaction of nickel(II) with the Hpamap ligand generated the binuclear Ni(II) complex [Ni(2)(pamap)(2)(NO(3))]NO(3) (D). The crystal of A (C(17)H(22)ClCuN(3)O) is orthorhombic Pbca (No. 61), a = 11.837(4) Å, b = 15.648(5) Å, c = 11.002(11) Å, Z = 8; that of B (C(34)H(44)B(2)Cu(2)F(8)N(6)O(2)) is triclinic P&onemacr; (No. 2), a = 9.147(0) Å, b = 10.375(0) Å, c = 10.535(1) Å, alpha = 107.20(0) degrees, beta = 91.19(0) degrees, gamma = 105.05(0) degrees, Z = 1; that of C (C(34)H(44)B(2)Cu(2)F(8)N(6)O(2)) is monoclinic P2(1)/c (No. 14), a = 9.158(2) Å, b = 10.714(2) Å, c = 19.085(4) Å, beta = 90.58(2) degrees, Z = 4; and that of D (C(34)H(44)N(8)NiO(8)) is monoclinic C2/c (No. 15), a = 13.849(0) Å, b = 13.609(0) Å, c = 19.558(1) Å, beta = 92.34 (0) degrees, Z = 4. The copper atoms of all three complexes are five-coordinate in the solid state, assuming the geometry of a distorted square pyramid with the deprotonated tetradentate ligand in the basal plane. The mononuclear complex A has a chloride ligand in the axial position, while each copper center in the binuclear complexes B and C has, in the axial position, a bridging phenolate O donor from the other unit of the dimer. Each nickel center in the binuclear complex D is six-coordinate, with the pseudo-octahedron formed by a deprotonated tetradentate ligand, a bridging nitrato oxygen atom, and a bridging phenoxy donor from the tetradentate ligand bound to the second nickel center.