ZINC(II) AND CADMIUM(II) COMPLEXES OF THE POTENTIALLY TRIDENTATE LIGANDS 2-[[2-PYRIDINYLMETHYL)AMINO]METHYL]PHENOL (HSALAMP) AND 2-[[[2-(2-PYRIDINYL)ETHYL]AMINO]METHYL]PHENOL (HSALAEP) - X-RAY CRYSTAL-STRUCTURES OF THE [ZN(SALAMP)(NO3)]2 AND THE [CD(SALAEP)(NO3)]2 DIMERS

Zinc(II) and cadmium(II) complexes with two potentially tridentate (NN O) ligands 2-[[(2-pyridinyl-methyl)amino]methyl]phenol (HSALAMP) and 2 -[[[2-(2-pyridinyl)ethyl]amino]methyl]phenol (HSALAEP) have been isola ted and structurally characterized through H-1, C-13 and 2-D NMR spect roscopy and in two cases by X-ray crystallography. HSALAMP behaves as a tridentate (NNO) or a bidentate (NN) ligand, depending upon the natu re of the anion and the reaction conditions and on reaction with zinc( II) salts gives three types of complex: (a) [Zn(SALAMP)X]2.yC2H5OH (X = Cl, y = 0 (I); X = I, y = 0 (II); X = NO3, y = 1 (III); (b) [Zn(HSAL AMP)X2].yH2O (X = Cl, y = 1 (IV); X = I, y = 0 (V); (c) [Zn(HSALAMP)2] (ClO4)2.C2H5OH.H2O (VI). However HSALAEP, a similar compound with one additional carbon atom in the chain, acts as a tridentate ligand irres pective of the nature of the anion and the reaction conditions, formin g compounds with zinc(II) and Cd(II) salts, [M(SALAEP)X]2.yC2H5OH (M = Zn, X = Cl, y = 0 (VII); M = Zn, X = 1, y = 0 (VIII); M = Zn, X = NO3 , y = 0 (IX) and M = Cd, X = NO3, y = 1 (X)). The single crystal X-ray structures of the [Zn(SALAMP)(NO3)]2 (III) and the [Cd(SALAEP)(NO3)]2 (X) dimers have been determined. III crystallized in the monoclinic s ystem, space group P2(1)/c, with a = 10.156(4), b = 17.424(4), c = 8.0 90(4) angstrom, beta = 107.56(2)-degrees, V = 1365(2) angstrom3 and Z = 4. X crystallized in the monoclinic system, space group P2(1)/n, wit h a = 9.728(2), b = 15.132(4), c = 10.223(4) angstrom, beta = 92.910(1 0)-degrees, V = 1502.9(8) angstrom3 and Z = 2. The structures of III a nd X are similar and consist of centrosymmetric dimers in which deprot onated phenolates bridge the two metal atoms and link the two halves o f the dimer. In III and X the zinc(II) and cadmium(II) ions have a hig hly distorted six-coordinate structure, bonded to two oxygen atoms fro m a bidentate nitrate group, the pyridine nitrogen, an amine nitrogen and a phenolate oxygen. The metal-metal separations are quite short (3 .063(1) angstrom (III), 3.429(1) angstrom (X)) with M-O-M angles of 98 .33(9) (III) and 99.2(1)-degrees (X). Compounds I and II and VII-IX ha ve been proposed to have dimeric structures similar to those of III an d X, with SALAMP or SALAEP acting as tridentate (NNO) ligands with the two zinc(II) ions bridged similarly by phenolate oxygens. Compounds I V, V and VI appear to have four-coordinate, monomeric structures with (HSALAMP) acting as a bidentate ligand (NN).