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
Ss. Tandon et al., 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, Inorganica Chimica Acta, 219(1-2), 1994, pp. 55-65
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).