Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

Chapitre I
Figure 3. Views of the supramolecular array generated by 13⋅H2O⋅CH2Cl2 in the solid state.
a) Top view, and b) side view. Color coding: nitrogen, blue; oxygen, red; chloride, green;
nickel, black.
When ligand 9 was reacted with NiCl2⋅6H2O in a 1:1 molar ratio at room temperature
in MeOH, it afforded the mononuclear complex 17 (Scheme 3). Its molecular structure was
determined by X-ray diffraction (Figure 4, Tables 1 and 2). Like its Zn(II) analog 45 complex
17 presents a zwitterionic structure, where the negative charge of the metalate moiety is
balanced by the ammonium cation resulting from an intramolecular proton shift.
9 NiCl 2⋅6H 2O
MeOH
O
HN
+
O
N
H
N
Me2 (not isolated)
NiCl 2
NMe 2
+
Me2HN HN
O
N
O
Cl
Ni
NMe 2
Scheme 3. Reaction of ligand 9 with NiCl2⋅6H2O affording the pentacoordinated complex 17.
The negative charge shown for clarity on the Ni(II) center is of course partly delocalized on
the ligands.
This zwitterionic complex contains only one tridentate ligand per nickel center and the
pentacoordination about the metal results in a slightly distorted square base pyramidal
geometry (Figure 4). The base is formed by the three ligand donor sites (N1, N3 and O1) and
Cl2 while Cl1 completes the coordination sphere in the apical position of the pyramid. The
17
Cl
9