Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

Chapitre I
As shown in Figure 1, the octahedral geometry around the metal center in complex
13⋅H2O⋅CH2Cl2 results from the coordination of two tridentate, monometalated ligands, with
their 2 electron donors imine nitrogen atoms N(1) and N(5) in mutual trans position and the
covalently bound oxygens O(1) and O(3) are trans to the X donors N(3) and N(7)
respectively.
Figure 1. ORTEP view of the crystal structure of 13 in 13⋅H2O⋅CH2Cl2 (ellipsoids drawn at
the 50% probability level).
The Ni-O and Ni-N bond distances in complex 13 (Table 1) are only slightly shorter than
those of its zinc analog (corresponding values: Zn-N1 2.021(4), Zn-N3 2.330(5), Zn-N5
2.037(4), Zn-N7 2.442(5), Zn-O1 2.123(4), Zn-O3 2.134(4) (Å)), 46 which parallels the
differences in metal radii (1.246 and 1.333 for Ni and Zn, respectively) 47 . Interatomic C-O, C-
C and C-N distances within the quinonemonoimine core of complex 13 indicate an alternation
of single and double bonds, which is consistent with a localized π system, as previously
observed for the analogous zinc complex, 46 whereas in the free ligand 45 and all related
crystallographic structures, 41,42,45,46,48 a perfectly delocalized form is present.
Examination of the crystal packing of complex 13⋅H2O⋅CH2Cl2 reveals intermolecular
interactions (N2⋅⋅⋅O2 = 2.971(6) and N6⋅⋅⋅O1 = 2.897(6) Å) which lead to a one-dimensional
wavelike chain arrangement in the solid (Figures 2 and 3). This arrangement also allows
stabilizing π-π interactions between quinone rings, with a C15⋅⋅⋅C18 distance of 3.650(6) Å.
A similar arrangement was also observed in its Zn(II) analog 45,46 However in the present case,
the complex crystallized with a molecule of water and of dichloromethane. The H2O
molecules interact through hydrogen bonding, with O2⋅⋅⋅Ο(H2O) and N4⋅⋅⋅Ο(H2O) distances
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