Abstract
The purpose of this study was to investigate whether co-crystals form by
simply mixing pure solutions of Ni(phen)(3)(PF6)(2) and
Ni(phen)(2)(phen-dione)(PF6)(2) where phen is 1,10-phenanthroline
and phen-dione is 1,10-phenanthroline-5,6-dione. The 1:1 cocrystal,
Ni(phen)(2)(phen-dione)Ni(phen)(3)(PF6)(4)center dot CH3CN has
been characterized by elemental analysis, IR, paramagnetic NMR, and
UV-vis spectroscopies, cyclic voltammetry, and single crystal X-ray
structure analysis. The title complex crystallized in triclinic crystal
system (z = 2) with space group of PA <<, a = 13.201(2) , b = 14.782(3)
, c = 22.294(4) , alpha = 81.575(15)(o), beta = 88.756(15)(o), gamma =
88.032(15)(o) and V = 4300.1(14) (3). A careful inspection of the
packing pattern in the lattice reveals that non-covalent interactions of
three different types, viz. C-H center dot center dot center dot F, C=O
center dot center dot center dot H-C and C-H center dot center dot
center dot pi interactions, are active in the lattice. The coordination
around the Ni(II) centers is a distorted octahedral, with bite angles of
78.3-79.8(o) for the chelating phen and phen-dione ligands. Cyclic
voltammetry of this co-crystal shows that the Ni(III/II) couple is
quasi-reversible. The effective magnetic moment (mu(eff)) of the
co-crystal was measured to be 2.87 BM per Ni(II) ion by Evans method.
The magnitude of mu(eff) is consistent with magnetic moment for
octahedral Ni(II) complexes.
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