Self-assembled Transition Metal Coordination Frameworks of ...

C0pper(II) complexes
The powder spectrum exhibits a g" value of 2.257 and g L value of 2.073.
The frozen DMF spectrum also exhibits similar values as evidenced by g" = 2.063
(with A1|= 196 G) and gi = 2.237. gu > gl > 2.0023 and G value of 3.60 at 298 K
in powder state and 3.87 at 77 K in DMF are consistent with a dx,_y, ground state.
The g" values obtained indicate a significant degree of covalency in the metal-ligand
bonds and the G values indicate some exchange interaction. However there was no
half-field signal. The (12 value of 0.7256 indicates that 72% electron density is in the
copper dx,_y, orbital.
4.3.6.1. Crystal structure 0f[Cu(L4“);Cl;]- CH3OH- H2O- H3O+Cf (I3a)
The crystallographic data and structure refinement parameters for the
compounds are given in Table 4.5. The data of single crystals of suitable dimension of
13a was collected with Bruker SMART APEX CCD diffractometer using graphite
monochromated Mo Ka (X = 0.71073 A) radiation at temperature 293(2) K at the
Department of Inorganic and Physical Chemistry, IISc, Bangalore, India. The trial
structure was solved using SHELXS-97 [50] and refinement was carried out by full­
matrix least squares on F2 (SHELXTL-97). Molecular graphics employed were PLATON
[51] and MERCURY [52].
The single crystal X-ray diffraction study shows the presence of a novel
c0pper(ll) complex of 3-(2-pyridyl)triazolo[l,5-a] pyridine (L4“‘), [Cu(L4°)2Cl2]­
CH3OH- H2O- H3O+Cl' (l3a). The asymmetric unit consists of half of two independant
molecules of [Cu(L4“)2Cl2], one chloride ion, one hydronium ion, a water and a
methanol molecule. Half part of each molecule was generated. However, hydrogen
atoms of water or hydronium ion could not be located by using difference Fourier
maps; and the assignment of hydronium ion was done by taking in consideration of
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