Self-assembled Transition Metal Coordination Frameworks of ...

g _,_,_ g g Copperfll) complexes
interactions between the Cu(ll) centers. The room temperature magnetic moment and
antiferromagnetic interactions rule out the possibility of tetranuclear grid formation, as
there is such a possibility also for the complexes. For example, the possibility of
molecular formula of 9 as [CuH2L2]4(ClO4)g' 3CHCl;' 4H2O will lead to a room
temperature magnetic moment of 5.2 ug, which is unreasonably high to the expected
spin only magnetic moment of (Z 4Si(Si + l))i‘ = 3.46 pf, for a system having four
independent Cu(lI) species. Complex 9 was assigned with four Cu(II) atoms
coordinated within the coordination pockets of two doubly deprotonated
thiocarbohydrazone ligands HZLZ. The complex 8 was synthesized by equimolar
reaction between HZLI and metal salt in methanol solution, but resulted into a product
of 3:2 metal ligand ratio. The formation of carbohydrazone complex 13 was found to
be distinctive as there is a report for similar reaction conditions for HQLS with CuCl2
resulted a degradation of -CO- group and cyclization to form a copper complex of 3­
phenyltriazolo[1,5-a]-pyridine [1 1]. However we could synthesize the chloride
complex of HZL4, compound 13, and found to undergo degradation only in solutions at
lower concentration on exposure to air. Instead of an expected bimetallic complex, the
compound 13 was formed with three Cu(II) centers. The complex 17 was synthesized
by metathetical displacement of acetate ions of the metal salt with azide ions.
The molecular formula of all the Cu(ll) complexes were tentatively assigned
by considering spectral, magnetic and conductance studies with agreeing elemental
analysis results. The existence of other possibilities, however, was not excluded for all
compounds on characterization. The TGA data of complex 14 shows a loss of six
water molecules (12.4%) within the temperature range 40-112 °C and then the loss of
one molecule of water (2%) in the range 112-210 °C. However at 247 °C the complex
had undergone an outburst. The TGA studies of other compounds are therefore not
carried out, to locate the water molecules, and so the positions of water molecules
were tentatively assigned. Molar conductance studies are found useful to assign the
133