Mondal, Kartik Chandra and Oindrila, Sengupta and Nethaji, Munirathinam and Mukherjee, Partha Sarathi (2008) Assembling metals $(Co^I^I and Mn^I^I)$ with pyridylcarboxylates in the presence of azide: synthesis, structural aspects and magnetic behavior of three coordination polymers. In: Dalton Transactions (6). pp. 767-775.
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The reaction between $Co(NO_3)_2·6H_2O$ and substituted pyridylcarboxylic acid [nicotinic acid (Hnic) or trans-3-pyridylacrylic acid (Htpa)] in the presence of $NaN_3$ under hydrothermal conditions yielded $[Co_1_._5(nic)_2 (Hnic)(N_3)]_n$ (1) and $[Co_1_._5(tpa)_2 (N_3)(H_2O)]_n$ (2), respectively. Single crystal structure analyses reveal that both complexes are 3D complicated coordination polymers. The basic repeating units in both of the complexes are $Co_3$ trinuclear clusters containing syn–syn bridging carboxylate and end-on azido linker. A similar reaction using $MnCl_2·4H_2O$ in presence of equimolar amounts of Htpa and $NaN_3$ yielded a 2D corrugated sheet $[Mn(tpa)_2]_n$ (3) containing no azide. Complex 3 can also be synthesized under hydrothermal conditions using Natpa in the absence of $NaN_3$. Surprisingly, the same reaction at room temperature yielded a known mononuclear complex $[Mn(tpa)_2(H_2O)_4]$. Variable temperature magnetic studies down to 2 K revealed the dominant antiferromagnetic nature of the first two complexes with a ferrimagnetic type of behavior despite the facts that they are homometallic and homospin systems. The susceptibility data in both cases were analyzed by a $Co_3$ trinuclear model as well as considering inter-trimer interactions. Complex 3 is weakly antiferromagnetic in nature with an exchange parameter of J =−2 $cm^-^1$ through the syn–anti bridging carboxylate pathway.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to The Royal Society of Chemistry|
|Department/Centre:||Division of Chemical Sciences > Inorganic & Physical Chemistry|
|Date Deposited:||04 Mar 2008|
|Last Modified:||19 Sep 2010 04:43|
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