# Self-Assembly of a $Mn_9$ Nanoscopic Mixed-Valent Cluster: Synthesis, Crystal Structure, and Magnetic Behavior

Mondal, Kartik Chandra and Song, You and Mukherjee, Partha Sarathi (2007) Self-Assembly of a $Mn_9$ Nanoscopic Mixed-Valent Cluster: Synthesis, Crystal Structure, and Magnetic Behavior. In: Inorganic Chemistry, 46 (23). pp. 9736-9742.

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## Abstract

A rare $Mn_9$ $\mu_3$-oxo-centered mixed-valent cluster $[Mn_9O_7(O_2CPh)_{11}(thmn)(py)_2 (H_2O)_3]$ (1) is prepared by assembling an oxo-centered $Mn^{II}Mn^{III}_2$ triangle, $[Mn_3O(O_2CPh)_6(py)_2(H_2O)]\bullet 0.5MeCN$, as the secondary building unit in the presence of a tripodal alcohol, 1,1,1-tris(hydroxymethyl)nitromethane $(H_3thmn)$, as the capping ligand. Complex 1 was formed along with a minor byproduct, $[Mn_6O_2(O_2CPh)_{10}(MeCN)_4]$ (2). Complex 1 was characterized by X-ray single-crystal structure analysis and was crystallized in a monoclinic system, space group $P2_1/n$, $a = 16.214(6) \AA$, $b = 25.874(10) \AA$, $c = 26.497(10) \AA$, and $\beta = 94.214(7)°$. The Manganese-oxo-carboxylate core in 1 looks like a funnel. Variabletemperature magnetic studies down to 2 K reveal the existence of dominant ferromagnetic interaction within the cluster. Alternating current susceptibility data of the cluster show strong frequency dependence of both the real and imaginary parts of susceptibility $\chi'$ and $\chi"$ below 5 K. Moreover, the calculated relaxation time, $\tau_0 = 1.2 \times 10^{-7}$ s, and the energy barrier, $\Delta E = 25 K$, are consistent with the single-molecule magnetic behavior of 1.

Item Type: Journal Article Copyright of this article belongs to American Chemical Society. Division of Chemical Sciences > Inorganic & Physical Chemistry 16 Jul 2008 19 Sep 2010 04:47 http://eprints.iisc.ernet.in/id/eprint/14984