New Mixed-Valent Mn Clusters from the Use of N,N,N ',N '-Tetrakis(2-hydroxyethyl)ethylenediamine (edteH(4)): Mn-3, Mn-4 Mn-6, and Mn-10

作者：Saha Arpita; Abboud Khalil A; Christou George^*

来源：Inorganic Chemistry, 2011, 50(24): 12774-12784.

DOI：10.1021/ic201916d

The syntheses, crystal structures, and magnetochemical characterization are reported for the new mixed-valent Mn clusters [(Mn2MnIII)-Mn-II(O2CMe)(2)(edteH(2))(2)](ClO4) (1), [(Mn2Mn2III)-Mn-II(edteH(2))(2)- (hmp)(2)cl(2)](Mn(II)cl(4)) (2), [(Mn6O2)-O-III(O2CBut)(6)(edteH)(2)(N-3)(2)] (3), [(Na2Mn8Mn2O4)-Mn-III-O-II(OMe)(2)(O2CEt)(6)(edte)(2)(N-3)(6)] (4), and (NEt4)(2)- [(Mn8Mn2O4)-Mn-III-O-II(OH)(2)-(O2CEt)(6)(edte)(2)(N-3)(6)](5), where edteH(4) is N,N,N',N'-tetrakis-(2-hydroxyethyl)ethylenediamine and hmpH is 2-(hydroxymethyl)pyridine. 1-5 resulted from a systematic exploration of the effect of different Mn sources, carboxylates, the presence of azide, and other conditions, on the Mn/edteH(4) reaction system. The core of 1 consists of a linear (MnMnMnII)-Mn-II-Mn-III unit, whereas that of 2 is a planar Mn-4 rhombus within a [(Mn2Mn2III)-Mn-II(mu(3)-OR)(2)] incomplete-dicubane unit. The core of 3 comprises a central [Mn-4(III)(OR)(2)] incomplete-dicubane on either side of which is edge-fused a triangular [Mn-3(III)(mu(3)-O)] unit. The cores of 4 and S are similar and consist of a central [(Mn2Mn2III)-Mn-II(mu(3)-OR)(2)] incomplete-dicubane on either side of which is edge-fused a distorted [(MnMn3III)-Mn-II(mu(3)-O)(2)(mu(3)-OR)(2)] cubane unit. Variable-temperature, solid-state direct current (dc) and alternating current (ac) magnetization studies were carried out on 1-5 in the 5.0-300 K range, and they established the complexes to have ground state spin values of S = 3 for 1, S = 9 for 2, and S = 4 for 3. The study of 3 provided an interesting caveat of potential pitfalls from particularly low-lying excited states. For 4 and 5, the ground state is in the S = 0-4 range, but its identification is precluded by a high density of low-lying excited states.

• 出版日期2011-12-19