Synthesis, structure and magnetism of a tetranuclear Fe(III) complex containing an [Fe4(μ3-O)2]8+ core

Ground Spin State Variation in Carboxylate‐Bridged Tetranuclear [Fe2Mn2O2]8+ Cores and a Comparison with Their [Fe4O2]8+ and [Mn4O2]8+ Congeners

“…Figure 1 shows a perspective view of the cation of 1. Although this complex contains an [Fe 4 (µ-diphenylglycolate) 3 (µ 3 -oxo) 2 ] core very similar to that in the previously reported [Fe 4 (µ-acetato) 3 (µ 3 -oxo) 2 ] complex, [4] we have included the description of the structure of 1 in this paper to show that the OH groups of the diphenylglycolate ligands are not coordinated to the oxophilic Fe III centres. It should also be noted that there are very few tetranuclear Fe III complexes with the [Fe 4 O 2 ] 8ϩ butterfly core reported (2) is 145.9°, which is slightly smaller than that in the corresponding acetate complex (153.9°).…”

“…Specifically, the carboxylate-bridged iron atoms are apparently ''pulled'' closer to one another [Fe(1)···Fe(3) earlier. [4] The structural parameters for 1 lie in the range reported for the other [Fe 4 O 2 ] 8ϩ complexes. [1Ϫ6] A perspective view of the cation of complex 3 is shown in Figure 2, and selected structural parameters are listed in Table 2.…”

“…Thus, tetramanganese butterfly [6,9Ϫ12] complexes with the [Mn 4 O 2 ] 8ϩ core have emerged as the most intensely studied oxide-bridged carboxylate clusters. Comparatively fewer studies of the butterfly [Fe 4 O 2 ] 8ϩ core have been perature (2−290 K) magnetic susceptibility measurements (1 T) and by Mössbauer spectroscopy. A ''2J'' model has been applied to simulate the experimental µ eff vs. T plots.…”

“…Although salicylaldoxime [22] has been known as a metal-chelating agent since 1930, reports on the ligating properties of salicylaldoxime towards trivalent transition metal ions are rare. [23,24] Our approach of using oximes as ligands has yielded several interesting 3d metal complexes with the cores [M A (oxime) 3 M B ] nϩ , [24] [M III 3 (µ 3 -O)(µ 2 -OPh)] 6ϩ (M ϭ Ti, V, Cr, Mn, Fe and Co), [25,26] [M III 6 (µ 3 -O) 2 (µ 2 -OOCR) 2 ] 12ϩ (M ϭ V, Cr, Mn, Fe) [27] and [(M III A ) 2 (µ 3 -O) 2 (M III B ) 2 ] 8ϩ (M A ϭ M B ϭ Fe III ; [4] M A ϭ Cr III , M B ϭ Fe III ; [13] M A ϭ Cr III , M B ϭ Mn III ). [14] In this paper we report the extension of our studies to complexes having tetranuclear cores, and include the preparation and characterisation of [L 2 Fe 4 (µ 3 -O) 2 (4) and [L 2 Fe 2 Mn 2 (µ 3 -O) 2 (µ 2 -carboxylate) 3 (salox) 2 ]ClO 4 (5Ϫ10) [carboxylate ϭ acetate (5), benzilate (diphenylglycolate) (6), triphenylacetate (7), benzoate (8), chloroacetate (9) and propionate (10)], where L is the cyclic amine 1,4,7-trimethyl-1,4,7-triazacyclononane and salox is the dianion of salicylaldoxime (H 2 salox).…”

Iron(III)‐Pivalate‐Based Complexes with Tetranuclear {Fe4(μ3‐O)2}8+ Cores and N‐Donor Ligands: Formation of Cluster and Polymeric Architectures

“…[16,[19][20][21][22][23] . We have summarized several characteristic data of these compounds in [22] and [L 2 Fe 4 (μ 3 -O) 2 (Ph 2 C(OH)CO 2 ) 3 (sao) 2 ] (ClO 4 ), [25] in which L = 1,4,7-trimethyl-1,4,7-triazacyclononane and H 2 sao = salicylaldoxime, are the exceptions from this family. They have atypical values of both bond lengths and angles as well as unusual conformations of their basic cores.…”