Structure and magnetic exchange in heterometallic 3d-3d transition metal triethanolamine clusters

Stuart Langley, Nicholas Frederick Chilton, Boujemaa Moubaraki, Keith Spencer Murray

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Abstract

Synthetic methods are described that have resulted in the formation of seven heterometallic complexes, all of which contain partially deprotonated forms of the ligand triethanolamine (teaH(3)). These compounds are [Mn(4)(III)Co2(III)Co(2)(II)O(2)(teaH(2))(2)(teaH)(0.82)(dea)(3.18)(O2CMe)(2)(OMe)(2)](BF4)(2)-(O2CMe)(2)center dot 3.18MeOH center dot H2O (1), [(Mn2Mn2Co2III)-Mn-II-Co-III(teaH)(4)(OMe)(2)(acac)(4)](NO3)(2)center dot 2MeOH (2), [(Mn2Ni4II)-Ni-III(teaH)(4)(O2CMe)(6)]center dot 2MeCN (3), [(Mn2Co2II)-Co-III(teaH)(2)(sal)(2)(acac)(2)(MeOH)(2)]center dot 2MeOH(4), [(Mn2Fe2III)-Fe-II(teaH)(2)(paa)(4)](NO3)(2)center dot 2MeOH center dot CH2Cl2 (5), [(MnMn2Co2O)-Mn-II-Co-III-O-III(teaH)(2)(dea)-(Iso)(OMe)(F)(2)(Phen)(2)](BF4)(NO3)center dot 3MeOH (6) and [(Mn2MnCo2III)-Mn-II-Co-III(OH)(teaH)(3)(teaH(2))(acac)(3)]-(NO3)(2)center dot 3CH(2)Cl(2) (7). All of the compounds contain manganese, combined with 3d transition metal ions such as Fe, Co and Ni. The crystal structures are described and examples of rods , tetranuclear butterfly and triangular Mn-3 cluster motifs, flanked in some cases by diamagnetic cobalt(III) centres, are presented. Detailed DC and AC magnetic susceptibility and magnetization studies, combined with spin Hamiltonian analysis, have yielded J values and identified the spin ground states. In most cases, the energies of the low-lying excited states have also been obtained. The features of note include the inverse butterfly spin arrangement in 2, 4 and 5. A S = 5/2 ground state occurs, for the first time, in the (Mn2MnII)-Mn-III triangular moiety within 6, the many other reported [Mn3O](6+) examples having S = 1 / 2 or 3/2 ground states. Compound 7 provides the first example of a MnII2MnIII triangle, here within a pentanuclear Mn3Co2 cluster.
Original languageEnglish
Pages (from-to)1033 - 1046
Number of pages14
JournalDalton Transactions
Volume41
Issue number3
DOIs
Publication statusPublished - 2012

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