Diacetoneglucose Complexes of Manganese(II) and Iron(II) and Their Organometallic Derivatization

Homoleptic metal−sugar complexes were obtained in the form of MnII− and FeII−diacetoneglucose derivatives.
The protolysis of [Mn3Mes6] and [Fe2Mes4] (Mes = 2,4,6-Me3C6H2) with DAGH (1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, diacetoneglucose) led to [M(DAG)2] [M = Mn (1), Fe (2)]. Although monomeric in solution,
they showed a different degree of aggregation in the solid state, iron being monomeric and manganese oligomeric
(see magnetic properties). Dimeric complexes from 1 and 2 were obtained in the reaction with 9,10-phenanthroline
[phen], leading to [(phen)2M(μ-DAG)2M(DAG)2] [M = Mn (3), Fe (4)]. The organometallic functionalization
of 1 and 2 was achieved via a ligand redistribution reaction mixing them with [Mn3Mes6] and [Fe2Mes4],
respectively. The reaction led to mixed alkoxo aryl trinuclear complexes in the form of [(Mes)2M2(μ-DAG)2M(μ-Mes)2] [M = Mn (5), Fe (6)]. Both have a linear trimetallic skeleton with Mn···Mn and Fe···Fe average
distances of 2.93 and 2.88 Å, respectively. The crystal data are as follows:  complex 5, C60H82Mn3O12, monoclinic,
space group P21, a = 10.289(5) Å, b = 20.878(5) Å, c = 14.015(5) Å, β = 93.19(2)°, Z = 2; complex 6,
C60H82Fe3O12, monoclinic, space group P21, a = 9.748(12) Å, b = 26.05(3) Å, c = 12.50(2) Å, β = 107.50(2)°,
Z = 2. The data were collected at −123 °C. For 5 and 6 the magnetic analysis showed a strong antiferromagnetic
coupling between the M(II) centers, with spin frustration leading to an overall S = 5/2 and S = 2 ground state,
respectively.