Iron-Promoted Nucleophilic Additions to Diimine-Type Ligands: A Synthetic and Structural Study
We report here three examples of the reactivity of protic nucleophiles with diimine-type ligands in the presence of Fe(II) salts. In the first case, the iron-promoted alcoholysis reaction of one nitrile group of the ligand 2,3-dicyano-5,6-bis(2-pyridyl)-pyrazine (L1) permitted the isolation of an stable E-imido-ester, [Fe(L1')(2)](CF(3)SO(3))(2) (1), which has been characterized by spectroscopic studies (IR, ES-MS, Mössbauer), elemental analysis, and crystallographically. Compound 1 consists of mononuclear octahedrally coordinated Fe(II) complexes where the Fe(II) ion is in its low-spin state. The iron-mediated nucleophilic attack of water to the asymmetric ligand 2,3-bis(2-pyridyl)pyrido[3…
Synthesis and characterization of a new family of bi-, tri-, tetra-, and pentanuclear ferric complexes.
Nine members of a new family of polynuclear ferric complexes have been synthesized and characterized. The reaction of Fe(O(2)CMe)(2) with polydentate Schiff base proligands (H(2)L) derived from salicylidene-2-ethanolamine, followed in some cases by reaction with carboxylic acids, has afforded new complexes of general formulas [Fe(2)(pic)(2)(L)(2)] (where pic(-) is the anion of 2-picolinic acid), [Fe(3)(O(2)CMe)(3)(L)(3)], [Fe(4)(OR)(2)(O(2)CMe)(2)(L)(4)], and [Fe(5)O(OH)(O(2)CR)(4)(L)(4)]. The tri-, tetra-, and pentanuclear complexes all possess unusual structures and novel core topologies. Mössbauer spectroscopy confirms the presence of high-spin ferric centers in the tri- and pentanuclear…
Cyano-bridged structures based on [MnIIN3O2-macrocycle)]2+: a synthetic, structural, and magnetic study.
Reactions between the complex [MnII(L)]2+, where L is a N3O2 macrocyclic ligand, and different cyanometalate precursors such as [M(CN)n]m- (M(III) = Cr, Fe; M(II) = Fe, Ni, Pd, Pt) lead to cyano-bridged molecular assemblies exhibiting a variety of structural topologies. The reaction between [MnII(L)]2+ and [FeII(CN)6]4- forms a trinuclear complex with formula [(MnII(L)(H2O))2(FeII(micro-CN)2(CN)4)] x 2MeOH x 10H2O (1) which crystallizes in the triclinic space group P1. The reaction between [MnII(L)]2+ and [M(II)(CN)4]2-, where M(II) = Ni (2), Pd (3), Pt (4), gives rise to three isostructural linear chain compounds with stoichiometry [(MnII(L))(M(II)(micro-CN)2(CN)2)]n and which crystallize …
Three-dimensional bimetallic octacyanidometalates $[M^{IV}{(\mu-CN)_{4}Mn^{II}(H_{2}O)_2}_2 \cdot 4H_{2}O]_{n}$ (M=Nb,Mo,W) : synthesis, single-crystal X-ray diffraction and magnetism
Abstract We report the synthesis, the single-crystal X-ray crystallographic structures and the magnetic properties of three new isostructural cyanido-bridged networks: [M IV {(μ-CN) 4 Mn II (H 2 O) 2 } 2 ·4H 2 O] n [M IV = Nb IV ( 1 ), Mo IV ( 2 ), W IV ( 3 )]. For compound 1 , the magnetic properties reveal a ferrimagnetic phase below 50 K. In contrast, compounds 2 and 3 show a paramagnetic behaviour with no magnetic ordering down to 2 K. The only electronic difference between the two kinds of compounds is the presence of two paired electrons on Mo IV ( 2 ) and W IV ( 3 ) (d 2 electronic configuration, S = 0) with no possible exchange interactions with Mn II ions (d 5 electronic configur…