Spin transition in a ferrous chloride complex supported by a pentapyridine ligand

Apparent high-spin complex with FeN5Cl coordination sphere exhibits a complete transition to the low-spin state on cooling.

Anion Influence on Spin State in Two Novel Fe(III) Compounds: [Fe(5F-sal2333)]X

Structural and magnetic data on two iron (III) complexes with a hexadentate Schiff base chelating ligand and Cl− or BPh4− counterions are reported. In the solid state, the Cl− complex [Fe(5F-sal2333)]Cl, 1, is high spin between 5–300 K while the BPh4− analogue [Fe(5F-sal2333)]BPh4, 2, is low spin between 5–250 K, with onset of a gradual and incomplete spin crossover on warming to room temperature. Structural investigation reveals different orientations of the hydrogen atoms on the secondary amine donors in the two salts of the [Fe(5F-sal2333)]+ cation: high spin complex [Fe(5F-sal2333)]Cl, 1, crystallizes with non-meso orientations while the spin crossover complex [Fe(5F-sal2333)]BPh4, 2, crystallizes with a combination of meso and non-meso orientations disordered over one crystallographic site. Variable temperature electronic absorption spectroscopy of methanolic solutions of 1 and 2 suggests that both are capable of spin state switching in the solution.

Transition metal complexes with thiosemicarbazide-based ligand: Part 45 - Synthesis, crystal and molecular structure of [2, 6-diacetylpyridine bis(S-methylisothiosemicarbazonato)]diazide-iron(III)

The template reaction of a warm methanolic solution of FeCl3.6H2O S-methylisothiosemicarbazidehydroiodide and 2,6-diacetylpyridine in the presence of LiOAc and NaN3 yielded the high-spin complex [Fe(HL)(N3)2], were HL is the monoanion of the ligand 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone). X-Ray analysis of the complex showed its pentagonal-bipyramidal configuration, with pentadenate (N5) HL in the equatorial plane and two monodentate azide groups in the axial positions. Crystal data are: monoclinic, P21/c,a=1.0263(2), b = 1.2525(2), c = 1.6660(3) nm, ?= 98.94?, V = 2.1154 nm3, Z = 4, ?x = 1.499 g cm-3, ?0 = 1.48 g cm-3, F(000) = 984, ?= 9.40 cm-1.

Übergangsmetallkomplexe mit Schwefelliganden, XCl+ Fell-Komplexe des fünfzähnigen Thioether-Thiolat-Aminliganden ′buNHS4′-H2: Synthese, Charakterisierung, Reaktivität und Stereochemie (′buNHS4′-H2 = 2,2′-Bis(2-mercapto-3,5-di-tertiärbutyl-phenylthio)diethylamin) / Transition Metal Complexes with Sulfur Ligands, XCI+ Fell Complexes of the Pentadentate Thioether-Thiolate-Amine Ligand ′buNHS4′-H2: Synthesis, Characterization, Reactivity and Stereochemistry (′buNHS4′-H2 = 2,2′-Bis(2-mercapto-3,5-di-tertiarybutyl-phenylthio)diethylamine)

In search of model compounds for the active centers of nitrogenases, [Fe(L)(′buNHS4')] complexes of the pentadentate thioether-thiolate-amine ligand ′buNHS4'2- (′buNHS4'-H2 = 2,2′-bis(2-mercapto-3,5-di-tertiarybutyl-phenylthio)diethylamine) were obtained.Alkylation of′buS2'-H2 with (BrC2H4)2NH yielded the new ligand ′buNHS4'-H2 as a mixture of positional isomers. Isolation of single isomers was achieved by reacting the mixture with FecL2•4H2O and CO in order to give the corresponding [Fe(CO)] complexes which were separated and hydrolyzed to yield the free ligands.Reaction of'buNHS4'-H2 with FeCl2•4H2O led to the high-spin complex [Fe(′buNHS4')] which is extremely air-sensitive in solution. It rapidly reacts with L = CO, NO, PMe3, and N2H4, and is the most suitable starting material for syntheses of [Fe(L)(′buNHS4')] complexes which were characterized for L = CO, NO+, NO, PMe3 and N2H4. All complexes are considerably better soluble in organic solvents than the corresponding parent compounds [Fe(L)(′NHS4')], (′NHS4'-H2 = 2,2′-bis(2-mercaptophenylthio)diethylamine), but have similar properties in most other respects. In the oxidation of [Fe(N2H4)(′buNHS4')] at low temperatures, there is evidence for the formation of the diazene complex [μ-N2H2{Fe(′buNHS4')}2].