Synthesis, structure and magnetism of iron-(III) and -(II) complexes of 1-thia-4,7-diazacyclononane and N,N ′-dimethyl-1-thia-4,7-diazacyclononane

Abstract

The mononuclear complexes [Fe([9]aneN 2 S)Cl 3 ] and [Fe(Me 2 [9]aneN 2 S)Cl 3 ] ([9]aneN 2 S = 1-thia-4,7diazacyclononane, Me 2 [9]aneN 2 S = N,NЈ-dimethyl-1-thia-4,7-diazacyclononane) have been prepared by addition of the cyclononane to an ethanolic solution of FeCl 3 . µ-Oxo-bis(µ-acetato)diiron() complexes [Fe 2 O(O 2 CMe) 2 ([9]aneN 2 S) 2 ][PF 6 ] 2 and [Fe 2 O(O 2 CMe) 2 (Me 2 [9]aneN 2 S) 2 ][PF 6 ] 2 have been synthesised by addition of sodium acetate to suspensions of the mononuclear complexes and isolated as the hexafluorophosphate salts. The iron() dimer [Fe 2 (OH)(O 2 CMe) 2 (Me 2 [9]aneN 2 S) 2 ]ClO 4 was prepared under anaerobic conditions. The four iron() complexes were characterised by crystal structural studies. On the bases of the isomer shift and quadrupole splitting observed in the Mössbauer spectra of the dimers (4.2 K) the iron-() and -() ions were determined to be in the high-spin configuration. The magnetic susceptibility (300-4.2 K) of [Fe 2 O(O 2 CMe) 2 ([9]aneN 2 S) 2 ][PF 6 ] 2 (Ᏼ = Ϫ2JS 1 ؒS 2 ) indicated that the iron() sites were antiferromagnetically coupled (J = Ϫ125 cm Ϫ1 ). In the case of the iron() dimer J = Ϫ7.4 cm Ϫ1 . The differences observed in the redox behaviour of [Fe 2 O(O 2 CMe) 2 ([9]aneN 2 S) 2 ][PF 6 ] 2 and [Fe 2 O(O 2 CMe) 2 (Me 2 [9]aneN 2 S) 2 ][PF 6 ] 2 are attributed to the presence of the sterically demanding ligand methyl substituents.

Exchange coupling constants using density functional theory: Long‐range corrected functionals

“…1). 39–44 The calculations of the exchange coupling constant for the experimental structures were performed using the NWChem 5.1.1 code,45, 46 Q‐Chem 3.2,47 and Gaussian 0948 employing an all‐electron triple‐ζ basis set with polarization proposed by Schaefer et al49 and similar integration grids: an atom‐centered numerical grid with 75 radial and 302 angular points was employed in Q‐Chem 3.2 and Gaussian 09 codes and 70 radial and 590 angular points in NWChem 5.1.1. A more detailed description of the computational strategy used in this work to calculate the exchange coupling constants can be found elsewhere 9, 13, 17, 18.…”

“… Representation of the six systems studied (from left above to right below): [Cu 2 (μ‐O 2 CH 3 ) 4 (H 2 O) 2 ] complex,39 [Cu 2 (μ‐OH) 2 (H 2 O) 2 (bipym) 2 ](NO 3 ) 2 ·2H 2 O complex,40 [Fe 2 (μ‐O)(μ‐O 2 CH 3 ) 2 ([9]aneN 2 S 2 )] 2+ cation,41 [V 2 O 2 (μ‐OCH 3 ) 2 (maltolato) 2 ] complex,42 [Mn III L(μ‐OOCCH 3 )Cu II (Dopn)](ClO 4 ) complex ( L = 1,4,7‐trimethyl‐1,4,7‐triazacyclononane; H 2 Dopn = 3,9‐Dimethyl‐4,8‐diazaundeca‐3,8‐diene‐2,10‐dione dioxime)43 and [Mn II Cu II (obze)(H 2 O) 4 ] complex (obze = Oxamido‐N‐benzoato‐N′‐ethanoato) 44. Copper, iron, manganese, and vanadium atoms are indicated with large spheres (blue, orange, pink, and red), sulphur atoms with yellow medium size spheres and oxygen, carbon and nitrogen atoms are represented by red, brown, and blue spheres.…”

Synthesis and characterization of the tetranuclear iron(iii) complex of a new asymmetric multidentate ligand. A structural model for purple acid phosphatases

“…15 Thus, we have previously investigated the synthesis of ligand systems leading to diiron(III), diiron(II) 16 and tetrairon(III) 15 complexes and the potential relevance of these complexes to metallobiosites.…”

Synthesis, Characterization, and Magnetism of Binuclear Iron(III) Complexes with Iodanilato as Bridging Ligand

“…If we compare the J values with those previously reported for the analogous m-chloranilato binuclear iron(III) complexes [ 4 ](ClO 4 ) 4 (L ¼ Me 2 phen, Ph 2 phen) is that there are different substituents on hydranilic acid, that is, there are two chlorine substituents (Cl) in the former case and two iodine substituents (I) in the latter, which may have effects on the electronic structure of the bridged groups. The results suggest that the different halogen substituents on hydranilic acid will have an effect on magnetic interactions between the metal ions of this kind of complexes.…”