scholarly journals Molybdenum Dithiolene Complexes: Trinuclear Mixed-Valence Complexes and Geometrical Isomers of Dinuclear Complexes

2017 ◽  
Vol 90 (6) ◽  
pp. 728-738 ◽  
Author(s):  
Haruo Akashi ◽  
Norihiko Machida ◽  
Takahiro Kamada ◽  
Hiroki Nihashi ◽  
Dai Aya ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Dinuclear Complexes ◽  
Geometrical Isomers

Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

1996 ◽  
Vol 510 (1-2) ◽  
pp. 189-195 ◽  
Author(s):  
María P. García ◽  
M.Victoria Jiménez ◽  
Teresa Luengo ◽  
Luis A. Oro
Keyword(s):  
Mixed Valence ◽  
Dinuclear Complexes

scholarly journals Structural Characterization of Iron(iii) Dinuclear Complexes

2014 ◽  
Vol 70 (a1) ◽  
pp. C1695-C1695
Author(s):  
Mauricio Fuentealba ◽  
Deborah Gonzalez ◽  
Vania Artigas
Keyword(s):  
Schiff Base ◽  
Mixed Valence ◽  
Iron Chloride ◽  
Dinuclear Complexes ◽  
Linear Optics ◽  
Non Linear Optics ◽  
Dinuclear Iron ◽  
Chloride Salts ◽  
Oxygen Atoms

Dinuclear complexes have been studied for different purposes: magnetic materials[1], Non-linear optics materials[2], molecular switches [3], mixed-valence systems, etc. With these antecedents in mind, we present in this work a new series of dinuclear Iron(III) complexes formed by different Schiff bases ligands. The reaction starting from the iron chloride salts with the 5-chloro or 5-bromo-salycilaldehyde and ethylendiamine yields two different kinds of dinuclear iron complexes in different reaction conditions. The first one (Fig N°1), are methoxo-bridged dinuclear iron(III) complexes in which each metal centre is coordinated with one mono-condensated Schiff base ligand, one 4-chloro or 4-bromo-2-(dimethoxymethyl)phenoxo ligand and two bridging methoxo ligands. The iron(III) centres are hexacoordinated (FeN2O4), the coordination sphere is formed by 2 nitrogen atoms of the ethylendiamine fragment, 2 oxygen atoms from the hydroxyl of the Schiff base and two O atoms from the methoxo ligands. Both iron(III) centres are related by a inversion centre. The second one (Fig N°2), the dinuclear complex is formed for the double condensation of ethylendiamine with 5-chloro or 5-bromo-salycilaldehyde and one oxygen from the dianionic ligand act as bridge with another unit. The iron (III) centres are also hexaccordinated (FeN2O3Cl) formed by 2 nitrogen atoms from ethylendiamine fragment and 3 oxygen atoms from hydroxyl from Schiff base ligands and one chloro ligand. Finally, the electronic and redox properties have been studied by UV-Visible and cyclic voltammetry. ACKNOWLEDGMENT FONDECYT N01130640, FONDEQUIP EQM120095 and Beca CONICYT folio 21130944

Electronic properties of mixed valence iron(II,III) dinuclear complexes with carboxylate bridges

Polyhedron ◽  
2006 ◽  
Vol 25 (9) ◽  
pp. 2026-2032 ◽  
Author(s):  
V. Paredes-García ◽  
D. Venegas-Yazigi ◽  
R.O. Latorre ◽  
E. Spodine
Keyword(s):  
Electronic Properties ◽  
Mixed Valence ◽  
Dinuclear Complexes

Electrochemical Behaviour of trans-[FeH(CN)(dppe)2] Adducts

2003 ◽  
Vol 68 (9) ◽  
pp. 1663-1676 ◽  
Author(s):  
Sílvia S. P. R. Almeida ◽  
M. Fátima C. Guedes Da Silva ◽  
Armando J. L. Pombeiro
Keyword(s):  
Electronic Communication ◽  
Electrochemical Behaviour ◽  
Mixed Valence ◽  
Electron Donors ◽  
Dinuclear Complexes ◽  
Ligand Parameters ◽  
Reduction Processes ◽  
Oxidation Potentials

Electrochemical behaviour of various metallo cyano adducts of trans-[FeH(CN)(dppe)2], viz. the dinuclear complexes [FeH(dppe)2(μ-CN)PdCl2(PPh3)], [FeH(dppe)2(μ-CN)NiCl2(PCy3)], and trinuclear [{FeH(dppe)2(μ-CN)}2(ReOCl3)], [{FeH(dppe)2(μ-CN)}2PtCl(Ph)] and [{FeX(dppe)2(μ-CN)}2WCl3(OH)] (X = Cl or OH, dppe = 1,2-diphenylphosphinoethane, PCy3 = P(C6H11)3), as well as the benzoylisocyanide mononuclear adduct trans-[FeH(CNCOPh)- (dppe)2], is reported. All of them exhibit FeII/FeIII-based oxidations (which are reversible, except for trans-[FeH(CNCOPh)(dppe)2]). The metallocyanide bridges C≡N-Re-N≡C and C≡N-W-N≡C in [{FeH(dppe)2(μ-CN)}2(ReOCl3)] and [{FeX(dppe)2(μ-CN)}2WCl3(OH)], respectively, allow electronic communication between the iron centres, with possible generation of mixed-valence FeII/FeIII complexes whose comproportionation constant could be estimated in the former case. From the values of the measured oxidation potentials, the electrochemical PL and EL ligand parameters have been estimated for the metallocyanide ligands that were shown to behave as stronger net electron donors than organoisocyanides, although weaker than cyanide itself. Ligand-centred reduction processes were also observed to lead, in the cases of complexes trans-[FeH(CNCOPh)(dppe)2] (CNCOPh-based reduction) and [FeH(dppe)2(μ-CN)PdCl2(PPh3)] (PdII-based reduction in the CNPdCl2(PPh3)- metallocyanide ligand), to the dissociation of the adduct, with regeneration of the parent cyano complex trans-[FeH(CN)(dppe)2], thus reflecting the reductive decrease of the electrophilic (or Lewis acidic) character of the benzoyl and {PdCl2(PPh3)} groups.

scholarly journals Selective Formation, Reactivity, Redox and Magnetic Properties of MnIII and FeIII Dinuclear Complexes with Shortened Salen-Type Schiff Base Ligands

2020 ◽  
Vol 21 (21) ◽  
pp. 7882
Author(s):  
Luca Rigamonti ◽  
Paolo Zardi ◽  
Stefano Carlino ◽  
Francesco Demartin ◽  
Carlo Castellano ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Coupling Constants ◽  
Dinuclear Complexes ◽  
X Ray Diffraction ◽  
Schiff Base Ligands ◽  
Bridging Ligands ◽  
Metal Centers ◽  
Bond Breakage ◽  
Dinuclear Compounds ◽  
Selective Formation

The reactivity of the shortened salen-type ligands H3salmp, H2salmen and H2sal(p-X)ben with variable para-substituent on the central aromatic ring (X = tBu, Me, H, F, Cl, CF3, NO2) towards the trivalent metal ions manganese(III) and iron(III) is presented. The selective formation of the dinuclear complexes [M2(μ-salmp)2], M = Mn (1a), Fe (2a), [M2(μ-salmen)2(μ-OR)2)], R = Et, Me, H and M = Mn (3a–c) or Fe (4a–c), and (M2(μ-sal[p-X]ben)2(μ-OMe)2), X = tBu, Me, H, F, Cl, CF3, NO2 and M = Mn (5a–g) or Fe (6a–g), could be identified by reaction of the Schiff bases with metal salts and the base NEt3, and their characterization through elemental analysis, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction of 2a·2AcOEt, 2a·2CH3CN and 3c·2DMF was performed. In the case of iron(III) and H3salmp, when using NaOH as a base instead of NEt3, the dinuclear complexes [Fe2(μ-salmp)(μ-OR)(salim)2], R = Me, H (2b,c) could be isolated and spectroscopically characterized, including the crystal structure of 2b·1.5H2O, which showed that rupture of one salmp3− to two coordinated salim− ligands and release of one salH molecule occurred. The same hydrolytic tendency could be identified with sal(p-X)ben ligands in the case of iron(III) also by using NEt3 or upon standing in solution, while manganese(III) did not promote such a C–N bond breakage. Cyclic voltammetry studies were performed for 3b, 4b, 5a and 6a, revealing that the iron(III) complexes can be irreversibly reduced to the mixed-valence FeIIFeIII and FeII2 dinuclear species, while the manganese(III) derivatives can be reversibly oxidized to either the mixed-valence MnIIIMnIV or to the MnIV2 dinuclear species. The super-exchange interaction between the metal centers, mediated by the bridging ligands, resulted in being antiferromagnetic (AFM) for the selected dinuclear compounds 3b, 4b, 5a, 5e,5f, 6a and 6e. The coupling constants J (–2JŜ1·Ŝ2 formalism) had values around −13 cm−1 for manganese(III) compounds, among the largest AFM coupling constants reported so far for dinuclear MnIII2 derivatives, while values between −3 and −10 cm−1 were obtained for iron(III) compounds.

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