Single-crystal absorption spectroscopy of binuclear complexes of iron(III) and manganese(III) with the μ-oxo-bis(μ-acetato)dimetal core

1995 ◽  
Vol 73 (2) ◽  
pp. 249-254 ◽  
Author(s):  
Yanick Pelletier ◽  
Christian Reber
Keyword(s):  
Single Crystal ◽  
Excited States ◽  
Absorption Spectroscopy ◽  
Variable Temperature ◽  
Exchange Interactions ◽  
Bimetallic Complexes ◽  
Binuclear Complexes ◽  
Metal Centers ◽  
Forbidden Transition ◽  
Significant Intensity

Single-crystal absorption spectroscopy at variable temperature is used to determine exchange couplings between transition metal centers in both the electronic ground and excited states in two new homobimetallic complexes with the formula [LM(μ-O)(μ-CH3CO2)2ML′](ClO4)2, where M is iron(III) or manganese(III). L and L' denote 1,4,7-triazacyclononane and 1,4,7-trimethyl-1,4,7-triazacyclononane, respectively. Values for the ground state exchange coupling constant J are −295 cm−1 and +10 cm−1 for the iron and manganese compounds, respectively, using Hex = −JS1•S2. Exchange interactions in excited states are qualitatively analyzed, indicating that a spin-forbidden transition of the Fe–Fe binuclear unit occurs with significant intensity by the single-ion mechanism, and not as expected by the Tanabe pair intensity mechanism for spin-forbidden transitions, the dominant mechanism for isoelectronic complexes of manganese(II). Keywords: absorption spectra, exchange interaction, magnetic properties, bimetallic complexes of iron(III), bimetallic complexes of manganese(III)

Magnetic field induced local structural transformations in the optically excited states 5F2 and 5F3 of HoFe3(BO3)4 single crystal

2019 ◽  
Vol 476 ◽  
pp. 177-182 ◽  
Author(s):  
A.V. Malakhovskii ◽  
S.L. Gnatchenko ◽  
I.S. Kachur ◽  
V.G. Piryatinskaya ◽  
I.A. Gudim
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Excited States ◽  
Structural Transformations

scholarly journals Syntheses, Structures, Magnetic Properties and Antibacterial Activities of Two Copper(II) Azido Complexes with Varied Nuclearities Containing Symmetrical 1,3-Diammine as Chelator

2021 ◽  
Vol 33 (2) ◽  
pp. 359-366
Author(s):  
Habibar Chowdhury ◽  
Chandan Adhikary
Keyword(s):  
Hydrogen Bonds ◽  
Variable Temperature ◽  
Antibacterial Activities ◽  
Metal Centers ◽  
X Ray ◽  
Pyramidal Geometry ◽  
Azide Ion ◽  
3D Network ◽  
Square Pyramidal Geometry ◽  
Dinuclear Structure

Two copper(II) azido complexes of the types mononuclear [Cu(TMEDA)2(N3)2] (1) and dinuclear [Cu(TMEDA)(μ1,1-N3)(N3)]2 (2) [TMEDA = trimethylenediamine; N3 – = azide ion] have been synthesized and characterized. X-ray structural analysis revealed that each copper(II) center in complex 1 adopts a distorted octahedron geometry with a CuN6 chromophore ligated through four N atoms of two different symmetrical TMEDA ligands as bidentate chelator and two N atoms of two terminal azides. In complex 2, each copper(II) center adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of TMEDA as bidentate chelator and two N atoms of two different azides as μ1,1-N3 bridging mode and one N atom of terminal azide ion. The two copper centers are connected through double μ1,1-N3 bridges affording a dinuclear structure with Cu···Cu separation 3.327(2) Å. In crystalline state, mononuclear units in complex 1 are associated through intermolecular N-H···N and C-H···N hydrogen bonds to form a 2D sheet structure viewed along crystallographic b-axis, whereas dinuclear entities in complex 2 are propagated through intermolecular N-H···N and C-H···N hydrogen bonds to form a 3D network structure viewed along crystallographic a-axis. The Variable-temperature magnetic susceptibility measurement evidenced a dominant antiferromagnetic interaction between the metal centers through μ1,1-azide bridges in complex 2 with J = − 0.40 cm-1. The antibacterial activities of the complexes have also been studied.

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