Predictable Electronic Tuning By Choice of Azine Substituent in Five Iron(II) Triazoles: Redox Properties and DFT Calculations |
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| Authors: | Santiago Rodríguez‐Jimnez Luca Bondì Mingrui Yang Anna L Garden Sally Brooker |
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| Institution: | Santiago Rodríguez‐Jiménez,Luca Bondì,Mingrui Yang,Anna L. Garden,Sally Brooker |
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| Abstract: | Five new mononuclear iron(II) tris‐ligand complexes, and four solvatomorphs, have been made from the azine‐substituted 1,2,4‐triazole ligands ( Lazine ): FeII( Lpyridazine )3](BF4)2 ( 1 ), FeII( Lpyrazine )3](BF4)2 ( 2 ), FeII( Lpyridine )3](BF4)2 ( 3 ), FeII( L2pyrimidine )3](BF4)2 ( 4 ), and FeII( L4pyrimidine )3](BF4)2 ( 5 ). Single‐crystal XRD and solid‐state magnetometry reveal that all of them are low‐spin (LS) iron(II), except for solvatomorph 5 ?4 H2O. Evans method NMR studies in CD2Cl2, (CD3)2CO and CD3CN show that all are LS in these solvents, except 5 in CD2Cl2 (consistent with L4pyrimidine imposing the weakest field). Cyclic voltammetry in CH3CN vs. Ag/0.01 m AgNO3 reveals an, at best quasi‐reversible, FeIII/II redox process, with Epa increasing from 0.69 to 0.99 V as the azine changes: pyridine< pyridazine<2‐pyrimidine<4‐pyrimidine< pyrazine. The observed Epa values correlate linearly with the DFT calculated HOMO energies for the LS complexes. |
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| Keywords: | azine density functional calculations Evans method iron redox chemistry triazoles |
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