Theoretical calculation and prediction for experimental design to obtain spin crossover complexes

Abstract

DFT methods were utilized to study SCO complexes. [Fe(2btz)2(NCX)2] (2btz = 2,2′‐bithiazoline, X = S (1) and Se (2)), [Fe(phen)2(NCX)2] (phen = 1,10‐phenantroline, X = S (3) and Se (4)), and [Fe(bpy)2(NCS)2] (5) (bpy = 2,2′‐bipyridine) compounds, which have experimentally shown SCO behavior, were calculated. B3LYP, B3LYP*, OPBE, and OLYP with 6‐31G* and 6‐311 + G** basis sets were employed to calculate the ΔEHS/LS energy gap as a clue to find complexes with SCO behavior. It is found that calculated result by B3LYP* with c3 = 0.14 and OPBE methods and 6‐31G* basis set are in agreement with experimentally observed SCO complexes. Then, newly designed Fe(N‐N)2(X)2 complexes, where N‐N are bidentate nitrogen donor chelating ligands and X= SCN‐, SeCN‐, Cl‐, Br‐, I‐, normalN3‐ were chosen to see their potential to be SCO compounds. ΔEHS/LS for potential SCO complexes are estimated from 0.8 to 6.5 kcal/mol in B3LYP* and 0.6–5.7 kcal/mol in OPBE. These calculations suggest [Fe(bpy)2(NCSe)2], [Fe(5dmbpy)2(NCS)2], and [Fe(3‐BrPhen)2(NCSe)2] compounds have the ability to show SCO behavior. © 2016 Wiley Periodicals, Inc.

Electronic and Steric Control of the Spin-Crossover Behavior in [(CpR)2Mn] Manganocenes

“…All density functional theory (DFT) calculations were carried out with the Gaussian 09 (revision D.01) electronic structure package with a 10 –8 convergence criterion for the density matrix elements, using the hybrid GGA functional OPBE. − This functional has been previously used to model spin-crossover processes in other transition-metal compounds, − and although we have been very successful in modeling SCO processes using the meta-hybrid TPSSh , functional, − for the particular case of [(Cp R ) 2 Mn] systems OPBE provides the correct ground state, while the TPSSh functional overstabilizes the high-spin state (see Table S3 in the Supporting Information). The fully optimized contracted triple-ζ all-electron Gaussian basis set developed by Ahlrichs and co-workers with polarization functions was employed for all of the elements .…”

DFT Prediction and Experimental Investigation of Valence Tautomerism in Cobalt-Dioxolene Complexes

“…Given accurate energetics for one transition-metal complex, the DFT method can accurately predict spin-state energies for similar compounds . The GGA functional OPBE, hybrid functional B3LYP*, and the meta-hybrid functional TPSSh have all been found to give accurate spin-state energetics for some cobalt VT or transition-metal SCO systems. − In particular, OPBE is cost-efficient and has given accurate spin-state energetics in many Fe­(II) and Fe­(III) SCO systems, − and some Co SCO and VT systems. ,, In Sato’s 2010 study on the VT mechanism in [Co­(bpy)­(H 4 diox) 2 ] (bpy = 2,2′-bipyridine), both B3LYP* and OPBE accurately reproduced the energy separation between the relevant doublet and sextet states. However, OPBE was unable to reproduce the ordering of the quartet state, which experimentally lies above the sextet state.…”

Peculiar Spin-Crossover Behavior in the 2D Polymer K[FeIII(5Cl-thsa)2]

“…Moreover, OLYP, OPBE (GGA), TPSS (mGGA), PBE0–15 (with 15% HF exchange), B3LYP, PBE0 (GH-GGA), and TPSSh (GH-mGGA) functionals were tested to predict the spin-crossover feasibility (Table ). − It is interesting to state that the OLYP and OPBE functionals also correctly predict the feasibility of the SCO transition for the K­[Fe­(5Cl-thsa) 2 ] complex, which is anticipated for purely DFT method . In contrast, TPSS and TPSSh functionals overestimate the low-spin state stability of 1 although they predict the correct ground spin state for the complex.…”