Steric and electronic control of the spin state in three-fold symmetric, four-coordinate iron(II) complexes

Hsiu-Jung Lin; Diana Siretanu; Diane A Dickie; Deepak Subedi; Jeremiah J Scepaniak; Dmitri Mitcov; Rodolphe Clérac; Jeremy M Smith

doi:10.1021/ja506425a

Steric and electronic control of the spin state in three-fold symmetric, four-coordinate iron(II) complexes

J Am Chem Soc. 2014 Sep 24;136(38):13326-32. doi: 10.1021/ja506425a. Epub 2014 Sep 10.

Authors

Hsiu-Jung Lin¹, Diana Siretanu, Diane A Dickie, Deepak Subedi, Jeremiah J Scepaniak, Dmitri Mitcov, Rodolphe Clérac, Jeremy M Smith

Affiliation

¹ Department of Chemistry and Biochemistry, New Mexico State University , Las Cruces, New Mexico 88003, United States.

PMID: 25157642
DOI: 10.1021/ja506425a

Abstract

The three-fold symmetric, four-coordinate iron(II) phosphoraminimato complexes PhB(MesIm)3Fe-N═PRR'R″ (PRR'R″ = PMePh2, PMe2Ph, PMe3, and P(n)Pr3) undergo a thermally induced S = 0 to S = 2 spin-crossover in fluid solution. Smaller phosphoraminimato ligands stabilize the low-spin state, and an excellent correlation is observed between the characteristic temperature of the spin-crossover (T1/2) and the Tolman cone angle (θ). Complexes with para-substituted triaryl phosphoraminimato ligands (p-XC6H4)3P═N(-) (X = H, Me and OMe) also undergo spin-crossover in solution. These isosteric phosphoraminimato ligands reveal that the low-spin state is stabilized by more strongly donating ligands. This control over the spin state provides important insights for modulating the magnetic properties of four-coordinate iron(II) complexes.