TY - JOUR
T1 - Magneto-Structural Correlations in Pseudotetrahedral Forms of the [Co(SPh)4]2- Complex Probed by Magnetometry, MCD Spectroscopy, Advanced EPR Techniques, and ab Initio Electronic Structure Calculations
AU - Suturina, Elizaveta A.
AU - Nehrkorn, Joscha
AU - Zadrozny, Joseph M.
AU - Liu, Junjie
AU - Atanasov, Mihail
AU - Weyhermüller, Thomas
AU - Maganas, Dimitrios
AU - Hill, Stephen
AU - Schnegg, Alexander
AU - Bill, Eckhard
AU - Long, Jeffrey R.
AU - Neese, Frank
PY - 2017/3/6
Y1 - 2017/3/6
N2 - The magnetic properties of pseudotetrahedral Co(II) complexes spawned intense interest after (PPh4)2[Co(SPh)4] was shown to be the first mononuclear transition-metal complex displaying slow relaxation of the magnetization in the absence of a direct current magnetic field. However, there are differing reports on its fundamental magnetic spin Hamiltonian (SH) parameters, which arise from inherent experimental challenges in detecting large zero-field splittings. There are also remarkable changes in the SH parameters of [Co(SPh)4]2- upon structural variations, depending on the counterion and crystallization conditions. In this work, four complementary experimental techniques are utilized to unambiguously determine the SH parameters for two different salts of [Co(SPh)4]2-: (PPh4)2[Co(SPh)4] (1) and (NEt4)2[Co(SPh)4] (2). The characterization methods employed include multifield SQUID magnetometry, high-field/high-frequency electron paramagnetic resonance (HF-EPR), variable-field variable-temperature magnetic circular dichroism (VTVH-MCD), and frequency domain Fourier transform THz-EPR (FD-FT THz-EPR). Notably, the paramagnetic Co(II) complex [Co(SPh)4]2- shows strong axial magnetic anisotropy in 1, with D = −55(1) cm-1 and E/D = 0.00(3), but rhombic anisotropy is seen for 2, with D = +11(1) cm-1 and E/D = 0.18(3). Multireference ab initio CASSCF/NEVPT2 calculations enable interpretation of the remarkable variation of D and its dependence on the electronic structure and geometry.
AB - The magnetic properties of pseudotetrahedral Co(II) complexes spawned intense interest after (PPh4)2[Co(SPh)4] was shown to be the first mononuclear transition-metal complex displaying slow relaxation of the magnetization in the absence of a direct current magnetic field. However, there are differing reports on its fundamental magnetic spin Hamiltonian (SH) parameters, which arise from inherent experimental challenges in detecting large zero-field splittings. There are also remarkable changes in the SH parameters of [Co(SPh)4]2- upon structural variations, depending on the counterion and crystallization conditions. In this work, four complementary experimental techniques are utilized to unambiguously determine the SH parameters for two different salts of [Co(SPh)4]2-: (PPh4)2[Co(SPh)4] (1) and (NEt4)2[Co(SPh)4] (2). The characterization methods employed include multifield SQUID magnetometry, high-field/high-frequency electron paramagnetic resonance (HF-EPR), variable-field variable-temperature magnetic circular dichroism (VTVH-MCD), and frequency domain Fourier transform THz-EPR (FD-FT THz-EPR). Notably, the paramagnetic Co(II) complex [Co(SPh)4]2- shows strong axial magnetic anisotropy in 1, with D = −55(1) cm-1 and E/D = 0.00(3), but rhombic anisotropy is seen for 2, with D = +11(1) cm-1 and E/D = 0.18(3). Multireference ab initio CASSCF/NEVPT2 calculations enable interpretation of the remarkable variation of D and its dependence on the electronic structure and geometry.
UR - http://www.scopus.com/inward/record.url?scp=85014542185&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.7b00097
DO - 10.1021/acs.inorgchem.7b00097
M3 - Article
AN - SCOPUS:85014542185
SN - 0020-1669
VL - 56
SP - 3102
EP - 3118
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 5
ER -