Direct Observation of Very Large Zero-Field Splitting in a Tetrahedral Ni~ⅡSe_4 Coordination Complex

摘要

The high-spin (S = l) tetrahedral Ni~Ⅱ complex [Ni{~iPr_2P(Se)NP-(Se)~iPr_2}_2] was investigated by magnetometry, spectroscopic, and quantum chemical methods. Angle-resolved magnetometry studies revealed the orientation of the magnetization principal axes. The very large zero-field splitting (zfs), D = 45.40(2) cm~(-1), E = 1.91(2) cm~(-1), of the complex was accurately determined by far-infrared magnetic spectroscopy, directly observing transitions between the spin sublevels of the triplet ground state. These are the largest zfs values ever determined-directly-for a high-spin Ni~Ⅱ complex Ab initio calculations further probed the electronic structure of the system, elucidating the factors controlling the sign and magnitude of D. The latter is dominated by spin-orbit coupling contributions of the Ni ions, whereas the corresponding effects of the Se atoms are remarkably smaller.