Influence of ligand field on magnetic anisotropy in a family of pentacoordinate Co^II complexes

Abstract

Three pentacoordinate CoII complexes were synthesized using a common tridentate ligand and varying the halide/pseudohalide ligand. The effect of the latter on the geometry and magnetic properties of the three complexes has been analysed.

Role of Coordination Number and Geometry in Controlling the Magnetic Anisotropy in FeII, CoII, and NiII Single‐Ion Magnets

“…Also, in the CASSCF calculations, the absence of dynamic correlation overestimates the D parameter and the addition of second‐order (PT2) correction was found to improve the D significantly. In Figure 5 c–e, three square pyramidal complexes are shown, of which complex ( 21 ) show a negative D of −28 cm −1 , whereas [Co(L)Br 2 ] (L=1‐mesityl‐ N , N ‐bis(pyridine‐2‐ylmethyl)methanamine)) [32b] ( 23 ) and [Co(tris[2‐(diphenylphosphino)ethyl]phosphine)Cl]ClO 4 [33d] ( 24 ) exhibit positive D values of +36 cm −1 and +40 cm −1 , respectively, estimated from ab initio calculations and SQUID measurements.…”

What controls the magnetic anisotropy in heptacoordinate high-spin cobalt(ii) complexes? A theoretical perspective

“…The CASSCF/NEVPT2 method has been shown to accurately estimate spin-Hamiltonian parameters of mononuclear transition metal complexes. 23,35,[39][40][41][42][43][44][45][46][47][48][49][50][51][52] The computed ZFS parameters of all 16 complexes considered here are assembled in Table 1 together with a structural parameter describing the inplane deviation from PBP symmetry and published experimental and computed ZFS parameters. To evaluate the accuracy of the theoretical methodology applied here, the experimental DC magnetic susceptibility and magnetization plots were simulated with the computed values: the DC SQUID data of complexes 1, 28 2, 29 3, 29 13, 37 and 16 38 were simulated with NEVPT2 computed parameters (see ESI, Fig.…”

Crystal structure of (7-{[bis(pyridin-2-ylmethyl)amino-κ3 N,N′,N′′]methyl}-5-chloroquinolin-8-ol)dibromidozinc(II)

“…The Zn-N bond lengths in the title compound are 2.1455 (18) and 2.1497 (18) A ˚for the pyridyl atoms (N8, N9), and 2.2670 (18) A ˚for the tertiary atom N7. In comparison, the Zn-N bond lengths in the crystal structure of a related complex with a mesityl methylene-appended dpa derivative are 2.093 (3), 2.066 (3), and 2.521 (3) A (MUDWEQ; Acharya et al, 2020). The bond lengths for the pyridyl N atoms are, hence, shorter and the bond length for the tertiary N atom is longer than those in the title compound.…”

“…The dihedral angle between the two pyridine rings in the title compound is 15.84 (13) . In a related complex (MUDWEQ; Acharya et al, 2020), this dihedral angle between two pyridine rings is widened to 23.53 (18) , concomitant with an increased parameter of 0.211. The phenolic oxygen O5 of the Hq moiety is bound to hydrogen atom H5, which was found and refined freely.…”

“…In the remaining five dibromido Zn II complexes with dpa derivatives (comprising four compounds), the tertiary N atoms are bound to aliphatic carbon atoms as in the title complex. Four of these five closely related structures exhibit square-pyramidal geometries with dpa being meridionally coordinated (YOZZOC; Abufarag et al, 1995;RUVCUI;S ˇkalamera et al, 2016;MUDWEQ;Acharya et al, 2020;IHIJIV;Juraj et al, 2020). The remaining exceptional structure is fac-{N,N 0 -bis[(pyridine-2-yl)methyl]propan-2-amine}dibromidozinc(II) (IHIJOB; Juraj et al, 2020), which adopts a trigonal-bipyramidal geometry with dpa being facially coordinated.…”