Synthetic diversity and change in nuclearity in [Co–Dy] coordination aggregates: bridge removal, solvent induced structural reorganization and AC susceptibility measurements

Abstract

Solvent induced structural reorganization, trapping of hitherto unknown DyIII–pivalate counter anion and different AC susceptibility behavior in three new CoII/III–DyIII aggregates has been discussed.

Modulating the structural topologies from star-shape to cross-shape for Co–Dy heterometallic complexes with slow magnetic relaxation behavior

“…It should be noted that the absence of χ ′′ maximum for 2 can also be found in other Co II 2 Dy complexes. 61 However, the energy barrier of 2 is obviously lower than the values of some linear Co II 2 Dy SMMs, 16 linear or butterfly Co II 2 Dy 2 SMMs, 17,18 and lower than the value of Co II 2 Co III 2 Dy 3 mixed-valence SMMs, 20 which mainly result from the compressed SAP-8 coordination geometry of Dy in 2 ( vide infra ).…”

“…Notably, the Dy–O bond lengths in 1 are dependent on the nature of the atoms, namely, the bonds formed by the alkoxido-type O atoms of L 3− (Dy1–O9 = 2.287(4) Å and Dy2–O10 = 2.247(4) Å) and the bonds formed by NO 3 − (Dy1–O11 = 2.454(5) Å and Dy2–O14 = 2.537(5) Å) represent the shortest and the longest Dy–O bonds, respectively. The coordination geometries of Dy1 and Dy2 in 1 were determined by SHAPE software, 49 indicating that Dy1 and Dy2 are the triangular dodecahedron 8,15,19,20,29,40 (TDD-8, D 2d ) and the muffin (MFF-9, C s ), 12,29 respectively, as the minimum values for the continuous shape measure (CShM) parameters of Dy1 and Dy2 are 3.061 and 1.971, respectively (Fig. 1b and c and Tables S6 and S7†).…”

“…However, the (py represent the shortest and the longest Dy-O bonds, respectively. The coordination geometries of Dy1 and Dy2 in 1 were determined by SHAPE software, 49 indicating that Dy1 and Dy2 are the triangular dodecahedron 8,15,19,20,29,40 (TDD-8, D 2d ) and the muffin (MFF-9, C s ), 12,29 respectively, as the minimum values for the continuous shape measure (CShM) parameters of Dy1 and Dy2 are 3.061 and 1.971, respectively (Fig. 1b and c and Tables S6 and S7 †).…”

“…For the Dy III ion in 2, it exhibits an eight-coordinated DyO 8 environment, in which eight O atoms originated from four L 3− ligands with Dy-O bond lengths in the range of 2.239(4)-2.530(5) Å. The coordination geometry of Dy III was also determined by SHAPE software, 49 indicating that the coordination geometry of Dy1 is a square antiprism (SAP-8, D 4d ), 14,15,20,[24][25][26][27][28]31,32 as the minimum value of the CShM parameter is 1.405 (Fig. 2b and Table S8 †).…”

“…So far, about twenty Co II – or Co II/III –Dy SMMs with different topologies like binuclear Co II Dy, 14 trinuclear Co II 2 Dy, 15,16 linear or butterfly Co II 2 Dy 2 , 17,18 Co II 4 Dy 4 , 19 and some Co II/III –Dy (ref. 20) have been reported. To our knowledge, the effective energy barrier ( U eff ) values of most complexes are lower than 100 K; the reason might be that the magnetic coupling between Co II and Dy III is still weak.…”