Photomagnetic properties of an Fe(ii) spin-crossover complex of 6-(3,5-diamino-2,4,6-triazinyl)-2,2′-bipyridine and its insertion into 2D and 3D bimetallic oxalate-based networks

Abstract

The Fe(ii) complex of the L ligand (L = 6-(3,5-diamino-2,4,6-triazinyl)-2,2'-bipyridine) has been used as a templating cation for the growth of oxalate-based networks. The magnetic characterization of the [Fe(L)](ClO)·CHCN (1) precursor in the solid state has been performed for the first time showing that the low-spin (LS) state is predominating from 2 to 400 K with 10% of Fe(ii), which undergoes a gradual and irreversible spin-crossover above 350 K. 1 presents the LIESST effect with a photo-conversion close to 25% and a T(LIESST) of 49 K. During the preparation of 1, a secondary product of the formula [Fe(L)(CHCN)(HO)](ClO)·CHCN (2) has been obtained. The magnetic characterization of 2 shows that it contains high-spin (HS) Fe(ii). 1 has afforded two novel oxalate-based compounds, the 2D compound of the formula [Fe(L)][MnCr(ox)]·(CHNO)·(CHOH)·(HO) (3) and the 3D compound of the formula [Fe(L)][MnCr(ox)]·(CHCN) (4), which have been obtained by changing the synthetic conditions. The magnetic properties show that in 3 the inserted Fe(ii) cation remains in the LS state from 2 to 340 K and presents a partial and irreversible spin-crossover of ∼20% at higher temperatures. In 4, most of the Fe(ii) complexes remain in the LS state from 2 to 230 K and present a partial and irreversible spin-crossover of ∼50% from 230 to 400 K. 3 and 4 do not present the LIESST effect.

Spin-crossover compounds based on iron(ii) complexes of 2,6-bis(pyrazol-1-yl)pyridine (bpp) functionalized with carboxylic acid and ethyl carboxylic acid

“…This could indicate that they present a higher T 0 (close to 170 K) or that T(LIESST) of compounds with high T 1/2 deviates significantly from that formula as observed for other Fe(II) with tridentate ligands. 19 Very recently, it has been proposed that a complicated relationship between T(LIESST) and T 1/2 may reflect low-temperature thermal and lightinduced symmetry breaking.…”

Heteroleptic Iron(II) Spin-Crossover Complexes Based on a 2,6-Bis(pyrazol-1-yl)pyridine-type Ligand Functionalized with a Carboxylic Acid

“…It is however consistent with the behavior observed in other compounds with T 1/2 well above room temperature, which also deviate from this formula. 21,[35][36][37] Deposition on substrates. In the last years, many studies have been focused on the charge transport properties of SCO compounds on surfaces as a first step prior to their integration into devices.…”

Insertion of single-ion magnets based on mononuclear Co(ii) complexes into ferromagnetic oxalate-based networks

“…In a previous work, we showed that the [Fe II (L) 2 ] 2+ complex with L = (3,5-diamino-2,4,6-triazinyl)2,2′-bipyridine (see Scheme 1) 19 stabilized both a 2D oxalate network and a chiral 3D structure. 20 Interestingly, the [Fe II (L) 2 ](ClO 4 ) 2 ·CH 3 CN precursor exhibited a photo-induced spin transition. 20…”

“…20 Interestingly, the [Fe II (L) 2 ](ClO 4 ) 2 ·CH 3 CN precursor exhibited a photo-induced spin transition. 20…”