Supramolecular Modulation of Spin Crossover in an Fe(II) Dinuclear Triple Helicate

Abstract

A spin-crossover (SCO) active dinuclear Fe(II) triple helicate of the form [Fe 2 L 3 ] 4+ was combined with additional supramolecular components in order to manipulate the interhelical separation and steric congestion and to study the magneto-structural effects on the ensuing composite materials. A more separated array of SCO units produced more extensive spin-transitions, while a tightly arranged lattice environment stabilized the low-spin state. This study highlights the important interplay between crystal packing, intermolecualr interactions, and the magentic behavior of SCO materials.

Dinuclear Iron(II) Triple Helicates Exhibiting Room Temperature Spin‐Transition Behaviour in Solid and Solution Phase

“…An abrupt decrease from 330 K (6.8 cm 3 K mol −1 ) to 270 K (2.38 cm 3 K mol −1 ) in the second step (T 1/2 =311 K) can be attributed to the presence of either [LS‐HS] intermediate or a 1 : 1 mixture of [HS‐HS] and [LS‐LS] spin isomers. The precise identity of this state cannot be confirmed by single‐crystal X‐ray experiments due to the presence of only one Fe(II) center in the asymmetric unit [21] . The third step of spin transition (T 1/2 =195 K) occurred between 260 K and 100 K, where complex 2 attained the [LS‐LS] state.…”

“…The precise identity of this state cannot be confirmed by single-crystal X-ray experiments due to the presence of only one Fe(II) center in the asymmetric unit. [21] The third step of spin transition (T1 = 2 = 195 K) occurred between 260 K and 100 K, where complex 2 attained the [LS-LS] state. Complex 3 undergoes a single-step spin transition behaviour with the T1 = 2 = 354 K, where the susceptibility value (0.7 cm 3 K mol À 1 ) at 300 K showed a mere 10 % conversion of the Fe(II) low-spin centres.…”

Unique Spin Crossover Pathways Differentiated by Scan Rate in a New Dinuclear Fe(II) Triple Helicate: Mechanistic Deductions Enabled by Synchrotron Radiation Studies

“…To date, most of the Fe(II) helicate structures exhibiting SCO properties involve an imidazolimine-based coordination environment. [20][21][22][23][24][25][26][27][28][29] Manipulation of the SCO properties in these dinuclear systems relies on the design of ligand structure(s) so as to induce a suitbale ligand field. Several distinct dinuclear triple helicates have been shown to exhibit spin switching, with different structures from those conjoining metal cations via ligand bridging.…”

Unique spin crossover pathways differentiated by scan rate in a new dinuclear Fe(ii) triple helicate: mechanistic deductions enabled by synchrotron radiation studies

“…To date, most of the Fe(II) helicate structures exhibiting SCO properties involve an imidazolimine-based coordination environment. [23][24][25][26][27][28][29][30][31][32] Manipulation of the SCO properties in these dinuclear systems relies on the design of ligand structure(s) so as to induce a suitable ligand field. Several distinct dinuclear triple helicates have been shown to exhibit spin switching, with different structures from those conjoining metal cations via ligand bridging.…”