Investigation of SCO property–structural relationships in a family of mononuclear Fe(ii) complexes

Abstract

Six complexes with the formula [FeL(NCE)2] (E = S, Se, BH3) have been reported. A survey of the magneto-structural relationship has been conducted.

Manipulating the spin crossover behaviour in a series of cyanide-bridged {FeIII2FeII2} molecular squares through NCE− co-ligands

“…The shift of T 1/2 from 214 to 250 to 288 K for 1 , 2 , and 3 is due to the increasing ligand field from NCS − to NCSe − to NCBH 3 − . 29 The synthetic strategy developed in this work can be used to explore other tridentate capping ligands, which should allow for rational tuning of the ligand field strength as well as the redox potential to achieve multi-stable materials. Studies in this direction are currently underway in our lab.…”

Site Selectivity for the Spin States and Spin Crossover in Undecanuclear Heterometallic Cyanido-Bridged Clusters

“…64 Thus, in a further pursuit to activate as much as possible potential SCO sites and appointing the new topologies of heterometallic clusters of modular potential, we exploited the self-assembly between [W(CN) 8 ] 3− and Fe II , Co II , or Ni II complexes with bulky N donors of various degrees of flexibility, commonly used to construct SCO complexes. 67,68 As a result, here we present an unprecedented series of cyanido-bridged clusters realizing new undecanuclear topology: Fe II 18MeOH (1), S15−S17). For the sake of simplicity, we will consider the M 7 W 4 forms as the fundamental structural components (see further description).…”

“…This feature definitely precluded the observation of multistability, although multichannel bistability was achieved through a solid/solution approach. , Furthermore, the weakly bonded MeOH molecules on the surface of a cluster allow facile ligand substitution chemistry at these specific positions to create extended clusters and polymers. − However, until now, only the use of dedicated capping 1,4,7-trimethyl-1,4,7-triazacyclononane (Me 3 tacn) ligands allowed one to extend the SCO behavior onto the peripheral cluster areas . Thus, in a further pursuit to activate as much as possible potential SCO sites and appointing the new topologies of heterometallic clusters of modular potential, we exploited the self-assembly between [W­(CN) 8 ] 3– and Fe II , Co II , or Ni II complexes with bulky N donors of various degrees of flexibility, commonly used to construct SCO complexes. , As a result, here we present an unprecedented series of cyanido-bridged clusters realizing new undecanuclear topology: Fe II [Fe II (bzbpen)] 6 [W V (CN) 8 ] 2 [W IV (CN) 8 ] 2 ·18MeOH ( 1 ), Na I [Co II (bzbpen)] 6 [W V (CN) 8 ] 3 [W IV (CN) 8 ]·28MeOH ( 2 ), Na I [Ni II (bzbpen)] 6 [W V (CN) 8 ] 3 [W IV (CN) 8 ]·27MeOH ( 3 ) (group I ), and Co II [Co II ( R / S -pabh) 2 ] 6 [W V (CN) 8 ] 2 [W IV (CN) 8 ] 2 ·26MeOH [ 4 R and 4 S ) (group II ); bzbpen = N 1 , N 2 -dibenzyl- N 1 , N 2 -bis­(pyridin-2-ylmethyl)­ethane-1,2-diamine; R / S -pabh = ( R / S )- N -(1-naphthyl)-1-(pyridin-2-yl)­methanimine]. The series was characterized by scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), flame atomic absorption spectroscopy (FAAS), single-crystal X-ray diffraction (XRD), powder XRD (PXRD), superconducting quantum interference device (SQUID) magnetometry, UV–vis–NIR (in the solid state and in solution), IR and 57 Fe Mössbauer spectroscopic techniques, and electrospray ionization mass spectrometry (ESI MS).…”

Cooperative Spin Crossover above Room Temperature in the Iron(II) Cyanoborohydride–Pyrazine Complex

“…Another family of molecular complexes is formed by tetradentate chelating ligands in the cis -α-conformation and two BH 3 CN – coligands in cis-positions. Thus, N , N ′-bis­(2-pyridylmethyl)-1,2-ethanediamine and its analogues can provide FeN 6 and FeN 4 S 2 coordination environments. These complexes demonstrate a complete SCO in a wide range of temperatures; however, in the case of large ligand molecules , a more distorted octahedral environment is formed, and it inhibits the occurrence of SCO.…”