Tuning of Inter- versus Intrachain Magnetic Interactions in Cyano-Bridged Ni^II/M^III (M = Cr, Fe, Co) Chain Complexes

Abstract

The reaction of [M(CN)6]3- (M = Cr3+, Fe3+, Co3+) with the nickel(II) complex of 2,4-diamino-1,3,5-triazin-6-yl-{3-(1,3,5,8,12-pentaazacyclotetradecane)} ([NiL]2+) in excess of ANO3 or ACl (A = Li+, Na+, K+, Rb+, Cs+, NH4+) leads to the cyano-bridged dinuclear assemblies A{[NiL][M(CN)6]}.xH2O (x = 2-5). X-ray structures of Li{[NiL][Cr(CN)6]}.5H2O, NH4{[NiL][Cr(CN)6]}.3.5H2O, K{[NiL][Cr(CN)6]}.4H2O, K{[NiL][Fe(CN)6]}.4H2O, Rb{[NiL][Fe(CN)6]}.3.5H2O, and Cs{[NiL][Fe(CN)6]}.3.5H2O, as well as the powder diffractometry of the entire Fe(III) series, are reported. The magnetic properties of the assemblies are dependent on the monocation A and discussed in detail. New efficient pathways for ferromagnetic exchange between Ni(II) and Fe(III) or Cr(III) are demonstrated. Field dependencies of the magnetization for the Fe(III) samples at low temperature and low magnetic field indicate a weak interchain antiferromagnetic coupling, which is switched to ferromagnetic coupling at increasing magnetic field (metamagnetic behavior). The interchain magnetic coupling can be tuned by the size of the A cations.

Magnetic properties and spin dynamics in the single-molecule paramagnetsCu6FeandCu6Co

“…This is surprisingly low, given the supposedly unquenched orbital momentum characterizing the 2 T 2g state of low spin Fe͑III͒ in octahedral sym- metry which should lead to a much larger average g value. 5 The same behavior has been recently reported for a linear, cyanide bridged, CuFeCu complex, and attributed to the peculiar geometrical distortion of Fe͑CN͒ 6 unit, leading to an almost complete quench of the angular momentum. 6 The obtained value of the Weiss constant correspond, in the framework of simple molecular-field approximation ͑MFA͒, = 2zs͑s+1͒J F 3k B…”

Bispidine Coordination Chemistry

“…These studies were based on melamine-derived mono-, bis-, and tris-macrocyclic copper(II) and nickel(II) complexes and their host-guest compounds with cyanometalates (341)(342)(343)(344)(345). Magnetic exchange through the cyano bridge was shown to lead to multivarious effects and based on a thorough interpretation, there is the possibility to tune the magnetic properties of heterooligonuclear complexes (345,346). A thorough theoretical study indicates that s, as well as p-MO effects, are of importance, and these can be varied through the geometry of the cyano bridges and the electronic ground states of the interacting metal centers (346).…”

Metallacycles or coexistence of isomeric metallacycle and chain: Anion-dependent luminescent Ag complexes of a flexible diaminotriazine–imidazole ligand

“…Furthermore, the excellent H-bonding ability of diaminotriazinyl (DAT) group has been successfully used in combination with coordination bonds in some DAT based rigid ligands for crystal engineering [24][25][26][27][28]. However, there are still no reports of flexible ligands incorporating the DAT group, and in this work, we selected a flexible ligand 2,4-diamino-6-[2-(2-methyl-1-imidazolyl) ethyl]-1,3,5-triazine (L) based on the following reasons.…”