Heterobimetallic cyanide-bridged Fe^III(μ-CN)M^IIcomplexes (M = Mn and Cu): synthesis, structure and magnetism

Abstract

Systematic magneto-structural studies reveal ‘[FeIII(Tp)(CN)2(μ-CN)MnIICl(L1/L2)]′ (both antiferromagnetic) and [FeIII(Tp)(CN)2(μ-CN)CuII(L1/L2)]+′(L1 ferro- and L2 antiferromagnetic).

Experimental and theoretical magnetostructural studies on discrete heterometallic cyanide-bridged dinuclear FeIIIMnII and tetranuclear FeIII2CuII2 complexes bearing tripodal pyrazolyl borate and tetradentate phenolate-based ligands

“…The extracted J value for complex 1 is comparable with those previously reported values for other structurally relevant dinuclear cyanide-bridged iron( iii )–manganese( ii ) complexes with antiferromagnetic coupling interactions between the metal ions. 12 The observation of antiferromagnetic coupling between low-spin Fe III ( S = 1/2) and high-spin Mn II ( S = 5/2) through cyanide bridging, Fe III – μ -CN–Mn II , is not unexpected taking into consideration their respective magnetic orbitals. The magnetic orbitals of the low-spin Fe III (t 2g 5 e g 0 ) are t 2g (π symmetry), whereas those of the high-spin Mn II (t 2g 3 e g 2 ) are t 2g (π symmetry) and e g (σ symmetry) and therefore both ferromagnetic (t 2g /e g ) and antiferromagnetic (t 2g /t 2g ) contributions can be involved in the magnetic coupling between these two magnetic centers.…”

“…Due to the strict orthogonality between the t 2g magnetic orbitals of the low-spin Fe III ion and the e g ones of the Cu II ion, ferromagnetic coupling between these ions is commonly found for cyanide-bridged systems. 10,12,14 b ,15 However, in the case of compound 2 , the magnetic exchange through the long exchange pathway (described by J 2 ) is weak and antiferromagnetic. The weakness of this interaction can be justified by the fact that the N atom of the cyanide bridging group is connected to an axial position of the elongated octahedral CuN 5 O coordination sphere with a long Cu–N distance of 2.534 Å due to the Jahn–Teller distortion effects.…”

Alkoxy-Bridged Dicopper(II) Cores Meet Tetracyanonickelate Linkers: Structural, Magnetic, and Theoretical Investigation of Cu/Ni Coordination Polymers

“…Heterometallic coordination polymers (CPs) incorporating magnetically active building blocks have gained increased attention in recent years because of possible cooperative phenomena of the magnetic spins. − The strongest magnetic coupling between the spins of the nearest-neighbor paramagnetic centers is typically mediated by short bridging ligands, including oxo, cyano, azido, or carboxylate moieties, which have extensively been studied due to their ability to transmit magnetic exchange of different nature and magnitude. − Considering the dependence of the magnetic interactions on the type of metal ion and the superexchange path, the selection of transition metals and bridging groups emerges as a key feature in the construction of heterometallic coordination systems. , …”