Two Cyanide-Bridged Mn^II–Nb^IV Coordination Chain Ferrimagnets Promoted by Interchain Ferromagnetic Interactions

Abstract

Two new coordination chain compounds based on octacyanoniobate(IV) are reported: {[Mn(II)(bpy)(H2O)2]2[Nb(IV)(CN)8]·5H2O}n (1) and {[Mn(II)(bpy)(H2O)2][Mn(II)(bpy)2][Nb(IV)(CN)8]·5H2O}n (2) (bpy = 2,2'-bipyridine). Both have the topology of vertex-sharing CN-bridged squares. The Mn2Nb2 units are mutually parallel in 1 and perpendicular in 2. The antiferromagnetic intrachain interactions between the Mn(II) and Nb(IV) centers in 1 and 2, typical for Mn(II)-[Nb(IV)(CN)8] family of compounds, lead to ferrimagnetic ground state of each single chain. Both compounds show bulk ferrimagnetic ordering below their critical temperatures (Tc) of 6.4 K in 1 and 4.7 K in 2. Such a behavior is due to the ferromagnetic interchain interactions, assured by the π-π contacts between the 2,2'-bipyridine rings and by the hydrogen bonds between the terminal cyanide ligands of the [Nb(IV)(CN)8]-building blocks and coordination/crystallization water molecules. 1 and 2 are rare examples of ferrimagnets promoted by interchain ferromagnetic exchange, and the Tc of 1 is one of the highest among similar 1-D coordination polymers.

Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light‐Induced Excited Spin State Trapping Behavior and Magnetic Exchange Photoswitching

“…Both compounds show a large increase of magnetization upon irradiation with 436 nm light ( d – d transition of the [M IV (CN) 8 ] 4− ) because of the octacyanidometalate‐centered LIESST and magnetic coupling photoswitching. The observed photomagnetism of Mn 2 W and Mn 2 Mo is compared to that of the non‐photomagnetic Nb IV analogue {[Mn II (bpy) 2 ][Mn II (bpy)(H 2 O) 2 ][Nb IV (CN) 8 ]⋅5 H 2 O} n Mn 2 Nb , as well as the non‐photomagnetic building block [Mn II (bpy) 2 Cl 2 ]. Moreover, we prepared and studied simple monometallic (H 4 cyclam)[W(CN) 8 ]⋅1.5 H 2 O and (H 4 cyclam)[Mo(CN) 8 ]⋅1.5 H 2 O systems to support the LIESST‐type photomagnetic behavior of Mn 2 W .…”

Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light‐Induced Excited Spin State Trapping Behavior and Magnetic Exchange Photoswitching

“…Theo bserved photomagnetism of Mn 2 W and Mn 2 Mo is compared to that of the non-photomagnetic Nb IV analogue {[Mn II (bpy) 2 ][Mn II (bpy)-(H 2 O) 2 ][Nb IV (CN) 8 ]·5 H 2 O} n Mn 2 Nb,[15] as well as the non- Herein, we present for the first time the photomagnetism of the octacyanidotungstate(IV) (Mn 2 W)i ncorporated into ab imetallic coordination chain compound {[Mn II (bpy) 2 ]because of the octacyanidometalate-centered LIESST and magnetic coupling photoswitching.…”

Molybdenum(III) Thiocyanate- and Selenocyanate-Based One-Dimensional Heteronuclear Polymers: Coordination Affinity-Controlled Assemblage of Mixed Spin and Mixed Valence Derivatives with Ni(II) and Co(II/III)

“…[1][2][3][4] One of the desirable conditions is a large energy separation between the ground spin state and the states of higher energy, which is obtained when strong exchange interactions take place between the magnetic centers. This has led to involve 4d or 5d metal ions as spin carriers for the design of chains [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] because of their spatially more extended valence orbitals (which encompass the magnetic orbitals) that contribute to stronger magnetic interaction between the magnetic centers. 25 These ions can also contribute to the magnetic anisotropy for favorable electronic configurations and geometry.…”