Synthesis, Crystal Structure, and Magnetic Properties of Hexanuclear [{MnL₂}₄{Nb(CN)₈}₂] and Nonanuclear [{MnL₂}₆{Nb(CN)₈}₃] Heterometallic Clusters (L = bpy, phen)

Abstract

A hexanuclear cyano-bridged {MnII4NbIV2} cluster (1) bearing 2,2'-bipyridine (bpy) as the blocking ligand at manganese is obtained from the reaction of cis-[MnCl2(bpy)2] and K4[Nb(CN)8]. When the blocking ligand is 1,10-phenanthroline (phen), a nonanuclear cluster {MnII6NbIV3} (2) is obtained. The structure of [{Mn(bpy)2}4{Nb(CN)8}2] has been solved by single-crystal X-ray crystallography, whereas the phen derivative has been confirmed by means of the structure analysis of the corresponding WIV analogue [{Mn(phen)2}6{W(CN)8}3(H2O)2]. Magnetic measurements revealed S=9 and 27/2 spin ground states for these aggregates as a result of antiferromagnetic Nb-Mn interaction with JNb-Mn=-18.1 cm(-1) (1) and -13.6 cm(-1) (2).

Synthesis and Redox‐Induced Structural Isomerization of the Pentagonal Bipyramidal Complexes [W(CN)5(CO)2]3− and [W(CN)5(CO)2]2−

“…As expected for a pentagonal bipyramidal complex of tungsten(II) with a low-spin d 4 Figure 1, right). [12] All five equatorial C atoms lie almost exactly within the mean equatorial plane, and the main deviation from the ideal geometry corresponds to a slightly bent C ax -W-C ax angle of 173.9(2)8.…”

“…It further exhibits hyperfine splitting, attributable to the 183 W isotope (I = 1/2, 14.3 % abundant), with A x = 150 G, A y = 20 G and A z = 120 G. This level of anisotropy is comparable to that observed for K 4 …”

“…The X-band EPR spectrum of 2 in a frozen CH 2 Cl 2 solution at 30 K is nearly axial, with g x = 1.92, g y = 1.89, and g z = 1.82 (see Figure S5 in the Supporting Information). It further exhibits hyperfine splitting, attributable to the 183 W isotope (I = 1/2, 14.3 % abundant), with A x = 150 G, A y = 20 G and A z = 120 G. This level of anisotropy is comparable to that observed for K 4 [Mo(CN) 7 ]·2 H 2 O (g k = 2.10, g ? = 1.97), wherein [Mo(CN) 7 ] 4À is suspected to adopt a monocapped trigonal prismatic geometry.…”

Multifunctional Magnetic Molecular {[MnII(urea)2(H2O)]2[NbIV(CN)8]}n System: Magnetization-Induced SHG in the Chiral Polymorph

“…The ordering 37 and -13.6 cm -1 for nonanuclear Mn 6 Nb 3 clusters. 38 The values of magnetic ordering temperatures T c of the {[Mn II (urea) 2 (H 2 O)] 2 [Nb IV (CN) 8 ]} n molecular system varies from 43/42 K through 70 and back to 47 K depending on the structural transformations R/βf2bf3 (Figure 9) but its soft ferrimagnetic character remains intact. Significant increase of the T c at the first stage of transformation R/β f 2b corresponds well with the proposed increase of the connectivity type.…”

[M6M′4] Cage Compounds with Chiral Bidentate Ligands

“…Discrete cyanide‐bridged polynuclear complexes have been reported to show a wide range of magnetic/electronic properties 1–11. Cyanide ligands can coordinate via their nitrogen and carbon donor groups to form approximately linear bridges between neighbouring metal centres and act as potent mediators of magnetic and electronic exchange.…”