[V₁₆O₃₈(CN)]^9–: A Soluble Mixed-Valence Redox-Active Building Block with Strong Antiferromagnetic Coupling

Abstract

A new discrete [V(16)O(38)(CN)](9-) cluster, which displays the hitherto unknown 8- charge on the cluster shell and is the first to encapsulate the cyanide anion, has been synthesized and characterized by IR and UV/vis/near-IR spectroscopy, electrochemistry, and magnetic susceptibility measurements. Bond valence sum calculations conducted on the basis of the crystal structure analysis of K(9)[V(16)O(38)(CN)]·13H(2)O confirm that this new member of the polyoxovanadate series is a mixed-valence complex. The intervalence charge transfer bands arising from intrametal interactions reveal that a localized (class II) assignment is appropriate for the cluster; however, a small degree of electronic delocalization is present. Interesting possibilities exist for the incorporation of this unit into higher dimensionality framework structures, where the redox, optical, and magnetic properties can be exploited and tuned.

Supramolecular Recognition Influences Magnetism in [X@HVIV8VV14O54]6− Self‐Assemblies with Symmetry‐Breaking Guest Anions

“…The supramolecular sphere of this POV hexaanion accommodates in its inner cavity a tetrahedral V V O 2 F 2 À unit, the molecular ion peak (m/z = 120.9) of which was detected among others (decomposition during ionization) by electrospray ionization mass spectrometry. The oxidation state of the central vanadium atom is confirmed by bond valence sum calculation (S bv = 4.77), and the resulting charge of the guest of À1 is in line with the fact that all other known {X@V 22 O 54 } species enclose monoanions. The intra- Figure 1.…”

“…The molecular structure of [VO 2 F 2 @HV 22 O 54 ] 6À in compound 1 is illustrated in Figure 1 (see also Figure S1 and Tables S1-S4 in the Supporting Information). The nano-sized {V 22 O 54 } shell (height: 1.27 nm, width: 1.10 nm) is made up of twenty-two edge-and corner-sharing {VO 5 } square pyramids and adopts a bulb-shaped or matroshka-like structural motif identical to that observed in compounds 2 and 3.…”

“…The molecular structure of [VO 2 F 2 @HV 22 O 54 ] 6À in compound 1 is illustrated in Figure 1 (see also Figure S1 and Tables S1-S4 in the Supporting Information). The nano-sized {V 22 O 54 } shell (height: 1.27 nm, width: 1.10 nm) is made up of twenty-two edge-and corner-sharing {VO 5 } square pyramids and adopts a bulb-shaped or matroshka-like structural motif identical to that observed in compounds 2 and 3. The supramolecular sphere of this POV hexaanion accommodates in its inner cavity a tetrahedral V V O 2 F 2 À unit, the molecular ion peak (m/z = 120.9) of which was detected among others (decomposition during ionization) by electrospray ionization mass spectrometry.…”

“…As expected given their quasi-identical structures, compounds 1, 2, and 3 exhibit similar ATR-FTIR spectra (Figure 2, see also Figure S2 in the Supporting Information). All three compounds display at approximately ñ = 990 cm À1 a very strong absorption band with a shoulder corresponding to the stretching vibrations of the terminal oxygen atoms in the V=O groups (bond order (BO) > 1) of the [X@HV 22 O 54 ] 6À polyoxoanion, which directly reflects the V IV /V V ratio. and ñ = s [VÀ(m 3 -O)ÀV] = 600 cm À1 (BO < 1) in compound 1.…”

Structural conversion from bowl- to ball-type polyoxovanadates: Synthesis of a spherical tetradecavanadate through a chloride-incorporated bowl-type dodecavanadate

“…, N 3 -, ClO 4 -, or CN -, in an anionic spherical cage were studied utilizing a template effect [15][16][17][18][19]. The electrostatic balance between an anionic template and a polyoxovanadate framework influenced the resulting structure of the sphere; i.e., the combination of weak repulsion with the polyoxovanadate oxygen atoms and the attraction of the vanadium cationic center (the highest valence state of V(V)) controlled the architecture of the anion-templated polyoxovanadate cage.…”