Magnetochemical Properties and Reactions of Vanadium(III) Thiolate Complexes:  Preparation of (NEt₄)₃[V₃Cl₆(edt)₃] and Mixed-Valence (NEt₄)[V₂(edt)₄] (edt = Ethane-1,2-dithiolate)

Abstract

Reactions of the previously reported dinuclear vanadium(III) thiolate anion [V(2)(edt)(4)](2)(-) (edtH(2) = ethane-1,2-dithiol) are described. Treatment of (NEt(4))(2)[V(2)(edt)(4)] (1) in MeCN with equimolar (C(12)H(8)S(2))BF(4) (C(12)H(8)S(2)(+) = the thianthrenium radical cation) results in a one-electron oxidation and isolation of the V(III),V(IV) complex (NEt(4))[V(2)(edt)(4)] (2). The same product can also be obtained by controlled-potential electrolysis of 1 at -0.20 V vs Ag/AgCl. Treatment of 1 in CH(2)Cl(2) with py gives no reaction, but addition of Me(3)SiCl leads to formation of the known V(2)OCl(4)(py)(6) (3). The latter is also formed by the reduction of a 1:1 mixture of VOCl(3) and VCl(3)(THF)(3) in CH(2)Cl(2)/py and by the reaction in CH(2)Cl(2) of VCl(3)(THF)(3) and py with edt(2)(-). Treatment of 1 in MeCN with bpy (2,2'-bipyridine) gives no reaction, but addition of Me(3)SiCl results in formation and isolation of [V(2)OCl(2)(bpy)(4)]Cl(2) (4) identified by spectroscopic comparison with literature data. The reaction of 1 in MeCN with equimolar VCl(3)(THF)(3) and NEt(4)Cl gives (NEt(4))(3)[V(3)Cl(6)(edt)(3)] (5). A more convenient procedure to 5 is the reaction in MeCN of VCl(3)(THF)(3), Na(2)edt, and NEt(4)Cl in a 1:1:1 molar ratio. Complex 5.MeCN crystallizes in triclinic space group P&onemacr; with (at -154 degrees C) a = 14.918(3) Å, b = 17.142(5) Å, c = 11.276(3) Å, alpha = 106.78(1) degrees, beta = 95.03(1) degrees, gamma = 106.18(1) degrees, and Z = 2. The anion contains a near-linear V(3) unit with a face-sharing trioctahedral structure: the three edt(2)(-) groups provide the six bridging S atoms; two edt(2)(-) groups are in a &mgr;-eta(2):eta(2) mode (as in 1), but the third is in a &mgr;(3)-eta(1):eta(2):eta(1) mode. The V.V separations (>3.1 Å) preclude V-V bonding. Variable-temperature solid-state magnetic susceptibility studies have been performed on complexes 1, 2, and 5 in a 1.0 kG field and 5.00-300 K temperature range. For 1, the effective magnetic moment (&mgr;(eff)) gradually decreases from 1.09 &mgr;(B) at 300 K to 0.26 &mgr;(B) at 5.00 K. The data were fit to the Bleaney-Bowers equation, and the fitting parameters were J = -419(11) cm(-)(1) and g = 2.05. The singlet-triplet gap is thus 838 cm(-)(1). For 2, &mgr;(eff) is essentially temperature-independent, slowly decreasing from 1.90 &mgr;(B) at 300 K to 1.86 &mgr;(B) at 55 K and then to 1.63 &mgr;(B) at 5.00 K. The complex thus is S = (1)/(2) with no thermally accessible S = (3)/(2) state. The combined data on 1 and 2, together with the results of EHT calculations, show that 1 and 2 contain a V-V single bond tying up two of the d electrons and that the remaining two d electrons in 1 are antiferromagnetically coupled to give an S = 0 ground state and S = 1 excited state; for 2, the one remaining d electron gives an S = (1)/(2) state. For 5, &mgr;(eff) increases from 5.17 &mgr;(B) at 320 K to a maximum of 6.14 &mgr;(B) at 30.0 K and then decreases slightly to 6.08 &mgr;(B) at 5.00 K. The data were fit to the appropriate theoret...

A Vanadium Chalcogenide Dicubane

“…The fit also deviated from paramagnetic behavior below 150 K and gave a θ value of –7.69 K, suggesting a weak antiferromagnetic interaction, likely between neighboring clusters. Similar weak antiferromagnetic coupling has also been reported in other vanadium complexes and clusters 29. Considering that the cluster has an odd number of total valence electrons, the one unpaired electron resides alone on the highest occupied molecular orbital (HOMO).…”

Synthesis, characterization and reactivity of linear-type S-bridged trinuclear complexes containing vanadium(III) ion. Crystal structures of [VIII{M(aet)3}2](ClO4)3 (M = RhIII, IrIII; aet = 2-aminoethanethiolate)†

“…7-11 The V-S distances in 1a and 2a are similar to the corresponding V-S(bridged) distances in [V 3 Cl 6 (edt) 3 ] 3-(edt = ethane-1,2-dithiolate; average 2.408(11) Å), which is a rare example containing the V III S 6 chromophore. 18 Complex 2a has somewhat longer V-S bonds than 1a. This seems to be caused by stronger affinity of iridium toward sulfur atoms than that of rhodium.…”

A journey into the electrochemistry of vanadium compounds

“…Redox properties, via CV, indicated that [V 2 (edt) 4 ] 2− undergoes two oxidation processes to V(IV) and V(V) ( Table 9, entry 1b), while the V(IV) species, formed with one S atom, [VS(edt) 2 ] 2− , displays no reversible redox processes, a result already reported by the same authors [195], with only an irreversible oxidation process at E pa = −0.46 V vs NHE was observed. The same compound, [V 2 (edt) 4 ] 2− , was studied again few years later (Table 9, entry 1c [196]). …”