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)†

Abstract

Reactions of fac(S)-[M(aet)3 ] (M = Rh III , Ir III ; aet = 2-aminoethanethiolate) with an excess of VCl 3 gave linear-type S-bridged trinuclear complexes [V III {M(aet) 3 } 2 ] 3ϩ (M = Rh III 1, Ir III 2). The ∆Λ isomers (1a(ClO 4 ) 3 and 2a(ClO 4 ) 3 ) were selectively crystallized and their structures were determined by X-ray diffraction. Both the complex cations consist of two terminal fac(S)-[M(aet) 3 ] units and a central vanadium atom, which is situated in an octahedral environment with a V III S 6 chromophore. The Ir complex 2a was also formed by using V IV OCl 2 instead of V III Cl 3 in a redox reaction, whereas the Rh complex 1a was not formed by a similar method. The optically active isomer (ΛΛ-1b) of the Rh complex was selectively obtained by using Λ-fac(S)-[Rh(aet) 3 ], and characterized by IR, UV-VIS absorption and CD spectra. All the obtained complexes exhibit a unique strong absorption band at ca. 18 × 10 3 cm Ϫ1 . Stability and reactivity relating to V-S bond cleavage for the complexes were investigated using UV-VIS absorption spectroscopic methods. These studies show first order decomposition or metal exchange. While 2a has weaker V-S bonds than 1a (from the X-ray analyses), the former is considerably more stable in water than the latter. Cyclic voltammograms of 1a and 2a in water show only irreversible oxidation and reduction waves including V IV/III and V III/II processes. The V() ions in the S-bridged trinuclear structures exhibit a lower magnetic moment (2.59 µ B for 1a and 2.27 µ B for 2a) at room temperature than the spin-only value for a d 2 electronic configuration. † Electronic supplementary information (ESI) available: Fig. S1 Absorption spectral change of ∆Λ-[V{Rh(aet) 3 } 2 ] 3ϩ (1a) upon addition of Co(); the curves show the spectra measured at 5 min intervals. See

Synthesis of Novel S‐Bridged Heterotrinuclear Complexes Containing Six‐Membered Chelate Rings: Structural, Spectroscopic, and Electrochemical Properties of [Co{Rh(apt)3}2]3+ (apt = 3‐Aminopropanethiolate)

“…Moreover, these spectral patterns are typical for linear-type, S-bridged trinuclear complexes in the range 4000-400 cm -1 . [2,3,[35][36][37][38] The IR spectra of 1, 2a(NO 3 ) 3 , and 2bBr 3 show characteristic bands in the range 3500-2800 cm -1 , corresponding to the vibration modes of the NH 2 and CH 2 groups. The bands for the bending mode of the NH 2 and CH 2 groups are observed at 1700-1000 cm -1 .…”

A journey into the electrochemistry of vanadium compounds

“…Ligand (CpP OMe Co) − , already discussed in oxido-V(IV) paragraph (Section 2.1, 3 ], where M is Rh(III) or Ir(III) and aetH is 2-aminoethanethiole, with an excess of VCl 3 gave linear-type S-bridged trinuclear complexes [225], where V maintains its oxidation state, at variance from what happened with sulfur bridged Rh and Ir complexes (see Section 3.2). [V{Rh(aet) 3 } 2 ] 3+ and [V{Ir(aet) 3 } 2 ] 3+ both displayed an irreversible reduction wave relative to the V(III) → V(II) process and irreversible oxidation waves, some of which appeared only after the reduction scan and therefore may be due to species forming after decomposition.…”

Trinuclear Early/Late‐Transition‐Metal Thiolate Complexes

“…Heterometallic thiolato complexes that contain vanadium in combination with another transition metal are limited to the trinuclear complexes [V III {M(aet) 3 } 2 ] 3+ (M = Rh III , Ir III ; aet = 2-aminoethanethiolate, en = ethylenediamine), which are bridged by bidentate 2-aminoethanethiolate ligands. [8] In contrast, no examples of heterometallic vanadium/cobalt or vanadium/nickel thiolato complexes were found in the literature. A series of trinuclear metal complexes of the type [LMMЈML] n+ with L = 1,4,7-tris(4-tertbutyl-2-mercaptobenzyl)-1,4,7-triazacyclononane like [LCoNiCoL] n+ (n = 2-4), [LNiCoNiL] n+ (n = 1-3), [9] [LFeNiFeL] n+ (n = 2-4), [10] [LFeMFeL] n+ (M = Cr, Co; n = 1-3) [11] and [LFeMFeL] n+ (M = Ge, Sn; n = 2,3) [12] have been synthesised and characterised with respect to their magnetic exchange properties.…”

“…Ab initio multireference calculations together with mapping approaches reveal that the magnetic properties of the anionic metal complexes can be described by different effective spin Hamiltonians that indicate different types of intramolecular interactions between the metal ions. In [Co 2 V(SPh) 8 ] 2-, we found at low temperatures an effective S = 3/2 behaviour with small zerofield splitting (ZFS) caused by a strong, symmetric antiferromagnetic exchange interaction. A weak direct Ni-V bond in [Ni 2 V(SPh) 8 ] 2-generates an effective two-centre system that consists of an effective spin of S = 1/2 from the weakly bound Ni-V pair and a pseudospin S = 1 located on the other nickel site, antiferromagnetically coupled to an S = 1/2 ground state.…”

“…In [Co 2 V(SPh) 8 ] 2-, we found at low temperatures an effective S = 3/2 behaviour with small zerofield splitting (ZFS) caused by a strong, symmetric antiferromagnetic exchange interaction. A weak direct Ni-V bond in [Ni 2 V(SPh) 8 ] 2-generates an effective two-centre system that consists of an effective spin of S = 1/2 from the weakly bound Ni-V pair and a pseudospin S = 1 located on the other nickel site, antiferromagnetically coupled to an S = 1/2 ground state.…”