A Vanadium-Containing Iron−Sulfur Cluster with a V₂Fe₂S₄ Cubane-like Core. Synthesis, Structure, and Characterization of (Et₄N)[V₂Fe₂S₄(Me₂dtc)₅]

Abstract

A cubane-type cluster (Et 4 N)[V 2 Fe 2 S 4 (Me 2 dtc) 5 ] (1) has been synthesized from an assembly system VS 4 3-/FeCl 2 / Me 2 dtc -/PhSin acetonitrile (Me 2 dtc -) dimethyldithiocarbamate). The compound 1‚2CH 3 CN crystallizes in the monoclinic space group P2 1 /c (No. 14), with a ) 12.174(3) Å, b ) 22.135(4) Å, c ) 19.712(5) Å, ) 105.43(2)°, V ) 5120.3 Å 3 , F calcd ) 1.50 g/cm 3 , and Z ) 4. The structure was solved from 6336 unique reflections (I > 3σ(I)) and refined by a full-matrix least-squares method to R ) 0.053. The cluster anion contains a cubanelike [V 2 Fe 2 S 4 ] 4+ core, in which the V-V, Fe-Fe, and V-Fe(mean) distances of the V 2 Fe 2 tetrahedron are 2.745-(2), 2.681(1), and 2.780 (6) Å, respectively. The Mössbauer effect and the structural parameters indicate that the oxidation states of the Fe and V atoms in the [V 2 Fe 2 S 4 ] 4+ core are both +3. The 1 H NMR shows the paramagnetism of the cluster. The chemical shift of 51 V NMR was observed at -391 ppm. The FAB-MS behavior of the cluster indicates the bond breaking of the cluster core. Case, E. E.; Morningstar, J. E.; Dzeda, M. F.; Mauterer,

Studies on the Synthetic System of V/Ag/S Cluster Compounds and Structural Characterizations of V2AgS4, V2Ag2S4, and V2O2(μ-S)2 Complexes

“…(2) There are two sets of M−S core bonds in all the complexes of which two short M−S bonds display the features of a MS double bond, indicating the relative independency of the moieties M 2 S 2 (μ-S) 2 in the M 2 Ag 2 S 4 cores similar to that of the moieties in M 2 AgS 4 defective cubane cores. This implies again the following aggregation mechanism: In contrast with the R 2 dtc - ligand that leads usually to two unequal chelating V−S bonds, − the trithiocarbonate chelating the V atom gives two V−S bonds of almost equal length (ca. 2.406 Å).…”

“…A broad resonance at 231 ppm was observed in the 51 V NMR (Figure b) of [Et 4 N] 2 2 , which is believed to be responsible for the V IV (μ-S) 2 V IV moiety with a V−V single bond and may also be an indication of the two V atoms being in a similar environment. A comparable example is [V 2 (S 2 ) 2 (CS 3 ) 4 ], − which shows its sharp 51 V resonance at 125 ppm in DMSO/CD 3 CN. It is obvious that V IV nuclei in complex [Et 4 N] 2 2 are less effectively shielded by five S atoms than those of [V 2 (S 2 ) 2 (CS 3 ) 4 ] 4- shielded by eight S atoms, giving rise to the 51 V signal downfield.…”

“…In contrast with the R 2 dtcligand that leads usually to two unequal chelating V-S bonds, [20][21][22][23][24] the trithiocarbonate chelating the V atom gives two V-S bonds of almost equal length (ca. 2.406 Å).…”

“…Our interest in this area concentrates on the riches of structure types of the V/S(O) complexes and studies on synthetic systems and clustering mechanisms. We have synthesized and structurally S0020-1669(97)01531-0 CCC: $ 15 characterized several V/S complexes, such as V 2 (η 2 -µ-S 2 ) 2 (Et 2dtc) 4 , 18 [V 3 S 7 (Me 2 dtc) 3 ] -, 19 [V 2 Cu 2 S 4 (R 2 dtc) 2 (PhS) 2 ] 2-(R 2 ) Me 2 , 20 C 5 H 10 , 21 and OC 4 H 8 ), 22 [V 2 Fe 2 S 4 (Me 2 dtc) 5 ] -, 23 [VFe 3 S 4 -(Et 2 dtc) 4 ] -, 24 [V 2 Ag 2 S 4 (OC 4 H 8 dtc) 2 (PhS) 2 ] 2-, 22 and [VS 4 Cu 4 -(R 2 dtc) n (PhS) 4-n ] 3-(R 2 ) OC 4 H 8 , n ) 0, 1, 2; R 2 ) Et 2 , n ) 1). 25 All the above complexes were obtained in this laboratory from an assembly system consisting of VS 4 3-, M n+ (M ) Fe, Cu, Ag), and R 2 dtcand/or PhS -.…”