STUDY ON AN ASSEMBLY SYSTEM INCLUDING TETRATHIOVANADATE - SYNTHESES AND STRUCTURAL CHARACTERIZATIONS OF V2CU2S4 CUBANE-LIKE CLUSTERS AND VS4CU4 BIMETALLIC AGGREGATES

摘要

The reaction system (NH4)(3)VS4/CuCl/R(2)dtcNa/PhSNa in DMF affords two types of V/Cu/S complexes. One is the VS4Cu4 complex [VS4Cu4(R(2)dtc)(n)(PhS)(4-n)](3-) (R(2) = Et or OC4H8; n = 0, 1, or 2), the other one is the cubane-like cluster [V2Cu2S4(R(2)dtc)(2)(PhS)(2)](2-) (R(2) = Me(2), OC4H8). (Et(4)N)(2)[V2Cu2S4(OC(4)H(8)dtc)(2)(PhS)(2)] crystallizes in the monoclinic space group C-2/c with a = 20.219(10) Angstrom, b = 14.972(13) Angstrom, c = 18.027(9) Angstrom, beta = 109.03(4)degrees, V = 5158.7 Angstrom(3), and Z = 4. With use of 1797 unique data (I > 3 sigma(I)) the structure was refined to R = 0.060. The dianion contains a V2Cu2S4 cuboidal core and a butterfly array of four metal atoms with a V-V single bond. (Et(4)N)(3)[VS4Cu4(OC(4)H(8)dtc)(PhS)(3)] crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a 16.917(5) Angstrom, b = 25.996(13) Angstrom, c = 14.937(9) Angstrom, V = 6568.5 Angstrom(3) and Z = 4. With use of 2793 unique data (I > 3 sigma(I)), the structure was refined to R = 0.059. (Et(4)N)(3)[VS4Cu4(Et(2)dtc)(PhS)(3)] crystallizes in the triclinic space group P1 with a = 10.391(2) Angstrom, b = 12.391(4) Angstrom, c = 12.586(5) Angstrom, alpha = 78.67(3)degrees, beta = 82.48(2)degrees, gamma = 81.59(2)degrees, V = 1563.1 Angstrom(3), Z = 1, and R = 0.039 using 4538 reflections (I > 3 sigma(I)). (Et(4)N)(3)[VS4Cu4(OC(4)H(8)dtc)(2)(PhS)(2)] crystallizes in the orthorhombic space group Pna2(1) with a = 24.333(7) Angstrom, b = 17.648(4) Angstrom, c = 14.822(6) Angstrom, V = 6364.8 Angstrom(3), Z = 4, and R = 0.058 using 2857 reflections (I > 1 sigma(I)). (Et(4)N)(3)[VS4Cu4(PhS)(4)] crystallizes in the orthorhombic space group Pbnm with a = 12.207(2) Angstrom, b = 15.493(3) Angstrom, c = 32.210(5) Angstrom, V = 6092.6 Angstrom(3), Z = 4 and R = 0.060 using 1109 reflections (I > 3 sigma(I)). All of the VS4Cu4 complexes contain a VS4 tetrahedral core and have a nearly planar VCu4 array. The overall symmetry of the VS4Cu4 unit closely approaches D-2d; however, the presence of ligands lowers the symmetry of all the anions. Structural, spectral, and magnetic data indicate that the VS4Cu4 complexes contain metal atoms with formal oxidation levels of V(V) + 4Cu(I). V-51 NMR spectra exhibit disproportion reactions caused by ligand exchange existing in the DMSO solution. With the variation of the mole ratio of [VS4Cu4(PhS)(4)](3-) to OC(4)H(8)dtcNa from 1:2 to 1:32 in DMSO solution, the complexes containing dtc ligands were detected by V-51 NMR spectra. This affords an evidence of the disproportions for [VS4Cu4(R(2)dtc)(n)(PhS)(4-n)](3-) (n = 1 and 2) in solution. A reaction of [VS4Cu4(PhS)(4)](3-) with a large excess of PPh(3) was performed. A V-51 chemical shift appearing downfield from that of [VS4Cu4(PhS)(4)](3-) was observed and was supposed to be associated with a skeletal conversion from VS4Cu4 to VS4Cu3. Electrochemical studies for both two types of complexes show no reversible redox process and give a support of dissociable property of the coordinated ligand in solution. [References: 57]