Synthesis and structural characterization of two new polynuclear metal thiosaccharinates: Hexakis(thiosaccharinato)hexasilver(I) and tetrakis(thiosaccharinato)tetracopper(l)

摘要

The title compounds, for short Ag-6(tsac)(6) (1) and [Cu-4(tsac)(4)(MeCN)(2)] center dot 2MeCN (2), were prepared by the reaction of thiosaccharin with Ag(I) or Cu(II) salts in different solvents. The new complexes were characterized by FT-IR, Raman, UV-Vis and NMR spectroscopy. Their crystal and molecular structures were determined by X-ray diffraction methods. The structures were solved from 1621 (1) and 7080 (2) reflections with I > 2 sigma(I) and refined to agreement R1-factors of 0.0261 (1) and 0.0456 (2). Ag-6(tsac)(6) molecule derives from the clustering of six Ag(tsac) moieties related to each other through the crystallographic 3-bar (S-6) symmetry operations of the R (3) over bar space group. This results in a highly regular molecular structure where the silver atoms are at the corners of an octahedral core slightly compressed along one of its three-fold axis [inter-metallic Ag center dot center dot center dot Ag contacts of 3.1723(4) and 3.1556(4) angstrom]. The six thiosaccharinate ligands bridge neighboring Ag atoms along the C-3-axis through Ag-N bonds [d(Ag-N) = 2.285(2) angstrom] at one end and bifurcated Ag-S(thione)Ag bonds [Ag-S distances of 2.4861(7) and 2.5014(8) angstrom] at the other end. In contrast, the 2 compound is arranged in the lattice as an irregular tetrameric copper complex [Cu-4(tsac)(4)(MeCN)(2)] where the metals show different environments. Two copper ions are four-fold coordinated to three tsac ions through the N-atom of one tsac [Cu-N distances of 2.112(3) and 2.064(3) angstrom] and the thione sulfur atom of the other two [Cu-S distances in the range from 2.284(1) to 2.358(1) angstrom] and to a MeCN solvent molecule [Cu-N distances of 1.983(4) and 2.052(3) angstrom]. The other two copper ions are in three-fold environment, one trans-coordinated to two tsac ions [Cu -N distances of 1.912(3) and 1.920(3) angstrom] and to the thione S-atom of a third ligand [d(Cu-S) = 2.531(1) angstrom], the other one to the thione sulfur atom of three tsac ligands [Cu-S distances in the range from 2.229(1) to 2.334(1) angstrom]. The clustering renders the metals to short distances from each other, the shorter Cu center dot center dot center dot Cu distance teing 2.6033(7) angstrom, as to presume the existence of weak inter-metallic interaction within the cluster. center dot center dot center dot 2007 Elsevier B.V. All rights reserved.