Structural and Spectroscopic Studies of [M((x)tu)4]+ Systems (M = Cu, Ag; (x)tu = (substituted) Thiourea)

In a low-temperature redetermination of improved precision of the structure of [Cu(tu)(4)](2)(SiF(6)) ('tu' = thiourea, SC(NH(2))(2)), CU-S range between 2.3173 - 2.3433(8), < > 2.336(11) angstrom, with S-Cu-S 92.72(3)-118.75(12)degrees. The first structure determination of it 1 :4 adduct of a silver(1) salt with a (substituted) thiourea ligand is also reported, for silver(l) nitrate with 'ethylenethiourea', ('etu' = SC(NHCH(2))(2)), as a monohydrate [Ag(ctu)(4)](NO(3)) center dot H(2)O, wherein Ag-S range between 2.544-2.637(2), < > 2.59(4) angstrom, S-Ag-S 87.88-117.57(7)degrees. Bands in the far-IR spectra of these compounds are assigned to v(MS) modes, and the frequencies are compared with those predicted by previously established correlations between v(MS) and the M-S bond length d(MS) for copper or silver complexes with tu or etu ligands.