Reactions of metal iodides as a simple route to heterometallics: synthesis, structural transformations, thermal and luminescent properties of novel hybrid iodoargentate derivatives templated by YL8 (3+) or YL7 (3+) cations (L = DMF or DMSO)
Résumé
A 1 : 3 molar reaction of YI3 and AgI in dimethylformamide (DMF) in the presence of NH4I afforded [Y(DMF)(8)][Ag-3(mu(3)-I)(mu-I)(3)I-2] (1) with good yield, whereas the similar reaction in dimethylsulfoxide (DMSO) gave complexes [Y(DMSO)(8)][Ag-2(mu-I)(3)I-2] (2) and/ or [Y(DMSO)(8)](2)[Ag-4(mu(3)-I)(2)(mu-I)(4)I-2][I](2) (3), depending on the reaction and crystallization conditions. These discrete heterometallic hybrid compounds 1-3 undergo solid- and solution-state transformations via condensation of iodoargentate anions. So in the confined and solvent-free environment of paratone, crystals of 1 transformed into a 1D zig-zag structure [Y(DMF)(8)](3+)[Ag-6(mu(4)-I)(2)(mu(3)-I)(2)(mu-I)(5)](1 infinity)(3-) (4), whereas those of 2 were first converted into 3 and finally into [Y(DMSO)(7)](4)[Ag-4(mu(3)-I)(4)I-4](3) (5). In solution phase, re-crystalization of 1 or 2 from DMSO-toluene gave 3 as an exclusive species, whereas reaction of 1 with 3 equiv of AgI in DMF afforded 4 with good yield. Alternatively, 4 could also be synthesized with excellent yield from a 1 : 6 molar reaction of YI3 and AgI. The above transformations suggest that, for a given metal-organic cation, an iodometallate cluster with higher nuclarity is thermodynamically more stable. Single crystal X-ray structures are reported for all the compounds and a mechanism for the structural transformation of 2 to 3 is proposed. In addition, spectroscopic, thermo-gravimetric and luminescent properties of the complexes 1, 3 and 4, which were obtained exclusively and in pure form, are also described.