A Twelve-Coordinated Iodide in a Cuboctahedral Silver(I) Skeleton

Three new halide-centered octanuclear silver(I) complexes, [Ag-8(X){S2P(CH2CH2Ph)(2)}(6)](PF6), X = F-, 1; Cl-, 2; Br-, 3; were prepared in the presence of the corresponding halide anions with silver(I) salts and dithio-phosphinate ligands. Structure analyses displayed that a Ag-8 cubic core can be modulated by the size effect of the central halide; however, an iodide-centered Ag-8 cluster was not found under similar reaction conditions. Interestingly, a luminescent dodecanuclear silver(I) cluster, [Ag-12(mu(12)-I) (mu(3)-I)(4){S2P-(CH2CH2Ph)(2)}(6)] (I), 4; was then synthesized. The structure of 4 contains a novel mu(12)-I at the center of a cuboctahedral silver(I) atom cage, which is further stabilized by four additional mu(3)-I and six dithiophosphinate ligands. To the best of our knowledge, the mu(12)-I revealed in 4 is the highest coordination number for a halide ion authenticated by both experimental and computational studies. Previously, the mu(12)-I was only observed in [PyH][{TpMo(mu(3)-S)(4)Cu-3}(4)(mu(12)-I)]. The synthetic details, spectroscopic studies including multinuclear NMR and ESI-MS, structure elucidations by single crystal X-ray diffraction, and photoluminescence of 4 are reported herein.