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

Three new halide-centered
octanuclear silver­(I) complexes, [Ag8(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 dithiophosphinate ligands. Structure analyses displayed
that a Ag8 cubic core can be modulated by the size effect
of the central halide; however, an iodide-centered Ag8 cluster
was not found under similar reaction conditions. Interestingly, a
luminescent dodecanuclear silver­(I) cluster, [Ag12(μ12-I)­(μ3-I)4{S2P­(CH2CH2Ph)2}6]­(I), 4; was then synthesized. The structure of 4 contains
a novel μ12-I at the center of a cuboctahedral silver­(I)
atom cage, which is further stabilized by four additional μ3-I and six dithiophosphinate ligands. To the best of our knowledge,
the μ12-I revealed in 4 is the highest
coordination number for a halide ion authenticated by both experimental
and computational studies. Previously, the μ12-I
was only observed in [PyH]­[{TpMo­(μ3-S)4Cu3}4(μ12-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.