General Assembly of Twisted Trigonal‐Prismatic Nonanuclear Silver(I) Clusters

A general class of C₃‐symmetric Ag₉ clusters, [Ag₉S(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)] ( 1 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)₂] ? CF₃SO₃ ( 2 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(NO₃)₂] ? NO₃ ( 3 ), and [Ag₉(tBuC₆H₄S)₇(dpph)₃(Mo₂O₇)_0.5]₂ ? 2 CF₃COO ( 4 ) (dpph=1,6‐bis(diphenylphosphino)hexane), with a twisted trigonal‐prism geometry was isolated by the reaction of polymeric {(HNEt₃)₂[Ag₁₀(tBuC₆H₄S)₁₂]}_n, 1,6‐bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag₉ twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S^2? and CF₃SO₃^? for compound 1 , 2×CF₃SO₃^? for compound 2 , 2×NO₃^? for compound 3 , and tBuC₆H₄S^? and Mo₂O₇^2? for compound 4 ). This trigonal prism is bisected by another shrunken Ag₃ trigon at its waist position. Interestingly, two inversion‐related Ag₉ trigonal‐prismatic clusters are dimerized by the Mo₂O₇^2? ion in compound 4 . The twist is amplified by the bulkier thiolate, which also introduces high steric‐hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver–sulfur clusters (namely, compounds 5 – 8 ) with their nuclearity ranging from 6–10 were solely characterized by single‐crystal X‐ray diffraction to verify the above‐described synergetic effect of mixed ligands in the construction of Ag₉ twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal‐centered (MC) d¹⁰→d⁹s¹ transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180–300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion‐ and surface‐controlled redox processes were determined for compounds 1 and 3 as well as compound 4 , respectively.