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

Abstract A general class of C 3 ‐symmetric Ag 9 clusters, [Ag 9 S( t BuC 6 H 4 S) 6 (dpph) 3 (CF 3 SO 3 )] ( 1 ), [Ag 9 ( t BuC 6 H 4 S) 6 (dpph) 3 (CF 3 SO 3 ) 2 ] ⋅ CF 3 SO 3 ( 2 ), [Ag 9 ( t BuC 6 H 4 S) 6 (dpph) 3 (NO 3 ) 2 ] ⋅ NO 3 ( 3 ), and [Ag 9 ( t BuC 6 H 4 S) 7 (dpph) 3 (Mo 2 O 7 ) 0.5 ] 2 ⋅ 2 CF 3 COO ( 4 ) (dpph=1,6‐bis(diphenylphosphino)hexane), with a twisted trigonal‐prism geometry was isolated by the reaction of polymeric {(HNEt 3 ) 2 [Ag 10 ( t BuC 6 H 4 S) 12 ]} n , 1,6‐bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag 9 twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S 2− and CF 3 SO 3 − for compound 1 , 2×CF 3 SO 3 − for compound 2 , 2×NO 3 − for compound 3 , and t BuC 6 H 4 S − and Mo 2 O 7 2− for compound 4 ). This trigonal prism is bisected by another shrunken Ag 3 trigon at its waist position. Interestingly, two inversion‐related Ag 9 trigonal‐prismatic clusters are dimerized by the Mo 2 O 7 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 Ag 9 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) d 10 →d 9 s 1 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.