Three copper(I) iodide clusters coordinated by different phosphine ligands formulated [Cu(4)I(4)(PPh(3))(4)] (1), [Cu(4)I(4)(Pcpent(3))(4)] (2), and [Cu(4)I(4)(PPh(2)Pr)(4)] (3) (PPh(3) = triphenylphosphine, Pcpent(3) = tricyclopentylphosphine, and PPh(2)Pr = diphenylpropylphosphine) have been synthesized and characterized by (1)H and (31)P NMR, elemental analysis and single crystal X-ray diffraction analysis. They crystallize in different space groups, namely, monoclinic P21/c, cubic Pa ̅3, and tetragonal I ̅42m for 1, 2, and 3, respectively. The photoluminescence properties of clusters 1 and 3 show reversible luminescence thermochromism with two highly intense emission bands whose intensities are temperature dependent. In accordance to Density Functional Theory (DFT) calculations, these two emission bands have been attributed to two different transitions, a cluster centered (CC) one and a mixed XMCT/XLCT one. Cluster 2 does not exhibit luminescence variation in temperature because of the lack of the latter transition. The absorption spectra of the three clusters have been also rationalized by time dependent DFT (TDDFT) calculations. A simplified model is suggested to represent the luminescence thermochromism attributed to the two different excited states in thermal equilibrium. In contrast with the pyridine derivatives, similar excitation profiles and low activation energy for these phosphine-based clusters reflect high coupling of the two emissive states. The effect of the Cu-Cu interactions on the emission properties of these clusters is also discussed. Especially, cluster 3 with long Cu-Cu contacts exhibits a controlled thermochromic luminescence which is to our knowledge, unknown for this family of copper iodide clusters. These phosphine-based clusters appear particularly interesting for the synthesis of original emissive materials.

CONSPECTUS:The chalcogenolato silver and copper superatoms are currently a topic of cutting edge research besides the extensively studied Au n (SR) m clusters. The crystal structural analysis is an indispensable tool to gain deep insights into the anatomy of these subnanometer clusters. The metal framework and spatial arrangement of the chalcogenolates around the metal core assist in unravelling the structure-property relationship and fundamental mechanistic involved in their fabrication. In this Account, we discuss our contribution towards the development of dichalcogenolato Ag and Cu cluster chemistry covering their fabrications and precise molecular structures. Briefly introducing the significance of the single crystal structures of the atomically precise clusters; the novel dichalcogenolated 2-electron superatomic copper and their alloy systems are presented first. The [Cu 13 {S 2 CNR} 6 {C≡CR'} 4 ] + is so far the first unique copper cluster having Cu 13 centred cuboctahedron, which is a miniature of bulk fcc. The galvanic exchange of the central Cu with Ag/Au results in a similar anatomy of formed bimetallic [Au/Ag@Cu 12 (S 2 CN n Bu 2 ) 6 (C≡CPh) 4 ][CuCl 2 ] species. This is unique in a sense that other contemporary M 13 cores in group 11 superatomic chemistry are compact icosahedra. The central doping of Ag or Au significantly affects the physiochemical properties of the bimetallic Cu rich clusters. It is manifested in the dramatic quantum 1 yield enhancement of the doped species [Au@Cu 12 (S 2 CN n Bu 2 ) 6 (C≡CPh) 4 ] + with a value of 0.59 at 77 K in 2-MeTHF. In the second part, the novel eight-electron dithiophosphate-and diselenophosphate-protected silver systems are presented. A completely different type of architecture was revealed for the first time from the successful structural determination of [Ag 21 {S 2 P(O i Pr) 2 } 12 ] + , [Ag 20 {S 2 P(O i Pr) 2 } 12 ] and [Au@Ag 19 {S 2 P(OPr) 2 } 12 ]. They exhibit a non-hollow M 13 (Ag or AuAg 12 ) icosahedron, capped by 8 and 7 Ag atoms in the former and latter two species, respectively. The overall metal core units are protected by 12 dithiophosphate ligands and the metal-ligand interface structure was found to be quite different from that of Au n (SR) m . Notably, the [Ag 20 {S 2 P(O i Pr)} 12 ] cluster provides the first structural evidence of silver superatom with a chiral metallic core. This chirality arises through the simple removal of one of capping Ag + cation of [Ag 21 {S 2 P(O i Pr) 2 } 12 ] + present on its C 3 axis. Further, the effects of the ligand exchange on the structures of [Ag 20 {Se 2 P(O i Pr) 2 } 12 ], [Ag 21 {Se 2 P(OEt) 2 } 12 ] + and [AuAg 20 {Se 2 P(OEt) 2 } 12 ] + are studied extensively. The structure of the former species is similar to its dithiophosphate counterpart (C 3 symmetry). The latter two (T symmetry) differ in the arrangement of 8 capping Ag atoms, as they form a cube engraving the Ag 13 (AuAg 12 ) icosahedron. The blue shifts in absorption spectra and photoluminescence further indicate the strong influence of ...