Synthesis and Optical Properties of [Cu₆E₆(SnPh)₂(PPh₂Et)₆] (E = S, Se, Te) Cluster Molecules

Abstract

A homologous series of three copper-tin-chalcogenide cluster molecules [CuE(SnPh)(PPhEt)] (E = S, Se, Te) was synthesized by reactions of CuO(O)CCH and PhSnCl with E(SiMe) in the presence of PPhEt. The cluster cage structures are similar, with slight differences in the bridging modes of the respective chalcogenide ligands E. The onset of the optical absorption displays a significant decrease of ca. 1.1 eV on going from sulfur to tellurium. The differences in bonding and electronic excitations can be rationalized by DFT and TDDFT calculations. All complexes display near-infrared phosphorescence at cryogenic temperatures. In parallel with the absorption, the emission maximum shifts to lower energies in a series of sulfur, selenium, and tellurium compounds. In particular, the copper-tin-tellurium complex emits at an energy as low as ca. 0.97 eV (1280 nm).

Systematic Access of Ternary Organotetrel‐Copper Chalcogenide Clusters by [PhTE3]3− Anions (T=Si, Sn; E=S, Se)

“…Notably, while the band gaps are the same, the general absorption behavior of these compounds is different, which explains the slightly different colors. Our experimental findings are in agreement with the colors and optical gaps reported for related compounds [(CuPPh 2 Et) 6 (PhSnE 3 ) 2 ] (2.83 eV/438 nm for E=S; 2.32 eV/534 nm for E=Se; 1.71 eV/725 nm for E=Te), [42] except the value for the Se compound measured by us being larger than its S congener and the reported Sn/Se cluster. Yet, it is in agreement with the macroscopic color of the compounds (see above).…”

“…A systematic study of the three chalcogenide homologues of [(CuPPh 2 Et) 6 (PhSnE 3 ) 2 ] (E=S, Se, Te) that focused on the optical properties of such multinary clusters was recently reported by Eichhöfer et al. [42] …”

“…[41] This was the first example of the inorganic cluster core archetype [(CuPPh 3-x R' x ) 6 (RTE 3 ) 2 ] (x = 0, 1, 2), consisting of six Cu atoms arranged in a chair conformation that is connected to two TE 3 groups to obtain an overall spherical architecture. A systematic study of the three chalcogenide homologues of [(CuPPh 2 Et) 6 (PhSnE 3 ) 2 ] (E = S, Se, Te) that focused on the optical properties of such multinary clusters was recently reported by Eichhöfer et al [42] We are interested in the whole series of compounds of the general type [(RT) 4 E 6 ] (T = Si, Ge, Sn; E = S, Se) for their peculiar non-linear optical properties [43][44][45][46] and also to address their postsynthetic expansion with regard to both the organic shell and the inorganic cluster core. [47] The ultimate goal of the project is providing a series of clusters based on ternary Cu/T/E architectures that may serve as precursors to thermal decomposition processes.…”

Copper nanoclusters: designed synthesis, structural diversity, and multiplatform applications

“…For instance, all three types of clusters in the series [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) share the same E6 octahedron and have almost identical ligand binding motifs. 152 On the same note, [Cu4M4(μ3-E)4(CAAC Cy )4] (M = Cu, Ag, Au; E = S, Se) clusters reported by John F. Corrigan and co-workers, have the same "butterfly"-geometries regardless of the heteroatom doping and bridging chalcogen. 158 [Cu12Se6(dppo)4] cluster 165 is isostructural to its sulphidebridged analog, 164 yet a slight variation in bond lengths is observed.…”

“…The formation of such mixed valence states of the metal in the cluster has also been observed previously for selenide-bridged copper and silver nanoclusters. 198,199 The group of Andreas Eichhöfer reported the synthesis of ternary copper−tin−chalcogenide clusters [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te, Scheme 1a) 152 176 through the reactions of CuO(O)CCH3 or CuCl and PhSnCl3 with E(SiMe3)2 in the presence of an excess PPh2Et. In the ref [152] the Cu : chalcogenide ratio in a series is 1:1 regardless of the chalcogenide type.…”