IR- und ramanspektren der rheniumclusterverbindungen Rb 4Re 6S 13 und Cs 4Re 6S 13,5

Abstract

IR and Raman spectra of Rb 4Re 6S 13≜Rb 4[Re 6S 8]S 2 2 (S 2) 4 2 and Cs 4Re 6S 13,5≜Cs 4[Re 6S 8]S 2 2 (S 2) 3 2 (S 3) 1 2 are presented and discussed with respect to the S 2 and S 3 bridging units and the ([Re 6S 8]S 6) clusters. The SS stretching modes observed (425–480 cm −1), which correlate fairly well with the respective SS bond lengths, reveal mainly covalent nature of the disulfide groups present. The S 3 group could be identified by the spectra of Cs 4Re 6S 13,5. The bands of the rhenium sulfide units are significantly shifted to higher wavenumbers compared to those of ([Mo 6Cl 8]Cl 6) 2− and [Mo 6S 8] units (Chevrel compounds) despite the larger mass of rhenium. This indicates strong ReRe and ReS bonding.