Synthesis and structures of 1,3-bis(organochalcogenyl) distannatrisilabicyclo[1.1.1]pentanes

Abstract

The heteronuclear [1.1.1]propellane Sn2Si3Mes6 (1; Mes = 2,4,6-Me3C6H2) was reacted with the dichalcogenyl compounds PhE–EPh (E = S, Se, or Te) to furnish the 1,3-bis(organochalcogenyl) distannatrisilabicyclo[1.1.1]pentanes 3 (E = S), 4 (E = Se), and 5 (E = Te). The E–E bond addition reaction is reminiscent of the formation of FcS–Sn(SiMes2)3Sn–SFc (2; Fc = ferrocenyl) reported previously. Contrary to 2, for which it was shown that its formation can be enhanced by daylight, the analogous clusters 3–5 are very sensitive to light in solution. Solid samples are, however, stable for a prolonged period of time. All three compounds were characterized in detail, including X-ray structure analyses on single crystals of 3 and 5. The core structure connectivities of the clusters were fully confirmed by 119Sn, 77Se, and 125Te NMR spectroscopy, among others. In particular, the 117Sn–119Sn coupling constant between the formally nonbonded bridgehead tin atoms nicely correlates with the interbridgehead distance, i.e., a larger distance is associated with a smaller 117Sn–119Sn coupling constant, and vice versa. This coupling is mediated by so-called “back-lobe-to-back-lobe” interactions through cage. The detection of two different 77Se–119Sn and 125Te–119Sn couplings each (i.e., 1J and 2J) further supported these findings.