Barium thiolates and selenolates: Syntheses and structural principles

The synthesis and structural characterization of a family of barium thiolat es and selenolates is described. The thiolates were synthesized by metallat ion of thiols, the selenolates by reductive insertion of the metal into the selenium-selenium bond of diorgano-diselenides. Both reaction sequences we re carried out by using barium metal dissolved in ammonia; this afforded ba rium thiolates and selenolates in good yield and purity. The structural pri nciples displayed in the target compounds span a wide range of solid-state formulations, including monomeric and dimeric species, and separated ion tr iples, namely [Ba(thf),(SMes*),] (1; Mes*=2,4,6tBu(3)C76H(2)), [Ba(thf),(Se Mes*)(2)] (2), [Ba([18]crown-6)(hmpa)(2)] [(SeMes*)(2)] (3), the dimeric [{ Ba(py)(3)(thf)(SeTrip)(2)}(2)] (4; py = pyridine, Trip = 2,4,6-1Pr(3)C(6)H( 2)), and [Ba([18]crown-6)(SeTriP)(2)] (5). The full range of association mo des is completed by [Ba([18]crown-6)(hmpa)SMes*][SMes*] (6) communicated ea rlier by this group. In the solid state, this compound displays an intermed iate ion coordination mode: one anion is bound to the metal, while the seco nd one is unassociated. Together these compounds provide structural informa tion about all three different association modes for alkaline earth metal d erivatives. This collection of structural data allows important conclusions about the influence of solvation and ligation on structural trends.