The Heaviest Bottleable Metallylone: Synthesis of a Monatomic, Zero‐Valent Lead Complex (“Plumbylone”)

Abstract

The elusive plumbylone {[Si II (Xant)Si II ]Pb 0 } 3 stabilized by the bis(silylene)xanthene chelating ligand 1,[Si II (Xant)Si II =PhC(NtBu) 2 Si(Xant)Si(NtBu) 2 CPh], and its isolable carbonyl iron complex {[Si II -(Xant)Si II ]Pb 0 Fe(CO) 4 } 4 are reported. The compounds 3 and 4 were obtained stepwise via reduction of the lead(II) dibromide complex {[Si II (Xant)Si II ]PbBr 2 } 2, prepared from the bis(silylene)xanthene 1 and PbBr 2 , employing potassium naphthalenide and K 2 Fe(CO) 4 , respectively. While the genuine plumbylone 3 is rather labile even at À 60 °C, its Pb 0 !Fe(CO) 4 complex 4 turned out to be relatively stable and bottleable. However, solutions of 4 decompose readily to elemental Pb and {[Si II (Xant)Si II ]Fe(CO) 3 } 5 at 80 °C. Reaction of 4 with [Rh(CO) 2 Cl] 2 leads to the formation of the unusual dimeric [(OC) 2 RhPb(Cl)Fe(CO) 4 ] complex 6 with trimetallic RhÀ PbÀ Fe bonds. The molecular and electronic structures of 3 and 4 were established by Density Functional Theory (DFT) calculations.

A linear C=Ge=C heteroallene with a di-coordinated germanium atom

“…In addition, heavy zero-valent group-14 compounds, so-called "tetrylones," with the general formula R2E:→E(0)←:ER2 (E = Si: silylone; Ge: germylone; Sn: stannylone; Pb: plumbylone) are heavy congeners of carbones that have attracted considerable interest. 3 Recently, the synthesis of the tin 4 and lead 5 analogues has been achieved, completing the synthesis of the entire series of tetrylones. Given that the central atom of the tetrylones has lone pairs with both s-character and p-character, their E-E-E angles should be close to 90° due to the p-character E-E bonds.…”