The monoatomic zero-valent tin complex (stannylone) {[Si II (Xant)Si II ]Sn 0 } 5 stabilized by a bis(silylene)xanthene ligand, [Si II (Xant)Si II = PhC(N t Bu) 2 Si(Xant)Si(N t Bu) 2 CPh], and its bis-tetracarbonyliron complex {[Si II (Xant)Si II ]Sn 0 [Fe(CO) 4 ] 2 } 4 are reported. The stannylone 5 bearing a two-coordinate zero-valent tin atom is synthesized by reduction of the precursor 4 with potassium graphite. Compound 4 results from the Sn II halide precursor {[Si II (Xant)Si II ]Sn II Cl}Cl 2 or {[Si II (Xant)Si II ]SnBr 2 } 3 through reductive salt-metathesis reaction with K 2 Fe(CO) 4 . According to density functional theory (DFT) calculations, the highest occupied molecular orbital (HOMO) and HOMO-1 of 5 correspond to a π-type lone pair with delocalization into both adjacent vacant orbitals of the Si II atoms and a σ-type lone pair at the Sn 0 center, respectively, indicating genuine stannylone character.

https://onlinelibrary.wiley.com/doi/10.1002/anie.202114073