A Monomeric Diarylstannanone with a Sn=O Double Bond: Synthesis and Characterization

Abstract A series of diarylstannylenes, (Rind) 2 Sn: ( 1 ) [Rind=1,1,7,7‐tetra‐R 1 ‐3,3,5,5‐tetra‐R 2 ‐ s ‐hydrindacen‐4‐yl: EMind ( a : R 1 =Et, R 2 =Me), Eind ( b : R 1 =R 2 =Et), and MPind ( c : R 1 =Me, R 2 = n Pr)], has been obtained as purple to blue crystals by the reaction of SnX 2  ⋅ dioxane (X=Br or Cl) with two equiv. of (Rind)Li. The less bulky EMind‐based stannylene, (EMnd) 2 Sn: ( 1 a ), reacted with N 2 O gas to afford a 1,3,2,4‐dioxadistannetane, (EMind) 4 Sn 2 ( μ ‐O) 2 ( 3 a ), through the dimerization of a stannanone, (EMind) 2 Sn=O ( 2 a ). In contrast, a similar oxidation reaction using the bulkier MPind‐based stannylene, (MPind) 2 Sn: ( 1 c ), produced a hitherto unknown acid‐base free monomeric diarylstannanone, (MPind) 2 Sn=O ( 2 c ), with an authentic Sn=O double bond. The stannanone 2 c was highly sensitive to air and moisture but remained thermally stable at room temperature. Isolating 2 c as a pure single crystalline material proved challenging due to its highly‐reactive nature; however, its structural characteristics and bonding properties were discussed based on both experimental findings and computational results. The Sn=O double bond in 2 c exhibits a weaker and more polarized character compared to the Ge=O double bond in the diaryl‐germanone, (Eind) 2 Ge=O ( A ).