A series of diarylstannylenes, (Rind)2Sn: (1) [Rind = 1,1,7,7-tetra-R1-3,3,5,5-tetra-R2-s-hydrindacen-4-yl: EMind (a: R1 = Et, R2 = Me), Eind (b: R1 = R2 = Et), and MPind (c: R1 = Me, R2 = nPr)], has been obtained as purple to blue crystals by the reaction of SnX2·dioxane (X = Br or Cl) with two equiv of (Rind)Li. The less bulky EMind-based stannylene, (EMnd)2Sn: (1a), reacted with N2O gas to afford a 1,3,2,4-dioxadistannetane, (EMind)4Sn2(μ-O)2 (3a), through the dimerization of a stannanone, (EMind)2Sn=O (2a). In contrast, a similar oxidation reaction using the bulkier MPind-based stannylene, (MPind)2Sn: (1c), produced a hitherto unknown acid-base free monomeric diarylstannanone, (MPind)2Sn=O (2c), with an authentic Sn=O double bond. The stannanone 2c was highly sensitive to air and moisture but remained thermally stable at room temperature. Isolating 2c 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 2c exhibits a weaker and more polarized character compared to the Ge=O double bond in the diarylgermanone, (Eind)2Ge=O (A).