Dichloro[1,1′-(5,9-dithia-2,12-diazoniatrideca-1,12-diene-1,13-diyl)d inaphthalen-2-olato-κ²O,O′]dimethyltin(IV) acetonitrile solvate

Reaction of the potentially hexadentate ligand 1,9-bis(2-hydroxy-l-naphthalenemethylimino)-3,7-dithianonane with dimethyltin chloride gave the title 1:1 adduct, in which the long ligand wraps around the SnCl₂Me₂ unit and in which the stereochemistry is fully trans. This compound crystallizes from acetonitrile as the 1:1 solvate [Sn(CH₃)₂(C₂₉H₃₀N₂O₂ S₂)Cl₂]-C₂H₃N. During the reaction, the hydroxyl protons move to the N atoms. Most of the chemically equivalent bond lengths agree to within experimental uncertainty, but the Sn-Cl bond that is inside the ligand pocket is substantially longer than the Sn-Cl bond that points away from the long ligand [2.668 (1) versus 2.528 (1) Å]. The O - Sn - O angle is 166.0(1)°. Comparison of the Sn - O, C - O and aryl C - C bond lengths with those of related compounds shows that the most important resonance forms for the Schiff base aryloxide ligand are double zwitterions, but that the uncharged resonance forms having carbonyl groups also contribute significantly.