Synthesis of a cyclic dinuclear organotin carboxylate via simultaneous debenzylation and decarbonylation reactions: X-ray crystal structure of [(PhCH2)2{O2CC6H4{N(H)single bondNdouble bond; length as m-dash(C6H3-4(double bond; length as m-dashO)-5-O)}-o}S

The complex, [(PhCH2)2{O2CC6H4{N(H)single bondNdouble bond; length as m-dash(C6H3-4(double bond; length as m-dashO)-5-O)}-o}Sn]2 (1), is obtained as the exclusive reaction product from the reaction of sodium 2-[(E)-2-(3-formyl-4-hydroxyphenyl)-1-diazenyl]benzoate and (PhCH2)3SnCl. The reaction possibly proceeds via Dakin type rearrangements where arylazosalicylaldehyde is oxidized to arylazocatechol, followed by facile Sn–C bond cleavage. Complete assignments were achieved by 1H, 13C, 2D 1H–119Sn HMQC (119Sn chemical shift), 1D gs 1H–15N HMQC (1J(15N, 1H) coupling constant) NMR and ESI-MS. The crystal structure of compound 1 as determined by X-ray diffraction analyses shows a cyclic centrosymmetric dinuclear moiety linked into extended chains by pairs of long Sn⋯O contacts of approximately 3.2 Å. Two polymorphs were identified and their structures differ primarily in the packing arrangement afforded by the benzyl groups. In one polymorph, when viewed along the Sn⋯Sn vector, the benzyl groups at each Sn-atom are oriented to form an S-shape, while they form a U-shape in the second polymorph.