Synthesis, characterization and structural systematics in diorganotin complexes with O,N,O'-tris-chelating semirigid diaza-scaffolds: Mono- vs. di-nuclear compounds

Synthesis and structural characterization of diorganotin(IV) complexes with a tridentate N‐heterocyclic podand ligand and investigation of their catalytic activity in Baeyer–Villiger oxidation of cyclic ketones to lactones

“…Absence of the amide NH proton signal of H 2 L in 1 – 3 suggests binding to the tin center, and the presence of a single set of both ligand and organotin signals indicates a symmetric structure. The dimethyl‐, dibutyl‐, and dibenzyl‐organotin(IV) complexes 1 – 3 have 119 Sn NMR chemical shifts of −247.5, −267.0, and −333.6 ppm, respectively (Figures S13–S15), confirming that the tin atoms possess five‐coordinate geometries 43,44 . Furthermore, the 1 J ( 13 C‐ 119 Sn) NMR coupling constants of 2 and 3 were observed, allowing the C‐Sn‐C bond angle in solution to be estimated using the relationship established by Lockhart et al 45 The C‐Sn‐C bond angles of complexes 2 and 3 were calculated as 145° and 139°, respectively, consistent with the 138.3° to 145.8° range of angles observed for 1 – 3 in the solid‐state (see Table 1 below) and confirming the structures are retained in solution.…”

“…The dimethyl-, dibutyl-, and dibenzyl-organotin(IV) complexes 1-3 have 119 Sn NMR chemical shifts of À247.5, À267.0, and À333.6 ppm, respectively (Figures S13-S15), confirming that the tin atoms possess five-coordinate geometries. 43,44 Furthermore, the 1 J ( 13 C-119 Sn) NMR coupling constants of 2 and 3 were observed, allowing the C-Sn-C bond angle in solution to be estimated using the relationship established by Lockhart et al 45 The C-Sn-C bond angles of complexes 2 and 3 were calculated as 145 and 139 , respectively, consistent with the 138.3 to 145.8 range of angles observed for 1-3 in the solid-state (see Table 1 The TGA curves of H 2 L and 1-3 are depicted in Figures S19-S22. The metal complexes are thermally stable up to about ca.…”

Design, synthesis and cytotoxic evaluation in tumor cell lines of organotin(IV) complexes with heteroditopic hydroxo-carboxylato polyaromatic ligands¶

“…To circumvent this, a range of new organotin(IV) carboxylates based on the diazenyl functionality has been developed, thereby increasing the stability and improved cytotoxicity in testing protocols [15][16][17]. Subsequently, imino and diazenyl functionalities were incorporated into a single ligand in the hope that both superior activity and extended stability would be attained in their organotin(IV) complexes [18][19][20][21][22]. As anticipated, tributyl and triphenyltin 2-[(E)-{3-[(E)-(adamantan-1-ylimino)methyl]-4-hydroxyphenyl}diazenyl]benzoates, which contain both diazenyl and imino functions, have demonstrated increased activity, stability and good selectivity [22].…”