Synthesis, characterization and crystal structures of homo- and hetero-substituents containing trans six-coordinate tin(IV) complexes of H2tmtaa (5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine), and the solid state NMR spectra study of Sn

The reaction of Sn(tmtaa)Cl₂ (H₂tmtaa=5,14-dihydro-6,8,15,17-tetramethyldi-benzo[b,i][1,4,8,11]tetraazacyclotetradecine) and ammonium thiocyanate or sodium azide under a mild condition resulted in trans six-coordinate tmtaa tin(IV) complexes, Sn(tmtaa)X₂ (X=NCS, 1; X=N₃, 2). However, the treatment of Sn(tmtaa)Cl₂ and sodium picrate produced Sn(tmtaa)(Cl)(OC₆H₂ (2,4,6-3NO₂)) (3). Only one chloro atom of Sn(tmtaa)Cl₂ was substituted because of low nucleophilicity of the 2,4,6-trinitrophenolic anion in 3. Furthermore, because of the steric hindrance between the 2,4,6-trinitrophenolic group and the tmtaa ligand, which has a non-planar, saddle-shaped conformation, two chloro atoms cannot be substituted by two 2,4,6-trinitrophenolic groups simultaneously. All complexes were characterized by IR spectra, UV spectra, mass spectra, NMR spectra and elemental analyses, as well as DSC measurements. X-ray crystal structures of 1 and 3 reveal that the complexes retain the characteristic saddle-shaped configuration of H₂tmtaa but have adopted the trans geometry. Solid state ¹¹⁹Sn NMR spectroscopy was used to study the bonding environment in the series of six-coordinate trans Sn(IV) tmtaa complexes. It can be found that the ¹¹⁹Sn chemical shifts of the Sn(IV) tmtaa complexes are almost not influenced by the substituents.