Structure–reactivity studies of chloro and isothiocyanato diorganotin (IV) complexes based on multidentate N‐donor ligands: Synthesis,spectral characterization and crystal structures

The reaction of [SnMe₂Cl₂] with the bidentate ligand 4,7‐phenanthroline (4,7‐phen) resulted in the formation of [SnMe₂Cl₂ (4,7‐phen)]_n ( 1a ) which is probably a polymeric chain in solution. On the other hand, the reaction of [SnEt₂Cl₂] with 4,7‐phen afforded the complex [Sn₂Et₄Cl₄ (κ¹‐N‐4,7‐phen)₂(μ‐κ²‐N,N‐4,7‐phen)] ( 1b ) which dissociates in dimethylsulfoxide solution. The reaction of [SnR₂Cl₂] (R = Me, Et) with 2,2′‐biquinoline (biq) yielded the complexes [SnMe₂Cl₂ (κ²‐N,N‐biq)] ( 2a ) and [SnEt₂Cl₂ (κ¹‐N‐biq)₂] ( 2b ) in the solid state. Moreover, the reaction of [SnR₂Cl₂] (R = Me, Et) with the tridentate ligand 4′‐(2‐furyl)‐2,2′:6′,2″‐terpyridine (ftpy) resulted in the formation of ionic penta‐ and hexa‐coordinated tin complexes [SnMe₂Cl (ftpy)][SnMe₂Cl₃] ( 3a ) and [SnEt₂Cl (ftpy)]Cl ( 3b ). The reaction of [SnMe₂ (NCS)₂] with ftpy afforded the hepta‐coordinated complex [SnMe₂ (NCS)₂(ftpy)] ( 4a ). The products were fully characterized using elemental analysis, and infrared, UV–visible, multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR, DEPT‐135°, HH‐COSY and HSQC NMR spectroscopies. The crystal structure of complex 3a reveals that it contains the simultaneous presence of penta‐ and hexa‐coordinated tin (IV) atoms. Notably, the crystal structure of complex 4a shows that tin (IV) is hepta‐coordinated in a pentagonal bipyramidal geometry SnC₂N₅ by three nitrogen atoms of ftpy, two nitrogen atoms of NCS^? and two Me groups with trans‐[SnMe₂] configuration. These data indicate the influence of halide or pseudo‐halide group on the coordination number and geometry of tin. Hirshfeld surface analysis and two‐dimensional fingerprint plots were calculated for 3a and 4a which show the π–π interaction between molecules in the solid is relatively weak.