New supramolecular architectures of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine based on tin complexes: Design, structural variations and thermal properties

Abstract

The reactions of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine (qtpy) with SnMe2Cl2 and SnMe2(NCS)2 have been investigated. The reaction of SnMe2Cl2 with qtpy resulted in the formation of the new complex [SnMe2Cl(qtpy)]+[SnMe2Cl3]− (1) while the reaction of SnMe2(NCS)2 with qtpy affords the complex [SnMe2(NCS)2(qtpy)] (2). The resulting products have been characterized using elemental analysis, IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. The new complex [SnCl2(qtpy)] (3) was characterized by X-ray crystallography from an acetone/n-hexane solution of 1 which reveals that 1 dissociates in solution. The new complex 2[SnMe2(NCS)2(qtpy)]·CH2Cl2·H2O (2.CH2Cl2·H2O) was characterized by X-ray crystallography from a dichloromethane/n-hexane solution of 2. Interestingly, the crystal structure of 3 reveals that the Sn(II) center is penta-coordinated as a slightly distorted square pyramid, as suggested by the index of the trigonality (τ) parameter. However, Sn(IV) is hepta-coordinated in 2.CH2Cl2·H2O which adopts a pentagonal bipyramidal geometry. The intermolecular hydrogen bond interactions and π…π stacking interactions establish to form the supramolecular assembly. The Hirshfeld surfaces analysis confirms that H…H and π…π interactions play major roles to stabilize the crystal architectures. The crystal structure of 2.CH2Cl2·H2O reveals the formation of porous material containing voids which have been occupied by the solvents. The volume of voids is 370 and 17 Å3, occupied by dichloromethane and water, respectively. Analysis of Sn-N bond lengths of complex 2.CH2Cl2·H2O shows that Sn-N bond lengths are greater than 2.39 Å for active organotin(IV) complexes, suggesting it as a good candidate for anti‐tumor activity. The thermal properties of the complexes indicate that 1 is stable up to 120 °C while 2 decomposes at 147 °C.