Design, structures and study of non-covalent interactions of mono-, di-, and tetranuclear complexes of a bifurcated quadridentate tripod ligand, N-(aminopropyl)-diethanolamine. (1st February 2017) - Sama, Farasha
Abstract : Supramolecular non-covalent interactions in novel mono-, di- and tetranuclear complexes are explored. Abstract : A series of five new complexes incorporating N -(aminopropyl)-diethanolamine, H2 apdea, has been synthesized and characterized by employing elemental, thermal, magnetic, spectroscopic and single crystal X-ray techniques. The reaction of transition metal salts with H2 apdea under ambient conditions affords mono-, di- or tetranuclear complexes with the compositions [Ni(H2 apdea)(SCN)2 ]0.5H2 O (1 ), [Co2 (Hapdea)(apdea)(SCN)2 ]NO3 ·1.5H2 O (2 ), [Co2 (Hapdea)(apdea)(H2 O)2 ]3NO3 ·H2 O (3 ), [Cu2 (Hapdea)2 (H2 O)2 ]2NO3 ·2H2 O (4 ) and [Zn4 (apdea)2 (OCOCH3 )2 (SCN)2 ]2MeOH (5 ). Single crystal X-ray crystallography of1–5 confirms that the ligand binds to the metal ions in neutral form (H2 apdea) in1, in mono- as well as dianionic form (Hapdea − and apdea 2− ) in2 and3, in monoanionic form (Hapdea − ) in4, and in dianionic form (apdea 2− ) in5 . Spectral data and crystal structures confirm the distorted octahedral (1–3 ), square pyramidal (4 ) and tetrahedral as well as TBP geometries (5 ) around the metal ions. While2 and3 are dinuclear Co(iii ) systems, the tetranuclear zinc cluster (5 ) shows interesting structural features with the first example of both two tetrahedral and two TBP Zn(ii ) centers present in the same molecule. As a result of non-covalent interactions, 1 forms a 2D sheet while2–5 exist as 3D supramolecular assemblies. A 2D sheet structure is formed due to the presence of S⋯H interactions in1 (O–H⋯S = 2.518 Å, N–H⋯S = 2.727 Å). Intermolecular O⋯H and S⋯H contacts (C–H⋯O = 2.595 Å, C–H⋯S = 2.894 Å, N–H⋯O = 2.123 and 2.403 Å) along with other H-bonding interactions in2 generate a 3D supramolecular assembly. Coexistence of a cyclic octamer of oxygen and nitrogen atoms also helps consolidate the architecture in2 . The O⋯H contacts, i.e., O–H⋯O, C–H⋯O and N–H⋯O interactions, play an important role in the aggregation of molecular entities of3 and4 to form a 3D supramolecular network. In the case of5, interactions between the two tetranuclear (Zn4 ) clusters i.e., N–H⋯C (2.795 Å) and N–H⋯O (2.229 Å) and the interactions formed via lattice solvent molecules (C–H⋯O = 2.495 Å, O–H⋯O = 2.003 Å, O–H⋯C = 2.741 Å) generate a robust 3D supramolecular network. The selected supramolecular interactions (like O⋯H and S⋯H) are further explored using Hirshfeld surface analyses, and electrostatic potential (ESP) and deformation density (DD) calculations.