Hydrogen bonding induced lowering of the intra-chain metal–metal distance in single end-on azide bridged one-dimensional copper(II) complexes with tridentate Schiff bases as blocking ligands

• Published in: Polyhedron 2014-01, Vol.68, p.346-356
• Main Authors: Bhaumik, Prasanta Kumar, Harms, Klaus, Chattopadhyay, Shouvik
• Format: Article
• Language: English
• Subjects: Coordination polymer; Copper(II); Crystal structure; End-on azide; Schiff base; Supramolecular interaction
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2013.10.031

Three copper(II) complexes, [Cu(L1)(N3)]n (1), [Cu(L2)(N3)]n·H2O (2) and [Cu(L3)(N3)]n {where HL1=2-[(2-dimethylamino-ethylimino)-methyl]-4-nitro-phenol, HL2=2-[(2-methylamino-ethylimino)-methyl]-4-nitro-phenol and HL3=2-[(2-ethylamino-ethylimino)-methyl]-4-nitro-phenol are tridentate Schiff-base ligands}, were synthesized and characterized. All the complexes feature single end-on azide bridged one-dimensional chains. The copper(II)⋯copper(II) distance is minimized by intra-chain hydrogen bonding. Three copper(II) complexes, [Cu(L1)(N3)]n (1), [Cu(L2)(N3)]n.H2O (2) and [Cu(L3)(N3)]n (3) {where HL1=2-[(2-dimethylamino-ethylimino)-methyl]-4-nitro-phenol, HL2=2-[(2-methylamino-ethylimino)-methyl]-4-nitro-phenol and HL3=2-[(2-ethylamino-ethylimino)-methyl]-4-nitro-phenol are tridentate Schiff-base ligands}, were prepared and characterized. Single crystal X-ray diffraction studies confirm that each complex is an end-on azide bridged one-dimensional polymer. All the complexes exhibit a square pyramidal geometry around the copper(II) centre. Weak forces like hydrogen bonding interactions lead to various supramolecular architectures. The copper(II)⋯copper(II) distance is minimized by intra chain hydrogen bonding in complex 3.