• Bryant, Macguire R.
• Kruger, Paul E.
• Hunter, Sally O.
• Hawes, Chris S.
• Keenan, Luke L.
• Mahon, Mary F.
• Richardson, Christopher
• Kelly, David J.
• Fitchett, Christopher M.
• Burrows, Andrew D.

Abstract

The synthesis, structural and thermal characterisation of a number of coordination complexes featuring the N,O-heteroditopic ligand 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, HL are reported. The reaction of H 2 L with cobalt(II) and nickel(II) nitrates at room temperature in basic DMF/H 2 O solution gave discrete mononuclear coordination complexes with the general formula {[M(HL 2 (H 2 O) 4 ]·2DMF} (M = Co (1), Ni (2)), whereas the reaction with zinc(ii) nitrate gave [Zn(HL) 2 ] ∞ , 3, a coordination polymer with distorted diamondoid topology and fourfold interpenetration. Coordination about the tetrahedral Zn(II) nodes in 3 are furnished by two pyrazolyl nitrogen atoms and two carboxylate oxygen atoms to give a mixed N 2 O 2 donor set. Isotopological coordination polymers of zinc(II), {[Zn(HL) 2 ]·2CH 3 OH·H 2 O} ∞ , 4, and cobalt(II), [Co(HL) 2 ] ∞ , 5, are formed when the reactions are carried out under solvothermal conditions in methanol (80°C) and water (180°C), respectively. The reaction of H 2 L with cadmium(II) nitrate at room temperature in methanol gives {[Cd(HL) 2 (MeOH) 2 ]·1.8MeOH} ∞ 6, a 2-D (4,4)-connected coordination polymer, whereas with copper(II) the formation of green crystals that transform into purple crystals is observed. The metastable green phase [Cu 3 HL) 4 (μ 2 -SO 4 )(H 2 O 3 ] ∞ , 7, crystallises with conserved binding domains of the heteroditopic ligand and contains two different metal nodes: a dicopper carboxylate paddle wheel motif, and, a dicopper unit bridged by sulfate ions and coordinated by ligand pyrazolyl nitrogen atoms. The resultant purple phase {[Cu(HL) 2 ]·4CH 3 OH·H 2 O} ∞ , 8, however, has single copper ion nodes coordinated by mixed N 2 O 2 donor sets with trans-square planar geometry and is threefold interpenetrated. The desolvation of 8 was followed by powder X-ray diffraction and single crystal X-ray diffraction which show desolvation induces the transition to a more closely packed structure while the coordination geometry about the copper ions and the network ...

Topics

• impedance spectroscopy
• single crystal X-ray diffraction
• polymer
• single crystal
• nickel
• phase
• Oxygen
• zinc
• Nitrogen
• powder X-ray diffraction
• Hydrogen
• copper
• thermogravimetry
• cobalt
• decomposition
• differential thermal analysis
• Cadmium