Synthesis and structures of pyridinecarboxylate-containing zinc(II) complexes in dien and tren system
摘要:
Four new zinc(II) complexes [Zn(dien)(mu-nic)](2)(BPh4)(2)center dot 2CH(3)OH (1), {[Zn(dien)(isonic)]BPh4}(n) (2), [Zn(tren)(nic)]BPh4 (3) and [Zn(tren)(isonic)]BPh4 (4) (dien/tren = diethylenetriamine/triethylenetriamine, nic/isonic = nicotinate/isonicotinate anion) were synthesized and structurally characterized by IR, H-1 NMR and single crystal X-ray diffraction. In the zinc(II) complexes of dien, both nicotinate and isonicotinate connect the zinc(II) ions via N,O-bis-monodentate mode. Complex 1 contains a centrosymmetric dinuclear unit bridged by two nicotinate anions in anti-parallel way. Complex 2 is characterized by an infinite one-dimensional zigzag chain bridged by isonicotinate anion in an end-to-end mode. The Zn center dot center dot center dot Zn distance is 6.782 for 1 and 8.805 angstrom for 2. While in the complexes of tren, both 3 and 4 are mononuclear complexes with nicotinate and isonicotinate coordinated to zinc(II) ion through only one oxygen atom of their carboxylate groups. The zinc(II) ions in all of the four complexes are in a distorted trigonal bipyramidal geometry. Complex 3 forms a dinuclear unit and complex 4 forms an infinite 2D sheet structure through intermolecular H-bonds. In all of the crystal lattices, the BPh4- counterions act to balance the electronic charge at the same time to construct different 3D structures through noncovalent interactions such as C-H center dot center dot center dot pi, N-H center dot center dot center dot pi and van der Waals interactions. (C) 2010 Elsevier B. V. All rights reserved.