Ali Akbar  Khandar,a*   Zolfaghar  Rezvani,b Kamelia  Nejati,c Alexander  I.  Yanovsky,d  Jesus M. Martineze
a Department of Inorganic Chemistry, Faculty of Chemistry, Tabriz University, Tabriz, Iran
b Department of Chemistry, Faculty of  Science, Tarbiat Moallem University of   Azarbaydjan  P. O. Box 51745-406 , Tabriz , Iran
c Payam Noor University –Tabriz Center , Department of Chemistry, Hakim Nezami  street  , Tabriz , Iran
d Institute of Organoelement Compounds , Russian Academy of Science,  28 Vavilov St., Moscow 117813, Russia
e Department of Chemistry, Faculty of Science,Valladolid University , 47005, Valladollid , Spain

A homologue series of Bis[5-((4-alkoxyphenyl)azo)-N-(n-alkyl-salicylaldiminato)]nickel(II) complexes(alkyl= n-pentyl, n-dodecyl, alkoxy=OnCnH2n+1; n=3-7) have been synthesized and characterized by elemental analyses and IR spectroscopy. The structure of bis[5-((4-propyloxyphenyl)azo)-N-(n-pentyl-salicylaldiminato)]Ni(II) has been  studied  by  single-crystal x-ray  diffraction . This complex crystallizes in triclinic system, space group P `1 (No. 2), a=9.609(3) ?, b=12.271(4) ?, c=17.929(10) ?, a=96.93(2)°, b=103.99(2)°, g=101.67(2)°, and Z=2. The refinement converges with R=0.0643 and Rw=0.1411 for 7476 reflections [I>2d(I)]. The ligand has an approximately trans-planar configuration around nickel. The coordination square is slightly distorted tetrahedrally. The angles N-Ni-N and O-Ni-O are 171.99° and 170.43°, respectively. Thermal behaviors of these complexes have been studied by using the polarizing microscope.