i m trying to synthesize bi nuclear and poly nuclear transition metal(Cr,Mn,Fe,Co) complexes with macro cyclic Schiff base ligands by metal template method.but i m not getting the single crystal.
This question has been asked many, many times here. It is also quite easy to find quite a number of documents with a simple Google search. This is part 1 of a multiple part series that comes up with a Google search (other parts are linked): http://www.chemistryviews.org/details/education/2532131/Tips_and_Tricks_for_the_Lab_Growing_Crystals_Part_1.html
Set up a whole series of different methods (vapor diffusion, slow evaporation, etc.) and solvents in a place that won't be disturbed and forget about them for two weeks. Each different compounds crystallizes differently. If it has anions, you could do an anion exchange with BPh4-, which packs well in crystals. You can then recrystallize it from acetonitrile with a vapor diffusion of ether into the solution.