Crystallographic evidence of theoretically novel anion-pi interactions

The reaction of Cu(NO3)(2)center dot 3H(2)O with the multidentate ligand N,N',N '',N'''- tetrakis{2,4-bis (di-2-pyridylamino)-1,3,5-triazin-6-yl} triethylenetetramine (dpatta) in acetonitrile at high temperature and pressure results in the formation of the tetranuclear coordination compound [Cu-4(dpatta)(NO3)(4)](NO3)(4)center dot 12H(2)O ( 1), whose crystal structure exhibits remarkable anion-pi interactions which have been calculated, considering the unexpected position of the anion toward the aromatic ring.