π-stacking induced complexes with Z-shape motifs featuring a complementary approach between electron-rich arene diamines and electron-deficient aromatic N-heterocycles

Based on ligands of N,N'-bis((diphenylphosphino) methyl) benzene-1,4-diamine (L1) and N,N'-bis((diphenylphosphino) methyl) naphthalene-1,5-diamine (L2), six complexes of {[Ag(L1)(0.5)(phen)](BF4)center dot(H2O)(0.5)}(2) (1), {[Cu(L1)(0.5)(phen)(CH3CN)](ClO4)center dot(H2O)(0.5)}(2) (2), {[Cu(L1)(0.5)(4,4'-bipyridine)(CH3CN)](ClO4)center dot(CH3COCH3)}(n) (3), {[Ag(L2)(0.5)(phen)(NO3)]}(2) (4), {[Cu(L2)(2,2'-bipyridine)](BF4)center dot(CH3CH2OCH2CH3)} n (5) and {[Ag(L2)(0.5)(4,4'-bipyridine)](CF3SO3)center dot(DMF)}(n) (6) are isolated. Single crystal X-ray diffraction analyses show that all of these complexes contain three-layer pi-stacking Z-shape motifs in which an electron-rich pi plane of arene diamine is sandwiched between two electron-deficient aromatic N-heterocycles. The complementarity in shape and electron between electron-rich and electron-deficient pi rings directs the formation of these complexes, and the flexible organophosphine ligands adopt a trans coordination mode to meet the need of electron complementarity between pi-systems. pi-pi Stacking interactions are discussed in detail in this report. As an extension of these studies, the intermolecular interactions are also roughly discussed.