Synthesis and crystal structures of silver(I), palladium(II), zinc(II) and cobalt(II) complexes of the ditoptic ligand 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene

Complexes of 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bitmb) with silver(I), palladium(II), zinc(II) and cobalt(II) salts have been characterized in the solid state by single-crystal X-ray analysis. The topology of the structures in the solid state, namely finite versus infinite, is found to dependent on the coordination geometry of the metal atoms. For Ag(I) (linear N-2 geometry) and Pd(II) (square-planar N-4), crystallization with bitmb produces an M2L2 cyclic dimer of composition [Ag-2(bitmb)(2)](PF6)(2). 2CH(3)CN (1) or an M2L4 cage complex [Pd-2(bitmb)(4)]Cl-4. 8H(2)O .1.5CH(3)CN (2). For Zn(II) (tetrahedral N2O2) or Co() (octahedral N-6), crystallization with bitmb produces a 1D zigzag chain network of [Zn(bitmb)(CH3CO2)(C2H5OH)](OH) (3) or an infinite 1D poly-macrocycle chain network [Co(bitmb)(2)(CH3CN)(2)](ClO4)(2). 2C(2)H(5)OH (4). It is also found that the conformations of the bitmb ligand are obviously controlled by the coordination number of the central metal ions. When coordinated with silver(I) (coordination number n = 2), palladium(II) (n = 4) or zinc(II) (n = 4), bitmb shows a cis, cis-conformation, but in the case of cobalt(II) (n = 6), bitmb shows a trans, trans-conformation. The results also show that the pi . . . pi interactions together with the hydrogen bonds co-affect inorganic supramolecular formation.