Bis(N-methylamidino-O-methylurea)copper(II) cation: a planar building block for the construction of hydrogen-bonded rhombic (4, 4) grids

Bis(N-methylamidino-O-methylurea)copper(II) cations and chloride anions self-assemble to form an elegant hydrogen-bonded rhombic (4, 4) grid. The four-fold connectivity of the square planar cation [Cu: 1.957(2), 1.970(2) Å, N..Cu..N 88.91(9)°] arises from the presence of four pairs of N-H donors, set at 90° to each other, which form hydrogen-bonds to four separate chloride anions. The rhombic (4, 4) grid [Cu...Cu separations: edge 10.388(2) Å, major diagonal 15.874(2) Å, minor diagonal 13.403(2) Å] arises from the fact that adjacent cations are twisted through 90° to generate the same hydrogen-bonded supramolecular synthon in all four directions. The sheets adopt a sinusoidal (corrugated) profile. This somewhat surprising observation is thought to result from a compromise between the structural requirements of the supramolecular synthon and the steric requirements of the four juxtaposed methyl groups which form lipophilic channels running parallel to the x-axi