Organic-inorganic hybrid materials assembled through weak intermolecular interactions.: Synthesis, structures and non-linear optical properties of [4,4′-bipyH2][M(NCS)4] (M = Mn2+, Co2+ or Zn2+; 4,4′-bipy=4,4′-bipyridine)

Three compounds [4,4'-bipyH(2)][M(NCS)(4)] (M=Mn2+, Co2+ or Zn2+; 4,4'-bipy=4,4'-bipyridine) were obtained from the reactions of 4,4'-bipy with M(SCN)(2) in acidic solution and their crystal structures determined by single-crystal X-ray diffraction. All crystallise isomorphously in the chiral orthorhombic space group P2(1)2(1)2. The tetrahedral [M(NCS)(4)](2-) anions are inter-connected by S ... S contacts (ca. 3.63 Angstrom) and are hydrogen bonded with the diprotonated [4,4'-bipyH(2)](2+) cations [N ... S 3.241 Angstrom in 1; 3.235 Angstrom in 2; 3.239 Angstrom in 3] to form two-dimensional, highly wavy networks with hourglass-shaped cavities (ca. 12.3 Angstrom long; 9.4 Angstrom wide at the ends, 6.8 Angstrom at the waist). These two-dimensional networks are stacked with each other to furnish a channel accommodating the diprotonated [4,4'-bipyH(2)](2+) cations. The three organic-inorganic hybrid compounds are thermally stable with melting points above 230 degrees C. The powder second harmonic generation efficiencies were measured as moderate.