Two versatile N,N '-bipyridine-type ligands for preparing organic-inorganic coordination polymers: New cobalt- and nickel-containing framework materials

The Schiff base ligands 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L1, mon oclinic, P2(1)/c, a = 3.856(1) Angstrom, b = 11.032(2) Angstrom, 12.738(3) Angstrom, beta 92.21(3)degrees, Z = 2) and 2,5-bis(4-pyridyl)-3,4-diaza-2,4 -hexadiene (L2, monoclinic, P2(1)/c, a = 10.885(2) Angstrom, b = 4.613(1) A ngstrom, 14.978(3) Angstrom, beta = 92.827(4) degrees, Z = 2) were used in the synthesis of four new organic-inorganic coordination polymers, each of them adopting a different structural motif. Synthesis, X-ray structural det erminations, and spectroscopic and thermogravimetric analyses are presented . The reaction between Co(NO3)(2 .)6H(2)O and L1 afforded a two-dimensional noninterpenetrating brick-wall structure, [CO(C12N4H10)(l.5)(NO3)(2)(H2O)( CH2Cl2)(2)](n) (1, triclinic, P (1) over bar; a=10.242(7) Angstrom, b=10.80 2(7) Angstrom, c=15.100(1) Angstrom, alpha = 70.031(1), beta = 75.168(11), gamma = 76.155(11), Z = 2), while Ni(NO3)(2 .)6H(2)O combined with L1 yield ed an interpenetrating three-dimensional rhombus-grid polymer, [Ni(C12N4H10 )(2)(NO3)(2)(OC4H8)(1.66)(H2O)(0.33)](n) (2, monoclinic, C2/c; a =20.815(8) Angstrom, b = 23.427(8) Angstrom, c = 17.291(6) Angstrom, beta = 116.148(6 ), Z = 8). The reaction of Co(NO3)(2). 6H(2)O and L2 was found to be solven t-sensitive and resulted in the formation of two different noninterpenetrat ing compounds: [Co(C14N4H14)(2)(NO3)(C6H6)(1.5)](n) (3, monoclinic, C2/c; a = 22,760(2) Angstrom, b = 21.010(3) Angstrom, c= 25.521(2) Angstrom, beta = 97.151(2), Z = 8), which adopts a two-dimensional square-grid motif forme d by propeller-type modules, and [Co(C14N4H14)(1.5)(NO3)(2)(CH2Cl2)(2)](n) (4, monoclinic, P2(1)/n; a = 14.432(2) Angstrom, b = 14.543(8) Angstrom, 15 .448(4) Angstrom, beta = 96.968(0), Z = 4), consisting of T-shaped building blocks assembled into a one-dimensional ladder-type structure. These four coordination polymers all exhibit impressive thermal stability. Thermogravi metric studies showed that after complete removal of the solvents, the fram eworks are stable to temperatures between 234 degreesC and 260 degreesC.