Pendant macrocyclic metallic building blocks for the design of cyano-bridged heterometallic complexes with 1D chain and 2D layer structures.

A series of cyano-bridged Ni(II)-Cr(I/III) complexes have been synthesized by the reactions of hexaazacyclic Ni(II) complexes with Cr(CN)(6) or Cr(CN)(5)(NO). Using the tetravalent Ni(II) complex Ni(H(2)L(2)) (L(2) = 3,10-bis(2-aminoethyl)-1,3,6,8,10,12-hexaazacyclotetradecane), one-dimensional chainlike complexes were produced and subject to magnetic studies, affording the intermetallic magnetic exchange constants of J(1) = +0.23 cm(-1) and J(2) = +8.4 cm(-1) for the complex [Ni(H(2)L(2))][Cr(CN)(5)(NO)]ClO(4).5H(2)O (1) and of J = +5.9 cm(-1) for the complex Ni(H(2)L(2))Cr(CN)(6)OH.15H(2)O (2). X-ray diffraction analysis shows that complex 1 has a zigzag chain structure, whereas complex 2 consists of a branched chain structure. Complex 2 exhibits antiferromagnetic ordering at 8.0 K (T(N)). When an octahedral Ni(II) complex cis-NiL(3)(en) (en = 1,2-ethylenediamine, L(3) = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane) was used for the synthesis, the common 2D honeycomb-layered complex NiL(3)Cr(CN)(5)(NO).8H(2)O (3) was obtained, which has a T(N) value of 3.3 K. Below T(N), a metamagnetic behavior was observed in complexes 2 and 3.