New higly unsaturated macrocyclic building blocks [CuLSCN]·ClO4 (1) (L=N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and [NiL(SCN)2] (2) (L=N-dl-5,12-dimethyl-7,14-diisopropyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) were synthesized and the crystal structures of both compounds were determined. Both complexes crystallizes in monoclinic, space group P21/n (1) and P21/c (2). Their magnetic properties were studied over the temperature range 1.8–300K using a Quantum Design SQUID magnetometer (MPMSXL-5-type). The results indicate that both compounds behave as weakly interacting paramagnetic centers in the crystal lattice. The effects of hydrogen bond mediating the magnetic exchange interactions on the spin density have been evidenced by DFT calculations. The NIR–Vis–UV diffuse-reflectance electronic spectra confirm the square pyramidal and octahedral geometry around Cu2+ and Ni2+ metal ions.

A new Cu(II)–Fe(III)–Cu(II) heterobimetallic trimer (CuLα)2[Fe(CN)6]·ClO4 (where Lα = N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene), 1 has been synthesized. This compound can be viewed as a heterobimetallic trinuclear unit Cu(II)–Fe(III)–Cu(II), in which the magnetic centers are linked by cyanate bridges. The coordination polyhedra of metal (M) atoms can be described as a slightly distorted tetragonal pyramid (Cu) and an almost ideal octahedron (Fe) with nitrogen atoms in axial positions. In the structure hydrogen bonds can be found, which create chains along the crystallographic [0 1 0] axis and a two-dimensional net in the crystallographic (1 0 0) plane. The magnetic behavior of complex 1 has been investigated over the temperature range 1.8–300 K. Complex 1 displays ferromagnetic coupling inside the trinuclear core of CuFeCu.