Magnetic and electrical properties of coordination polymers formed with copper and rubeanic acid

A crystalline form of a rubeanato‐copper coordination polymer has been synthesized by a solid‐solid reaction. The electrical and magnetic properties of the crystalline form have been studied and compared with the properties of the normally synthesized amorphous form. Molecular structures are proposed for both forms, which are consistent with the resistivity of the samples. Infrared spectra support the proposed structures. In particular, the static magnetic susceptibility was measured in a temperature range from 100–380°K. Typical values at room temperature are: 271 × 10−6 c.g.s.‐e.m.u. for the crystalline form and 236 × 10−6 c.g.s.‐e.m.u. for the amorphous form. The d.c. resistivities at room temperature are 1010 and 4 × 104 Ω‐cm. for the crystalline and amorphous forms, respectively. Also the temperature variation of the ESR absorption was studied. The anomalous behavior of the magnetic susceptibility, i.e. (1) it exhibits very low value, and (2) it exhibits essentially no temperature dependence, requires a new magnetic model to be set forth. Three models are considered: (1) Copper aceta e model, (2) One‐dimensional Heisenberg model, (3) “Equiinteraction” model. Either the second and third model may be employed to explain the behavior as seen. By these models, the effective number of the magnetic copper chain is estimated as nine.