Cobalt intermolecular interactions

The chromium(III) complexes represent the most simple systems in which magnetic interactions between paramagnetic ions can be studied. The cobalt(lll) systems may serve as matrixes in which the intermolecular interactions between the paramagnetic ions can be diminished. In these connections it is noteworthy that a mixed dihydroxo complex, (-)s89-A,A-[(en)2Cr(OH)2Co(en)2]has been described recently. This compound may serve as a model compound that represents the magnetic properties of the individual chromium(III) ion of the di-/a-hydroxochromium(lII) complex in the absence of a pair interaction. 

Citrate is also used frequently in reports of cobalt(II) SMMs however, Co SMMs remain poorly understood. Several examples have been reported, but in most cases the behaviour is significantly different to SMMs involving Mn or Fe The examples reported are difficult to assess. Sometimes there are significant intermolecular interactions, which suggest the magnetic behaviour could be due to extended structures rather than single molecules. In the physical data reported there are often low ratios of in AC susceptibility measurements, which... 

The effects of solvent exposure on the viscoelastic properties of several vinyl ester resins (phenohc-novolac epoxy, propoxylated bisphenol-A fu-marate, urethane and bisphenol-A epoxy based) and various unsaturated polyester resins (terephthalic or isophthaUc acid with a standard glycol based) containing 10wt% glass fiber were studied [130]. The results of dynamic mechanical analysis showed that the influence of exposure time to the solvent as well as the influence of temperature depended on the styrene content and chemical composition of the studied resins, while the amount of cobalt octoate used for the synthesis as the accelerator had no influence on the viscoelastic properties of the prepared materials after solvent exposure. It was also found that not fully cured urethane vinyl ester and the terephthahc acid-based unsaturated polyester resins showed excellent resistance to sulfuric acid exposure. However, interactions between the tested resins and petroleum could possibly occur through intermolecular bonding between the non-polar chains of the cured resins and the solvent. 

The complexation of cobalt-60 radiation-crosslinked POE and of linear POE with molybdenum-VI salts indicated that, in the linear form, complexation is extremely weak and of low stability—40 to 80 times weaker than that with sodium salts (134). This was related to vacant d-orbitals in molybdenum being involved in the interaction process. This resulted in greater polarizability of the cations and steric restriction in coordination with the ether oxygen atoms of the polymer chains. However, when the salts were complexed with the crosslinked POE, stability constants two orders of magnitude higher than those obtained with linear POE were found. This was interpreted as being related to intermolecular rather than intramolecular complexation. Stoichiometry for the crosslinked POE system was 4.5 ethylene oxide units per molybdenum cation. 

---