Cobalt interatomic distance

It is indicated by the observed interatomic distances and shown by magnetic data that there occurs some deviation from this simple and attractive scheme in the middle region of the sequence. From chromium to cobalt the interatomic distances do not continue to decrease in value, as expected with increase in the number of bonds instead they remain nearly constant Cr, A2, 2.49A Mn, no simple structure Fe, A2, 2.48A, Al, 2.52A Co, Al, A3, 2.50-2.51A Ni,... 

Mean cobalt-cobalt and nickel-nickel distances observed in these complexes are very close to interatomic distances determined at ambient temperatures in cobalt and nickel metals (Co-Co 2.489(7) A vs. 2.507 A in a-cobalt (33) Ni-Ni 2.469(6) A vs. 2.492 A in the metal (39)). The mean M-H bond lengths, as well as hydride displacements from M3 faces, are less for nickel in H3Ni4(Cp)4 than for cobalt in HFeCo3(CO)9(P(OMe)3)3. Although the differences are marginally significant within error limits (Ni-H 1.691(8) A vs. Co-H 1.734(4) A displacements from plane Ni3 0.90(3) A vs. Co3 0.978(3) A), they are in the expected direction since the covalent radius should vary inversely with atomic number within a transition series. However, other effects such as the number of electrons in the cluster also can influence these dimensions. 

Typical domain walls are smooth and extend over many interatomic distances. However, deviations from this continuum picture occur in very hard materials (narrow walls), at grain boundaries and in the case of geometrical constraints. Narrow-wall phenomena, which have been studied for example in rare-earth cobalt permanent magnets [189] and at grain boundaries [95, 96], involve individual atoms and atomic planes and lead to comparatively small corrections to the extrinsic behavior. 

A new set of data was collected and refined.57 Although the crystals suffer from severe disorder, it is clear that the skewed arrangement is correct, with the interatomic distances showing that each cobalt atom is bonded to only one of the oxygen atoms and that the bridging group is a superoxide radical, rather than a peroxide ion. 

Third, the doublet and, especially, sextet models require very precise superimposing of the molecule on the catalyst lattice. We have found that the cyclohexane derivatives, in accordance with the sextet model, smoothly dehydrogenate only on the following metals nickel, cobalt, iridium, palladium, platinum, ruthenium, osmium, and rhenium, all of which crystallize in Al, A3 lattices with certain interatomic distances. These results extend to the alloys of these metals. The catalytic activity of rhenium for this reaction was predicted by the multiplet theory as this metal maintains the square of activity this prediction was realized experimentally in the laboratory of the author. Similar correlations take place in the exchange of cyclanes with deuterium. 

The constitution of the platinum complex has been elucidated by crystal structure investigation 82), and the molecule (XXXVa-e) has been found to be completely planar. The interatomic distances and bond angles are given in Fig. 2. As would be expected, the nickel compound is diamagnetic, and the cobalt and iron compounds show paramagnetism, corresponding with one and two unpaired d-electrons, respectively 41). These... 

Inspection of the details of the calculation shows that the positive contributions to I arise from electron-electron or nucleus-nucleus interactions in the energy term of the operator H. Thus they will be most evident when there is a considerable overlap of electron clouds, which occurs most markedly in atoms possessing d and / electrons (quantum number 1 = 2 and 3). This factor tends to locate ferromagnetism in transition elements. For electron overlap to outweigh electron-nucleus interaction, the nuclei should not be too close. Nor, on the other hand, should they be too far apart, or aU interaction of any kind becomes feeble. This factor makes for further specificity, and in fact for the elements iron, cobalt, and nickel the ratio (interatomic distance/radius of d electron shell) does lie within a special rather narrow range. 

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