Crystal structure studies, coordination

As far as I know, crystal structure studies have not been published on this kind of compound. But I think they would be revealing and by analogy perhaps tell us something about the melt situation. If one can determine—and I am sure it is possible by x-ray analysis of these compounds—what the nitrate coordination is around the metal ion, one might be able to infer something about the melt situation. 

Mn is an essential element and occurs in a number of enzymes and is also known to stimulate enzymic activity by reversible association. ESR and NMR line broadening are particularly useful techniques for studying Mn" environments in proteins.148 These measurements and crystal structure studies (concanavalin, Table 11) suggest near regular octahedral coordination by O and N donors. 

SO can coordinate in a number of modes apart from simple a donation (bent), it may bridge two or three metal centers (via sulfur) and there is one example of a fully characterized edge-on bridging mode. From X-ray crystal structural studies it appears that the coordinated S2O hgand behaves as a 7r-acid, as it has a substantially lengthened S S bond compared to the free S2O. 

X-ray single crystal structure study of the complex 2 revealed that the C—C bond of the ethylene ligand in 2 (1.366 A) was much shorter than those in analogous ethylene complexes of Ni(0) and Pt(0).t The shormess of the ethylene carbon-carton bond in 2 accords with the relatively poor rr-donor ability of the d ° palladium species. The weaker rr-donation from the palladium center in 2 results in the weaker Pd-ethylene bond. Indeed, exchange between the coordinating and free ethylenes was observed by NMR. In the NMR spectrum of 2, signals due to the pairs of diastereotopic coordinated ethylene proton are detected in the absence of free ethylene. 

Thus,in the octahedral coordination polyhedra of all of the metal ions studied, except for Cu, there are slight but significant deviations from regularity. Since these deviations are of exactly the same nature for all of the metal ions, they must be ascribed to effects of the crystal structure. The coordination... 

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