Mobility, lanthanide

This technique (see Section 4.1.1.4.) is well suited to the exploration of double-bond configurations. This is because these compounds arc often rigid and therefore there are no conformational rearrangements to complicate lanthanide induced shift (LIS) interpretations. However, if present, mobile groups within a molecule must be taken into consideration. 

The electrical transport in the filled skutterudites is altered by the presence of the rattlers. Relative to the analogous unfilled compounds, the filled skutterudites exhibit larger effective masses and smaller mobilities. Good overall electrical transport is maintained as indicated by the large values of ZT at elevated temperatures (figs. 23-26). The high carrier concentrations in the filled skutterudites are due mostly to the fraction of the lanthanide sites that remain... 

The difficulties in preparing dicyclopentadienyl lanthanide of lighter lanthanides, La, Ce, Pr and Nd are overcome by increasing the steric hindrance around Ln by using multisubstituted Cp ligand or by decreasing the mobility of the Cp ligand by catenation. 

The residence time for lanthanides in sea water varies from 200 years for the lighter lanthanides and 50 years for the heavier lanthanides. The difference in residence times among the lanthanides may be due to higher stability and hence higher mobility of the heavier lanthanides [133]. 

It appears unlikely, that lanthanides are mobile. They appear to remain in situ as insoluble precipitates or bound to insoluble materials formed during weathering, as for example, clay minerals [139], iron, manganese oxide minerals [133] and possible soil organic materials. 

The goodness of fit between observed and calculated shifts needs to be assessed, and methods of performing significance testing of lanthanide-induced shifts have been evaluated and reviewed . Complexities arise when fitting lanthanide shift data for compounds with conformationally mobile groups . Procedures for fitting free and hindered rotation have been described . Reviews of the utilization of lanthanide-induced shifts for conformational analysis have been published , and studies to further refine the utilization of lanthanide-induced shift data for such analyses continue . ... 

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