Electronic structure coordination sphere effects

IR and Raman spectroscopy have been commonly used and, for example, the effects of pressure on the Raman spectrum of a zinc compound with a N2C12 coordination sphere around the metal, have been investigated.28 IR spectroscopy has been utilized in studies of the hydration of zinc in aqueous solution and in the hydrated perchlorate salt.29 Gas phase chemistry of zinc complexes has been studied with some gas phase electron diffraction structures including amide and dithiocarbamate compounds.30-32... 

Outer-Sphere Electron Transfer The minimal interpenetration of the coordination spheres of the reactants is inherent in any mechanistic formulation of the outer-sphere process for electron transfer. As such, steric effects provide a basic experimental criterion to establish this mechanism. Therefore we wish to employ the series of structurally related donors possessing the finely graded steric and polar properties described in the foregoing section for the study of both homogeneous and heterogeneous processes for electron transfer. 

Although Fe "and Mn " have similar ionic radii, Mn " does not fit as readily into the goethite structure as does Fe " because owing to its four d electrons, Mn " has a tetragonally distorted coordination sphere on an octahedral site Jahn-Tdler effect). 

The study of the structure of the weak second coordination sphere around a metal complex in solution using NMR methods is now well established. (264) Second sphere effects are due primarily (but not solely) to dipolar interactions with unpaired electrons. Such interactions lead to an enhanced relaxation rate in the second sphere (usually measured by T m) and, in many cases, dipolar shifts [equation (13)]. 

In contrast, similar plots of AG against AGet for the oxidants TCNE and hexa-chloroiridate(IV) deviate substantially from the simulated curve for outer-sphere electron transfer (see Figures 19B, C). Moreover, the most pronounced deviations are observed with the least hindered tetraalkyltin donors. The fact that steric effects are only observed in the latter cases, but not with the FeL3 acceptor, leads to the conclusion that the inner coordination spheres of the tetraalkyltin donors are perturbed by TCNE and hexachloroiridate in the ET transition state. In other words, the electron transfers to TCNE and iridate(IV) exhibit strong inner-sphere character and thus occur from wai i-five-coordinate precursor complexes reminiscent of a variety of trigonal-bipyramidal structures known for tin(IV) derivatives, i.e. 

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