Hydrogen lanthanide contraction

Although in many respects relativistic effects and the lanthanide contraction serve to make the postlanlhanide elements less reactive than would otherwise be the case, in other respects their bonding ability is increased. For example, bis(phosphine)plati-num(0) complexes react with molecular hydrogen, but the analogous palladium complexes do not 3... 

From the standpoint of chemical reactivity, the 5s and 5p shells of lanthanides can be considered to be core electrons. Indeed arguments to this effect could be made for Ln 4f orbitals, given their extremely contracted nature. Shown in Figure 3 is a plot from a DHF calculation of a 4f spinor for Gd(III). Note the maximum in the wavefunction at 0.57 A that is, a value comparable to a hydrogen Is orbital Dolg et al. - examined various lanthanide core sizes and found essentially no difference in state splittings of the Ce atom between all-electron calculations and those in which a 28-electron core ([Ar]3d °) is used, Satisfactory results are also obtained for a 46-electron core ([Kr]4di°). Inclusion of 5s and 5p into the core (i.e, a 54-electron [Xe] core)... 

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