Band-terminating configuration

Fig.l. Schematic illustration of a band terminating configuration and its evolution with spin. 

Fig. Ic. Postulated movements of the various/, t2g and band features under pressure, for the two terminal configurations / and d in SmS. The latter condition holds for P > 50 kB.

We discuss so called terminating states which occur because of the finiteness of rotational bands and which are associated with a gradual shape change until the rotation takes place around a symmetry axis. Predictions on terminating configurations in nuclei with 10-12 valence particles outside the 1% Gd core are compared with recent experimental data. Observed and calculated spectra show a remarkable similarity, at least for ls6Er and 1 Er which nuclei are discussed in detail here. 

Finally we should briefly mention the purple acid phosphatases, which, unlike the alkaline phosphatases, are able to hydrolyse phosphate esters at acid pH values. Their purple colour is associated with a Tyr to Fe(III) charge transfer band. The mammalian purple acid phosphatase is a dinuclear Fe(II)-Fe(III) enzyme, whereas the dinuclear site in kidney bean purple acid phosphatase (Figure 12.13) has a Zn(II), Fe(III) centre with bridging hydroxide and Asp ligands. It is postulated that the iron centre has a terminal hydroxide ligand, whereas the zinc has an aqua ligand. We do not discuss the mechanism here, but it must be different from the alkaline phosphatase because the reaction proceeds with inversion of configuration at phosphorus. 

In summary we have discussed the shape transition associated with the evolution of finite rotational bands to their points of termination. Many such terminating bands are predicted in configurations with 10-12 valence particles (and holes) relative to a 146Gd core. According to the calculations, the very low energy of the terminating states is a prominent... 

A report of the X-ray crystallographic studies of enan-tiopure ( -allyl)Fe(CO)2(NO) complex (170) has appeared, though httle detail was provided. The same report described the CD spectrum of this complex in more detail the negative band at ca. 350 mn and the positive band at ca. 450 nm can be used to assign the configuration of the complex. Diastere-omeric complexes exhibit the opposite Cotton effect. The crystal structures of corresponding monophosphine complexes (145) have been determined. ft is possible to consider these complexes as either trigonal bipyramidal (bidentate allyl) or tetrahedral see Tetrahedral) (monodentate allyl), with the central carbon of the allyl closer to the iron atom (2.084 A) than the terminal carbon atoms (2.117 and 2.142 A). These complexes are chiral at the iron atom, and it has proved possible to separate the diastereomeric complexes formed by enantiomerically pure aminophosphines. 

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