Berry twist

Pt and 119Sn NMR data show Pt(SnCl3)5 to be non-rigid (on the NMR timescale) down to 183 K, owing to an intramolecular process, possibly a Berry twist mechanism [132],... 

Fig. 7. Structures of five-coordinate Cu2+ from first principles molecular dynamics. A Berry twist mechanism for the interconversion of the two structures is shown (from left to right) the reorientation of the main axis of a square pyramidal configuration by pseudo-rotations via a trigonal bipyramidal configuration. The grey atoms in the plane of the trigonal bipyramid are all candidates for becoming apical atoms in a square pyramid.

Figure 74 (a) The Berry-twist mechanism connecting a trigonal bipyramidal and square pyramidal geometry (b) e modes of vibration (c) correlation of one-electron energy levels... 

Berry twist an axial pair exchanges with an equatorial pair, the third equatorial ligand acting as the pivot i Turnstile a facial set of three ligands rotates, thereby exchanging one equatorial with one axial ligand (the sequence in the trigonal plane is inverted)... 

Barbituric acid, methyl-5-nitroso-zinc complexes, 958 Bayldonite, 960 Benzeneselenic acid metal complexes, 977 Benzimidazole metal complexes, 949 Benzoquinoline zinc complexes, 953 Benzothiazole zinc complexes, 981 Benzotriazole zinc complexes, 950 Benzoxazole metal complexes, 951 Berry twist... 

From the energy point of view, the solvated complex [Cu(H20)5] " undergoes frequent transformations between square pyramidal and trigonal bipyramidal (TBP) configurations by a Berry twists mechanism (Scheme 3). 

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