In asymmetric catalysis using chiral transitionmetal complexes, binaphthyl or biphenyl groups have often been used as chiral scaffolds to produce an excellent asymmetric environment. [1] Among these ligands with chiral binaphthyl or biphenyl bridges, the most representative example is the C 2 symmetric 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) (1). [2] Changes in the steric and/or electronic properties of the ligands are known to dramatically influence the selectivity and the reactivity of transition-metal complexes. The framework of chiral ligands not only sways the enantioselectivity but can also remarkably change the reactivities of the metal complexes. During the course of our research on the development of chiral diphosphine ligands, we were interested to see if varying the dihedral angle of the chiral backbone would have an effect on the enantioselectivity of asymmetric hydrogenation. Additionally, in spite of a sparsity of information in the literature concerning the mechanism of the asymmetric control, one of the predominant factors could be the dihedral angle in the chiral backbone. This correlates to the natural bite angle in metal complexes. [3] The dihedral angles of the binaphthyl or biphenyl systems are expected to exert influence on the effect of the steric bulk of the diphenylphosphino group as illustrated in Figure 1. This working hypothesis is based on steric considerations and does not consider the electronic properties of the complex, or the metal's valence.Additionally, the following experimental results support our working hypothesis. Thus, the enantioselectivities in the hydrogenation of 2-oxo-1-propanol (2a) to (2R)-1,2-propanediol (3a) are influenced re-264 Figure 1. Steric considerations based on the effect of varying the dihedral angle (q) in biaryl backbone.Abstract: A series of novel optically active diphosphine ligands, (4,4'-bi-1,3-benzodioxole)-5,5'-diylbis(diarylphosphine)s (6), which are called SEG-PHOS, has been designed and synthesized with dihedral angles in the Ru complexes being less than that in the corresponding BINAP-Ru complex. The stereorecognition abilities of SEGPHOS-Ru complex catalysts in the asymmetric catalytic hydrogenation of a wide variety of carbonyl compounds are superior to those observed with BINAP-Ru complex catalysts.

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Underlying principles of RF coil techniques are described. A set of coaxial slotted-tube resonators is explicitly introduced. The coil has two coaxial slotted-tubes which can resonate independently and dependently together. The principles of the resonator set, i.e., how the set works, are described. The fabrication details of the coaxial resonators are described. An example of /RI data of an okra obtained at the field of 4.7 Tesla is displayed.

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