Isomers, distortionally equivalent

Attempts to prepare related hpp complexes of tantalum were only partially successful. Reaction of 2 equivalents of either (hpplSiMes or in situ generated Li[hpp] with Tads afforded a solid that analyzed correctly for the compound (hpp)2TaCl3. X-ray structural analysis of the crystallized product identified the coordination isomer [Ta(hpp)4][TaCl6], with a distorted dodecahedral cation and a regular octahedral anion (Figure 28). °... 

In the present study, we focus on the effects of substituting one of the protons by a deuteron. While giving only one isomer of the unionized molecule, this produces two inequivalent isomers of the Jahn-Teller distorted ion one isomer where the deuteron occupies one of the two sites on the C2 symmetry axes (Hj or H4) and one where it occupies one of the four equivalent remaining sites (H2, H3, H5 or H6). The effects on the ESR spectrum will below be illuminated both theoretically and experimentally. 

The dimeric iron compound proved to be robust both in solution and the soHd state. Although catalyticaUy inactive, the electronic structure of [( PDAl)Fe]2 was of interest Observation of a single Mdssbauer doublet with an isomer shift of 0.84mms i estabhshed equivalent high-spin iron centers. These data, in combination with the distortions to the pincer ligand observed by X-ray diffraction, estabhshed overall two-electron reduction of the chelate, one in the unperturbed portion of the ligand and the other in the q -imine coordinated to the adjacent iron. 

Figure 2.6 Short-time (0.25 ps) averaged kinetic energy per atom (KE) (a) and atomic equivalence indexes a,(r) (b) as functions of time for trajectories initialized by distorting the D4d structures (isomer I) of the cluster. For convenience, the corresponding total energies per atom (in...

Note that aldehyde derivatives prepared from trihydroxy bases will be one carbon shorter than those from equivalent dihydroxy bases, and the number of hydroxyl groups must be determined from the TLC behaviour of the base or its DNP derivative. The proportions of the various isomers within each class of base can be determined with reasonable accuracy by GC, but artefact formation during the hydrolysis stage may distort the apparent relative proportions of the various classes of base to each other. 

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