One-state structural solutions

Structural solution obtained by minimization in the absence of distance constraint pseudoenergies. One state structural solution obtained by minimization with distance constraint pseudoenergies. Two state structural solution obtained by minimization with distance constraint pseudoenergies. 

In Figure 7, we present a stereo view of the superposition of the dominant conformers from the lowest energy two-state structural solutions, D A and D B and the one-state structural solutions B and C when all atoms in the oligosaccharide moiety of globoside were included in the comparison. In Figure 7, we also present... 

Figure 5. Stereoview of the superposition of the NMR refined one-state structural solution. A" (—), B" (- ), and C" (—) (a) with unconstrained exocyclic groups included in the comparison and (b) excluded from the comparison.

From the data in Table VI and Figure 7, it is clear that the dominant conformer from the lowest energy two-state structural solution is quite similar to the lowest energy one-state structural solution, the chief difference being in the orientation of the terminal /3-D-GalNAc residue. We conclude, therefore, that structures which are similar to the lowest energy one-state structural solution A", represent the predominant conformer present in solution. The one-state procedure thus provides a reasonable and time efficient approach to structural analysis for this molecule. 

ET-IR spectroscopy was employed to investigate the structures of the 1 1 complexes between Li" and the guanidine-substituted azo compounds pyiidine-2-azo-p-phenyltetramethylguanidine and 4,4 -bis(tetramethylguanidine)azoben-zene. Both Li" complexes exist as dimers in acetonitrile solution.The structural chemistry of potassium N,N -di(tolyl)formamidinate complexes has been investigated in detail. These compounds were prepared by deprotonation of the parent Af,N -di(tolyl)formamidines with potassium hydride (Scheme 13). The resulting adducts with either THE or DME display one-dimensional polymeric solid-state structures that exhibit /r-fj fj -coordinated formamidinates. 

The solution structure of [Ir(bpy)H2(PRPh2)2]X, R = Me, Ph, X = PF6, BF4, CF3S04, BPh4, as determined from NMR studies, is compared to solid-state structure.152 The main difference between the two structures is the location of the counter ion X. In solution, X is positioned on the side of the bpy ligand remote from the Ir, whereas in the solid state X is found close to one of the pyridine rings and one hydride ligand. Theoretical calculations at the QM/MM (B3PW91/ UFF) level support the experimental results. 

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