Molecular distortion

In the naphthyridine ring with its 10 delocalized 7r-electrons located on five distorted molecular orbitals, due to an electron drift toward the nitro-... 

Mn(phen)3]2+ possesses a similar distorted molecular structure.37... 

Interesting redox activity is displayed by the N4C12 coordinated Mn(II) complex of the macrocycle 4,10-dimethyl-1,4,7,10-tetraazabicy-clo[5.5.2]tetradecane, [MnL ClJ, the distorted molecular structure of which is illustrated in Figure 27.44... 

An important class of porphyrins is that constituted by confor-mationally distorted porphyrins, which mimic the non-planar geometry of the porphyrins present in photosynthetic systems.89 Obtainment of such non-planar distortions is associated with the introduction into the macrocyclic frame of proper crowding substituents, which therefore not only cause structural distortion but also affect, through their electronic effects, the redox potentials. A typical case is that constituted by [Cun(OETPP)] (OETPP = 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin), the saddle-distorted molecular structure of which is illustrated in Figure 56.102... 

The crystal structure of [l,8]-naphthyridinium-l-tetraphenylborate has been reported and has shown, contrary to the usual pyramidalization of nitrogen, a flattened, spatially distorted molecular structure <1996M391>. 

Since the presence of small amounts of alkylated (branched) products can distort molecular weights, NMR spectroscopy was used to analyze the PSt content and the molecular weight of the PSt blocks. Molecular characteristics of select samples obtained by GPC, NMR, and conversion are summarized in Table 3. The Mj of PIB stars determined by GPC (LLS) were slightly higher than theoretical. This M and the mole fraction of St obtained by NMR spectroscopy were used to calculate the M of PSt segments and the PSt content in star... 

Keywords Y-junctions of nanotubes, defects of bonds and geometrical distortions, molecular simulation, quantum-chemical calculations. 

The completion of an organic structure is a challenging task, since the electron density maps resulting from the application of DM usually contain partial and distorted molecular fragments. Tanahashi et al. ° accomplished it by combining DM with a MC approach borrowed from the procedure described in Harris et al. The positions of three missing atoms were found by varying their coordinates in each MC move. 

Barbasiewicz et al. [99] reported on the Hoveyda-Grubbs metathesis catalyst bearing a chelating benzylidene ligand assembled on / en -substituted naphthalene 8.68, as shown in Eq. (8.22). In contrast to usual naphthalene-based compounds 8.67, it exhibits a very fast initiation behavior for a ring-closing metathesis reaction (Eq. (8.22)), which is attributed to a distorted molecular structure and reduced i-electron delocalization within a weakly stabilized six-membered chelate ring. 

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