Dihedral angles linkage

In comparing complex and hybrid type structures it is assumed that the / angle at thea-D-Man-(l-3)-P-D-Man linkage changes only by —10° [141]. Thus, the bisected hybrid type structures have dihedral angles of

newly formed p-D-GlcjVAc linkage at the 4-position of the P-mannose 3. 

The tetraort/io-substitutions create a steric hindrance about the diaryl linkage, which results in a dihedral angle of 56.4° between the two aromatic rings [296]. 

Figure 3.30 Structure of ABPAC, a 9-aryl, 10-methyl derivative of the acrdinium cation, where the aryl group is 4 -amino-4-biphenylyl. The dihedral angles associated with the single bonds linking the phenyl groups are labeled 03 (phenyl/acridinium) and 02 (the biphenylyl moiety), with zero defined by coplanarity (as drawn). For the aminophenyl linkage (NC), 01 refers to the dihedral angle between the HNC and NCC planes associated with the HNCC bonded sequence. The optimized H2N moiety is pyramidalized, and is nearly symmetrically disposed with respect to the mean plane of the attached phenyl group (with 01 = 17°) [29].

The conformational dependence of the 33S isotropic a in dimethyldisulphide, (CH3)2S2, has been studied by HF calculations using the IGLO method.121 (CH3)2S2 is a good model for the disulphide linkage in polypeptides and proteins. 33S a has been calculated as a function of the dihedral angle C-S-S-C. Predicted chemical shifts vary between —84.4 ppm (< C-S-S-C = 0°) and —42.3 ppm (Calculated values refer to CS2 and cannot be converted to the SO4 scale, since the absolute shielding of the SQj anion has not been reported... 

The if geometry is compatible with the orbital template for a C2vML3( Cplanar sulfur bound coordination (dihedral angle = 60°) and spectroscopic studies indicate r Cpianar to -( r-N=S) linkage isomerization in solution ... 

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