Bond angles hydroperoxides

The analysis of the IR spectrum of hydrogen peroxide and cumyl hydroperoxide gave the following values of frequencies (cm-1) of valence and bond angle vibrations [60]. 

Hydroperoxide moiety takes part in the formation of hydrogen bond (0)H...Br- in all obtained complexes. In all stmetures distances (0)H... Br-are within 2.03 2.16 A, bond angle O-H...Br-ishigherthan90°and... 

The second largest number of hydrogen bonds in crystal structures of alkyl hydroperoxides refers to interactions of the type OO—H OR R, where R is an alkyl group and R denotes H, alkyl or R O. The OO OR R distances vary between 2.67-2.91 A and the associated O—H O angles range from 152 to 177°. In some compounds, formation of intramolecular hydrogen bonds of the type OO—H 0=X would in principle have been feasible. The number of examples documented in the literature so far is clearly in favor of the intermolecular type of H bonding. 

A survey of crystal structures of 29 compounds (Table 8), in which the alkyl hydroperoxide anions serves as ligand to metal ions, transition metal ions or group 13-17 elements, provides a mean 0—0 bond length of 1.46 0.03 A, an O—O—C angle of 109 2.1° and a M—O—O angle of 112 6.9°. More specialized aspects that deserve to be addressed separately refer to the nature of the M—O bond, the magnitude of the dihedral angle M—O—O—C and the tetrahedral distortion of the peroxide bound C atom. 

Alkyl halides, hydroperoxide synthesis, 327-8 Alkyl hydroperoxides anion ligands, 114-19 covalent radii, 114, 118-19 dihedral angles, 119 geometric parameters, 115-8 tetrahedral distortion, 119 artemisinin formation, 133-4 chlorotriorganosilane reactions, 779-83 crystal structure, 105-14 anomeric effect, 110-11 geometric parameters, 106-9 hydrogen bonding, 103-5, 111-14 tetrahedral distortion, 110 determination, 674... 

Figure 3.2 Potential barrier for the internal rotation about the transCH3CH=CH—OOH bond in vinyl hydroperoxide. The minimum barrier is at a dihedral angle of OOCdCd = 0 degrees.

A potential energy diagram for internal rotation versus Cb—OOH torsion angle in DBFOOH is shown in Figure 7.3 (Cb Cbenzene bond)- The data show three-fold, potentials with barriers near 3.6 kcal mof. This barrier is comparable to those obtained for the vinyl hydroperoxide species reported in chapter 3. The same rotational barrier in the Cb—00 of the corresponding radical DBF—00 is however, higher by 1.3 kcal mof. The radical DBFOO shows a two-fold symmetry with a barrier to be found at 4.9 kcal mof (Figure 7.4). 

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