Planar acetone

Non planar acetone-like molecules without the cog-wheel effect between the rotors and the wagging atom. 

Table 7 Character table for the double internal rotation in planar acetone with interaction between the rotors.

FVom this character table, and the symmetry eigenvectors of planar acetone (54-56), the symmetry eigenvectors of pyramidal acetone are easily deducible. For this purpose, linear combinations of the eigenvectors, which exhibit the same behavior for all the operations except for WU and VU, are built up. In addition, to the coefBcients of which are trigonometric functions of the wagging angle, a. The coefficients are chosen in such a way that the linear combinations fulfill the characters corresponding to operators WU and VU,... 

The eigenvectors of such a group may be derived easily from those of planar acetone (96) multiplying them by cosA/a or sinA/a. 

Let us remark that when the third set of terms of this equation is neglected this expression coincides with that for planar acetone of Gzs symmetry [4]. Since the coefficients of these terms are generally small, both descriptions are considered in the following. 

Five-coordinate Ni111 complexes (89) have been prepared by oxidation of the square planar Ni11 precursor complexes [Ni(L)X] with either X2 or CuX2, and the crystal structure of the iodo derivative has been determined. The geometry at Ni is best described as square pyramidal, with the Ni atom displaced approximately 0.34 A out of the basal plane towards the apical I atom. EPR confirms the Ni111 oxidation state, in which the unpaired electron of the low-spin d1 system is situated in the dz2 orbital.308,309 In aqueous solution full dissociation of both X anions occurs, while in acetone solution dissociation is not significant. The redox couple [Nin NCN (H20)]+/ [Ni111 NCN (H20)ra]2+ in water is +0.14V (vs. SCE). 

Aleksic et al. [47] estimated the hydrophobicity of miconazole and other antimycotic drugs by a planar chromatographic method. The retention behavior of the drugs have been determined by TLC by using the binary mobile phases acetone-n-hexane, methanol toluene, and methyl ethyl ketone toluene containing different amounts of organic modifier. Hydrophobicity was established from the linear relationships between the solute RM values and the concentration of organic modifier. Calculated values of RMO and CO were considered for application in quantitative structure activity relationship studies of the antimycotics. 

The red [SSNO] anion (37) is produced by the reaction of an ionic nitrite with elemental sulfur or a polysulfide in acetone, DMF or DMSO.115 The [SSNO] anion has a planar cis structure with a short S-S distance (1.99 A), and S-N and N-O distances of 1.67 and 1.22 A, respectively. The treatment of [SSNO]- with triphenylphosphine produces the thionitrite anion [SNO]- (38) with a bond angle of ca. 120° at nitrogen and S-N and N-O bond lengths of 1.69 and 1.21 A, respectively. 

Thus, pyrrole and acetone react as shown above. This involves pyrrole acting as the nucleophile to attack the protonated ketone in an aldol-like reaction. This is followed by elimination of water, facilitated by the acidic conditions. This gives an intermediate alkylidene pyrrolium cation, a highly reactive electrophile that reacts with another molecule of nucleophilic pyrrole. We then have a repeat sequence of reactions, in which further acetone and pyrrole molecules are incorporated. The presence of the two methyl substituents from acetone forces the growing polymer to adopt a planar array, and this eventually leads to a cyclic tetramer, the terminal pyrrole attacking the alkylidene pyrrolium cation at the other end of the chain. 

Lozano, A., B. Yip, and R. K. Hanson. 1992. Acetone A tracer for concentration measurements in gaseous flows by planar laser-induced fluorescence. Experiments Fluids 13 369-76. 

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