CH3 + CO channel

The results presented here show that our instrument can also be used to investigate dissociation channels in which the mass disparity of the two fragments is very large, namely the H + CH2CO channel the study of this channel was facilitated by using CD2CDO. Although the dynamics of this channel cannot be elucidated at the same level of detail as the CH3 + CO channel, our ability to study it at all represents an important extension of the capabilities of the instrument. 

Fig. 29. Photofragment translational energy distributions P(Et) and angular distributions 0(Et) for the CH3 + CO product channel of CH2CIIO(/ 2 A"). Vibronic assignments are given in addition to the excess energy for each transition.

Photofragment coincidence data were taken at several of the peaks in Fig. 1. Mass analysis of the fragments showed that only coincidences corresponding to channel (1), CH3 + CO (or CD3 + CO), were seen at all dissociation wavelengths examined. As discussed previously, the time and position data yield a coupled translational energy and angular distribution P(ET, 0), which can be written as... 

D. M. Neumark We indeed take the translational energy distribution from CH3O dissociation to be evidence for exit channel interactions on a repulsive potential-energy surface. This is in contrast to photodissociation of the vinoxy radical, for which very little variation of the CH3 + CO translational energy distribution occurs over a 0.5-eV range of excitation energy. 

Figure 4 Proposed ACS mechanisms. The major difference between the two mechanisms is the oxidation state of the proximal Ni. In both cases, CO emerges from the channel and binds to the proximal metal of the A-Cluster to form a Ni-CO intermediate. Then, the Ni center performs nucleophilic attack on the methyl group of methylated CFeSP to form a (CH3)(CO) intermediate state of the A-Cluster. Then, carbon-carbon bond formation occurs by condensation of the methyl and carbonyl groups to form an acetyl-metal species. Finally, CoA binds to cleave the acetyl group as acetyl-CoA. See text for more details...

Channel-type structure of (CH3 )4 N BO(OH)f 2 (NH2 )2 CO H2 0(12). In compound 12 [5c], both independent urea molecules and the BO(OH)2 ion in the asymmetric unit occupy special positions of symmetry m such that only the C-O or B-O bond lies on the mirror plane. A projection of the crystal structure along the [010] direction is presented in Figure 8.22. The host lattice consists of a parallel arrangement of unidirectional channels whose cross-section has the shape of a peanut. The diameter of each spheroidal half is about 7.04 A, and the separation between two opposite walls at the waist of the channel is about 5.85 A. The well-ordered tetramethylammonium cations are accommodated in double columns within each channel. 

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