J. Am. Chem. Soc. 1992, 114, 8711-8713
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in Figure 1 and the supplementary material. The cyanohydrin I can now be confidently assigned as the progenitor of diasteralkoxide complex (q5-C5H5)Re(NO)(PPh3)(OCH(CN)C6F5)(2a) emelection. However, certain observations suggest other subtleties that must be incorporated into any comprehensive model of the formed in quantitative NMR yields as 96-97:3-4 mixtures of reaction coordinate. Study of these secondary effects is in progress. (RS,SR)/(RR,Ss) diastereomers.8 The dominant diastereomer is consistent with (among possibilities analyzed earlier)4,6CNAcknowledgment. We thank the NIH for support of this reattack upon (1) la, from a direction opposite to rhenium or (2) search. the trans u isomer (,!?)-la, from a direction opposite to the bulky PPh3 ligand (Scheme I). Supplementary Material Available: Experimental procedures Figure 1 shows that the rate of reaction of la, depends upon and tables of rate and characterization data (3 pages). Ordering [CN-] at lower [CN-] but approaches zero order in [CN-] at information is given on any current masthead page. higher [CN-1. Such behavior ("saturation kinetics") requires an intermediate9and is readily interpreted in the context of the model in Scheme I and the attendant expression for kobs. First, any residual slope in Figure 1 at high [CN-] provides an upper bound Accessibility to the Active Site of Methane on k,, the rate constant for the direct reaction of la, and CNMonooxygenase: The First Demonstration of to give 2a (
