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Title: Synthesis and reactivity of air-stable (LRe(NO)(CO)(CH/sub 3/))/sup +/ (L = 1,4,7-triazacyclononane). Kinetics and mechanism of its reactions with HX (X = Cl, Br, NO/sub 3/). Formation of ((LRe(NO)(CO))/sub 2/(. mu. -CH/sub 2/OCH/sub 2/))I/sub 2/ containing a bridging 2-oxapropane-1,3-diide

Journal Article · · Inorg. Chem.; (United States)
DOI:https://doi.org/10.1021/ic00294a025· OSTI ID:6260215

The reaction of (LRe(NO)(CO)/sub 2/)BF/sub 4/ in aqueous solution with NaBH/sub 4/ affords red, racemic (LRe(NO)(CO)(CH/sub 3/))BF/sub 4/ (1), which has been resolved into its enantiomerically pure form as the (1S)-3-bromocamphorsulfonate salt (L = 1,4,7-triazacyclononane, C/sub 6/H/sub 15/N/sub 3/). 1 reacts in aqueous solution with HX (X = F, Cl, Br, I) to yield the compounds (LRe(NO)(CO)X)/sup +/ and methane. The kinetics of the reactions have been measured. A third-order rate law, -d(1)/dt = k(1)(X)(H/sup +/), has been established. The formal substitution reaction proceeds with retention of configuration at the Re center. A mechanism is proposed that involves the acid-catalyzed cleavage of an Re-N/sub amine/ bond, followed by nucleophilic attack of the nucleophile X/sup -/ at the 16e fragment with concomitant expulsion of CH/sub 3//sup -/ (which is immediately protonated) and rapid re-formation of the Re-N/sub amine/ bond. 1 reacts with I/sub 2/, forming (LRe(NO)(CO)(CH/sub 2/I))/sup +/, which dimerizes in aqueous solution generating ((LRe(NO)(CO))/sub 2/(..mu..-CH/sub 2/OCH/sub 2/))I/sub 2/, which contains the novel bridging group 2-oxapropane-1,3-diide. (LRe(NO)(CO)(O/sub 2/CCF/sub 3/))/sup +/ (2) has been prepared from 1 in F/sub 3/CCO/sub 2/H. 2 reacts with bromine to form the paramagnetic Re(II) complex (LRe(NO)(CO)Br)/sup 2 +/, which is reduced by BH/sub 4//sup -/ to yield (LRe(NO)(CH/sub 3/)Br); oxidation of the latter species with Br/sub 2/ yields (LRe(NO)Br/sub 2/)/sup +/, which is reduced by zinc amalgam to (LRe(NO)Br/sub 2/). Spectroscopic (IR, /sup 1/H NMR, /sup 13/C NMR) and magnetic properties of all new compounds are reported as well as their electrochemical behavior. 36 references, 6 figures, 2 tables.

Research Organization:
Ruhr-Universitaet, Bochum (West Germany)
OSTI ID:
6260215
Journal Information:
Inorg. Chem.; (United States), Vol. 27:21
Country of Publication:
United States
Language:
English