ISSN:
0009-2940
Keywords:
Triple-decker complexes
;
Cobaltadicarba-closo-octaborane
;
Cobaltadicarba-closo-decaborane
;
Rearrangements
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The three-component reactions of the sandwich anion [(η5-C5H5)Co(η5-Et4MeC3B2)]- (4-H)- and various dicarbaborane anions with metal halides are described. Thus, (4-H)-, nido-4,5-C2B6H9- (5), and CoCl2 form the 30VE triple-decker [η5-C5H5)Co(μ,η5-Et4MeC3B2)Co(η5-2,3-C2B5H7)] (6). An analogous three-component reaction of (4-H)-, arachno-4,5-C2B7H-2 (7), and CoCl2 yields [(η5-C5H5)Co(μ,η5-Et4-MeC3B2)Co(η5-6,9-C2B7H9)] (8), which rearranges on heating (57°C) to give the 1,6-isomer [(η5-C5H5)Co(μ,η5-Et4-MeC3B2)Co(η5-1,6-C2B7H9)] (9) with an activation energy of 127 · 10 kJ/mol. The thermodynamically most stable 1,10-isomer [(η5-C5H5)Co(μ,η5-Et4MeC3B2)Co(η5-1,10-C2B7H9)] (10) is formed by heating of 9 at 180°C. An alternative route to 9 is provided by the reaction of arachno-6,8-C2B7H12- (11) with (4-H)- and CoCl2. The analogous reaction with RhCl3 leads to [(η5-C5H5)Co(μ,η5-Et4MeC3B2)Rh(1,6-C2B7H9)] (15) and unexpectedly to closo-2-(η5-C5H5)Co(1,6-C2B7H9) (12). The constitutions of the described compounds are derived from their 1H-, 11B-, 13C-NMR data as well as mass spectral data. The X-ray structure analyses of 10 and 12 show the expected metal complexes with a CoC2B7H9 framework. In 10 the carbon atoms occupy the capping positions of a bicapped square antiprism. The short Co-Co distance of 3.20 Å is in agreement with the 30VE configuration of 10. In both 10 and 12, the distance from the cobalt to the four-coordinate C4 is the shortest Co-to-cage atom distance.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19961290215
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