Rearrangement of Closo-3,3-(PPh3)2-3-H-1-(R)-3,1,2-IrC2B9H10 to Closo-2,2-(PPh3)2-H-8-(R)-2,1,8-IrC2B9H10. Synthesis and X-Ray Structure of Closo-2,2-(PPh3)2-2-H-8-(C6H5)-2,1,8-IrC2B9H10.
CALIFORNIA UNIV LOS ANGELES DEPT OF CHEMISTRY AND BIOCHEMISTRY
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During the continuing investigation of the chemistry of the known alkene hydrogenation and isomerization catalyst, closo-3,3-PPh32-3-H-3,1,2-RhC2B9H111 Ia, the iridum congener and its derivatives, closo-3,3-PPH32-1-R-3-H-3,1,2-IrC2B9H10, R H IIa1, R C6H5 IIb2, R CH3 IIc2 and R 1-closo-1,2-C2B10H11 IId2 were prepared and notable differences between the reactivity of the Rh and Ir systems were observed. Syntheses of IIb-d, the exo-nido complexes derived from these compounds, and the dimeric complex derived from IIa will be reported in a future paper. Although thermally induced migration of carbon atoms over the surface of polyhedral cobaltacarboranes is a well-established phenomenon, 3 similar isomerization reactions are not so well known for other metallacarboranes. The formation of 2,1,8 isomers of icosahedral metallocarboranes have been observed previously 3 only during high temperature vapor phase thermal isomerization of n-C5H5CoC2B9H11 isomers. The 2,1,8 isomer of this system was observed as the dominant kinetic product 74 arising from the 3,1,2 isomer during such reactions at temperatures near 500 degrees C however, three other isomers were also detected in the reaction mixture. Here we report the ready polytopal rearrangement of IIb and IIc under mild thermolytic conditions in toluene solvent at the reflux temperature.
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy