- Chiral phosphine ligands in asymmetric synthesis. IV. Hydrosilation of ketones, and the structure of (bicyclohepta-2,5-diene)rhodium(I) perchlorate
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The crystal structure and absolute configuration of (bicyclohepta-2,5-diene)rhodium(I) perchlorate, ClO4, have been determined from three-dimensional X-ray data collected by counter methods.The complex crystallizes in the orthorhombic space group P212121 with four formula units in a cell dimensions a = 15.773(3), b = 18.660(4), c = 8.990(3) Angstroem.Full-matrix least-squares techniques on F, using 2257 reflections with F > 1.5?(F), were used to refine the structure to a final agreement factor of R1 = 0.042.The cation displays a small tetrahedral distortion from square planar geometry (if the diene is viewed as a bidentate ligand) with Rh-P and Rh-N distances of 2.398(2) and 2.212(6) Angstroem, respectively.The absolute configuration of the aminophosphine ligand was determined to be R by the Bijvoet method.The six-membered chelate ring adopts a δ twist-boat conformation with the methyl substituent of the chiral C atom axially disposed.Rh complexes of the aminophosphine ligand were shown to catalyze the homogeneous hydrosilation of prochiral ketones, but failed to produce an optical bias in any of systems investigated.
- McKay, Ian D.,Payne, Nicholas C.
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p. 1930 - 1935
(2007/10/02)
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