ic701936x_si_004.cif (237.73 kB)

Insertion of CO2, Ketones, and Aldehydes into the C−Li Bond of 1,3,5-Triaza-7-phosphaadamantan-6-yllithium

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posted on 21.01.2008, 00:00 by Gene W. Wong, Wei-Chih Lee, Brian J. Frost
The synthesis and structures of a series of new water-soluble phosphine ligands based on 1,3,5-triaza-7-phosphaadamantane (PTA) are described. Insertion of aldehydes or ketones into the C−Li bond of 1,3,5-triaza-7-phosphaadamantan-6-yllithium (PTA−Li) resulted in the formation of a series of slightly water-soluble β-phosphino alcohols (PTA−CRR‘OH, R = C6H5, C6H4OCH3, ferrocenyl; R‘ = H, C6H5, C6H4OCH3) derived from the heterocyclic phosphine PTA. Insertion of CO2 yielded the highly water-soluble carboxylate PTA−CO2Li, S25° ≈ 800 g/L. The compounds have been fully characterized in the solid state by X-ray crystallography and in solution by multinuclear NMR spectroscopy. The addition of PTA−Li to symmetric ketones results in a racemic mixture of PTA−CR2OH ligands with a single resonance in the 31P{1H} NMR spectrum between −95 and −97 ppm. The addition of PTA−Li to aldehydes results in a mixture of diasteromeric compounds, PTA−CHROH, with two 31P{1H} NMR resonances between −100 and −106 ppm. Three (η6-arene)RuCl2(PTA−CRR‘OH) complexes of these ligands were synthesized and characterized, with the ligands binding in a κ1 coordination mode. All the ligands and ruthenium complexes are slightly soluble in water with S25° = 3.9−11.1 g/L for the PTA−CRR‘OH ligands and S25° = 3.3−14.1 g/L for the (η6-arene)RuCl2(PTA−CRR‘OH) complexes.