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Synthesis of Novel Phosphaalkene-Based Bidentate Ligands Mes*PCH(3-R-Ar) (R = Pyridyl, Carbaldimino) and Formation of Three-Membered Palladacycles Mes*(Me)P−CH(3-R-Ar)−PdCl by Carbapalladation of the PC Double Bond

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posted on 13.03.1999, 00:00 by Marcel van der Sluis, Vincent Beverwijk, Arjan Termaten, Friedrich Bickelhaupt, Huub Kooijman, Anthony L. Spek
Novel functionalized phosphaalkene-based bidentate ligands of the type 1-[(E)-Mes*PC(H)]-3-R-benzene (8, R = N-phenylcarbaldimino; 2, R = 2-pyridyl; Mes* = 2,4,6-tri-tert-butylphenyl) were prepared via a Pd(0)-catalyzed cross-coupling reaction of (Z)-bromophosphaalkene (Z)-1 with Grignard reagents. The reaction of 8 and 2 with MePdCl(COD) furnished three-membered phosphapalladacycles of the type (9, R = N-phenylcarbaldimino; 10, R = 2-pyridyl), displaying intramolecular coordination between the phosphine ligand and palladium(II). The structure of 10 was established by an X-ray structure determination, showing a dimeric structure. The addition of triphenylphosphine to 9 and 10 causes rupture of the interconnecting Pd−N bonds, furnishing 11 and 12, respectively.