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Synthesis and Study of Triphenylphosphines Functionalized at the 4-Positions through the Nitrogen Atoms in 1,4,7,10-Tetraoxa-13-azacyclopentadecane and the X-ray Structure of the Oxide of the Molecule Substituted at All Three Positions

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journal contribution
posted on 02.02.2001, 00:00 by Mathew T. Mizwicki, Fereshteh Haddadian, T. Shane Kimmerling, Brian S. Muehl, Biing-Jahn Sheu, Bruce N. Storhoff, John C. Huffman
Hybrid phosphine crown ether ligands have been obtained from PhP(OMe)2 and P(OPh)3 and carbanions generated by low-temperature Li/Br exchange reactions involving 4‘-bromo-N-phenylaza-15-crown-5 and n-butyllithium. The A1 ν(CO) values for the Ni(CO)3L complexes of these phosphines have been found to be 2063.7 and 2060.8 cm-1, for the bis (1b) and tris (1c) crown species, respectively, indicating the significant electron-donating abilities of the nitrogen atoms. Addition of NaSCN salts in dichloromethane causes these frequencies to increase by 2.40 (1b) and 3.70 cm-1 (1c), indicating that the P(III) centers detect the presence of crown-coordinated ions. The oxide of 1c has been prepared and the X-ray structure obtained. A prominent feature of that structure, R3̄ symmetry, is that the nitrogen atoms are nearly planar and the ring carbon-to-nitrogen distances are 1.375 Å, features that are also consistent with a significant amount of sp2 C−N double-bond character. The phenyl rings are arranged in a typical propeller shape with torsion angles of 132.4°.

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