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4,6 Nonanedione, 2,8-dimethyl

Condensation reactions on nickel(II) matrices are sensitive to steric effects. X-Ray structm analysis showed [310, 320-328] that H2L263 and its metal complexes are saddle-like, rather than planar. The sources of structural nonplanarity are steric repulsions between methyl groups R, 4 and orr/K>-aromatic protons of the Schiff bases. The increase in the bulk of the groups in these positions hinders macrocyclisation. For example, 3,5-heptanedione, 4,6-nonanedione and 1-phenyl-2,4-pentanedione form cyclic products [Ni(L274)]-[Ni(L276)J, whereas dibenzoyl-methane, 2,6-dimethyl-3,5-heptanedione and 2,2,6,6-tetramethyl-2,5-heptanedione do not give macrocyclic compounds in the presence of nickel(II) and o-phda [300, 320]. In the case of dibenzoylmethane, the nickel(II) )ff-diketonate bis-diamine adduct is isolated (Eq. 2.164) [319]. [Pg.123]

See other pages where 4,6 Nonanedione, 2,8-dimethyl is mentioned: [Pg.44]    [Pg.23]    [Pg.44]    [Pg.23]    [Pg.196]    [Pg.311]    [Pg.248]    [Pg.421]    [Pg.421]    [Pg.1011]    [Pg.1099]    [Pg.1184]    [Pg.1251]    [Pg.1258]    [Pg.1331]   
See also in sourсe #XX -- [ Pg.28 , Pg.44 ]

See also in sourсe #XX -- [ Pg.28 , Pg.44 ]

See also in sourсe #XX -- [ Pg.28 , Pg.44 ]



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2,4-Nonanedione

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