Push-pull ligand

New orthopalladated NLO chromophores based on a parallel alignment of two different push-pull ligands have been synthesized by Centore et al. [153] and their second-order NLO activity has been measured by the EFISH technique working in CHCI3 with an incident wavelength of 1.907 pm. The maximum value of p Si.9i(EFISH) (610 x 10 " esu) was obtained for the NLO chromo-... 

Anthony SP, Radhakrishnan TP (2004) Coordinatieni polymers of Cu(I) with a chiral push-pull ligand Hierarchical network structures and second harmonic generation. Cryst Growth Des 4 ... 

The investigations indicate that, in agreement with the calculations on the cations, the push-pull substituted diphosphenes tend to form a bridged structure of one ligand the other substituent can easily depart under formation of an ion pair structure. 

Why is the complex OsHCl(CO)(P Pr3)2 stable, when it is unsaturated It has been argued that lone pairs on the alpha atom of a ligand M—X (M is a transition metal) can have a major influence on reactivity and structure. If M has empty orbitals of appropriate symmetry, X M tt donation creates an M—X multiple bond, with consequent transfer of electron density to M decreasing its Lewis acidity.23 The presence of a carbonyl ligand in OsHCl(CO)(P Pr3)2) increases the n-donor capacity of chloro by means of the push-pull effect making this molecule not a truly 16-valence electron species. 

In Sect. 5.2, the strong 7r-donor ability of methoxide and fluoride has been elaborated. These two ligands effect a push-pull effect on the nitrosonium ion bound in Os(OEP)NO(OMe) [31c] and Os(OEP)NO(F) [3Id], as indicated by the low NO-stretching frequencies of the NO ion as compared with the dinitrosyl Os(OEP)(NO)2 [31e] and the perchlorato complex, 0s(0EP)N0(0C103) ([3If], Table 11). Thus, the a/7r-donor balance for the coordinated anions decreases in the series OMe > F > NO > OClOf. [31c] and [3Id] can be vaporized at 200°C/10-6 Torr in a mass spectrometer, while the dinitrosyl [31e] decomposes above 100 °C. This demonstrates the push-pull effect also in a chemical sense. 

Shavaleev, N.M., Scopelliti, R., Gumy, R, andBunzli, J.C.G. (2008) Visible-light excitation of infrared lanthanide luminescence via intra-ligand charge-transfer state in 1,3-diketonates containing push-pull chromophores. European Journal of Inorganic Chemistry, (9), 1523-1529. 

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