Organometallic complexes for second-order non-linear optics: synthesis andmolecular quadratic hyperpolarizabilities of eta(5)-monocyclopentadienyliron(II) nitrile derivatives with different phosphines. X-ray crystal structure of [FeCp(DPPE)(p-NCC6H4NO2)][PF6]center dot CH2Cl2
Mh. Garcia et al., Organometallic complexes for second-order non-linear optics: synthesis andmolecular quadratic hyperpolarizabilities of eta(5)-monocyclopentadienyliron(II) nitrile derivatives with different phosphines. X-ray crystal structure of [FeCp(DPPE)(p-NCC6H4NO2)][PF6]center dot CH2Cl2, J ORGMET CH, 619(1-2), 2001, pp. 252-264
New complexes of the type [FeCp(P_P)(p-NCR)][PF6] (P_P=(S)-PROLOPHOs, DPPE
and (R)-PROPHOS ((S)-PROLOPHOS= (S)-N-(diphenylphosphino)-2-diphenylphosphi
nooxymethylpyrrolidine; DPPE = 1,2-bis(diphenylphosphino)ethane; (R)-PROPHO
S = (R)-(+)-1,2-bis(diphenylphosphino)propane); R = C6H4N(CH3)(2), C6H4NO2,
(E)-C(H)=C(H)C6H4NO2, C6H4C6H4NO2) have been synthesized and characterized
. Spectroscopic data were evaluated in order to correlate the tuning of the
electronic density at the metal center with the first molecular hyperpolar
izabilities (beta) determined by hyper-Rayleigh scattering at 1064 nm. Expe
rimental beta values increase with chain length and with the enhancement of
the donor ability of the bidentate phosphine. [FeCp(DPPE)((E)-p-NC-C(H)=C(
H)C6H4NO2)][PF6] is found to have the highest beta value (570 x 10(-30) esu
) in the series. Molecular orbital calculations were carried out to underst
and the geometric and electronic factors involved and also to compute the s
tatic hyperpolarizabilities, beta (0). These results are consistent with th
e trend observed in the beta (0) values derived from experiment on the basi
s of the two-level model. The complex [FeCp(DPPE)(p-NCC6H4NO2)][PF6] was cr
ystallographically characterized. The compound crystallizes in the centrosy
mmetric space group Pbcn. Bond distances within the nitrile ligand were dis
cussed in order to evaluate the extension of pi -backdonation suggested by
spectroscopic data. (C) 2001 Elsevier Science B.V. All rights reserved.