The linear and nonlinear optical properties of organometallic chromophores derived from ferrocene, [Fe(#eta#~5-C_5H_5)_2(CO)_2(#eta#-C-CH_3)]~+[BF_4]~- and terthienyl spacers. Crystal structure of 2-[(E)-2-ferrocenylethenyl]-5-(2-thienyl)thiophene

摘要

Several chromophores based on ferrocnee, [Fe(#eta#~5-C_5H_5)_2(CO)_2(#eta#-C-CH_3)]~+[BF_4]~- and terthiophene or dithienylbenzo[c]tiophene have been synthesized. Both thienyls have been shown to act as god donor end groups in their own right but contrary to our expectation the benzo[c]thiophene merocyanine has a lower hyperpolarizablity (344 X 10~(-30) esu) than its thienyl congener (650 X 10~(-30) esu). The structure of 2-[(E)-2-ferrocenylethenyl]-5-(2-thienyl)thiophene has been determined by single crystal X-ray diffraction. The terminal thienyl (thp) group is disordered over two orientations about the bithienyl C(sp~2)-C(sp~2) bond such that the two sulfur toms in either thp ring are positioned trans/cis inthe ratio 0.628(4):0.372(4). The integrity of the alkenyl -C=C- remains with a bond length of 1,332(2) A and the -C-C- lengths adjacent are 1.453(4)/1.441(4) A. Twisting of the rings from planarity occurs along the Fc-C=C-(thp)-(thp) axis: the angle which the ethenylthiophene -C=C-C_4H_2S moiety makes with the C_5H_4 is 11.2(2) deg, and with the major orientationofthe disordered terminal thienyl group, 16(1) deg.