TY - JOUR
T1 - Organometallic complexes for nonlinear optics. 3.1 Molecular quadratic hyperpolarizabilities of ene-, imine-, and azo-linked ruthenium σ-acetylides
T2 - X-ray crystal structure of Ru((E)-4,4′-C≡CC6H4CH=CHC6H 4NO2)(PPh3)2(η-C 5H5)
AU - Whittall, Ian R.
AU - Humphrey, Mark G.
AU - Persoons, André
AU - Houbrechts, Stephan
PY - 1996/4/2
Y1 - 1996/4/2
N2 - The series of complexes Ru((E)-4,4′-C≡CC6H4X=CHC6H 4NO2)(PR3)2(η-C 5H5) (X = CH, R = Ph 11a; X = CH, R = Me, 11b; X = N, R = Ph, 12a; X = N, R = Me, 12b) has been synthesized by reaction of RuCl(PR3)2(η-C5H5) with (E)-4,4′-HC≡CC6H4X=CHC6H 4NO2 and deprotonation of the intermediate vinylidene complex. Complex 11a has been structurally characterized; it is the first example of a donor-acceptor organometallic "extended" chromophore bearing the prototypical acceptor -NO2 to be crystallographically studied. Molecular quadratic hyperpolarizabilities at 1.9 μm were evaluated computationally for the complexes above and imine- and azo-linked analogues by employing ZINDO with crystallographically obtained atomic coordinates. The results are consistent with a substantial increase in quadratic nonlinearity for (i) chain lengthening of the organometallic chromophore (replacing 4-C≡CC6H4NO2 by (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2) and (ii) an azo linkage compared with an ene linkage (replacing (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2 by (E)-4,4′-C≡CC6H4N=NC6H 4NO2). Little variation in computed response was found upon substituting an imine linkage for an ene linkage in the organometallic chromophore (replacing (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2 by (E)-4,4′-C≡CC6H4N=CHC6H 4NO2 or (E)-4,4′-C≡CC6H4-CH≡NC6H 4NO2). Molecular quadratic optical nonlinearities were determined experimentally for 11a, 12a, and Ru(C≡CC6H4NO2-4)(PR3) 2(η-C5H5) (R = Ph, Me) by electric-field-induced second-harmonic generation (EFISH; 11a and 12a only) and hyper-Rayleigh scattering (HRS) techniques. EFISH-derived μβ1064 values for 11a (9700 × 10-48 cm5 esu-1) and 12a (5800 × 10-48 cm5 esu-1) are large compared to those for other organometallic complexes. Resonance-enhanced quadratic nonlinearities at 1.06 μm from HRS are large (1455 × 10-30 cm5 esu-1, 11a; 840 × 10-30 cm5 esu-1, 12a). Two-level-corrected values confirm a substantial increase in quadratic nonlinearity for chain lengthening but suggest a significant decrease in nonlinearity on replacing an ene linkage by an imine linkage; the latter is contrary to the ZINDO result, and the reasons for this are discussed.
AB - The series of complexes Ru((E)-4,4′-C≡CC6H4X=CHC6H 4NO2)(PR3)2(η-C 5H5) (X = CH, R = Ph 11a; X = CH, R = Me, 11b; X = N, R = Ph, 12a; X = N, R = Me, 12b) has been synthesized by reaction of RuCl(PR3)2(η-C5H5) with (E)-4,4′-HC≡CC6H4X=CHC6H 4NO2 and deprotonation of the intermediate vinylidene complex. Complex 11a has been structurally characterized; it is the first example of a donor-acceptor organometallic "extended" chromophore bearing the prototypical acceptor -NO2 to be crystallographically studied. Molecular quadratic hyperpolarizabilities at 1.9 μm were evaluated computationally for the complexes above and imine- and azo-linked analogues by employing ZINDO with crystallographically obtained atomic coordinates. The results are consistent with a substantial increase in quadratic nonlinearity for (i) chain lengthening of the organometallic chromophore (replacing 4-C≡CC6H4NO2 by (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2) and (ii) an azo linkage compared with an ene linkage (replacing (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2 by (E)-4,4′-C≡CC6H4N=NC6H 4NO2). Little variation in computed response was found upon substituting an imine linkage for an ene linkage in the organometallic chromophore (replacing (E)-4,4′-C≡CC6H4CH=CHC6H 4NO2 by (E)-4,4′-C≡CC6H4N=CHC6H 4NO2 or (E)-4,4′-C≡CC6H4-CH≡NC6H 4NO2). Molecular quadratic optical nonlinearities were determined experimentally for 11a, 12a, and Ru(C≡CC6H4NO2-4)(PR3) 2(η-C5H5) (R = Ph, Me) by electric-field-induced second-harmonic generation (EFISH; 11a and 12a only) and hyper-Rayleigh scattering (HRS) techniques. EFISH-derived μβ1064 values for 11a (9700 × 10-48 cm5 esu-1) and 12a (5800 × 10-48 cm5 esu-1) are large compared to those for other organometallic complexes. Resonance-enhanced quadratic nonlinearities at 1.06 μm from HRS are large (1455 × 10-30 cm5 esu-1, 11a; 840 × 10-30 cm5 esu-1, 12a). Two-level-corrected values confirm a substantial increase in quadratic nonlinearity for chain lengthening but suggest a significant decrease in nonlinearity on replacing an ene linkage by an imine linkage; the latter is contrary to the ZINDO result, and the reasons for this are discussed.
UR - http://www.scopus.com/inward/record.url?scp=0037820823&partnerID=8YFLogxK
U2 - 10.1021/om950487y
DO - 10.1021/om950487y
M3 - Article
AN - SCOPUS:0037820823
SN - 0276-7333
VL - 15
SP - 1935
EP - 1941
JO - Organometallics
JF - Organometallics
IS - 7
ER -