The series of complexes Au(C=CR)(PPh(3)) (R=Ph (2), 4-C6H4NO2 (3), 4,4
'-C6H4C6H4NO2 (4), (E)-4,4'-C6H4CH=CHC6H4O2 (5), (Z)-4,4'-C6H4CH=CHC6H
4NO2 (6), 4,4'-C6H4C=CC6H4NO2 (7), 4,4'-C6H4N=CHC6H4NO2 (8)) have been
synthesized by reaction of AuCl(PPh(3)) with the corresponding acetyl
ene and methoxide, and complexes 3-8 have been structurally characteri
zed. The molecular first hyperpolarizabilities for the complexes have
been determined by hyper-Rayleigh scattering at 1064 nm. Introduction
of the nitro substituent (in proceeding from 2 to 3) leads to a signif
icant increase in nonlinearity. Experimental beta values increase as 3
< 4 < 6 approximate to 7 < 8 < 5 consistent with nonlinearity increas
ing with (i) chain lengthening, (ii) replacing biphenyl (4) or yne lin
kage (7) by ene linkage (5), (iii) replacing (Z)-ene stereochemistry (
6) with (E)-ene stereochemistry (5), and (iv) ene linkage (5) being mo
re efficient than imino linkage (8). The same trend is observed with t
wo-level-corrected data. A linear correlation of both experimentally-d
etermined and two-level-corrected nonlinearities of the acetylides wit
h precursor acetylenes is observed.