Synthesis and Second-Order NLO Properties of Donor−Acceptor σ-Alkenyl Ruthenium Complexes

The compounds p-R−C6H4−CHCH−C⋮C−TMS (R = NO2, N(CH3)2, OCH3) were obtained from
Wittig olefination of TMS−C⋮C−CH2PPh3Br with p-R−C6H4−CHO in THF, which can be desilylated
to give p-R−C6H4−CHCH−C⋮C−H. Treatment of RuHCl(CO)(PPh3)3 with p-R−C6H4−CHCH−C⋮C−H produced RuCl(CO)(PPh3)2(CHCH−CHCH−C6H4−R-p). The later complexes reacted with
4-phenylpyridine (PhPy), 2,6-(Ph2PCH2)2C5H3N (PMP), and KTp (Tp = hydridotris(pyrazolyl)borate)
to give RuCl(CO)(PhPy)(PPh3)2 (CHCH−CHCH−C6H4−R-p), RuCl(CO)(PMP)(CHCH−CHCH−C6H4−R-p), and RuTp(CO)(PPh3) (CHCH−CHCH−C6H4−R-p), respectively. The structure of RuTp(CO)(PPh3)(CHCH−CHCH−C6H4−R-p) (R = N(CH3)2, 7b) has been confirmed by X-ray diffraction.
The NLO properties (hyper-Rayleigh scattering measurements) of the complexes 5, 6, and 7 reveal that
changes induced in the ligands of ruthenium (5a−7a or 5b,6b) have a large impact on the
hyperpolarizability.