Synthesis and second-order nonlinear optical properties of donor-acceptor sigma-alkynyl and sigma-enynyl indenylruthenium(II) complexes. X-ray crystal structures of [Ru{C CCH=C(C6H4NO2-3)(2)}(eta(5)-C9H7)(PPh3)(2)] and (EE)-[Ru{C C(CH=CH)(2)-C6H4NO2-4}(eta(5)-C9H7)(PPh3)(2)]

sigma-Alkynyl complexes [Ru(C equivalent to C-C6H4R-4)(eta(5)-C9H7)L-2] (L = PPh3, R = NO2 (3a), C equivalent to C-C6H4- NO2-4 (4), N=CH-C6H4NO2-4 (5) ; L-2= 1,2-bis(diphenylphosphino)ethane (dppe), R=NO2(3b); L-2 = bis(diphen ylphosphino)methane (dppm), R = NO2 (3c)) have been prepared by reaction of [RuCl(eta(5)-C9H7)L-2] (1a-c) with HC equivalent to C-C6H4R-4 and NaPF6, v ia deprotonation of the corresponding intermediate vinylidene derivatives. The treatment of the alkynyl-phosphonio complex [Ru{C equivalent to CCH2(PP h3)}(eta(5)-C9H7)(PPh3)(2)][PF6] (6) with (LiBu)-Bu-n and the appropriate a ldehyde or ketone yields, via Wittig type reactions, sigma-enynyl complexes [Ru{C equivalent to CCH=CR1(CH=CH)(n)R-2}(eta(5)-C9H7)(PPh3)(2)] (n = 0, R -1= H, R-2 = C6H4NO2-4 (7a), C4H2ONO2-3,4 (8a), C4H2SNO2-3,4 (8b), C6H4CN-4 (13), C5H4N-4 (16); n = 0, R-1= R-2 = C6H4NO2-3 (9); n = 1, R-1 = H, R-2 = C6H4NO2-4 (7b)) isolated as mixtures of the corresponding E and Z stereois omers. The structures of complexes 7b and 9 have been confirmed by X-ray di ffraction. Structural data in the solid state as well as in solution (C-13{ H-1} NMR) show an extensive electronic delocalization between the donor fra gment [Ru(eta(5)-C9H7)(PPh3)(2)] and the acceptor nitroaryl group. In accor dance with this, values of resonantly enhanced molecular quadratic hyperpol arizabilities (beta) for these donor-acceptor derivatives (beta(1064) (nm)= 100-1320 x 10(-30) esu), determined by the hyper-Rayleigh scattering techn ique (HRS) at 1064 nm which are dependent on the molecular design of the br idged enynyl chain, are significantly larger than those of their analogous organic chromophores. Mixed-valence bimetallic donor-acceptor derivatives [ (eta(5)-C9H7)(PPh3)(2)Ru{(mu-C equivalent to N)ML5}][CF3SO3](n) (n = 0, ML5 = Cr(CO)(5) (11a), W(CO)(5) (11b); n = 3, ML5 = Ru(NH3)(5) (12)), [(eta(5) -C9H7)(PPh3)(2)Ru{(mu-C equivalent to CCH=CH-C6H4C equivalent to N-4)ML5}][ CF3SO3](n) (n = 0, ML5 = Cr(CO)(5) )[(E, Z)-14a], W(CO)(5) [(E, Z)-14b]; n = 3, ML5 = Ru(NH3)(5) [(E, 2)-15] and [(eta(5)-C9H7)(PPh3)(2)Ru{(mu-C equiv alent to CCH=CH-C5H4N-4)M(CO)(5)}] (M = Cr [(E)-17a], W [(E)-17b]) have als o been prepared in high yields. Static quadratic hyperpolarizabilities valu es of these derivatives (beta(o) = 10-150 x 10(-30) esu) surpass the larges t reported to date for bimetallic compounds. The bimetallic sigma-enynyl complex [Ru(C equivalent to CCH=CH)(eta(5)-C5H4 )Fe(eta(5)-C5H5)(eta(5)-C9H7)(PPh3)(2)] [(E)-18] was obtained stereoselecti vely from the alkynyl-phosphonio complex 6, (LiBu)-Bu-n, and {eta(5)-C5H4(C HO)}Fe(eta(5)-C5H5). Protonation of(E)-18 with HBF4 yields the vinylidene d erivative [Ru{=C=C(H)CH=CH(eta(5)-C5H4)Fe(eta(5)-C5H5)}(eta(5)-C9H7)(PPh3)( 2)][BF4] (19) Quadratic hyperpolarizabilities for these ruthenium(II)-iron( II) bimetallic complexes are also reported.