ortho-Metallated triphenylphosphine chalcogenide complexes of platinum and palladium: synthesis and catalytic activity.

Treatment of [PtI2(COD)] (COD = 1,5-cyclooctadiene) with 2-LiC6H4P(S)Ph2 gives the complex cis-[Pt{κ(2)-2-C6H4P(S)Ph2}2] () containing a pair of ortho-metallated triphenylphosphine sulfide rings. The selenium counterpart, [Pt{κ(2)-2-C6H4P(Se)Ph2}2] (), which exists as cis- and trans-isomers in solution, and the palladium analogues, cis-[Pd{κ(2)-2-C6H4P(X)Ph2}2] [X = S (), Se ()], are obtained by transmetallation of [MCl2(COD)] with the organotin reagent 2-Me3SnC6H4P(X)Ph2 in a 1 : 2 mol ratio. The reaction of [PdCl2(COD)] with 2-Me3SnC6H4P(X)Ph2 in a 1 : 1 mol ratio, and the reaction of with palladium(ii) acetate, give dinuclear, anion-bridged complexes [Pd2(µ-Cl)2{κ(2)-2-C6H4P(X)Ph2}2] [X = S (), Se ()] and [Pd2(µ-OAc)2{κ(2)-2-C6H4P(S)Ph2}2] (), respectively. Complexes and could not be made directly from triphenylphosphine sulfide by standard ortho-palladation procedures. The bridging framework in complexes and is cleaved by tertiary phosphines to give mononuclear derivatives [PdCl{κ(2)-2-C6H4P(X)Ph2}(PR3)] [X = S, R = Ph (); X = Se, R = Ph (); X = Se, R = 4-tolyl ()]. The selenium-containing compounds and decompose slowly in solution giving dinuclear complexes [PdCl(µ2-Se-κ(2)-P,Se-2-SeC6H4PPh2)PdCl(µ-2-C6H4PPh2)(PR3)] [R = Ph (), 4-tolyl ()]. The structure of complex establishes that the bridging 2-C6H4PPh2 group is generated by reduction of the phosphine selenide unit, not by ortho-metallation of the coordinated triphenylphosphine. The chloro-bridges of and are also cleaved by acetylacetonate (acac) and deprotonated Schiff bases forming mononuclear species [Pd{κ(2)-2-C6H4P(X)Ph2}L2] [L2 = acac, X = S (), Se (); L2 = 2-OC6H4CH[double bond, length as m-dash]NC6H4-4-R, X = S, R = OMe (), NO2 (); X = Se, R = OMe (), NO2 ()]. The ability of complexes , and the Schiff base-derivatives to catalyse Heck-Mizoroki and Suzuki-Miyaura C-C bond-forming reactions has also been investigated.

Functionalized styryl bipyridine as a superior chelate for a ruthenium sensitizer in dye sensitized solar cells.

The new sensitizer MC119 has been synthesized and the solar cell constructed with 0.25 cm(2) active area photoelectrode in combination with an electrolyte composed of 0.6 M dimethylpropyl-imidazolium iodide (DMPII), 0.05 M I(2), 0.5 M TBP and 0.1 M LiI in acetonitrile achieved a solar to electric energy conversion efficiency (η) of 8.36% under Air Mass (AM) 1.5 sunlight, while the reference N719 sensitized solar cell exhibited η-value of 7.2%.