A group of P-stereogenic monodentate phosphines S-PPhRR′ (R ) 1-naphthyl, 9-phenanthryl, or o-biphenylyl and R′ ) CH 3 -, i-C 3 H 8 -, and Ph 3 SiCH 2 -) have been prepared by succesive substitution reactions on the oxazaphospholidineborane obtained from (-)ephedrine and bis(N,N-diethylamino)phenylphosphine. The reaction with binuclear allyl compounds [Pd(µ-Cl)(allyl)] 2 gives neutral [PdCl(allyl)P*] complexes. When allyl ) 2-CH 3 -C 3 H 4 (5), two isomers appeared in solution due to the R-or S-geometry around the palladium atom. The discrimination effect of the phosphines is small and the maximum isomeric ratio is observed for PPh(o-Ph 2 )(CH 2 SiPh 3 ). The molecular structure determined by X-ray diffraction of two complexes with P* ) PPh(o-Ph 2 )(i-Pr) and PPh(o-Ph 2 )(OMe) showed a very similar nonsymmetric coordination of the allyl moiety according to the greater trans influence of the phosphorus atom. When allyl ) 1-C 6 H 5 -C 3 H 4 (6), the NMR spectroscopy showed up to four isomers due to the R-or S-geometry around palladium and the Z-or E-disposition of P* and the phenyl substituent of the allyl moiety. The E-isomers are the major species in solution, unique with PPh(o-Ph 2 )(CH 2 SiPh 3 ). The usual, well-defined dynamic exchanges by π-σ-π and pseudorotation of the allyl moiety have been observed. The codimerization reaction between styrene and ethylene has been tested using filtered CH 2 Cl 2 solutions of [PdCl(2-CH 3 -C 3 H 4 )P*] (5) complexes and AgBF 4 as catalytic precursors. Moderate activity (TOF < 225 h -1 at 25 °C) and good selectivities to 3-Ph-1-butene (∼90% at 80% conversion) are obtained. The ee is moderate (<40% ee) and different from the discrimination effects observed in the solutions of neutral complexes [PdCl(ally)P*]. The reaction carried out with deuterated styrene shows the clean C-H addition to the vinyl double bond of stryrene and confirms the irreversible nature of the insertion of styrene in the palladium hydride intermediate. The hydrovinylation reaction using substituted styrene with a potentially secondary coordination atom occurs only when the substitution is in the phenyl ring and without significant improvements of the ee.

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In the present study, the potential anti-neoplastic properties of a series of ruthenium half-sandwich complexes of formula [Ru­(η6-arene)­Cl2(PR1R2(1-pyrenyl))] (η6-arene = p-cymene and R1 = R2 = methyl for 1; η6-arene = methylbenzoate and R1 = R2 = methyl for 2; η6-arene = p-cymene and R1 = R2 = phenyl for 3; η6-arene = methylbenzoate and R1 = R2 = phenyl for 4; η6-arene = p-cymene, R1 = methyl and R2 = phenyl for 5; η6-arene = methylbenzoate, R1 = methyl and R2 = phenyl for 6) have been investigated. The six structurally related organoruthenium­(II) compounds have been prepared in good yields and fully characterized; the X-ray structures of three of them, i.e., 1, 2, and 4, were determined. Although the piano-stool compounds contain a large polycyclic aromatic moiety, viz. a 1-pyrenyl group, they do not appear to interact with DNA. However, all the piano-stool complexes show significant cytotoxic properties against five human cell lines, namely, lung adenocarcinoma (A549), melanoma (A375), colorectal adenocarcinoma (SW620), breast adenocarcinoma (MCF7), and nontumorigenic epithelial breast (MCF10A), with IC50 values in the micromolar range for most of them. In addition, the most active compound, i.e., 2, induces a remarkable decrease of cell viability, that is in the nanomolar range, against two human neuroblastoma cell lines, namely, SK-N-BE(2) and CHLA-90. Complexes 1–6 are all capable of inducing apoptosis, but with various degrees of magnitude. Whereas 1, 3, 5, and 6 have no effect on the cell cycle of A375 cells, 2 and 4 can arrest it at the G2/M phase; furthermore, 2 (which is the most efficient compound of the series) also stops the cycle at the S phase, behaving as the well-known anticancer agent cisplatin. Finally, 2 is able to inhibit/reduce the cell migration of neuroblastoma SK-N-BE(2) cells.