New highly water-soluble rhodium complexes bearing 1,3,5-triaza-7-phosphaadamantane (PTA) and/or tris(hydroxymethyl) phosphine (THP)

Synthesis, structure and anti-cancer activity of osmium complexes bearing π-bound arene substituents and phosphane Co-Ligands: A review

While many examples of osmium complexes, as anti-cancer agents, have been reported and some reviews have been devoted to this topic, a particularly interesting and synthetically accessible sub-class of these compounds namely those bearing a π- bound arene and phosphane co-ligand have escaped review. These complexes have made a surprisingly late entry in the literature (2005) in terms of anti-cancer investigations. This is somewhat surprising considering the plethora of analogous complexes that have been reported for the lighter analogue, ruthenium. Herein we review all complexes, neutral and ionic, bearing the "(ƞ⁶-arene)Os(PR₃)" moiety focusing on their synthesis, reactivity, structural features (by X-ray diffraction analysis) as well as anti-cancer biological activity. An attempt is made throughout the article to contrast these to each other and to analogous Ru systems, and a full summary of all existing in vitro biological data is presented.

Cytotoxic Half-Sandwich Rh(III) and Ir(III) β-Diketonates

A series of half-sandwich pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes [Cp*M(DBM/HDB/AVB)Cl] and [Cp*M(DBM/HDB/AVB)(PTA)][SO₃CF₃], where Cp* = pentamethylcyclopentadienyl, the proligands DBMH = dibenzoylmethane, HDBH = o-hydroxydibenzoylmethane, AVBH = avobenzone, and PTA = 1,3,5-triaza-7-phosphaadamantane, is reported. All the complexes were characterized by IR, ¹H and ¹³C NMR spectroscopy, electrospray ionization mass spectrometry, elemental analysis, and DFT calculations. Five of the complexes have also been characterized in the solid-state by X-ray crystallography. The cytotoxicity of the complexes has been evaluated against human ovarian A2780 and A2780cisR cell lines and, with the only exception of complexes 1 and 2 that display a negligible cytotoxicity, exhibit moderate cytotoxicity toward both cancer cell lines. However, the complexes do not show cancer cell selectivity with respect to human embryonic kidney HEK293 cells.

Organometallic rhodium(III) and iridium(III) cyclopentadienyl complexes with curcumin and bisdemethoxycurcumin co-ligands

A series of half-sandwich cyclopentadienyl rhodium(III) and iridium(III) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(II) complexes.