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Time-dependence of cisplatin (CDDP) and oxaliplatin (L-OHP) cytotoxic effects in A431 and A431/Pt cells (sensitive and CDDP-resistant human cervical tumor cells) were investigated.The drug application modes were pulse (12.5, 25 or 50 microM up to 72 h) and pulse-plus-chase (50 microM for 2, 4 or 6 h, followed by washing and 72 h-incubation in drug-free medium).In the A431 cells, the pulse drug application showed time-effect curves with two plateaux; the inhibitory activity of CDDP was higher than that of L-OHP. The same growth-inhibition fraction was reached by L-OHP in a longer time than CDDP. In the A431/Pt cells, the curve shapes for both drugs were similar in both application modes and had the same general characteristics, noted in the parental cell line. CDDP appeared less active than L-OHP.Different cytotoxicity curves of Pt-drugs could be dictated by the presence of the bulky diaminocyclohexane (DACH) ligand, affecting the kinetics of Pt-DNA binding; mismatch repair (MSH2) protein is involved in the resistance.

The reaction of diazo compounds with alkenes catalysed by complex [RuCl(cod)(Cp)] (cod= 1,5-cyclo-octadiene, Cp=cyclopentadienyl) has been studied. The catalytic cycle involves in the first step the decomposition of the diazo derivative to afford the reactive [RuCl(Cp){=C(R-1)R-2}] intermediate and a mechanism is proposed for this step based on a kinetic study of the simple coupling reaction of ethyl diazoacetate. The evolution of the Ru-carbene intermediate in the presence of alkenes depends on the nature of the substituents at both the diazo N-2=C(R-1)R-2 (R-1, R-2 = Ph, H; Ph, CO2Me; Ph, Ph; C(R-1)R-2 = fluorene) and the olefin substrates R-3(H)C=C(H)R-4 (R-3, R-4 = CO2Et, CO2Et; Ph, Ph; Ph, Me; Ph, H; Me, Br; Me, CN; Ph, CN; H, CN; CN, CN). A remarkable reactivity of the complex was recorded, especially towards unstable aryldiazo compounds and electron-poor olefins. The results obtained indicate that either cyclopropanation or metathesis products can be formed: the first products are favoured by the presence of a cyano substituent at the double bond and the second ones by a phenyl.

Novel palladium(II) complexes with oxazolin-2-ylidene ligands have been synthesized via direct reaction of palladium acetate and oxazolium salts, prepared in turn by alkylation of oxazole with methyl iodide or benzylic bromides. The resulting complexes have been characterized and used as catalysts in Heck coupling reactions of aryl bromides, where they exhibit remarkable catalytic activity, higher than that of the closely related bis-imidazolin- 2-ylidene and bis-benzothiazolin-2-ylidene complexes.

2-(Azidomethyl)phenyl isocyanide, 2-(CH2N3) C6H4N?C (AziNC), coordinates to some cationic Pt(II) and Pd(II) species to afford isocyanide complexes of the type trans-[MCl(AziNC)(PPh3)2][BF4] (M=Pt, l; Pd, 2). AziNC is coordinated also in some neutral Pt(II) and Pd(II) species such as [MCl2(AziNC)2] (M=Pt, 3; Pd, 4) derived from the reactions of 2? of AziNC with [PtCl2(COD)] and [PdCl2(MeCN)2], respectively. Complexes 1 and 2 react with 1? of PPh3 affording the heterocyclic carbene complexes trans-[MCl{CN(H)} (PPh3)2][BF4] (M=Pt, 5; Pd, 6). Complexes 3 and 4 react with 1? of PPh3 displacing the isocyanide with the formation of the complexes cis-[MCl2 (AziNC)(PPh3)] (M=Pt, 7; Pd, 8. These latter ones react with 2 equiv. of PPh3 affording as the final products the cationic carbene species trans-[MCl{CN(H)}(PPh3)2][Cl] (M=Pt, 9; Pd, 10). Complex 5 was also characterized by single crystal X-ray diffraction. The carbene complex is square-planar and the angle formed between the platinum square plane and the heterocyclic carbene ligand is 87.9(2)°. The C(1)-N(1) and C(1)-N(2) bond distances in the latter of 1.32(2) and 1.30(2) Å, respectively, are short for a single bond and indicate extensive ?-bonding between the nitrogen atoms and the carbene carbon.

We have been involved since several years in the synthesis of functionalized isocyanides whose reactivity, when coordinated to a suitable transition metal center, has been shown to depend on the type of the function. The chemistry described in this work led us to further explore the reactivity of new transition-metal coordinated functionalized isocyanides with the aim, in this case, of synthesizing cyclic aminocarbenes.

An improved synthesis of platinum acetate is reported in detail. This tetrameric complex reacts with PPh3 or P–n-Bu3 at room temperature to give the thermodynamically unstable bis-substituted trans-[Pt(OAc)2L2] complexes, which are not easily accessible via other routes. The structure of the new compound trans-[Pt(OAc)2(PPh3)2] has been determined by X-ray analysis.