The challenge of deciphering linkage isomers in mixtures of oligomeric complexes derived from 9-methyladenine and trans-(NH3)2Pt(II) units.

Metal coordination to N9-substituted adenines, such as the model nucleobase 9-methyladenine (9MeA), under neutral or weakly acidic pH conditions in water preferably occurs at N1 and/or N7. This leads, not only to mononuclear linkage isomers with N1 or N7 binding, but also to species that involve both N1 and N7 metal binding in the form of dinuclear or oligomeric species. Application of a trans-(NH3)2Pt(II) unit and restriction of metal coordination to the N1 and N7 sites and the size of the oligomer to four metal entities generates over 50 possible isomers, which display different feasible connectivities. Slowly interconverting rotamers are not included in this number. Based on (1)H NMR spectroscopic analysis, a qualitative assessment of the spectroscopic features of N1,N7-bridged species was attempted. By studying the solution behavior of selected isolated and structurally characterized compounds, such as trans-[PtCl(9MeA-N7)(NH3)2]ClO4⋅2H2O or trans,trans-[{PtCl(NH3)2}2(9MeA-N1,N7)][ClO4]2⋅H2O, and also by application of a 9MeA complex with an (NH3)3Pt(II) entity at N7, [Pt(9MeA-N7)(NH3)3][NO3]2, which blocks further cross-link formation at the N7 site, basic NMR spectroscopic signatures of N1,N7-bridged Pt(II) complexes were identified. Among others, the trinuclear complex trans-[Pt(NH3)2{µ-(N1-9MeA-N7)Pt(NH3)3}2][ClO4]6⋅2H2O was crystallized and its rotational isomerism in aqueous solution was studied by NMR spectroscopy and DFT calculations. Interestingly, simultaneous Pt(II) coordination to N1 and N7 acidifies the exocyclic amino group of the two 9MeA ligands sufficiently to permit replacement of one proton each by a bridging heterometal ion, Hg(II) or Cu(II), under mild conditions in water.

Organotin(IV)-loaded mesoporous silica as a biocompatible strategy in cancer treatment.

The strong therapeutic potential of an organotin(IV) compound loaded in nanostructured silica (SBA-15pSn) is demonstrated: B16 melanoma tumor growth in syngeneic C57BL/6 mice is almost completely abolished. In contrast to apoptosis as the basic mechanism of the anticancer action of numerous chemotherapeutics, the important advantage of this SBA-15pSn mesoporous material is the induction of cell differentiation, an effect unknown for metal-based drugs and nanomaterials alone. This non-aggressive mode of drug action is highly efficient against cancer cells but is in the concentration range used nontoxic for normal tissue. JNK (Jun-amino-terminal kinase)-independent apoptosis accompanied by the development of the melanocyte-like nonproliferative phenotype of survived cells indicates the extraordinary potential of SBA-15pSn to suppress tumor growth without undesirable compensatory proliferation of malignant cells in response to neighboring cell death.

[3-Meth-oxy-1-(phenyl-sulfan-yl)prop-yl]triphenyl-tin(IV) benzene 0.17-solvate.

In the title compound, [Sn(C(6)H(5))(3)(C(10)H(13)OS)]·0.17C(6)H(6), the Sn(IV) atom exhibits a slightly distorted tetra-hedral coordination geometry built up by four C atoms, which are the three ipso-C atoms of the phenyl rings and the α-C atom of the deprotonated γ-O-functionalized propyl phenyl sulfide. The benzene mol-ecule lies about a threefold rotoinversion axis.

Chlorido[1-diphenyl-phosphanyl-3-(phenyl-sulfan-yl)propane-κ(2)P,S](η(5)-penta-methyl-cyclo-penta-dien-yl)iridium(III) chloride monohydrate.

The crystal structure of the title compound, [Ir(C(10)H(15))Cl(C(21)H(21)PS)]Cl·H(2)O, consists of discrete [Ir(η(5)-C(5)Me(5))Cl{Ph(2)P(CH(2))(3)SPh-κP,κS}](+) cations, chloride anions and water mol-ecules. The Ir(III) atom is coordinated by an η(5)-C(5)Me(5) ligand, a chloride and a Ph(2)P(CH(2))(3)SPh-κP,κS ligand, leading to a three-legged piano-stool geometry. In the crystal, two water molecules and two chloride anions are linked by weak O-H⋯Cl hydrogen bonding into tetra-mers that are located on centers of inversion. The H atoms of one of the methyl groups are disordered and were refined using a split model.

(Acetato-κO)(2,2'-bipyridine-κN,N')trimethyl-platinum(IV) monohydrate.

In the title hydrate, [Pt(CH(3))(3)(CH(3)COO)(C(10)H(8)N(2))]·H(2)O, the Pt(IV) atom exhibits a distorted octa-hedral coordination geometry built up by three methyl ligands in a facial arrangement, a bipyridine ligand and a monodentately bound acetate ligand. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds are observed between the water mol-ecule and the platinum complex, which link the mol-ecules into chains along the c axis.

(OC-6-33)-(2,2'-Bipyridine-κN,N')trimeth-yl(2-methyl-sulfanyl-2-thia-zoline-κN)platinum(IV) tetra-fluoridoborate.

The asymmetric unit of the title complex, [Pt(CH(3))(3)(C(10)H(8)N(2))(C(4)H(7)NS(2))]BF(4), contains two crystallographically independent mol-ecules. The Pt(IV) atom in each complex cation exhibits a distorted octa-hedral coordination geometry, built up by three methyl ligands in a facial binding fashion, a bipyridine ligand and a monodentately N-bound 2-methyl-sulfanyl-2-thia-zoline ligand (configuration index: OC-6-33). In the crystal structure, weak inter-molecular C-H⋯F hydrogen bonds are found between the complex cations and BF(4) (-) anions.

Synthesis of trimethylplatinum(IV) complexes with N,N- and N,O-heterocyclic carbene ligands and their reductive C-C elimination reactions.

Reactions of the platinum(IV) complexes [PtMe(3)(OCMe(2))(3)](BF(4)) (1(BF(4))), [(PtMe(3)I)(4)] (2), and [PtMe(3)I(py)(2)] (3) with the N,N-heterocyclic carbene 1,3-dimethylimidazol-2-ylidene (N,N-hc, 4) resulted in a rapid reductive elimination of ethane, yielding platinum(II) complexes [PtMe(N,N-hc)(3)](+) (7), trans-[PtMeI(N,N-hc)(2)] (8), and cis-[PtMe(py)(N,N-hc)(2)](+) (10), respectively. Subsequent substitution of the iodo ligand in 8 by pyridine resulted in the formation of trans-[PtMe(py)(N,N-hc)(2)](CF(3)COO) (9(CF(3)COO)). 9 and 10 are stereoisomers. In contrast to this, the analogous reaction of [PtMe(3)(OCMe(2))(3)](BF(4)) (1(BF(4))) with the N,O-heterocyclic carbene 3-methyloxazol-2-ylidene (N,O-hc, 5) was found to yield the tris(carbene)trimethylplatinum(IV) compound [PtMe(3)(N,O-hc)(3)](BF(4)) (12(BF(4))), which is thermally stable up to 218 degrees C in the solid state. Furthermore, reactions of [{PtMe(3)(acac)}(2)] (15) with the N,X-heterocyclic carbenes (X = N, O, S; N,S-hc = 3-methylthiazol-2-ylidene, 6) resulted in the formation of monocarbenetrimethylplatinum(IV) complexes [PtMe(3)(acac)(N,X-hc)] (X = N, 16; X = O, 17; X = S, 18), which were found to be stable against reductive C-C elimination at ambient temperature. Reactions of 16 and 17 with 2,2'-bipyridine (bpy) in the presence of stoichiometric amounts of H(BF(4)) yielded cationic monocarbeneplatinum(IV) complexes, which were isolated as tetrafluoroborate salts [PtMe(3)(bpy)(N,X-hc)](BF(4)) (X = N, 19(BF(4)); X = O, 20(BF(4))). The compounds have been fully characterized analytically and NMR spectroscopically, and for the bis(carbene)platinum(II) compound 9(CF(3)COO) as well as the monocarbeneplatinum(IV) compounds 16 and 20(BF(4)) by single-crystal X-ray diffraction analyses. DFT calculations of mono-, bis-, and tris(carbene)trimethylplatinum(IV) complexes and their propensity to reductive eliminate ethane were performed. In accordance with the experimental findings, a much higher stability of the tris(N,O-hc)- compared with the tris(N,N-hc)trimethylplatinum(IV) complexes against reductive ethane elimination was found, which could be ascribed mainly to a higher steric demand of the N,N-hc ligand.

Synthesis and in vitro antitumoral activity of novel O,O'-di-2-alkyl-(S,S)-ethylenediamine-N,N'-di-2-propanoate ligands and corresponding platinum(II/IV) complexes.

Syntheses of two novel ligand precursors O,O'-diisopropyl- (1a) and O,O'-diisobutyl-(S,S)-ethylenediamine-N,N'-di-2-propanoate dihydrochloride monohydrate (1b) and the corresponding dichloroplatinum(II) (2a and 2b) and tetrachloroplatinum(IV) complexes (3a and 3b) are described here. The substances were characterized by IR, (1)H and (13)C spectroscopy and elemental analysis. Crystal structures were determined for 1a and the corresponding platinum(IV) complex, 3a. In vitro antiproliferative activity was determined against tumor cell lines: human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, rested and stimulated normal immunocompetent cells (human peripheral blood mononuclear PBMC cells) using KBR test (Kenacid Blue Dye binding test). The IC(50)(microM) values for the most active compound 3a were: 30.48+/-2.54; 12.26+/-2.60; 13.68+/-3.22; 80.18+/-24.07 and 71.30+/-21.70, respectively.

Dichlorido(9-methyl-adenine-κN)(η-penta-methyl-cyclo-penta-dien-yl)iridium(III) dichloromethane solvate.

In the title complex, [Ir(C(10)H(15))Cl(2)(C(6)H(7)N(5))]·CH(2)Cl(2) or [Ir(η(5)-C(5)Me(5))Cl(2)(9-MeAde-κN(7))]·CH(2)Cl(2) (9-MeAde = 9-methyl-adenine), the coordination geometry of the Ir(III) atom approximates to a three-legged piano stool. The 9-methyl-adenine ligand is coordinated in a monodentate fashion to the Ir centre through its N-7 atom. The crystal structure contains centrosymmetric pairs of mol-ecules, inter-acting through two N-H⋯N hydrogen bonds. An intra-molecular N-H⋯Cl hydrogen bond is formed between the H atom of an NH(2) group and a chlorido ligand. Further short intra- and inter-molecular C-H⋯Cl contacts are observed.

Bis[1,2-bis-(dimethyl-phosphino)ethane-κP,P']rhodium(I) dichlorido[(1,2,5,6-η)-1,5-cyclo-octa-diene]rhodium(I).

In the title complex, [Rh(C(6)H(16)P(2))(2)][RhCl(2)(C(8)H(12))], the asymmetric unit contains two [Rh(dmpe)(2)] [dmpe = 1,2-bis-(dimethyl-phosphino)ethane] half-cations, lying on inversion centers, and an [RhCl(2)(cod)](-) (cod = 1,5-cyclo-octa-diene) anion, wherein Rh is coordinated by two chloride ligands and two olefinic π-bonds of the cyclo-octa-diene ligand. The Rh atoms in the cations and anion exhibit square-planar coordination and are separated without any unusual inter-actions.

Platinum(II) complexes with l-methionylglycine and l-methionyl-l-leucine ligands: synthesis, characterization and in vitro antitumoral activity.

Four dipeptide complexes of the type [PtX(2)(dipeptide)] x H(2)O (X=Cl, I, dipeptide=l-methionylglycine, l-methionyl-l-leucine) were prepared. The complexes were characterized by (1)H, (13)C, (195)Pt NMR and infrared spectroscopy, DTG and elemental analysis. From the infrared, (1)H and (13)C NMR spectroscopy it was concluded that dipeptides coordinate bidentately via sulfur and amine nitrogen donor atoms. Confirmed with (13)C and (195)Pt NMR spectroscopy, each of the complexes exists in two diastereoisomeric forms, which are related by inversion of configuration at the sulfur atom. The (1)H NMR spectrum for the platinum(II) complex with l-methionylglycine and chloro ligands exhibited reversible, intramolecular inversion of configuration at the S atom; DeltaG( not equal)=72 kJ mol(-1) at coalescence temperature 349 K was calculated. In vitro cytotoxicity studies using the human tumor cell lines liposarcoma, lung carcinoma A549 and melanoma 518A2 revealed considerable activity of the platinum(II) complex with l-methionylglycine and chloro ligands. Further in vitro cytotoxic evaluation using human testicular germ cell tumor cell lines 1411HP and H12.1 and colon carcinoma cell line DLD-1 showed moderate cytotoxic activity for all platinum(II) complexes only in the cisplatin-sensitive cell line H12.1. Platinum uptake studies using atomic absorption spectroscopy indicated no relationship between uptake and activity. Potential antitumoral activity of this class of platinum(II) complexes is dependent on the kind of ligands as well as on tumor cell type.

Tris(propane-1,2-diamine-κN,N')nickel(II) tetra-cyanidoplatinate(II).

In the title compound, [Ni(C(3)H(10)N(2))(3)][Pt(CN)(4)], the [Pt(CN)(4)](2-) anion with the environment of the Pt(II) atom, lying on a mirror plane, is square planar, whereas the Ni(II) atom in the [Ni(C(3)N(2)H(10))(3)](2+) cation, also lying on a mirror plane, has a slightly distorted octa-hedral coordination geometry. Three chiral 1,2-diamino-propane mol-ecules, which are disordered equally over two sets of positions, adopt Δ(δδδ) and Δ(λλλ) configurations. The average Ni-N and Pt-C bond lengths are 2.131 (10) and 1.988 (10) Å, respectively. The cations and anions are connected by N-H⋯N hydrogen bonds.

Biological Potential of Halfsandwich Ruthenium(II) and Iridium (III) Complexes.

In vitro studies with the ruthenium(II) and analogous iridium(III) complexes [Ru(η6- p-cymene)Cl2{Ph2PCH2CH2CH2S(O)xPh-κP}], [Ru(η6-p-cymene)Cl{Ph2PCH2CH2CH2S(O)xPh- κP,κS}][PF6] (1-4), [Ir(η5-C5Me5)Cl2{Ph2PCH2CH2CH2S(O)xPh-κP}] and [Ir(η5-C5Me5)Cl{Ph2 PCH2CH2CH2S(O)xPh-κP,κS}][PF6] (5-8; x = 0, 1) revealed the high selectivity toward the 8505C, A253, MCF-7, SW480 and 518A2 cancer cell lines. Thus, the cationic ruthenium complex 4 proved to be the most selective one. In case of the neutral and cationic ruthenium complexes 1-4 the caspase-dependent apoptotic cell death was proven as the main cause of the drug's tumoricidal action on 8505C cell line.

Lithiated sulfoxides: α-sulfinyl functionalized carbanions.

Reactions of alkyl aryl sulfoxides H-CRR'S(O)Ar with n-BuLi-TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine) afforded α-sulfinyl functionalized alkyl aryl lithium compounds of the type [Li2{CRR'S(O)Ar}2(TMEDA)2] (1, R/R' = H/H, Ar = Ph; 2, R/R' = H/H, Ar = p-Tol; 3, R/R' = Me/Me, Ar = Ph; 4, R/R' = H/Ph, Ar = Ph; 5, R/R' = Me/Ph, Ar = Ph). The compounds were characterized by (1)H, (13)C and (7)Li NMR spectroscopy and, except for 5, by single-crystal X-ray diffraction analyses. In crystals of 1, 2, 3 and 4 ·Et2O dinuclear molecules with four-membered Li2O2 rings were found. There are no LiCα contacts, thus, "free" carbanions are the main structural feature. Reactions of 1-6 (6, R/R' = H/Me, Ar = Ph) with benzaldehyde and benzophenone afforded the corresponding sulfoxides of the type ArS(O)CRR'CHPhOH (1a-6a) and ArS(O)CRR'CPh2OH (1b-6b), respectively. The reactions yielding / and / proceeded with high diastereoselectivities. By X-ray diffractometry it has been shown that in the case of and the diastereomers consisting of the two enantiomers SSRC and RSSC were formed.

Synthesis, Reactivity, and Structure of [H(13)O(6)][PtCl(5)(H(4)O(2))].2(18-cr-6): A Crown Ether Complex of a Pentachloroaquaplatinic Acid with an [H(13)O(6)](+) Cation in a Cage of Three Crown Ether Molecules.

An aqueous solution of H(2)[PtCl(6)].6 H(2)O reacts with crown ether 18-crown-6 to give [H(13)O(6)][PtCl(5)(H(4)O(2))]. 2(18-cr-6)(1) (1) and (H(3)O)(2)[PtCl(6)].2(18-cr-6) (2a). In the presence of HCl, only 2a is formed; in an analogous manner, (H(3)O)(2)[PtCl(6)].2(15-cr-5).2 H(2)O (2b) and (H(3)O)(2)[PtCl(6)].2(DCH-18-cr-6)(1) (2c) were obtained. 1 is gradually decomposed in water to give [PtCl(4)(H(2)O)(2)].(18-cr-6).2H(2)O (3). 1-3 were characterized by microanalysis and IR and NMR spectroscopy ((1)H, (13)C, (195)Pt). The X-ray structure analysis of 1 (orange needles; space group P2(1)2(1)2(1), a = 7.938(1) Å, b = 15.691(2) Å, c = 34.861(4) Å; Z = 4) shows an anionic entity [PtCl(5)(H(4)O(2))](-) and a cationic entity [H(13)O(6)](+) which are separated by a crown ether molecule 18-cr-6. The [H(13)O(6)](+) cations exhibit the structure [H(3)O(H(4)O(2))(2)(H(2)O)](+) and are also separated by crown ether molecules in such a way that the crystal is threaded by chains built up of 18-cr-6/[H(13)O(6)](+) units at which the 18-cr-6/[PtCl(5)(H(4)O(2))](-) moieties are fixed as lateral branches. Thus, the cations [H(13)O(6)](+) are embedded in three crown ether molecules. All terminal hydrogens are involved in hydrogen bridges to oxygen atoms of the crown ether molecules. The O(w).O(cr) distances are distinctly longer in the mean than the O(w).O(w) distances within the [H(13)O(6)](+) moiety.

The First Platinum(IV) Complexes with Glucopyranoside Ligands. A New Coordination Mode of Carbohydrates.

[(PtMe(3)I)(4)] reacts with AgBF(4) in acetone to give fac-[PtMe(3)(Me(2)CO)(3)]BF(4) (2) which was isolated as strongly moisture and air sensitive, colorless crystals and characterized by microanalysis and NMR spectroscopy ((1)H, (13)C, (195)Pt). The X-ray structure analysis (orthorhombic, Pcab, a = 15.599(3) Å, b = 15.685(2) Å, c = 15.763(3) Å, Z = 8) reveals that 2 is monomeric and that the cation exhibits local C(3)(v)() symmetry. The reaction of 2 with glucopyranoses (1,6-anhydro-beta-D-glucopyranose (3a), 1-methyl-alpha-D-glucopyranoside (3b), and 1-phenyl-beta-D-glucopyranoside (3c)) yields carbohydrate complexes [PtMe(3)L]BF(4) (4a-4c, L = 3a-3c). The complexes were characterized by microanalysis, ESI mass spectrometry and by NMR spectroscopy ((1)H, (13)C, (195)Pt) displaying that the carbohydrates act as tridentate chelating ligands coordinated by the hydroxyl groups 2-OH and 4-OH and by the acetal oxygen atom of the pyranose ring. This structure was also confirmed by X-ray structure analysis of 4a (orthorhombic, P2(1)2(1)2(1), a = 6.404(1) Å, b = 8.636(2) Å, c = 27.161(5) Å, Z = 4). The cyclic system of the two five-membered and the one six-membered 1,3,2-dioxaplatina rings is not free from angle strain; two O-Pt-O angles are distinctly smaller than 90 degrees (O2-Pt-O5 73.6(2), O4-Pt-O5 75.6(2) degrees ). The Pt-O bond to the acetal oxygen atom in the pyranose ring is significantly longer (Pt-O5 2.288(5) Å) than the two Pt-OH bonds (Pt-O2 2.246(5), Pt-O4 2.248(4) and belongs to the longest Pt-O bonds at all.

Protonated nucleobase ligands: synthesis, structure and characterization of 9-methyladeninium hexachloroplatinate and pentachloro(9-methyladeninium)platinum(IV).

Na(2)[PtCl(6)] was found to react with (9-MeAH)Cl(.)H(2)O (2) (9-MeA=9-methyladenine) in aqueous solution yielding (9-MeAH)(2)[PtCl(6)](.)2H(2)O (3). The same compound was obtained from hexachloroplatinic acid and 9-methyladenine. Performing this reaction at 60 degrees C, complex formation took place yielding the 9-methyladeninium complex [PtCl(5)(9-MeAH)](.)2H(2)O (4a). An analogous complex, [PtCl(5)(9-MeAH)](.)1/2(18C6)(.)H(2)O (4b, 18C6=crown ether 18-crown-6), was formed in the reaction of aquapentachloroplatinic acid (H(3)O)[PtCl(5)(H(2)O)](.)2(18C6)(.)6H(2)O (1) with 9-methyladenine in 1:1 ratio. All complexes were isolated in moderate to good yields as yellow powder (4b) and crystals (3, 4a), respectively. They were fully characterized by microanalysis, IR and NMR ((1)H, (13)C, (195)Pt) spectroscopies, and in part (2, 3, 4a) also by single-crystal X-ray diffraction analysis. Molecular structure of complex 4a exhibited that the 9-methyladeninium ligand is N1 protonated and coordinated through N7 to platinum(IV).

Anticancer potential of (pentamethylcyclopentadienyl)chloridoiridium(III) complexes bearing κP and κP,κS-coordinated Ph2 PCH2 CH2 CH2 S(O)x Ph (x=0-2) ligands.

Iridium(III) complexes of the type [Ir(η(5) -C5 Me5 )Cl2 {Ph2 PCH2 CH2 CH2 S(O)x Ph-κP}] (x=0-2; 1-3) and [Ir(η(5) -C5 Me5 )Cl{Ph2 PCH2 CH2 CH2 S(O)x Ph-κP,κS}][PF6 ] (x=0-1; 4 and 5) with 3-(diphenylphosphino)propyl phenyl sulfide, sulfoxide, and sulfone ligands Ph2 PCH2 CH2 CH2 S(O)x Ph were designed, synthesized, and characterized fully, including X-ray diffraction analyses for complexes 3 and 4. In vitro studies against human thyroid carcinoma (8505C), submandibular carcinoma (A253), breast adenocarcinoma (MCF-7), colon adenocarcinoma (SW480), and melanoma (518A2) cell lines provided evidence for the high biological potential of the neutral and cationic iridium(III) complexes. Neutral iridium(III) complex 5 proved to be the most active, with IC50 values up to about 0.1 µM, representing activities of up to one order of magnitude higher than cisplatin. Using 8505C cells, apoptosis was shown to be the main mechanism through which complex 5 exerts its tumoricidal action. The described iridium(III) complexes represent potential leads in the search for novel metal-based anticancer agents.

Cationic arene ruthenium(II) complexes with chelating P-functionalized alkyl phenyl sulfide and sulfoxide ligands as potent anticancer agents.

The synthesis and characterization of cationic ruthenium(II) complexes of the type [Ru(η(6)-p-cym)Cl{Ph(2)P(CH(2))(n)S(O)(x)Ph-κP,κS}][PF(6)] (n = 1-3; x = 0, 1; p-cym = p-cymene) are presented. Furthermore, their high biological potential even against cisplatin-resistant tumor cell lines and their structure-activity relationships are discussed.

Biological activity of neutral and cationic iridium(III) complexes with κP and κP,κS coordinated Ph2PCH2S(O)xPh (x = 0-2) ligands.

Neutral iridium(III) complexes of the type [Ir(η(5)-C5Me5)Cl2{Ph2PCH2S(O)xPh-κP}] (1-3) with diphenylphosphino-functionalized methyl phenyl sulfides, sulfoxides, and sulfones Ph2PCH2S(O)xPh (x = 0, L1; 1, L2; 2, L3) and the cationic complex [Ir(η(5)-C5Me5)Cl{Ph2PCH2SPh-κP,κS}][PF6] (4) were synthesized and fully characterized analytically and spectroscopically. Furthermore, the structure of 2 was determined by X-ray diffraction analysis. The biological potential of the neutral and cationic iridium(III) complexes was tested in vitro against the cell lines 8505C, A253, MCF-7, SW480 and 518A2. Complex [Ir(η(5)-C5Me5)Cl2{Ph2PCH2S(O)Ph-κP}] (2), with ligand L2 κP coordinated containing a pendent sulfinyl group, is the most active one (IC50 values of about 3 µM), thus, with activities comparable to cisplatin. Complex 2 proved to have an even a higher antiproliferative activity than cisplatin against 8505C and SW480 cell lines, used as a model system of highly anaplastic cancers with low sensitivity to conventional chemotherapeutics such as cisplatin. Additional experiments demonstrated that apoptosis and autophagic cell death contribute to the drug's tumoricidal action.