Platinum and Palladium Complexes Bearing New (1R,2R)‐(–)‐1,2‐Diaminocyclohexane (DACH)‐Based Nitrogen Ligands: Evaluation of the Complexes Against L1210 Leukemia

The reaction of (1R,2R)‐(–)‐1,2‐diaminocyclohexane ( 1 ) [DACH] with the aldehyde (1R)‐(–)‐myrtenal ( 2 ) in MeOH afforded the bidentate diimine ligand, (1R,2R)‐(–)‐N¹,N²‐bis{(1R)‐(–)myrtenylidene}‐1,2‐diaminocyclohexane ( 3 ) in a high yield. Reduction of 3 using LiAlH₄ led to the formation of the desired ligand ( 4 ) (1R,2R)‐(–)‐N¹,N²‐bis{(1R)‐(–)myrtenyl}‐1,2‐diaminocyclohexane. Treatment of compound 4 with K₂PtCl₄ or K₂PdCl₄ yielded the corresponding platinum(II) and palladium(II) complexes, Pt‐5 and Pd‐6 , respectively. The reaction of compound 3 with K₂PtCl₄ gave the diimine complex Pt‐7 . The cytotoxic activity of the complexes Pt‐5 , Pd‐6 and Pt‐7 was tested and compared to the approved drugs, cisplatin ( Cis ‐Pt ) and oxaliplatin ( Ox‐Pt ). The complexes ( Pt‐5 , Pd‐6 and Pt‐7 ) inhibit L1210 cell line proliferation with an IC₅₀ of 0.6, 4.2, and 0.7 μL, respectively as evidenced by measuring thymidine incorporation.     

Hydrogen‐bonded chains in three cis‐dichloridoplatinum(II) complexes bearing piperidine and amine ligands

The crystal structures of cis‐dichlorido(ethylamine‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₂H₇N)(C₅H₁₁N)], (I), cis‐dichlorido(3‐methoxyaniline‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₇H₉NO)], (II), and cis‐dichlorido(piperidine‐κN)(quinoline‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₉H₇N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N—H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head‐to‐tail fashion. Hydrogen‐bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π–π stacking interactions are of greater importance.     

Kinetics of the substitution reactions of some Pt(II) complexes with 5′‐GMP and L‐histidine

The reactions of platinum(II) complexes, [PtCl₂(dach)] (dach = (1R,2R)‐1,2‐diaminocyclohexane) and [PtCl₂(en)] (en = ethylenediamine) with biologically relevant ligands such as 5′‐GMP (guanosine‐5′‐monophosphate) and l ‐His (l ‐histidine) were studied by UV–vis spectrophotometry, ¹H NMR spectroscopy, and high‐performance liquid chromatography (HPLC). Spectrophotometrically, these reactions were investigated under pseudo‐first‐order conditions at 310 K in 25 mM Hepes buffer (pH 7.2) and 10 mM NaCl to prevent the hydrolysis of the complexes. The [PtCl₂(en)] complex reacts faster than [PtCl₂(dach)] in the reaction with studied nucleophiles. This confirms the fact that the reactivity of studied Pt(II) complexes depends on the structure of the inert bidentate ligand. Also, the substitution reactions with l ‐His are always faster than the reactions with nucleotide 5′‐GMP. The reactions of [PtCl₂(dach)] and [PtCl₂(en)] complexes with l ‐histidine are studied by ¹H NMR spectroscopy. The obtained rate constants are in agreement with those obtained by UV–vis. The same reactions were studied by HPLC comparing the obtained chromatograms during the reaction. The changes in intensity of signals of the free and coordinated ligand show that after a few days there is only one dominant product in the system. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 99–106, 2011     

Bis(8‐quinolinolato‐N,O)platinum(II) and its synthetic intermediate, 8‐hydroxyquinolinium dichloro(8‐quinolinolato‐N,O)platinate(II) tetrahydrate

Bis(8‐quinolinolato‐N,O)­platinum(II), [Pt(C₉H₆NO)₂], (I), has a centrosymmetric planar structure with trans coordination. The molecules form an inclined π stack, with an interplanar spacing of 3.400 (6) Å. 8‐Hydroxy­quinolinium dichloro(8‐quinolinolato‐N,O)­platinate(II) tetrahydrate, (C₉H₈NO)[PtCl₂(C₉H₆NO)]·4H₂O, (II), is soluble in water and is regarded as the synthetic intermediate of the insoluble neutral compound (I). The uncoordinated 8‐hydroxy­quinolinium cations and the monoquinolinolate complexes form an alternating π stack. The origins of fluorescence and phosphorescence in (II) are assigned to the 8‐hydroxy­quinolinium cation and the monoquinolinolate–Pt complex, respectively.     

Dichloro­(4,4′‐dialkyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), where alkyl is pentyl and heptyl

Dichloro­(4,4′‐dipentyl‐2,2′‐bipyridine‐κ²N,N′)platinum(II), [PtCl₂(C₂₀H₂₈N₂)], adopts a discrete π–π stacking structure, where the alkyl chains are located in a random manner. In contrast, dichloro­(4,4′‐diheptyl‐2,2′‐bipyridine‐κ²N,N′)platinum(II), [PtCl₂(C₂₄H₃₆N₂)], forms a layer structure comprised of alkyl chain layers and paired coordination sites, as observed for analogous complexes with longer alkyl chains.     

Solution Behaviour and Biomolecular Interactions of Two Cytotoxic trans‐Platinum(II) Complexes Bearing Aliphatic Amine Ligands

A novel trans‐platinum(II) complex bearing one dimethylamine (dma) and one methylamine (ma) ligand, namely trans‐[PtCl₂(dma)(ma)], recently synthesised and characterised in our laboratory, displayed relevant antiproliferative properties in vitro, being more active than the parent complex, trans‐[PtCl₂(dma)(ipa)], which has isopropylamine (ipa) in place of methylamine. We have analysed comparatively the solution behaviour of these two complexes under various experimental conditions, and investigated their reactivity with horse heart cytochrome c by mass spectrometry, inductively coupled plasma–optical emission spectroscopy (ICP‐OES), 2D [¹H,¹⁵N],[¹H,¹³C] HSQC and [¹H,¹H] NOESY NMR. Some important changes that occurred in the [¹H,¹³C] HSQC NMR spectrum of cytochrome c treated with trans‐[PtCl₂(dma)(ma)] in water, after two days’ incubation, most probably arose from direct platinum coordination to the protein side chain; this was proved conclusively by [¹H,¹H] NOESY NMR and [¹H,¹⁵N] HSQC NMR measurements. Met65 was identified as the primary Pt binding site on cytochrome c. Electrospray mass spectrometry (ESIMS) results provided evidence for extensive platinum–protein adduct formation. A fragment of the [Pt(amine)(amine′)] type was established to be primarily responsible for protein metalation. ICP‐OES analysis revealed that these trans‐platinum(II) complexes bind preferentially to the serum proteins albumin and transferrin rather than to calf thymus DNA. Pt binding to DNA was found to be far lower than in the case of cisplatin. The implications of the results for the mechanism of action of novel cytotoxic trans‐platinum complexes are discussed.     

cis‐ and trans‐Dichloro(3,6‐dihydro‐1,2‐oxazine‐N)(dimethyl sulfoxide‐S)‐platinum(II)

Both the cis, (I), and trans, (II), isomers of the title complex, [PtCl₂(C₄H₇NO)(C₂H₆OS)], possess relatively undistorted square‐planar geometries about the Pt atoms. For (I), cisL—Pt—L angles are in the range 88.8 (2)–91.08 (8)°, while trans angles are 178.61 (8) and 179.4 (2)°. For (II), cisL—Pt—L 86.1 (3)–93.7 (1)°, and transL—Pt—L 175.5 (1) and 179.1 (3)°. The di­methyl sulfoxide (dmso) ligand adopts a normal pyramidal geometry in both complexes. In (I), the S=O bond essentially eclipses the adjacent Pt—N bond, while the oxazine ligand in (I) is twisted so as to avoid steric interactions with the adjacent chloride ligand. By contrast, the dmso ligand in (II) is rotated such that the S=O bond is approximately perpendicular to the square plane, while the oxazine ligand is once again twisted out of the plane by a similar amount as in (I). These are the first structural examples of square‐planar platinum(II) complexes containing a 1,2‐oxazine ligand.     

Synthesis,structure and in vitro cytotoxicity of platinum(II) complexes containing eugenol and a quinolin‐8‐ol‐derived chelator

The synthesis of potassium (η²‐4‐allyl‐2‐methoxyphenol)trichloridoplatinate(II), K[PtCl₃(C₁₀H₁₂O₂)], ( 1 ), starting from Zeise's salt and Ocimum sanctum L. oil has been optimized. Starting from ( 1 ), three new platinum(II) complexes, namely (η²‐4‐allyl‐2‐methoxyphenol)chlorido(2‐methylquinolin‐8‐olato‐κ²N ,O )platinum(II), ( 2 ), (η²‐4‐allyl‐2‐methoxyphenol)chlorido(5‐nitroquinolin‐8‐olato‐κ²N ,O )platinum(II), ( 3 ), and (η²‐4‐allyl‐2‐methoxyphenol)chlorido(5,7‐dichloroquinolin‐8‐olato‐κ²N ,O )platinum(II), [Pt(C₉H₄Cl₂NO)Cl(C₁₀H₁₂O₂)], ( 4 ), containing eugenol and a quinolin‐8‐ol derivative (R‐OQ), have been synthesized and characterized by elemental analyses, MS, IR, ¹H NMR and NOESY spectra. For ( 1 ) and ( 4 ), single‐crystal X‐ray diffraction studies were also carried out. Complexes ( 2 )–( 4 ) show good inhibiting abilities on three human cancer cell lines, i.e. KB, Hep‐G2 and LU, with IC₅₀ values of 1.42–17.8 µM . Complex ( 3 ) gives an impressively high activity against KB, Hep‐G2, LU and MCF‐7, with IC₅₀ values of 1.42–4.91 µM , which are much lower than those of cisplatin and some other platinum(II) complexes.     

A luminescent bis(pyridyl)‐substituted benzimidazole platinum(II) complex exhibiting an intermolecular anagostic interaction

The photophysical properties of transition metal complexes of the 5,6‐dimethyl‐2‐(pyridin‐2‐yl)‐1‐(pyridin‐2‐ylmethyl)‐1H‐benzimidazole ligand are of interest. Dichlorido[5,6‐dimethyl‐2‐(pyridin‐2‐yl)‐1‐(pyridin‐2‐ylmethyl)‐1H‐benzimidazole‐κ²N ²,N ³]platinum(II), [PtCl₂(C₂₀H₁₈N₄)], is luminescent in the solid state at room temperature. The compound displays a distorted square‐planar coordination geometry. The Pt—N(imidazole) bond length is shorter than the Pt—N(pyridine) bond length. The extended structure reveals that symmetry‐related molecules display weak C—H…N, C—H…Cl, and C—H…Pt hydrogen‐bonding interactions that are clearly discernable in the Hirshfeld surface and fingerprint plots. The intermolecular C—H…Pt and C—H…N interactions have been explored using density functional theory. The result of an analysis of the distance dependence of C—H…Pt yields a value consistent with that observed in the solid‐state structure. The energy of interaction for the C—H…Pt interaction is found to be about −11 kJ mol⁻¹.     

Kinetic Studies of Oxidative Addition Reaction of Arylplatinum(II) Complex Containing 4,4′‐Bipyridine and Calculation of Activation Parameters

New complexes of arylplatinum(II) and arylplatinum(IV) containing a bridging ligand, 4,4′‐bipyridine, were synthesized by the reaction of starting material of platinum(II) including para‐tolyl groups,[(p‐MeC₆H₄)₂Pt(SMe₂)₂], with the 4,4′‐bipyridine ligand in 1:1 molar stoichiometry. In the synthesized complexes, the ligand was bonded to the platinum center through the nitrogen donor atoms. To investigate the kinetic reaction of the platinum(II) complex with iodomethane (CH₃‐I) as a reagent, the oxidative addition reaction of this reagent with Pt(II) was performed in dichloromethane and a Pt(IV) complex with the octahedral geometry was formed. The synthesized complexes have been characterized by different spectroscopic methods such as FT‐IR, ¹H NMR, UV–vis, and elemental analysis. Moreover, the conductivity measurements showed nonelectrolyte characteristics for these complexes. The obtained data showed that the complexes have 1:1 metal‐to‐ligand molar ratio. Also, the oxidative addition reaction of CH₃I with the arylplatinum(II) complex at different temperatures was used for obtaining kinetic parameters such as rate constants, activation energy, entropy, and enthalpy of activation using the Microsoft Excel solver. From the acquired data, an S_N2 mechanism was suggested for the oxidative addition reaction.     

On the Ligand‐to‐Metal Charge‐Transfer Photochemistry of the Copper(II) Complexes of Quercetin and Rutin

In contrast to the UV‐photoinduced ligand photoionization of the flavonoid complexes of Fe^III, redox reactions initiated in ligand‐to‐metal charge‐transfer excited states were observed on irradiation of the quercetin ( 1 ) and rutin ( 2 ) complexes of Cu^II. Solutions of complexes with stoichiometries [Cu^IIL₂] (L=quercetin, rutin) and [Cu^II₂L_n] (n=1, L=quercetin; n=3, L=rutin) were flash‐irradiated at 351 nm. Transient spectra observed in these experiments showed the formation of radical ligands corresponding to the one‐electron oxidation of L and the reduction of Cu^II to Cu^I. The radical ligands remained coordinated to the Cu^I centers, and the substitution reactions replacing them by solvent occurred with lifetimes τ<350 ns. These are lifetimes shorter than the known lifetimes (τ>1 ms) of the quercetin and rutin radical's decay.     

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η2‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC1)platinum(II)]

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)platinum(II)], [Pt₂(C₁₅H₁₉O₄)₂Cl₂], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform–diethyl ether or methylene chloride–diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile‐κN)(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chloridoplatinum(II) monohydrate, [Pt(C₁₅H₁₉O₄)Cl(CH₃CN)]·H₂O, (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethylformamide‐κO)platinum(II), [Pt(C₁₅H₁₉O₄)Cl(C₂H₇NO)], and (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethyl sulfoxide‐κS)platinum(II), determined as the analogue {η²‐2‐allyl‐4‐methoxy‐5‐[(ethoxycarbonyl)methoxy]phenyl‐κC¹}chlorido(dimethyl sulfoxide‐κS)platinum(II), [Pt(C₁₄H₁₇O₄)Cl(C₂H₆OS)]. The crystal structures confirm that acetonitrile interacts with the Pt^II atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt—Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C—H…O and C—H…π interactions, but no π–π interactions are observed despite the presence of the aromatic ring.     

Nanostructured polymetallaynes of controlled length: Synthesis and characterization of oligomers and polymers from 1,1′‐bis‐(ethynyl)4,4′‐biphenyl bridging Pt(II) or Pd(II) centers

The reactivity of square planar palladium(II) and platinum(II) complexes in trans or cis configuration, namely trans or cis‐[dichlorobis(tributylphosphine)platinum(II)] and trans‐[dichlorobis(tributylphosphine)palladium(II)] with 1,1′‐bis(ethynyl) 4,4′‐biphenyl, DEBP, leading to π‐conjugated organometallic oligomeric and polymeric metallaynes, was investigated by a systematic variation of the reaction conditions. The formation of polymers and oligomers with defined chain length [? M(PBu₃)₂ (C?C? C₆H₄? C₆H₄? C?C? )]_n (n = 3–10 for the oligomers, n = 20–50 for the polymers) depends on the configuration of the precursor Pt(II) and Pd(II) complexes, the presence/absence of the catalyst CuI, and the reaction time. A series of model reactions monitored by XPS, GPC, and NMR ³¹P spectroscopy showed the route to modulate the chain growth. As expected, the nature of the transition metal (Pt or Pd) and the molecular weight of the polymers markedly influence the photophysical characteristics of the polymetallaynes, such as optical absorption and emission behavior. Polymetallaynes with nanostructured morphology could be obtained by a simple casting procedure of polymer solutions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3311–3329, 2007     

(6,7‐Dimethyl‐2,3‐di‐2‐pyridyl­quinoxaline)bis­(3‐methyl­pyridine)­platinum(II) bis­(hexa­fluoro­phosphate) acetone solvate 0.5‐hydrate

The crystal structure of the title compound, [Pt(C₆H₇N)₂(C₂₀H₁₆N₄)](PF₆)₂·C₃H₆O·0.5H₂O, is composed of a bivalent square‐planar platinum(II) complex, two PF₆⁻ counter‐ions and solvent mol­ecules. The di‐2‐pyridylquinoxaline ligands are known to confer an `L shape' on square‐planar platinum(II) complexes, which also display inter­calating properties. The structural characterization reported here is a contribution to a wide‐ranging study focused on structural and dynamical analyses of these substrates, which may provide better insight into their biological mechanisms and activities. The expected `L‐shaped' skeleton of the metallic complex combined with the antiparallel orientation of substituted pyridines (anti conformation) generates chiral objects, found in the solid state as a racemic mixture.     

Synthesis and anticancer activity of chalcogenide derivatives and platinum(II) and palladium(II) complexes derived from a polar ferrocene phosphanyl–carboxamide

The polar phosphanyl‐carboxamide, 1′‐(diphenylphosphanyl)‐1‐[N‐(2‐hydroxyethyl)carbamoyl]ferrocene ( 1 ), reacts readily with hydrogen peroxide and elemental sulfur to give the corresponding phosphane‐oxide and phosphane‐sulfide, respectively, and with platinum(II) and palladium(II) precursors to afford various bis(phosphane) complexes [MCl₂( 1 ‐κP)₂] (M = trans‐Pd, trans‐Pt and cis‐Pt). The anticancer activity of the compounds was evaluated in vitro with the complexes showing moderate cytotoxicities towards human ovarian cancer cells. Moreover, the biological activity was found to be strongly influenced by the stereochemistry, with trans‐[PtCl₂( 1 ‐κP)₂] being an order of magnitude more active than the corresponding cis isomer. Copyright © 2010 John Wiley & Sons, Ltd.     

Monomere und polymere Dimethylaminothioquadratato‐Komplexe: Die Kristallstrukturen von Nickel(II)‐, Cobalt(II)‐, Silber(I)‐, Platin(II)‐, Gold(I)‐, Quecksilber(II)‐ und Blei(II)‐Dimethylaminothioquadrataten

Monomeric and Polymeric Dimethylaminothiosquarato Complexes: The Crystal Structures of Nickel(II), Cobalt(II), Silver(I), Platinum(II), Gold(I), Mercury(II) and Lead(II) Dimethylaminothiosquarates The ligand 2‐dimethylamino‐3, 4‐dioxo‐cyclobut‐1‐en‐thiolate, Me₂N‐C₄O₂S⁻ (L) forms neutral and anionic complexes with nickel(II), cobalt(II)‐, silver(I)‐, platinum(II)‐, gold(I)‐, mercury(II)‐ and lead(II). According to the crystal structures of seven complexes the ligand is O, S‐chelating in [Ni(L)₂(H₂O)₂]·2 H₂O, [Co(L)₂(CH₃OH)₂] and (with limitations) in [Pb(L)₂·DMF]. In the remaining compounds the ligand behaves essentially as a thiolate ligand. The platinum, gold and mercury complexes [TMA]₂[Pt(L)₄], [TMA] [Au(L)₂] and [Hg(L)₂] are monomeric. In [TMA][Ag₂(L)₃]·5.5 H₂O a chain‐like structure was found. In the asymmetric unit of this structure eight silver ions, with mutual distances in the range 2.8949(4) to 3.1660(3)Å, are coordinated by twelve thiosquarato ligands. [Pb(L)₂·DMF] has also a polymeric structure. It contains a core of edge‐bridged, irregular PbS₄ polyhedra. TMA[Au(H₂NC₄O₂S)₂] has also been prepared and its structure elucidated.     

Asymmetric structure of cis‐[N‐(9‐anthracenylmethyl)‐1,2‐ethanediamine]dipyridineplatinum(II) dinitrate

Platinum antitumour agents, containing aromatic rings, which are used for targeting DNA in effective therapies for the treatment of cancer. We have synthesized the title metallocomplex with an aromatic ligand and determined its crystal structure. In many cases, complexes of platinum and other metals have a symmetrical structure. In contrast, the platinum(II) complex with pyridine and N‐(9‐anthracenylmethyl)‐1,2‐ethanediamine as ligands (systematic name: cis‐{N‐[(anthracen‐9‐yl)methyl]ethane‐1,2‐diamine‐κ²N ,N ′}bis(pyridine‐κN )platinum(II) dinitrate), [Pt(C₅H₅N)₂(C₁₇H₁₈N₂)](NO₃)₂, is asymmetric. Of the two pyridine ligands, only one is π‐stacked with anthracene, resulting in an asymmetric structure. Moreover, the angle of orientation of each pyridine ligand is variable. Further examination of the packing motif confirms an intermolecular edge‐to‐face interaction.     

Ligand Substitution Reactions on Aquapentachloro‐ and Hexachloroplatinic Acid — Synthesis and Characterization of Tetrachloroplatinum(IV) Complexes with Heterocyclic N,N Donors

Reactions of aquapentachloroplatinic acid, (H₃O)[PtCl₅(H₂O)]·2(18C6)·6H₂O ( 1 ) (18C6 = 18‐crown‐6), and H₂[PtCl₆]·6H₂O ( 2 ) with heterocyclic N, N donors (2, 2′‐bipyridine, bpy; 4, 4′‐di‐tert‐butyl‐2, 2′‐bipyridine, tBu₂bpy; 1, 10‐phenanthroline, phen; 4, 7‐diphenyl‐1, 10‐phenanthroline, Ph₂phen; 2, 2′‐bipyrimidine, bpym) afforded with ligand substitution platinum(IV) complexes [PtCl₄(N∩N)] (N∩N = bpy, 3a ; tBu₂bpy, 3b ; Ph₂phen, 5 ; bpym, 7 ) and/or with protonation of N, N donor yielding (R₂phenH)₂[PtCl₆] (R = H, 4a ; Ph, 4b ) and (bpymH)⁺ ( 8 ). With UV irradiation Ph₂phen and bpym reacted with reduction yielding platinum(II) complexes [PtCl₂(N∩N)] (N∩N = Ph₂phen, 6 ; bpym, 9 ). Identities of all complexes were established by microanalysis as well as by NMR (¹H, ¹³C, ¹⁹⁵Pt) and IR spectroscopic investigations. Molecular structures of [PtCl₄(bpym)]·MeOH ( 7 ) and [PtCl₂(Ph₂phen)] ( 6 ) were determined by X‐ray diffraction analyses. Differences in reactivity of bpy/bpym and phen ligands are discussed in terms of calculated structures of complexes [PtCl₅(N∩N)]^— with monodentately bound N, N ligands (N∩N = bpy, 10a ; phen, 10b ; bpym, 10c ).     

trans‐Di­iodo­bis(1,3,5‐tri­aza‐7‐phosphaadamantane)­platinum(II)

The crystal structure of the title compound, trans‐[PtI₂(C₆H₁₂N₃P)₂], describes one of the few platinum(II) complexes containing two of the water‐soluble 1,3,5‐tri­aza‐7‐phosphaadamantane ligands reported to date. The complex crystallizes on an inversion centre with the most important bond lengths and angles being Pt—P 2.3128 (12) Å, Pt—I 2.6022 (6) Å, P—Pt—I 90.94 (3)° and P′—Pt—I 89.06 (3)°.     

Platinum(II)–Gadolinium(III) Complexes as Potential Single‐Molecular Theranostic Agents for Cancer Treatment

Theranostic agents are emerging multifunctional molecules capable of simultaneous therapy and diagnosis of diseases. We found that platinum(II)–gadolinium(III) complexes with the formula [{Pt(NH₃)₂Cl}₂GdL](NO₃)₂ possess such properties. The Gd center is stable in solution and the cytoplasm, whereas the Pt centers undergo ligand substitution in cancer cells. The Pt units interact with DNA and significantly promote the cellular uptake of Gd complexes. The cytotoxicity of the Pt–Gd complexes is comparable to that of cisplatin at high concentrations (≥0.1 mM ), and their proton relaxivity is higher than that of the commercial magnetic resonance imaging (MRI) contrast agent Gd–DTPA. T₁‐weighted MRI on B6 mice demonstrated that these complexes can reveal the accumulation of platinum drugs in vivo. Their cytotoxicity and imaging capabilities make the Pt–Gd complexes promising theranostic agents for cancer treatment.