X-ray Crystal Structure Of Cis Research Articles

Nitric Oxide Uncaging from a Hydrophobic Chromium(III) PhotoNORM: Visible and Near-Infrared Photochemistry in Biocompatible Polymer Disks.

Devices consisting of polymer disks (PDs) of optically clear or translucent, medical-grade silicone loaded with a new hydrophobic, oxygen-stable, photoactivated nitric oxide-releasing moiety (photoNORM) are described. The photoNORM is the new O-nitrito chromium(III) complex trans-[Cr(PetA)(ONO)2](BF4) (PetA = 5,14-dimethyl-7,12-diphenyl-1,4,8,11-tetraaza-cyclotetradecane), of which the synthesis, X-ray crystal structure, and solution-phase photochemistry are described. Several different commercially available silicone polymers were tested with this photoNORM, and nitric oxide photouncaging with 451 nm light from these systems is compared. In addition, PDs were loaded with the photoNORM and neodymium-sensitized upconverting nanoparticles (Nd-UCNPs). The Nd-UCNPs absorb NIR light at ∼800 nm and activate NO release from the trans-[Cr(PetA)(ONO)2]+ cation. The use of such ensembles as implants provides a potential strategy for the in vivo uncaging of NO at physiological targets triggered by tissue-transmitting NIR excitation. Also reported are the X-ray crystal structures of cis- and trans-{Cr(PetA)Cl2]Cl.

Development of a novel carboplatin like cytoplasmic trackable near infrared fluorophore conjugate via strain-promoted azide alkyne cycloaddition

The successful design and pre-clicked synthesis of a non-toxic and cytosol trackable carboplatin-like near infrared fluorophore conjugate via strain-promoted azide alkyne cycloaddition (SPAAC) is reported. Reaction of cis-[Pt(2-azidopropane-1,3-diamine)(cbdca)] (cbdca = cyclobutane-1,1-dicarboxylato) and a bicyclo[6.1.0]non-4-yne near-infrared (NIR) azadipyrromethene fluorophore gave the corresponding clicked Pt-Fluorophore conjugate. The X-ray crystal structure of cis-[Pt(2-azidopropane-1,3-diamine)(cbdca)] was determined featuring the azide on the bidentate 1,3-diaminopropane ligand. The Pt-fluorophore conjugate is the first example of a Pt conjugate clicked via strain-promoted azide alkyne cycloaddition (SPAAC) where the reactive azide handle is on the amine carrier ligand. The in vitro cytotoxicity and widefield fluorescence imaging of the Pt-Fluorophore conjugate in A2780P and A2780cisR cells are described.

Synthesis, X-ray structure, spectroscopic, DFT study and catalytic activity of cis-[RuCl2(L)(EPh3)] complexes (E = P, As, Sb; L = NN′N″ tridentate azoimine-quinoline ligands)

Abstract New of complexes of formula cis-[RuCl2(L)(PPh3)] (C1–C5) where L = XC6H4N NC(COCH3) NC9H6N, X = H, L1 (C1); CH3, L2 (C2); Br, L3 (C3); CN, L4 (C4), F, L5 (C5)} and cis-[RuCl2(L1)(EPh3)] where E = As (C6); E = Sb (C7) have been synthesized by refluxing [RuCl2(EPh3)3 ] and L in a mixture of (5:1) chloroform/ethanol solution. The complexes have been characterized by the spectroscopic techniques (IR, NMR and UV–Vis) and geometries have been confirmed by X-ray crystal structures of cis-[RuCl2(L3)(PPh3)] (C3). The electronic structure, redox and absorption properties of the complexes have been explained based on DFT and TDDFT results. Cyclic voltammetric studies show one reversible Ru(III)/Ru(II) oxidation couple and two successive one electron reductions leading to the formation of L(0/−1) and L(−1/−2), respectively. The complexes cis-[RuCl2(L)(EPh3)](C1–C7) catalyze the transfer hydrogenation of acetophenone in 2-propanol at 86 °C and in the presence NaOCH3.

Structural and Conformational Aspects of Equatorial and Axial Trifluoromethyl, Difluoromethyl, and Monofluoromethyl Groups.

The X-ray crystal structures of cis- and trans-1-(indol-3-yl)-4-methyl cyclohexane and its congeners with stepwise fluorination of the methyl group are reported. The trans-configured compounds adopted diequatorial conformations, whereas the cis analogues adopted regular cyclohexane chair conformations with the methyl group preferentially assuming the axial position, even in the case of the CF3 group. Surprisingly, although the axial CF3 derivative displayed distinct valence deformations in the cyclohexane moiety, the observed structural changes were relatively modest. The cis derivatives with axial mono- and difluorinated methyl groups exhibited conformational disorder in the crystals with significant population levels for the staggered conformations that had one fluorine atom in the endo position; their respective trans counterparts adopted unique conformations, but again with one fluorine atom in the endo position. Theoretical calculations for a series of cis- and trans-1,4-dimethyl cyclohexane model compounds with stepwise fluorination of one equatorial or axial methyl group reproduced the experimentally observed structural response patterns very well, reproduced the experimentally determined nonlinear correlation of the axial-equatorial energy difference with the degree of methyl fluorination in a satisfactory manner, and provided further insights into important conformational aspects of partially fluorinated methyl groups.

Combining anti-cancer drugs with artificial sweeteners: Synthesis and anti-cancer activity of saccharinate (sac) and thiosaccharinate (tsac) complexes cis-[Pt(sac)2(NH3)2] and cis-[Pt(tsac)2(NH3)2

The new platinum(II) complexes cis-[Pt(sac)2(NH3)2] (sac=saccharinate) and cis-[Pt(tsac)2(NH3)2] (tsac=thiosaccharinate) have been prepared, the X-ray crystal structure of cis-[Pt(sac)2(NH3)2].H2O reveals that both saccharinate anions are N-bound in a cis-arrangement being inequivalent in both the solid-state and in solution at room temperature. Preliminary anti-cancer activity has been assessed against A549 human alveolar type-II like cell lines with the thiosaccharinate complex showing good activity.

Complexes of cis-dioxomolybdenum(VI) and oxovanadium(IV) with a tridentate ONS donor ligand: Synthesis, spectroscopic properties, X-ray crystal structure and catalytic activity

New cis-dioxomolybdenum(VI) and oxovanadium(IV) complexes of the Schiff base, derived from S-methyl dithiocarbazate and 2,3-dihydroxybenzaldehyde (H2dhsm), have been synthesized. The complexes of the type cis-[MoO2(dhsm)] (1a), cis-[MoO2(dhsm)(D)] (1b–1d) [D=neutral monodentate ligand; EtOH, pyridine (py) or imidazole (imz)], [VO(dhsm)(NN)] (2a, 2b) [NN=2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen)] and [VO(dhsm)] (2c) have been isolated, characterized by 1H NMR, IR, UV–Vis and EPR spectral studies and investigated by cyclic voltammetry. The X-ray crystal structure of cis-[MoO2(dhsm)(EtOH)] (1b) has been determined and shows that the complex has a distorted octahedral geometry in which the H2dhsm behaves as a dianionic ONS tridentate ligand coordinating via phenoxide oxygen, hydrazinic nitrogen and thiolate sulfur. The oxomolybdenum(IV) complex [MoO(dhsm)] (1e) has obtained from dioxomolybdenum(VI) complex (1b) by oxo abstraction with PPh3. The reactivity of the complexes toward catalytic oxidation of alcohols in the presence of H2O2 and t-BuOOH as co-oxidants under solvent free conditions is reported.

ChemInform Abstract: Synthesis, Electrochemistry and X-Ray Crystal Structure of cis-(Ru(III) L1(Cl)(H2O))(ClO4)2×2 H2O (L1: N,N′-dimethyl-N,N′-bis(2- pyridylmethyl)ethylenediamine); Electrochemical Oxidation of Alcohols and Tetrahydrofuran by cis-(Ru(V)L1

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Cis -Diammine(pyridine)chloroplatinum(II), a monofunctional platinum(II) antitumor agent: Uptake, structure, function, and prospects

We have identified unique chemical and biological properties of a cationic monofunctional platinum(II) complex, cis-diammine(pyridine)chloroplatinum(II), cis-[Pt(NH(3))(2)(py)Cl](+) or cDPCP, a coordination compound previously identified to have significant anticancer activity in a mouse tumor model. This compound is an excellent substrate for organic cation transporters 1 and 2, also designated SLC22A1 and SLC22A2, respectively. These transporters are abundantly expressed in human colorectal cancers, where they mediate uptake of oxaliplatin, cis-[Pt(DACH)(oxalate)] (DACH = trans-R,R-1,2-diaminocyclohexane), an FDA-approved first-line therapy for colorectal cancer. Unlike oxaliplatin, however, cDPCP binds DNA monofunctionally, as revealed by an x-ray crystal structure of cis-{Pt(NH(3))(2)(py)}(2+) bound to the N7 atom of a single guanosine residue in a DNA dodecamer duplex. Although the quaternary structure resembles that of B-form DNA, there is a base-pair step to the 5' side of the Pt adduct with abnormally large shift and slide values, features characteristic of cisplatin intrastrand cross-links. cDPCP effectively blocks transcription from DNA templates carrying adducts of the complex, unlike DNA lesions of other monofunctional platinum(II) compounds like {Pt(dien)}(2+). cDPCP-DNA adducts are removed by the nucleotide excision repair apparatus, albeit much less efficiently than bifunctional platinum-DNA intrastrand cross-links. These exceptional characteristics indicate that cDPCP and related complexes merit consideration as therapeutic options for treating colorectal and other cancers bearing appropriate cation transporters.

Dynamics of a cis-Dihydrogen/Hydride Complex of Iridium

Insertion of CS2 into one of the Ir-H bonds of [Ir(H)5(PCy3)2] takes place to afford the dihydrido dithioformate complex cis-[Ir(H)2(eta2-S2CH)(PCy3)2] accompanied by the elimination of H2. Protonation of the dithioformate complex using HBF4.Et2O gives cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] wherein the H atom undergoes site exchange between the dihydrogen and the hydride ligands. The dynamics was found to be so extremely rapid with respect to the NMR time scale that the barrier to exchange could not be measured. Partial deuteration of the hydride ligands resulted in a J(H,D) of 6.5 and 7.7 Hz for the H2D and the HD2 isotopomers of cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4], respectively. The H-H distance (d(HH)) for this complex has been calculated to be 1.05 A, which can be categorized under the class of elongated dihydrogen complexes. The cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] complex undergoes substitution of the bound H2 moiety with CH(3)CN and CO resulting in new hydride derivatives, cis-[Ir(H)(L)(eta2-S2CH)(PCy3)2][BF4] (L = CH3CN, CO). Reaction of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] with electrophilic reagents such as MeOTf and Me3SiOTf afforded a new hydride aquo complex cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] via the elimination of CH4 and Me3SiH, respectively, followed by the binding of a water molecule (present in trace quantities in the solvent) to the iridium center. The X-ray crystal structures of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] and cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] have been determined.

Reaction of platinum(II) derivatives with 1-hydroxyalkyl-3,5-dimethylpyrazole ligands. Cleavage of the N(pz)C(sp 3) bond. X-ray crystal structure of cis-[PtCl 2(HL 2) 2] (HL 2=1-(2-hydroxyethyl)-3,5-dimethylpyrazole) and trans-[PtCl 2(dmpz) 2] (dmpz=3,5-dimethylpyrazole)

The reactions of 1-hydroxymethyl-3,5-dimethylpyrazole (HL 1) and 1-(2-hydroxyethyl)-3,5-dimethylpyrazole (HL 2) with several platinum starting materials ([PtCl 2(CH 3CN) 2], cis- and trans-[PtCl 2(PhCN) 2], PtCl 2 and K 2PtCl 4) under different conditions have been examined and compared with those obtained from the reactions with Pd(II). cis and trans Pt(II) adducts are obtained in a different ratio depending on the metallic starting complex. The reaction of HL 1 with any of the Pt(II) complexes differs from that with Pd(II) and also from the equivalent reaction of HL 2 with Pt(II). This reaction implies the rupture of the ligand: the cleavage of the N(pz)C(sp 3) bond leads to [PtCl 2(dmpz) 2] (dmpz=3,5-dimethylpyrazole). For comparison, the direct reaction of dmpz with Pt(II) has also been studied. The crystal structure of cis-[PtCl 2(HL 2) 2] and trans-[PtCl 2(dmpz) 2] are here reported.

Cis-[PtCl2(NH3){2-(2-hydroxyethyl)pyridine}] − an Analogue of the Anticancer Drug AMD473: Unusual Hydrolysis Rates and pKa Values for the Diaqua Adduct

The X-ray crystal structure of cis-[PtCl2(NH3){2-(2-hydroxyethyl)pyridine}] shows that it has similar structural features to the 2-picoline analogue, the anticancer drug AMD473 (ZD0473), but undergoes aquation much more rapidly. The diaqua adduct has unusually low pKa values which have been rationalised by molecular modelling. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Versatility in the mode of coordination [(C) −, (N,S), (C,N) − or (C,N,S) −] of the Schiff base: C 6H 5–CHN–CH 2–CH 2–SEt to palladium(II). X-ray crystal structures of cis-[Pd{C 6H 5–CHN–CH 2–CH 2–SEt}Cl 2] and [Pd{C 6H 4–CHN–CH 2–CH 2–SEt}Cl

The reaction of ligand C 6H 5–CHN–CH 2–CH 2–SEt ( 1) with Na 2[PdCl 4] is studied. It yields, depending on the experimental conditions, two different sorts of palladium(II) complexes: cis-[Pd{C 6H 5–CHN–CH 2–CH 2–SEt}Cl 2] ( 2b) and [Pd{C 6H 4–CHN–CH 2–CH 2–SEt}Cl] ( 3b). Compounds 2b and 3b differ in the mode of binding of the ligand to the palladium: as a neutral (N,S) group in 2b or as a monoanionic (C,N,S) − terdentate ligand in 3b. The results presented here show that the formation of 3b is promoted thermally and requires the presence of sodium acetate. The cyclopalladated complex 3b reacts with PPh 3, in a 1:1 or 1:2 molar ratio, to produce [Pd{C 6H 4–CHN–CH 2–CH 2–SEt}Cl(PPh 3)] ( 4b) or [Pd{C 6H 4–CHN–CH 2–CH 2–SEt}Cl(PPh 3) 2] ( 5b), respectively. All the complexes have been characterised by elemental analysis, infrared and NMR spectroscopy. Compounds 2b and 3b have also been characterised structurally: 2b is triclinic, space group P1̄, with a=8.081(2), b=8.230(2), c=10.836(2) Å, α=109.16(3), β=96.65(3) and γ=92.29(3)° and 3b is triclinic, space group P1̄, with a=10.201(2), b=11.927(2), c=17.568(4) Å, α=104.35(3), β=94.21(3) and γ=111.56(3)°. The structural studies confirmed the mode of binding of the ligand to the palladium and revealed that the ligand has the Z-form in 2b and the E-form in 3b. Semiempirical calculations based on the pm3(tm) method have also been used to explain the isomerisation of 2b.

Single- and Double-Stranded Chains Assembled via Concomitant Metal Coordination and Hydrogen Bonding

The synthesis and X-ray crystal structures of two novel cationic metal complexes bearing ligands capable of multiple hydrogen-bonding interactions (isonicotinamide) are reported. cis-(Et3P)2Pt(NC5H4CONH2)2(NO3)2 (2) crystallizes as its monohydrate via the amide functionality, resulting in infinite, parallel zigzag chains. (C5Me5)Rh(NC5H4CONH2)3(OTf)2 (3), along with one molecule of acetone, crystallizes via the amide functionality, resulting in infinite, doubly stranded, interwoven chains. The preparation and X-ray crystal structure of cis-(Et3P)2Pt(NO3)2 (1) is also reported.

Synthesis and characterisation of platinum(II) complexes containing heterobidentate S,N-chelating ligands: X-ray crystal structure of cis-[Pt{SPPh 2NC(Me)NH- S,N}(PMe 2Ph) 2]Cl

Deprotonation of the terminal amino group in the N-thiophosphoryl compounds Me 2P(S)NC(NH 2) 2 (HL 1), Ph 2P(S)NC(Me)NH 2 (HL 2) or Ph 2P(S)NC(NH 2) 2 (HL 3) using potassium tert butoxide in thf, followed by treatment with cis-[PtCl 2(PR 3) 2] (PR 3=PMe 2Ph or 1 2 dppe) generates monocationic complexes cis-[Pt(L n - S,N)(PR 3) 2]Cl ( 1– 6), which have been characterised by 31P{ 1H} NMR, IR and FAB + mass spectroscopies, and for cis-[Pt(L 2- S,N)(PMe 2Ph) 2]Cl ( 2) by single crystal X-ray diffraction. The molecular structure of 2 reveals bidentate coordination of the platinum(II) centre by a bidentate S,N-chelating [Ph 2P(S)NC(Me)NH] − anion, giving a six-membered platinacycle, which adopts a chaise-longue conformation, with a strong hydrogen-bonding interaction between the chloride counterion and the nitrogen-bound proton.

The first X-ray crystal structures of cobalt complexes containing monodentate and bridging ethylenediamine ligands

The X-ray crystal structures of cis-[CoCl(en) 2(enH)]Cl(ZnCl 4) ( 1) and rac-μ-en[ cis-CoCl(en) 2] 2(ZnCl 4) 2 ( 2) are reported. Complex 1 crystallises in the monoclinic space group P2 1/ n with Z=4, while 2 is in the chiral orthorhombic space group P2 12 12 1 with Z=4. These represent the first X-ray crystal structures of cobalt complexes containing either a monodentate or bridging ethylenediamine ligand. The conformations of the en ligands are also discussed.

Palladium (II) and platinum (II) compounds containing bi- and terdentate ferrocenyl ligands. X-ray crystal structure of cis-[Pd{(η 5-C 5H 5)Fe{(η 5-C 5H 4)–CHN–CH 2–CH 2–N(CH 3) 2]}Cl 2

The synthesis, characterization and study of the three ferrocenyl Schiff bases: [(η 5-C 5H 5)Fe{(η 5-C 5H 4)–CHN–CH 2–CH 2–N(CH 3) 2}] ( 1a), [(η 5-C 5H 5)Fe{(η 5-C 5H 4)–CHN–CH 2–CH 2–S–CH 2–CH 3}] ( 1b) and [(η 5-C 5H 5)Fe{(η 5-C 5H 4)–CHN–CH(COOCH 3)–CH 2–CH 2–S–CH 3}] ( 1c) are reported. Reactivity studies of these substrates versus palladium (II) and platinum (II) salts have allowed us to isolate and characterize different sorts of complex. The coordination complexes: cis-[M(ligand)Cl 2] {where M=Pd ( 2a– 2c) or Pt ( 3a– 3c)} were prepared by treatment of the corresponding ligand and Na 2[PdCl 4] (for 2a– 2c) or cis-[PtCl 2(dmso) 2] (for 3a– 3c) in methanol. In compounds 2, 3a– c the ligand acts as a neutral bidentate group. The cyclopalladated complex: [Pd{(η 5-C 5H 5)Fe[(η 5-C 5H 3)–CHN–CH 2–CH 2–N(CH 3) 2]}Cl] ( 4a) can be isolated by reaction of stoichiometric amounts of 1a, Na 2[PdCl 4] and Na(CH 3COO) · 3H 2O in methanol for 8 days. In complex 4a the ligand acts as a monoanionic (C, N, N′) − terdentate group. The reaction of compound 4a with an equimolar amount of PPh 3 produces [Pd{(η 5-C 5H 5)Fe[(η 5-C 5H 3)–CHN–CH 2–CH 2–N(CH 3) 2]}Cl(PPh 3)], in which the ligand acts as a monoanionic (C, N) − bidentate ligand. All the compounds included in this study have been characterized by infrared and NMR spectroscopy and complex 2a has also been characterized structurally: monoclinic, P2 1/ m, with a=6.034(2) Å, b=14.502(2) Å, c=10.236(2) Å and β=104.61(2)°. The crystal structure of complex 2a reveals that the imine adopts the Z-form.

X-ray crystal structure of cis-{(±)-6,6′-[[1,1′-biphenyl]-2,2′-diylbis(oxy)]bis–dibenzo[d,f][1,3,2]dioxaphosphepin} diiodoplatinum(II)·dichloromethane

Bis(dibenzo[d,f][1,3,2]dixoaphosphepin) ligands are extensively used in catalysts for asymmetric alkene hydroformylation; however, few crystal structures of complexes of these ligands have been reported. In this paper, the synthesis and X-ray crystal structure of cis-{(±)-6,6′-[[1,1′-biphenyl]-2,2′-diylbis(oxy)]bis-dibenzo[d,f][1,3,2]dioxaphosphepin} diiodoplatinum (II)·dichloromethane are presented. This complex crystallizes in the triclinic space group P1¯ with a = 12.0842(2,3) b = 12.6993(15) c = 13.2801(18) A; α = 85.852(10), β = 76.723(13), γ = 72.400(12)°, V = 1890.7(10) A3 and Z = 4. The diastereomer that has crystallized has an R*R*R*(S*S*S*) configuration. This X-ray crystal structure supports previous observations that bis(phosphite) ligands with bridging groups derived from 2,2′-biphenol can exhibit a wide range of bite angles (>20°).

Selective cleavage of a PN bond promoted by alcohols in cis-[Cl 2M{ S-(Ph 2P) 2NC(H)(R′)(R″)}] complexes (M = Pd, Pt) X-ray crystal structure of cis-[Cl 2Pt(PPh 2OMe) { S-Ph 2PN(H) C(H) (Me) (Ph)}] · 0.75MeOH

The reaction of MCl 2(tht) 2 (M = Pd, Pt; tht = tetrahydrothiophene) with S-(Ph 2P) 2NC(H)(Me)(Ph) ( S-peap) or S-(Ph 2P) 2NC(H)(CH 2Ph)(CO 2Me) ( S-plap) results in the formation of the neutral mononuclear derivatives cis- rCl 2M( S-peap)] (MPd, 1, Pt 3) or cis-[Cl 2M( S-plap)] (M  Pd 2, Pt 4) in which the chiral diphosphazane ligands are P, P′-chelated. Complexes 1– 4 react with linear alcohols ROH (R  Me, Et, nPr; reflux temperature) resulting in the selective cleavage of only on of the PN bonds of the diphosphazane group and formation of the neutral mononuclear derivatives cis-[Cl 2M(PPh 2OR){ S-Ph 2PN(H)C(H)(R′)(R″)}] (R′  Me, R″  Ph; R  Me, M  Pd 5, Pt 7; R  Et, M  Pt 9; R  nPr, M  Pt 10; R  CH 2CH 2OH, M  Pt 11; and R′  CH 2Ph, R″ &'.dbnd; CO 2Me, R  Me; M  Pd 6, Pt 8). The cleavage of the remaining PN bond was not observed, even at long reaction times, suggesting that the disappearance of the steric constraint in the four-membered metallacycles 1– 4 could be responsible for the observed reactivity. In spite of this, no reaction takes place between 1– 4 and branced alcohols such as 2-propanol, 2-methyl-2-propanol or 2-methyl-1-butanol, nor with water or weak acids. The characterization of all of these complexes has been carried out through spectroscopic methods and through the determination of the single-crystal X-ray structure of cis-[Cl 2Pt(PPh 2OMe){ S-Ph 2PN(H)C(H)(Me)(Ph)}] · 0.75MeOH.

The bonding of thiazoles to platinum(II) complexes. X-ray crystal structure of cis- and trans-[Pt(dimethyl sulfoxide)(thiazole)Cl 2

The crystal structures of neutral cis- and trans-[Pt(dimethyl sulfoxide)(thiazole)Cl 2] have been determined by X-ray diffraction. The longer C4–C5 bond distance of the N-coordinated thiazole in both the square planar complexes, as compared to the free ligand, is interpreted in terms of a negative charge density transfer toward the antibonding orbital system of the thiazolic ring.

Decomposition pathways of platinum(II) complexes containing alkyl and halide ligands investigated by electrospray mass spectrometry. The X-ray crystal structure of cis-[PtCl{CH 2C(O)CH 2Cl}(PPh 3) 2

The platimun(II) alkyl-halide complexes cis[PtCl{CH 2C(O)CH 2Cl}(PPh 3) 2], cis- [PtCl{CH 2C(O)CH 3}(PPh 3) 2], trans-[PtI(Me)(PPh 3) 2], [Pt{EtSCH 2C(O)CH 2}Br(PPh 3)] and [Pt{MeSCH 2C(O)CH 2}I(PPh 3)] have been investigated by electrospray mass spectrometry (ESMS). For all complexes, loss of halide ion provides the initial ionization pathway and the resulting ions may contain coordinated ligands from the solvent (acetonitrile, ammonia and added pyridine). At high cone voltages, all complexes undergo cyclometallation of one of the triphenylphosphine ligands. However, for the chloroacetonyl complex cis-[PtCl{CH 2C(O)CH 2Cl}(PPh 3) 2], fragmentation to the ion [PtCl(PPh 3) 2] + preceeds cyclometallation. It is proposed that this complex fragments via initial oxidative addition of the CCl bond, forming an unstable platina (IV)cyclobutan-3-one (oxodimethylenemethane) complex, which undergoes reductive elimination of cyclopropanone. The X-ray crystal structure of cis-[PtCl{CH 2C(O)CH 2Cl}(PPh 3) 2] is also reported.