Preparation of a series of NiL(η2-C60) complexes (L = 1,2-bis(diphenylphosphino)ethane,and 1,1′-bis(diphenylphosphino)ferrocene) by zinc dust reduction

A simple method for preparation of nickel-fullerene coordination complexes has been developed. NiLCl₂(Br₂) and C₆₀ mixtures are reduced by zinc dust upon heating in o-dichlorobenzene. Diffusion of hexane into the reaction mixture results in formation of crystals of NiL(η²-C₆₀)?solvent (L = 1,2-bis(diphenylphosphino)ethane (dppe, 1), 1,3-bis(diphenylphosphino)propane (dppp, 2) and 1,1′-bis(diphenylphosphino)ferrocene (dppf, 3)). Nickel coordinates to the 6–6 bonds of C₆₀ by η²- type and has distorted square-planar geometry. The average Ni–C(C₆₀) bond lengths are 1.936(6)–1.977(3)?Å. We found that increase in the P(L)–Ni–P(L) angle and the dihedral angle between the PNiP and CNiC planes results in elongation of the Ni–C(C₆₀) and Ni–P(L) bonds by 0.04–0.06?Å. Complexes 1–3 contain zero-valent nickel since fullerenes are neutral according to the IR- and visible-NIR spectra. Some of the IR-active bands of C₆₀ are split into three bands in spectra of 1–3 due to C₆₀ symmetry lowering, and the F_1u(4) C₆₀ mode is shifted to lower wave numbers due to the π-back donation. The formation of 1–3 is accompanied by appearance of new bands in the visible range at 435–447 and 661–680 nm.     

Investigations of olefin hydrogenation catalysts. The major species present in solutions containing rhodium(I) complexes of chelating diphosphines

¹H and ³¹P NMR spectroscopy are used to determine the nature of the species present in catalytically active solutions prepared by treating [RhCl(C₂H₄)₂]₂ with diphosphines and [Rh(norbornadiene)diphosphine]BF₄ with hydrogen (diphosphine = 1,3-bis(diphenylphosphino)propane (dppp) and isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane (diop)).     

Preparation of organogold(III) complexes by oxidizing dichloro-, or bis(pentafluorophenyl)-μ-bis(diphenylphosphino)ethanedigold(I)

The oxidation of compounds of the type XAu(dpe)AuX [dpe = 1,2-bis(diphenylphosphino)ethane] leads to organogold(III) complexes. When X is Cl, treatment with BrTl(C₆F₅)₂ leads to oxidative addition of two C₆F₅ groups to each gold atom and formation of Cl(C₆F₅)₂ Au(dpe)Au(C₆F₅)₂Cl, which by metathesis with KBr or KI gives the corresponding bromo (or iodo) derivative. When X is C₆F₅ oxidation with halogens leads in the case of X′ = Cl or Br to formation of X′₂ (C₆F₅)Au(dpe)Au(C₆F₅)X′₂ whereas, for X′ = I reductive elimination of IC₆F₅ takes place to give IAu(dpe)AuI.     

Copolymerization of trans-2,6-diazido-hexaphenylcyclophosphonitrile tetramer with 1,4-bis(diphenylphosphino)butane or 4,4′-bis(diphenylphosphino)biphenyl

Polymers [N(PN)₄(C₆H₅)₆N?P(C₆H₅)₂(CH₂)₄P(C₆H₅)₂]_x and [N(PN)₄(C₆H₅)₆N?P–(C₆H₅)₂C₆H₄C₆H₄P(C₆H₅)₂]_x have been formed by thermal copolymerization of trans-2,6-diazidohexaphenylcyclophosphonitrile [N₃(PN)₄(C₆H₅)₆N₃] with either 1,4-bis-(diphenylphosphino)butane [(C₆H₅)₂P(CH₂)₄P(C₆H₅)₂] or 4,4′-bis(diphenylphosphino)-biphenyl [(C₆H₅)₂C₆H₄C₆H₄P(C₆H₅)₂]. The maximum molecular weights obtained were about 10,000. A polymer endcapped with triphenyl phosphine was stable to 400°C.     

The Synthesis by Decarboxylation Reactions and Crystal Structures of 1, n–Bis(diphenylphosphino)alkane(pentafluorophenyl)‐platinum(II) Complexes

Decarboxylation reactions between the complexes cis–[PtCl₂L] (L = 1, n–bis(diphenylphosphino)–ethane (n = 2, dppe), –propane (n = 3, dppp) or –butane (n = 4, dppb)) and thallium(I) pentafluorobenzoate in pyridine give cis–[PtCl(C₆F₅)L] and cis–[Pt(C₆F₅)₂L] complexes in high yields with short reaction times. X–ray crystal structures of cis–[PtCl(C₆F₅)(dppe)] · 0.5 C₅H₅N, cis–[PtCl(C₆F₅)(dppp)], cis–[PtCl(C₆F₅)(dppb)] · C₃H₆O, cis–[Pt(C₆F₅)₂L] (L = dppe, dppp and dppb) and the reactants cis–[PtCl₂(dppp)] (as a CH₂Cl₂ solvate) and cis–[PtCl₂(dppb)] show monomeric structures with chelating diphosphine ligands in all cases rather than dimers with bridging diphosphines. ³¹P NMR data are consistent with these structures in solution.     

Derivatives of 1,1′-bis(diphenylphosphino)ferrocene (dppf): Electrochemistry, complexation and the X-ray structures of 1,1′-bis(diphenylphosphino)osmocene (dppo) and [PdCl2(dppo)]

The oxidative electrochemistry of 1,1′-bis(diphenylphosphino)osmocene (dppo) and 1,1′-bis(diphenylarsino)ferrocene (dpaf) was studied in dichloromethane with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. The [MCl₂(P^∩P)] (M = Pd or Pt; P^∩P = dppo or 1,1′-bis(diphenylphosphinoindenyl)iron) complexes were prepared, studied electrochemically and the X-ray structures of dppo and [PdCl₂(dppo)] were determined.     

Ruthenafuran Complexes Supported by the Bipyridine-Bis(diphenylphosphino)methane Ligand Set: Synthesis and Cytotoxicity Studies

Mononuclear and dinuclear Ru(II) complexes cis-[Ru(κ²-dppm)(bpy)Cl₂] (1), cis-[Ru(κ²-dppe)(bpy)Cl₂] (2) and [Ru₂(bpy)₂(μ-dpam)₂(μ-Cl)₂](Cl)₂ ([3](Cl)₂) were prepared from the reactions between cis(Cl), cis(S)-[Ru(bpy)(dmso-S)₂Cl₂] and diphosphine/diarsine ligands (bpy = 2,2′-bipyridine; dppm = 1,1-bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino)ethane; dpam = 1,1-bis(diphenylarsino)methane). While methoxy-substituted ruthenafuran [Ru(bpy)(κ²-dppe)(C^O)]⁺ ([7]⁺; C^O = anionic bidentate [C(OMe)CHC(Ph)O]⁻ chelate) was obtained as the only product in the reaction between 2 and phenyl ynone HC≡C(C=O)Ph in MeOH, replacing 2 with 1 led to the formation of both methoxy-substituted ruthenafuran [Ru(bpy)(κ²-dppm)(C^O)]⁺ ([4]⁺) and phosphonium-ring-fused bicyclic ruthenafuran [Ru(bpy)(P^C^O)Cl]⁺ ([5]⁺; P^C^O = neutral tridentate [(Ph)₂PCH₂P(Ph)₂CCHC(Ph)O] chelate). All of these aforementioned metallafuran complexes were derived from Ru(II)–vinylidene intermediates. The potential applications of these metallafuran complexes as anticancer agents were evaluated by in vitro cytotoxicity studies against cervical carcinoma (HeLa) cancer cell line. All the ruthenafuran complexes were found to be one order of magnitude more cytotoxic than cisplatin, which is one of the metal-based anticancer agents being widely used currently.     

Regiospecific and sequential P-C bond activation/cluster transformations in the reaction of PhCCo2MoCp(CO)8 with the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf)

Thermolysis of the mixed-metal cluster PhCCo₂MoCp(CO)₈ (1) with the diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) in CH₂Cl₂ leads to the sequential formation of the phosphido-bridged cluster Co₂MoCp(CO)₅[μ₂,η²,η¹-C(Ph)CC(PPh₂)C(O)OC(O)](μ-PPh₂) (3) and the bis(phosphido)-bridged cluster Co₂MoCp(CO)₄[η³,η¹,η¹-C(Ph)CCC(O)OC(O)](μ-PPh₂)₂ (4). 3 and 4 have been isolated and characterized in solution by IR and NMR (¹H, ¹³C, and ³¹P) spectroscopies, and the solid-state structures have been established by X-ray diffraction analyses. Both clusters contain 48e- and exhibit triangular Co₂Mo cores. The structure of 3 reveals the presence of a phosphido moiety that bridges the Co-Co vector and a six-electron μ₂,η²,η¹-C(Ph)CC(PPh₂)C(O)OC(O) ligand that caps one of the Co₂Mo faces. The X-ray structure of 4 confirms that the five-electron η³,η¹,η¹- C(Ph)CCC(O)OC(O) ligand is σ-bound to the two cobalt centers in an η¹ fashion and π-coordinated to the molybdenum center through a traditional η³-allylic interaction. The reaction between PhCCo₂MoCp(CO)₈ and the chiral diphosphine ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) proceeds similarly, furnishing the phosphido-bridged cluster Co₂MoCp(CO)₅ [μ₂,η²,η¹-C(Ph)CC(PPh₂)C(O)OCH(OMe)](μ-PPh₂) (6), followed by conversion to Co₂MoCp(CO)₄[η³,η¹,η¹-C(Ph)CCC(O)OCH(OMe)](μ-PPh₂)₂ (7). The identities of clusters 6 and 7 have been ascertained by solution spectroscopic methods and X-ray crystallography. The overall molecular structure of cluster 6 is similar to that of cluster 3, except that the P-C(furanone ring) bond cleavage occurs with high regioselectivity and high diastereoselectivity. The cleavage of the remaining P-C(furanone ring) bond in cluster 6 gives rise to the bis(phosphido)-bridged cluster 7, whose structure is discussed relative to its bma-derived analogue 4. The diastereoselectivity that accompanies the formation of 6 and 7 is discussed relative to steric effects within the Co₂Mo polyhedron. The cyclic voltammetric properties of cluster 3 have been examined, with three well-defined one-electron processes for the 0/+1, 0/−1, −1/−2 redox couples found. The composition of the HOMO and LUMO in 3 was established by extended Hückel MO calculations, with the data discussed relative to the parent tetrahedrane cluster 1.     

Synthesis, characterization and electrochemical studies of the heterometallic diclusters [{Fe2(μ-CO)(CO)6(μ-PPh2)Au}2(diphosphine)] (diphosphine=dppm, dppip, dppe, dppp)

Treatment of [(ClAu)₂(diphosphine)] {diphosphine=bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)} with two equivalents of the anion [Fe₂(μ-CO)(CO)₆(μ-PPh₂)]⁻ in the presence of TlBF₄ gives the new heterometallic diclusters [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₂(diphosphine)] that have been isolated and characterized. Their ³¹P-NMR spectra show different patterns as a function of the diphosphine ligand. The electrochemical behavior of these compounds has been investigated and compared with that of the mono- [Fe₂(μ-CO)(CO)₆(μ-PPh₂)(μ-AuPPh₃)] and tricluster [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₃(triphos)] derivatives.     

Synthesis and characterisation of dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts

The novel dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts (R₂Sn)(O,O′-dpmaa) [1a, R = Me; 1b, R = Bu; dpmaa = bis(diphenylphosphino)maleic acid] were synthesised from dpmaa and R₂SnCl₂ or Bu₂SnO. They were fully characterised by elemental analysis, IR- and multinuclear NMR-spectroscopies as well as X-ray crystallography [in the case of 1a as its Ph₂P(O)(CH₂)₂P(O)Ph₂ adduct]. Both were found to be cyclic trimers in the solid state that dissolve in the case of 1b into an equilibrium mixture of oligomers.     

Bis(alkoxycarbonyl) complexes of platinum: preparation,reactivity and their role in carbonylation reactions

bis(alkoxycarbonyl) complexes of platinum of the type [Pt(COOR)₂L] [L = 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), l,4-bis(diphenylphosphino)butane (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppf) or 1,2-bis-(diphenylphosphino)benzene (dpb); R = CH₃, C₆H₅ or C₂H₅] were obtained by reaction of [PtCl₂L] with carbon monoxide and alkoxides. Palladium and nickel complexes gave only carbonyl complexes of the type [M(CO)L] or [M(CO)₂L]. The new complexes were characterized by chemical and spectroscopic means. The X-ray structure of [Pt(COOCH₃)₂(dppf] · CH₃OH is also reported. The reactivity of some alkoxycarbonyl complexes was also investigated.     

Metal—olefin bonding. X-ray structures of trichloro-1,6-bis(diphenylphosphino)-trans-hex-3-enerhodium(III) and dichlorocarbonyl-1,6-bis(diphenylphosphino)-trans-hex-3-eneruthenium(II)

X-ray structures have been determined for the olefin-containing complexes RuCl₃(BDPH) and RuCl₂(CO)(BDPH); BDPH = 1,6-bis(diphenylphosphino)-trans-hex-3-ene. Both compounds crystallise in space group Pbca with eight molecules in unit cells of dimensions RhCl₃(BDPH) a 16.109(8), b 20.359(12), c 17.194(4) Å; RuCl₂(CO)(BDPH) a 16.279(1), b 20.160(1), c 17.334(1) Å. Least-squares refinement returned residuals, R, of 0.030 and 0.067 respectively. In the ruthenium complex the CO and one Cl ligand are statistically interchanged. Both complexes are characterised by weak metal—olefin bonding and a twisted olefin orientation. The geometries are compared with those in other Ir^I and Ir^III complexes containing the BDPH ligand.     

Synthesis,electrochemistry, MO properties,and X-ray diffraction structures of the new redox-active diphosphine ligand 2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (tbpcd) and the rhenium compound fac-BrRe(CO)3(tbpcd)

Knoevenagel condensation of 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) with thiophene-2-carboxaldehyde furnishes the second-generation unsaturated diphosphine ligand 2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (1, tbpcd) in high yield. The substitution chemistry of the rhenium compounds BrRe(CO)₅ and BrRe(CO)₃(THF)₂ with tbpcd has been investigated and found to produce fac-BrRe(CO)₃(tbpcd) (2). Compounds 1 and 2 have been isolated and fully characterized in solution by IR and NMR (¹H and ³¹P) spectroscopies, in addition to mass spectrometry, and X-ray crystallography. The redox properties of 1 and 2 have been examined by cyclic voltammetry, and these data are discussed relative to the results obtained from extended Hückel MO calculations and emission spectroscopic studies, as well as related ligand derivatives previously prepared by us. Our data indicate that the lowest excited state in tbpcd and fac-BrRe(CO)₃(tbpcd) arises from a π → π^∗ intraligand (IL) transition confined exclusively to the tbpcd ligand.     

The Coordination Chemistry of 1,2-Bis[(diphenylphosphino)methyl]benzene with Nickel(II), Palladium(II), Platinum(II), and Platinum(0) and the X-Ray Crystals Structure of [Pt{1,2-bis[(diphenylphospino)methyl]benzene}(C2H4)]

The preparation of complexes [MX₂( 1 )] (M = Ni, Pd, and Pi; X - Cl, Br, and I; 1 = 1,2-bis[(diphenylphosphino)methyl]benzene). [Pt(OSO₂CH₃)Et( 1 )], [Pt(alkene)( 1 )] (alkene - C₂H₂, and CH₂ = CHCN), and [( 1 )Pt-(μ-H)₂PtH( 1 )][BPh₄] is reported. Their ¹H- and ³¹P-NMR spectra were recorded and used lor structural assignments. The X-ray crystal structure of [Pt(C₂H₄)( 1 )] was determined. It is shown that the P? Pt? P bond angle in this complex differs significantly from those found in related compounds with monodentate phosphines, and that this difference is likely to be due to intramolecular contacts.     

[μ‐4,5‐Bis(diphenylphosphino)‐9,9‐dimethylxanthene]bis[(trifluoroacetato)gold(I)] and its dichloromethane 0.58‐solvate

The dinuclear Au^I complex containing the 4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene (xantphos) ligand and trifluoroacetate anions exists in a solvent‐free form, [μ‐4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene]bis[(trifluoroacetato)gold(I)], [Au₂(C₂F₃O₂)₂(C₃₉H₃₂OP₂)], (I), and as a dichloromethane solvate, [Au₂(C₂F₃O₂)₂(C₃₉H₃₂OP₂)]·0.58CH₂Cl₂, (II). The trifluoroacetate anions are coordinated to the Au^I centres bridged by the xantphos ligand in both compounds. The Au^I atoms are in distorted linear coordination environments in both compounds. The phosphine substituents are in a syn arrangement in the xantphos ligand, which facilitates the formation of short aurophilic Au...Au interactions of 2.8966 (8) Å in (I) and 2.9439 (6) Å in (II).     

Molecular and Crystal Structures of Pentafluorophenyl‐platinum(II) Complexes with Bis(diphenylphosphino)methane,Bis(diphenylarsino)methane and 1,2‐Bis(diphenylarsino)ethane

The X‐ray crystal structures of [PtCl₂(dppm)], [Pt(C₆F₅)₂L] (L = dppm (bis(diphenylphosphino)methane), dpam (bis(diphenylarsino)methane), dpae (bis(diphenylarsino)ethane)) and [PtCl(C₆F₅)(dpae)] show the complexes to be monomeric with chelating dipnictido ligands, and not alternatives with bridging ligands. In [Pt(C₆F₅)₂(dpam)₂], there are two unidentate diarsine ligands in a cis‐arrangement.     

Trichlorostannato(diphosphine)rhodium(I) complexes. Crystal structure of [Rh(SnCl3)(1,5-cyclooctadiene)(dppp)]

The molecular structure of [Rh(SnCl₃)(1,5-cyclooctadiene)(dppp)] [dppp = 1,3-bis(diphenylphosphino)propane] has been determined to R_F = 3.6% single-crystal X-ray techniques. The crystal contains two discrete molecules 1 and 2 per asymmetric unit. Molecule 1 is best described as distorted trigonal bipyramidal with the diolefin and the diphosphine occupying both apical and equatorial positions and the SnCl₃ group on an equatorial position, and molecule 2 as distorted square pyramidal with the equatorial positions occupied by the diolefin and the diphosphine, respectively, and the SnCl₃ fragment in the apical position. In solution at room temperature, complexes [Rh(SnCl₃)(COD)(diphosphine)] exhibit tin dissociation and various intramolecular rearrangements.     

Symmetric Ni(II) dithiocarbamates with bidentate phosphines ligands

Ni(II) mononuclear dithiocarbamate complexes with bidentate P,P ligands of composition [Ni(R₂dtc)(P,P)]X {R?=?pentyl (pe), benzyl (bz); dtc?=?S₂CN^?; P,P?=?1,2-bis(diphenylphosphino)ethane (dppe), 1,4-bis(diphenylphosphino)butane (dppb), 1,1′-bis(diphenylphosphino) ferrocene (dppf); X?=?ClO₄, Cl, Br, NCS} and binuclear complexes of composition [Ni₂(μ-dpph)(R₂dtc)₂]X₂ with a P,P-bridging ligand {P,P?=?1,6-bis(diphenylphosphino)hexane (dpph); X?=?Cl, Br, NCS} have been synthesized. The complexes have been characterized by elemental and thermal analysis, IR, electronic and ³¹P{¹H}-NMR spectroscopy, magnetochemical and conductivity measurements. Single crystal X-ray analysis of [Ni(pe₂dtc)(dppf)]ClO₄ confirmed a distorted square planar coordination in the NiS₂P₂ chromophore. For selected samples, the catalysis of graphite oxidation was studied.     

Methylenverbindungen von Nichtmetallen. VI. Amide der Methan-bis(phosphonigsäure), -bis(phosphonsäure) und -bis(thiophosphonsäure)

Methylene Compounds of Non-Metals. VI. Amides of Methane-bis(phosphonous Acid), -bis(phosphonic Acid) and -bis(thiophosphonic Acid) Symmetrical- and asymmetrical-substituted amides of methane-bis(phosphonous acid), -bis(phosphonic acid) and -bis(thiophosphonic acid) have been obtained by stepwise aminolysis of the chlorides Cl₂(Z)PCH₂P(Z)Cl₂ ( 1 : Z = electron pair; 7 : Z = S; 13 : Z = O) and the fluoride F₂(S)PCH₂P(S)F₂ 19 with dimethylaminotrimethylsilane. Oxidation reactions of trivalent phosphonous amides with sulfur and dimethylsulfoxide have also been investigated.     

A cyclometalated diplatinum complex containing 1,1′-bis(diphenylphosphino)ferrocene as spacer ligand: Antitumor study

Cyclometalated platinum(II) complex [Pt(C^N)Cl(dmso)], 1, in which C^N = N(1),C(2′)-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, was reacted with 1 equiv of 1,1′-bis(diphenylphosphino)ferrocene, dppf, to give the cyclometalated diplatinum(II) complex [Pt₂(C^N)₂Cl₂(μ-dppf)], 2, along with 0.5 equiv of unreacted dppf. However, the related reaction with 0.5 equiv of dppf produced complex 2 in pure form. Complex 2 in solution was fully characterized by using multinuclear NMR spectroscopy (¹H, ¹³C, ³¹P, and ¹⁹⁵Pt) and a number of 2D NMR experiments. The structure of complex 2 in solid state was determined by X-ray crystallography showing that the bridging dppf ligand is arranged close to “antiperiplanar staggered” conformation. Cytotoxicity of the complex 2 was studied in three human cancer cell lines derived from ovarian carcinoma(CH1), lung carcinoma(A549), and colon carcinoma (SW480) by means of the MTT assay (MTT = 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide).