IRREVERSIBLE REDOX REARRANGEMENT OF DIOXYGEN COMPLEXES. I. SELECTIVE OXIDATION OF DIPEPTIDES COORDINATED TO COBALT(II)

Abstract

The decomposition of the cobalt dioxygen complexes of three dipeptides has been investigated by removal of the metal from the final reaction mixtures, followed by gas chromatographic and mass spectrometric analyses of the organic reaction products. The results indicate that the reaction involves the oxidation of coordinated dipeptide, and that the ligands are oxidized exclusively at the N-terminal amino acid residue.     

RUTHENIUM (II) COMPLEXES IN CATALYTIC OXIDATION

Abstract

Ruthenium (II) complexes of the type RuL(CO)₂Cl₂, [RuL(CO)₂L^? ₂]²⁺ and [RuL(CO)₂Cl L′]⁺ [L = bipyridine (bpy), phenanthroline (phen), biquinoline (biq) and L′ = pyridine (py), 4-chloropyridine (Cl-py), 4-methoxypyridine (MeO-py)] were synthesized from [Ru(CO)₂Cl₂]_n and L, to produce the intermediate RuL(CO)₂Cl₂ followed by hydrolysis and reaction with L′. The catalytic activity of these complexes in epoxidation of olefins with iodosylbenzene under ambient conditions was investigated. A possible mechanism of these reactions, explaining the effects of the ligands on the reaction was explored. At least one carbonyl ligand remained bound to the metal through the reaction. The formation of an oxo intermediate was inferred from spectroscopic detection of bridged oxygen Ru—O—Ru and Ru=O species.     

SYNTHESIS OF MONOSUBSTITUTED PENTAKIS(2,6-DIETHYLPHENYLISO-CYANIDE)COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE LIGANDS. II. BIMETALLIC COMPLEXES

Abstract

Reaction of bidentate tertiary phosphines with excess [Co(CNR)₅]BF₄, or reaction of [Co(CNR)₄L-L]BF₄ with excess [Co(CNR)₅]BF₄, leads to bimetallic complexes of the form, [(RNC)₄CoL-LCo(CNR)₄](BF₄)₂, R = 2,6-Et₂C₆H₃, L-L = p-Ph₂PC₆H₄PPh₂, Ph₂PC═CPPh₂, Me₂PCH₂CH₂PMe₂, Ph₂PCH₂CH₂PPh₂, Ph₂PCH₂CH₂CH₂PPh₂. Comparison of the v(? N═C) IR patterns, electronic spectra, and molar conductivity values of these bimetallic complexes with data for other Co(I)-organoisocyanide complexes indicates that the two -Co(CNR)₄ moieties are almost totally independent of each other. Recorded λ_max values are the same as for the [Co(CNR)₄L-L]BF₄ complexes, but the ε values, although very large, are less than double. Λ_M values in acetone, and probably also in CH₂Cl₂, are better interpreted as twice the normal conductivity for 1:1 electrolytes than conductivity for 2:1 electrolytes.     

REACTIVITY OF HALIDE COMPLEXES OF TIN(II) I. The Reduction of Methyl Orange

Abstract

Halide ion is required for the reduction of methyl orange by Sn(II). Equilibrium data on the formation of SnCl^2-n _n and SnI^2-n _n combined with kinetic data indicate that SnCl₃ ^? and SnI₃ ^? form activated complexes with protonated methyl orange. The data also suggest pathways involving SnCl₄ ^? SnCl₅ ³, SnI₅ ³ and SnI₇ ^5-.     

COMPLEXES WITH PYRROLE LIGANDS II. THE STABILITY OF THE COMPLEXES OF AG(I) WITH 2-(4-SULFONYL)-PYRRYLMETHYL-METHYL-AMINE

Abstract

The silver(I) complexes of 2-(4-sulfonyl)-pyrrylmethyl-methyl-amine (PSMA) in aqueous solution are investigated by means of alkalimetric titrations. The deprotonated pyrrole group stabilizes the Ag⁺ complex to an extent similar to that of a 2-pyridyl-methyl or 2′-aminoethyl group with equal basicity.     

COMPLEXES OF BINUCLEATING LIGANDS. VII. SOME COPPER(II) COMPLEXES OF TWO SULPHUR-CONTAINING LIGANDS

Abstract

The following cupric complexes of the new binucleating ligand 2-hydroxy-5-methylisophthalaldehyde di-2′-methyl-mercaptoanil, (hereafter MeLH, the ligand strictly being the derived anion MeL^?) and of the related trianionic ligand (hereafter L^3-) formally derived from 2-hydroxy-5-methylisophthalaldehyde di-2′-mercaptoanil have been isolated and characterized:- Cu₂(MeL)Cl₃, Cu₂(MeL)Br₃, Cu₃(MeL)Br₅, Cu₂(MeL)(OH)(ClO₄)₂, Cu₂(L)Cl · DMSO, Cu₂(L)(NCO), Cu₂(L)(tz) (where tz is the anion of 1,2,4-triazole (tzH)). Magnetic properties are consistent with binuclear arrangements in all cases except Cu₃(MeL)Br₅.     

COMPLEXES OF BINUCLEATING LIGANDS. X. SOME COPPER(II), NICKEL(II), PALLADIUM(II), AND PLATINUM(II) COMPLEXES OF SULPHUR-CONTAINING LIGANDS

Abstract

Copper(II) and nickel(II) complexes of the trianionic binucleating ligand (R^3-) derived from 4-hydroxy-bis-3,5-[N-(S-methyl-dithiocarbamate) formimidoyl]toluene have the general form RM₂(Z) where Z represents a range of monoanionic bridging species. Palladium(II) and platinum(II) complexes formed by R^3- and the related trianionic ligands derived from 2-hydroxy-5-methylisophthalaldehyde di-2′-mercaptoanil and 2-hydroxy-5-methylisophthalaldehyde dithiosemicarbazone have the 2:1 formulation [(ligand)M₂(Z)] only when the bridging species, Z, coordinates strongly enough to give the binucleating ligand substantial assistance in maintaining the binuclear structure. In the absence of a ‘good’ bridging group and in the presence of pyridine, 3:2 complexes of the form [(ligand)₂ M₃ (pyridine)₂] (where M = Pd, Pt) are produced in which the binucleating ligand fails to bind the two metals in close proximity.     

UNSYMMETRICAL TETRADENTATE COMPLEXES OF COPPER (II)

Abstract

Four mixed tetradentate Cu(II) chelates were prepared by reacting a copper salt, acety acetone, and ethylene-diamine with salicylaldehyde, o-hydroxyacetophenone, o-hydroxypropiophenone, and o-hydroxybutyrophenone, respectively. The I.R., optical, and E.S.R. spectra were obtained and discussed with regard to the expected bonding changes and/or those predicted by a model molecular orbital calculation for mixed ligand complexes.     

2,6-二乙酰吡啶类双希夫碱配合物的合成和研究 Ⅱ.Cu(Ⅱ)配合物的合成和研究

合成了五个2,6-二乙酰吡啶缩肼基硫代甲酸酯双希夫碱合铜(Ⅱ)配合物,用元素分析、磁化率、红外光谱及紫外-可见光谱等对它们进行了表征,研究了配合物的电化学性质和Cu₃L₂²X₂(X=Cl^-、SCN^-)的光电子能谱。结果表明:五个Cu(Ⅱ)配合物均为三核配合物,在Cu₃L₂²(SCN)₂中存在Cu(Ⅱ)间的自旋-交换作用。     

STEREOSELECTIVITY OF ELECTRON TRANSFER REACTIONS (II); REACTION OF Λ-[Co(EDDS)]− AND Co(II) COMPLEXES WITH STEREOSPECIFIC DIAMINE LIGANDS

Abstract

Stereoselective electron-transfer between optically active Λ-[Co(EDDS)]^? and [Co(diamine)₃]²⁺ (diamine = racemic-1,2-diaminopropane (pn); R-1,2-diaminopropane (R-pn)) have been investigated in aqueous and in DMSO solutions. In aqueous solution, the reaction between Λ-[Co(EEDS)]^? and [Co(pn)₃]²⁺ produces four conformational isomers of the [Co(pn)₃]³⁺ complex which have the Λ-forms in excess. Their optical purities are increased ob₃>lelob₂> lel₂ob> lel₃ . In contrast, the reaction in DMSO results in more δ isomers than Λ and the sequence of optical purities are in reversed order.

The reaction between Λ-[Co(EDDS)]^? and [Co(R-pn)₃]²⁺ in aqueous solution produces two conformational isomers of [Co(R-pn)₃]³⁺; their absolute configurations are identified as δ-lel₂ob and Λ-ob₃ . In DMSO, in contrast, the reaction produces only one isomer which is identified as δ-lel₂ob.     

STRUCTURES OF PYRIDINE CARBOXYLATE COMPLEXES OF COBALT(II) AND COPPER(II)

Abstract

The syntheses and crystal structures of [Co(nic)₂(H₂O)₄] (1). [Co(iso)₂(H₂O)₄] (2). [Cu(nic)₂(H₂O)₄] (3), and [Cu(iso)₂(H₂O)₄] (4) (nic = nicotinate; iso = isonicotinate) are reported. Complex 1 crystallizes in monoclinic, space group C2/m with cell parameters a =14.150(4). b = 6.883(2)., c = 8.497(2) Å, β= 118.28(2)° and Z = 2. The other crystals. 2. 3. and 4. are all triclinic, Pī; a = 9.777(3), b = 6.348(4), c = 6.888(3)Å, a= 113.10(6)., β= 110.55(3). γ = 97.61(5)°, and Z=l for 2; a = 7.0281(4), b = 7.7176(6), c = 8.6978(7)Å, a = 68.103(7), β = 68.526(5), γ = 62.550(6)°, and Z=1 for 3; a = 9.1807(4), b = 6.3334(3), c = 6.8871(3)Å, a= 108.213(4), β = 99.433(4), γ= 105.190(4)°, and Z= 1 for 4. The arrangements around the metal ions are trans-octahedra with two pyridyl nitrogens and two aqua oxygens in the equatorial positions and two aqua oxygens in the axial positions, although the Cu(II) complexes show a larger Jahn-Teller distortion.     

SYNTHESIS OF MONOSUBSTITUTED PENTAKIS(2,6-DIETHYLPHENYLISO CYANIDE)- COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE LIGANDS. I. MONOMETALLIC COMPLEXES

Abstract

Reaction of [Co(CNC₆H₃Et₂-2,6)5]BF₄ with bidentate phosphines leads to monosubstituted Co(I) complexes, [Co(CNC₆H₃Et₂-2,6)₄(L-L)]BF4, where L-L = Ph₂P(CH₂)n PPh₂, n = 1-4,6; Ph₂PCH₂-CH₂AsPh₂, Ph₂PC₆H₄PPh₂-p, Ph₂PCH[dbnd]CHPPh₂-trans. Reaction conditions are such that disubstitution would be possible, but bidentate bridging to form bimetallic complexes is not favoured. Comparison of v([sbnd]N°C) IR, electronic spectra, and molar conductivities with values for [Co(CNC₆H₃Et₂-2,6)4L]X, where X = ClO₄, BF₄; L = monodentate triarylphosphine; indicates that these new complexes must also be five-coordinate Co(I) complexes, in which the potentially bidentate phosphine ligands are coordinated through only one P atom. Structures are approximately trigonal bipyramidal in solution and the solid state, with the phosphine ligand occupying an axial position.     

REACTIONS OF COPPER (I) THIOLATES WITH HALOAROMATICS

Abstract

Recent studies have shown that replacement of I or Br and not C1 or F in haloaromatic compounds occurred when copper (I) thiolates, CuSR, were used as nucleophiles. Some proto debromination was also observed. Conversely using the free thiolate anion, SR^?, in solution, replacement of F or C1 rather than I or Br in haloaromatic compounds was observed. These general observations have been confirmed in the reactions of the isomeric dibromotetrafluorobenzenes with copper (I) methanethiolate, copper (I) pentafluorothiophenolate, and the methanethiolate anion.     

Cu(II) AND Cu(I) COMPLEXES OF A MACROCYCLIC TETRATHIOETHER-INFLUENCE OF THE ANION ON STRUCTURE

Abstract

The macrocycle S₄-propano [16] (1,3,5,9–13-tetrathiacyclohexadecane) acts as a tetradentate ligand with copper(I) and copper(II) tetrafluoroborate but as two bidentate ligands in the presence of chloride.     

2,6—二乙酰吡啶类双希夫碱配合物的合成和研究 Ⅱ.Cu(Ⅱ)配合物的合成和研究

合成了五个2,6-二乙酰吡啶缩肼基硫代甲酸酯双希夫碱合铜(Ⅱ)配合物,用元素分析、磁化率、红外光谱及紫外-可见光谱等对它们进行了表征,研究了配合物的电化学性质和Cu_3L_2~2X_2(X=Cl~-、SCN~-)的光电子能谱。结果表明:五个Cu(Ⅱ)配合物均为三核配合物,在Cu_3L_2~2(SCN)_2中存在Cu(Ⅱ)间的自旋—交换作用。     

ESCA OF TETRAAZA MACROCYCLIC COMPLEXES OF SILVER(II)

Abstract

ESCA results for four tetraaza macrocyclic ligands and their silver(II) complexes have been measured. The Ag 3d binding energies of these complexes fall in the narrow range of 374.3–375.3 eV (3d_3/2) and 368.2–375.3 eV (3d_3/2) and 368.2–369.3 eV (3d_5/2) which are in agreement with the E_b values published previously for silver(II) complexes containing nitrogen donor ligands. Ring substitution with methyl groups has no pronounced influence on the Ag 3d, binding energies while ring size variation does cause a small shift in the binding energies. Ring strain energy is invoked as the probable reason for the observed effect.     

COMPLEXES OF AMINOPHOSPHONATES PART 9.1 COPPER(II) COMPLEXES OF CIT RIC ACID DERIVATIVES

Abstract

Complex formation between copper(II) and 3-amino-3-phosphonoglutaric acid (Apga), an ambidentate aminophosphonate or citric acid derivative, was studied in aqueous solution by pH-potentiometry and EPR and electronic spectroscopy. Complexation with the parent molecules citric acid and tricarballylic acid was reinvestigated. The stoichiometries and stability constants of the complexes formed in these systems were determined at 25°C at an ionic strength of 0.20 mol dm^?3 (KCl). Stability constant data and spectroscopic results revealed that in the acidic pH range Apga behaves as a citric acid derivative, forming the phosphonate-bridged dimeric species Cu₂A₂H₂, while in the basic pH range, with decreasing proton competition at the amino binding site, it rearranges to yield mononuclear complexes involving aminophosphonate-like (NH₂, PO₃ ^2-, CO₂) coordination.     

SYNTHESIS AND CHARACTERIZATION OF ANTI-2-FURAN CARBOXALDOXIME COMPLEXES WITH COBALT(II), COPPER(II & I) AND SILVER(I)

Abstract

The ligand, 2-furan carboxaldoxime exists in two geometrical isomeric forms: anti-(β-form) and syn-(α-form). Six different complexes of Co(II), Cu(II), Cu(I) and Ag(I) with anti-2-furan carboxaldoxime (FDH) have been prepared and characterized by elemental analysis, molecular weights, conductance studies, magnetic moments and infra-red spectral studies. These are [Co(FDH)₄Cl₂], [Co(FD)₂], [Cu(CH₃COO)₂ (FDH)]₂, [Cu(FD)(OH)]₂, Cu(FDH)₂ Cl and AgNO₃·2FDH. Under the similar conditions, syn- form does not form any complex with these metal ions. The complexes [Co(FDH)₄Cl₂] and [Co(FD)₂] are neutral, monomeric and para-magnetic (μ=4.88 and 4.52 BM respectively); the former may be considered as octahedral with FDH acting as monodentate, and the latter as tetrahedral with FD^? as a bidentate ligand. Both the Cu(II) complexes are neutral, dimeric, weakly para-magnetic (μ=0.44 and 0.28 BM respectively) with the bridging acetato groups in [Cu(CH₃ COO)₂ (FDH)]₂ and with bridging hydroxo groups in [Cu(FD)(OH)]₂. The Cu(I) complex may be polymeric, being insoluble in most solvents. The Ag(I) compound is cationic 1:1 electrolyte in nitrobenzene. In all these complexes the ligand functions as monodentate and/or bidentate, coordinating with furan oxygen and oxime oxygen in the latter case. The C[sbnd]O[sbnd]C stretching frequency of furan may be taken as the criterion for the denticity of this ligand which is observed at 1240 cm^?1 (in the free ligand). A shift to lower frequency is observed in the complex if the ligand acts as bidentate. However this frequency is not affected if the ligand acts as monodentate coordinating through the oxime oxygen atom. The ligand has been shown to be present in the ionized and/or unionized form in these complexes.     

PSEUDOTETRAHEDRAL METAL (II) COMPLEXES OF TRIS- (t-BUTYL) PHOSPHINE

Abstract

The synthesis of divalent metal complexes of the type [Bu^t ₃PH] [(Bu^t ₃P)MX₃] (M = Ni; X = Cl, Br, I; M = Co; X = Br; M = Zn; X = Cl) is reported. Characterization of the solids by conductivity, magnetic susceptibility, electronic and vibrational spectral measurements indicate that the structures are similar and unchanged in solution from the solid state. On the basis of an earlier X-ray single crystal analysis of [Bu^t ₃PH] [(Bu^t ₃P)NiBr₃] and a comparison of the physical measurements for the series of complexes, the inner coordination geometry of the anions can be represented as pseudotetrahedral with C_3v local symmetry. The unexpected formation of these ionic complexes is attributed to the bulkiness of tris-(t-butyl) phosphine. The isolation and probable geometry of the anion are also discussed for an orange-brown [Bu^t ₃PH] [Ni(NCS)₃] complex.     

PLATINUM(II) COMPLEXES OF P(III) CYCLOPHOSPHAMIDE DERIVATIVES

Abstract

The syntheses of the P(III) analogues of cyclophosphamide, isophosphamide and triphosphamide are reported. These compounds (4–6, respectively) polymerize easily at room temperature but are sufficiently stable in solution to react with Cl₂Pt(NCPh)₂, forming cis-Cl₂Pt(4)₂, cis-Cl₂Pt(5)₂ and cis-Cl₂Pt(6)₂ (complexes 9–11, respectively). Complex 10 can also be made by condensing cis-Cl₂Pt[ClPN(CH₂CH₂Cl)CH₂CH₂CHO]₂ with ClCH₂CH₂NH₂, while an alternate route to 9 and 11 is afforded by the condensation of cis-Cl₂Pt[Cl₂PN(CH₂CH₂Cl)₂]₂ with H₂NCH₂CH₂CH₂OH and ClCH₂CH₂NHCH₂CH₂CH₂OH, respectively. Complexes 9–11 exist in two diastereomeric configurations and these can be separated in the cases of 9 and 11 by column chromatography. ³¹P NMR spectral data for the complexes are discussed and the results of NCl antitumor screening are presented.