Studies on the intermolecular interactions of metal chelate complexesVIII: On the interactions of dithiocarbamato-copper(II) and -copper(I) complexes with haloalkanes

The interaction of Cu(II)(dtc)₂ and Cu(I)(dtc) complexes with haloalkanes were studied by the EPR method. It was found that the Cu(II)(dtc)₂ complex reacted with haloalkanes only in the presence of weak Lewis bases which formed adducts with it. The intermediate reaction product is the mixed-ligand complex Cu(II)(dtc)X_n (X = Cl, Br, n = 1 or 2); the final products being CuX₂B_n (B = Lewis bases, n = 1 or 2) and unstable resin-like residue. Cu(I)(dtc) reacted with haloalkanes without any promoters giving the mixed-ligand complex Cu(II)(dtc)X_n as product. Free radicals were detected in the reaction of Cu(I)(dtc) using the method of “radical scavenger” and were not found in the reaction of Cu(II)(dtc)₂. The reported results confirmed one of the two reaction mechanisms proposed in the previous studies. The role of the solvent on the EPR parameters of the mixed-ligand Cu(II)(dtc)X complex is also discussed.     

Studies on the intermolecular interactions of metal chelate complexesIX: On the interaction of copper(II) dithiocarbamate with some lewis acids

The intermediate products of the reaction between copper(II) dithiocarbamate complex and some Lewis acids (HgI₂, HgBr₂, GeCl₄, AsBr₃, CoCl₂, C(NO₂)₄) as well as some organometallic compounds (SnEt₄ and PbEt₄) were studied using EPR spectroscopy. In non-polar and non-coordinating solvents HgI₂, HgBr₂ and GeCl₄ formed adducts with Cu(dtc)₂, whereas in polar and coordinating solvents the mixed-ligand complexes of the type Cu(dtc)⁺…A^?(A = HgX₃) were obtained with a complex counterion in the second coordination sphere of copper(II). With C(NO₂)₄ the intermediate reaction product in non-polar solvents was assumed to be Cu(dtc)·NO₂ which dissociates to Cu(dtc)⁺…NO₂^? in polar solvents. Similar EPR spectra were obtained with SnEt₄ and PbEt₄. The reaction of Cu(dtc)₂ with CoCl₂, AsBr₃ and SbCl₃ yielded the mixed-ligand complexes of the type Cu(dtc)X_n (n = 1 or 2) exhibiting well resolved superhyperfine splitting from one or two halogen nuclei. The influence of the medium on the above interaction is also discussed.     

Collision-Induced Decomposition (CID) of Triangular [Mo3S7-xSex]4+ Complexes (x = 0,3,7). A liquid SIMS and FTMS/MS study of [Mo3S7-xSex(Et2NCS2)3] +

[Mo₃S(S₂)₃(dtc)₃]I, [Mo₃S(SeS)₃(dtc)₃](dtc), and [Mo₃Se(Se₂)₃(dtc)₃](dtc) (dtc = N,N-diethyldithiocarbamate) were investigated by liquid SIMS-FTMS. The fragmentation pathways were essentially the same for the three compounds and can be explained by two types of fragmentation processes: stepwise abstraction of S/Se atoms as exemplified by the series [Mo₃X_z(dtc)₃]⁺ (4 ? z ? 7, X = S, Se), and ligand dissociation, as indicated by the generation of [Mo₃X_z(dtc)₂]⁺ (5 ? z ? 7, X = S, Se). The exclusive elimination of the Se-atoms from [Mo₃S(S_ax-Se_eq)₃(dtc)₃]⁺ confirmed the inequivalent reactivity of the bridging atoms in axial and equatorial position as observed in previous studies. Collision-induced decomposition (CID) of [Mo₃S₇(dtc)₃]⁺ ( 1 ), [Mo₃S₆(dtc)₃]⁺ ( 2 ), [Mo₃S(S_ax–Se_eq)₃(dtc)₃]⁺ ( 3 ), and [Mo₃Se₇(dtc)₃]⁺ ( 4 ) revealed distinctly different fragmentation reactions for the SIMS and CID mode. CID of 1, 3 , and 4 resulted in a two-step reaction with the exclusive elimination of diatomic molecules XY (X,Y = S/Se). In the case of 3 , the selective elimination of Se₂ indicated the abstraction of two Se-atoms located in equatorial positions of two different bridging groups. This result is discussed in terms of mechanisms, based on labile M? X_eq and inert M? X_ax bonds with an intramolecular formation of a X₄ fragment prior to the elimination of X₂.     

13C and 14N ENDOR study on Copper(II)/Nickel(II) bis-(diethyl-dithiocarbamate) Cu/Ni(et2dtc)2

The ¹³C and ¹⁴N ENDOR spectra of Cu(et₂dtc)₂ substituted into single crystals of Ni(et₂dtc)₂ are reported. The centrosymmetric, planar structure of the host molecule has been retained by the guest. Comparison between the ¹³C ENDOR data obtained for Cu/Ni(et₂dtc)₂ and Cu/Zn(et₂dtc)₂ has been made considering the different structures of the et₂dtc complexes of Cu, Ni and Zn.     

The effect of chloroalkane/alcohol solvent composition on the photochemical properties of copper(II) dithiocarbamate mixed-ligand complexes. EPR study

The EPR technics has been used to study the effect of solvent composition on the photochemical conversion of Cu(II) dithiocarbamate mixed-ligand complexes Cu(Et₂dtc)X (X=Cl⁻, Br⁻) and Cu(Et₂dtc)⁺…Y⁻ (Y⁻=ClO₄⁻, NO₃⁻) in chloroalkane/alcohol solutions, where chloroalkane=CCl₄, CHCl₃ or CH₂Cl₂ and alcohol=MeOH, EtOH, i-PrOH or i-BuOH. The obtained results allow to get some insight into the behaviour of the mixed-ligand complexes towards the halogen donation power of chloroalkanes and the co-ordination abilities of alcohols. The paper deals with the nature of the complexes obtained as intermediate products of photolysis.     

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.     

Complexes of nickel and copper with aromatic dithiocarbamates

Summary Phenylglycine and phenylalanine react with CS₂ in a basic medium to yield the corresponding dithiocarbamates, which react with Ni²⁺ and Cu²⁺ salts to form complexes of the general formula [Ni(dtc aa)₂] and [Cu(dtc aa)], respectively (aa = amino acid). Both series of complexes are diamagnetic and were characterized by analytical and physico-chemical techniques. It is concluded that the nickel compounds are square planar, while for the copper complexes reduction to the Cu⁺ state has taken place during synthesis.     

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.     

REACTIONS OF CuX (X = SCN AND CN) WITH 2-BENZOYLPYRIDINE. SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [9-OXO-INDOLO[1,2-a] PYRIDINIUM] DITHIOCYANATOCUPRATE(I) AND POLYMERIC μ-CYANO(2-BENZOYLPYRIDINE) COPPER(I)

Abstract

When a mixture of excess CuSCN and 2-benzoylpyridine (2-Bzpy) stands in an ethanolic medium for about ten days in contact with air, the intramolecular oxidative cyclization of 2-Bzpy occurs with formation of the ionic compound [9-oxo-indolo[1,2-a]pyridinium]⁺ [Cu(SCN)₂]^? (1). In contrast, interaction of CuCN and 2-Bzpy in ethanol leads to formation of the polymer [Cu(CN)(2-Bzpy)]_n (2). The reaction of Cu(II) and 2-Bzpy in presence of excess SCN^? in ethanol affords (1) and the green monomer [Cu(SCN)₂(2-Bzpy)₂] (4). These complexes, along with the 1:1 CuSCN complex of 2-Bzpy (3) are studied by IR, Raman and electronic spectroscopic methods and X-ray structural analysis of (1) and (2). Crystals of (1) are monoclinic, space group P2₁/n (No. 14), with a = 5.887(1), b = 36.142(7), c = 7.083(1) Å, B = 109.56(1)°, Z = 4, and R_F = 0.033 for 2487 observed MoKα data, (2) monoclinic, space group P2₁/c (No. 14), a = 14.393(3), b = 8.881(2), c = 9.287(2) Å, B = 103.80(3)°, Z = 4, and R_F = 0.036 for 2030 observed MoKα data. The structure of (1) consists of a packing of [9-oxo-indolo [1,2-a]pyridinium]⁺ cations and [Cu(SCN)₂]^? anions. Puckered layers are formed by the [Cu(SCN)₂]^? component with four-coordinate Cu(I) and one tridentate μ(N,S,S)-thiocyanato ligand. Complex (2) features distorted tetrahedral Cu(I) geometry, formed by a bidentate chelating 2-Bzpy and linear C- and N-bonded bidentate cyano groups, which link adjacent copper centers to form zigzag chains extending along the c axis. Complexes (1) and (2) do not fluoresce at room temperature.     

Studies on the interactions of copper(II) chelate complexes with SO2

The reaction of bis (acetylacetonato) copper(II) with SO₂ yields CuSo₄ as a final product. Using e.p.r. technique mixed-ligand complexes of the type Cu(acac) (acacSO₂) have been detected at 100 K. The e.p.r. spectrum of the latter complex disappeared under passing argon through the sample. Lewis bases accelerated the reaction. No interaction of SO₂ with other complexes containing CuO₂N₂, CuN₂S₂, CuS₄ chromophores has been detected. In a common solution of Cu(acac)₂ and Cu(dtc)₂ the reaction proceeded only with Cu(acac)₂ though a mixed-ligand complex Cu(acac) (dtc) was formed. The addition of bases accelerated the reaction, all spectra disappeared and only Cu^I(dtc) has been found as a final product.     

Gemischtligandkomplexbildung durch Thermische Reaktion von Metall(II) - Thioselenocarbamaten EPR- und massenspektrometrische Untersuchungen

Mixed Ligand Complex Formation by Thermal Reactions of Metal(II) Thioselenocarbamate Chelates. EPR and Mass Spectrometric Investigations At higher temperatures metal(II) thioselenocarbamates M(R₂tsc)₂ (M = Cu, Ni, Pd, Pt) react to form M(R₂tsc)(R₂dsc) and M(R₂tsc)(R₂dtc) (dtc = dithiocarbamate, dsc = diselenocarbamate) mixed-ligand chelates. If Cu^II species are participated the mixed-ligand complex formation can be the followed by EPR spectroscopy. The reaction is irreversible, and the rate depends on the temperature, the substituent R, and the solvent used. The complexes M(Et₂tsc)(Et₂dsc) and M(Et₂tsc)(Et₂dtc) formed during the thermal reaction of M(Et₂tsc)₂ chelates (M = Ni, Pd, Pt) can be detected by EPR spectroscopy using the ligand-exchange reaction with [Cu(mnt)₂]^2?(mnt = maleonitriledithiolate). As results the spectra of [Cu(mnt)(Et₂tsc)]^?, [Cu(mnt)(Et₂dsc)]^? and [Cu(mnt)(Et₂dtc)]^? are observed.     

Metal derivatives of thiosemicarbazones: crystal structure of [chloro bis(triphenylphosphino) (thiophene-2-carbaldehyde thiosemicarbazone) copper(I)] complex

Reactions of copper(I) halides (X = Cl, Br, I) with thiophene-2-carbaldehyde thiosemicarbazone and triphenylphosphine in 1 : 1 : 2 molar ratio yield tetrahedral mononuclear complexes, [CuX(η¹-S-Httsc)(Ph₃P)₂] (X = Cl, 1; Br, 2; I, 3), characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P), and single crystal X-ray crystallography (1). The unit cell of 1 has two independent distorted tetrahedral molecules (1a and 1b) with different bond parameters. One acetonitrile is entrapped between them. Crystal data: C₈₆H₇₇Cl₂Cu₂N₇P₄S₄ 1: triclinic, P-1, a = 12.8810(9), b = 18.5049(13), c = 18.7430(13) Å, α = 63.7130(10), β = 89.0960(10), γ = 85.5010(10)°, V = 3992.4(5) ų, Z = 2, R _(int) = 0.0314. Bond parameters: 1a, Cu(1A)–Cl(1A), 2.3803(5); Cu(1A)–S(1A), 2.3822(5); Cu(1A)–P(1A), 2.2498(5) Å; P(1A)–Cu(1A)–P(2A), 124.294(19)°; 1b, Cu(1B)–Cl(1B), 2.3975(5); Cu(1B)–S(1B), 2.3756(5); Cu(1B)–P(1B), 2.2777(5) Å; P(1B)–Cu(1B)–P(2B), 127.156(19)°.     

Iron(II) carbonyl complexes containing xanthate,dithiocarbamate or dithiophosphate ligands

Summary Starting from Fe(CO)₄I₂, octahedral Fe^II carbonyl derivatives of the types Fe(CO)₂(xan)₂, Fe(CO)₃(xan)I and Fe(CO)₃(dtc)I were prepared (xan = xanthate, dtc = dithiocarbamate). Infrared evidence was obtained for the formation of Fe(CO)₂(dtp)₂ complexes (dtp = dithiophosphate). The dixanthate complexes are also formed from Fe^II salts and potassium xanthates by CO absorption in MeOH/H₂O solution.     

The crystal structure,equilibrium and spectroscopic studies of bis(dialkyldithiocarbamate) copper(II) complexes [Cu2(R2dtc)4] (dtc=dithiocarbamate)

Four copper(II) complexes of bis(dialkyldithiocarbamate) [Cd(R₂dtc)₂] (R=Me, Et, Pr, i-Pr; dtc=dithiocarbamate) have been prepared and characterized by elemental analysis, IR and ESR spectra studies. Their equilibrium constants (K), determined by a UV–vis spectrometry in EtOH, were influenced by the alkyl groups in the following order: i-Pr>n-Pr≈Et>Me. The single crystal structures of complex [Cu₂(R₂dtc)₄] have been determined using X-ray diffraction methods. The compounds [Cu₂(Et₂dtc)₄] and [Cu₂(Pr₂dtc)₄] are built of centrosymmetric neutral dimeric [Cu₂(R₂dtc)₄] entities. The copper atom lies in a distorted square–pyramidal environment. The four equatorial donors are two bidentate chelate sulfur atoms from two dtc ligands. One of the sulfur atoms from the third dtc ligand acts as a bridging ligand occupying the apical position of the symmetry-related copper atom in the dimer structure, which is viewed as two edge-sharing distorted square–pyramids. The structure of [Cu₂(i-Pr₂dtc)₄] is square planar with an exactly planar CuS₄ unit and nearly planar NCS₂ moieties. The Cu–S distances shows small decreases along the series n-Pr>Et>i-Pr, the biggest change being for the diisopropyl complex. The alkyl substituents at the nitrogen atom affect their coordination number and Cu⋯Cu distance. In the solid, [Cu₂(n-Pr₂dtc)₄] has the shortest Cu⋯Cu distance and [Cu(i-Pr₂dtc)₂] has the longest one.     

Synthesis of cationic gold(III) complexes using iodine(III)

Abstract

We report the synthesis and characterization of cationic Au(III) complexes supported by nitrogen-based ligands. The syntheses are achieved by reacting Au(I) complexes [Au(N-Me-imidazole)₂]⁺ and [Au(pyridine)(NHC)]⁺ with iodine(III) reagents PhI(OTf)(OAc) and [PhI(pyridine)₂]²⁺ yielding a series of cationic gold(III) complexes. In contrast, reactions of phosphine ligated gold(I) complexes with iodine(III) reagents results in the oxidation of the phosphine ligand.     

A 13C endor study on Copper(II)/Zinc(II) bis-(diethyl-dithiocarbamate) Cu/Zn(et2dtc)2

¹³C ENDOR spectra of Cu(et₂dtc)₂ substituted into a single crystals of Zn(et₂dtc)₂ are reported. The symmetry of the incorporated guest molecule appears to be considerably influenced by the Zn(et₂dtc)₂ host lattice. The unexpectedly large isotropic ¹³C hfs coupling can be understood assuming a “transannular overlap” mechanism.     

Copper(I) complexes of neutral,deprotonated and protonated 4,6-dimethylpyrimidine-2 (1H)-thione

Summary The following copper(I) complexes of 4,6-dimethylpyrimidine-2(1H)-thione (HL), its protonated cation (H₂L⁺) and deprotonated anion (L^–) have been prepared: CuL, Cu(HL)X (X = Cl, Br or I), Cu(HL)₂X (X = C1 or Br), Cu₂(HL)₃Br₂, Cu(H₂L)X₂ (X = Cl or Br), Cu₃(HL)₂LA₂ (A = ClO₄ or BF₄ ). The i.r. spectra show that in all the HL and L^– complexes and in the Cu(H₂L)Br₂ complex, the ligands are S, N coordinated to the metal ion, while in Cu(H₂L)Cl₂ only the thiocarbonylic sulphur is coordinated, probably bridging two copper(I) atoms. Thev(CuN) (288–317 cm^–1 ) andv(CuS) (191–225 cm^–1 ) have uniform frequency values in all the complexes. The halide ions are, in all their complexes, wholly or in part coordinated giving twov(CuX) bands which may indicate an asymmetrical Cu-X Cu halide bridging bond.Author to whom all correspondence should be directed.     

Effect of solvent and remote ligand substituents on the photochemical behaviour of copper(II) dithiocarbamates and dithiophosphates

The photochemical properties of bis(dithiocarbamato)Cu^II, Cu(R¹dtc)₂, and bis(dithiophosphato)Cu^II, Cu(R₂ ²dtp)₂, complexes with different remote ligand substituents (R¹ = piperidine, morpholine, pyrrolidine and 4-phenylpiperazine; R² = Me, Et and i-Pr) have been studied in chloromethanes (CCl₄, CHCl₃, CH₂Cl₂), chloromethanes/EtOH and PhMe. The monomeric species Cu^II(R¹dtc)Cl and its chloride-bridged dimeric form Cu₂(R¹dtc)₂Cl₂ were subsequently obtained during Cu(R¹dtc)₂ photolysis in chloromethane/EtOH mixtures and the steady-state concentration of Cu₂(R¹dtc)₂Cl₂ was found to depend on the EtOH content in the mixed solvents as well as on the nature of R¹ and the oxidising ability of the chloromethane. The appearance of the mixed-ligand complex Cu^II(R₂ ²dtp)Cl has been observed as an intermediate photoproduct after longer u.v.-irradiation of Cu(R₂ ²dtp)₂ in chloromethanes/EtOH.     

Stabilities and Redox Properties of Cu(I) and Cu(II) Complexes with Macrocyclic Ligands Containing the N2S2 donor Set

The complexation of Cu(I) and Cu(II) by a series of 12-, 14- and 16-membered macrocyclic ligands 1–6 containing the N₂S₂ donor set has been studied potentiometrically, spectrophotometrically and voltammetrically. In the case of Cu(II), mononuclear complexes CuL²⁺ with stability constants of 10¹⁰–10¹⁵ are formed. In addition, partially hydrolyzed species Cu(L)OH⁺ are observed at pH > 10 for the 12-membered ligands. For Cu(I), beside the specis CuL⁺ with stabilities of 10¹²–10¹⁴, the unexpected formation of protonated species CuLH²⁺ was detected. In contrast to the well-known general trends in coordination chemistry, the stability of these protonated species increases relative to that of the complexes with the neutral ligand when the ring size and concomitantly the distance between neighbouring donor atoms is decreased. From the stability constants of the Cu(I)- and Cu(II)-complexes the redox potentials have been calculated and are compared to the values of E^1/2 obtained by cyclic voltammetry. Despite the identical donor set the Cu(II)/Cu(I) redox potentials of the complexes are spanning a range of 340 mV or six orders of magnitude in relative stability, reflecting the importance of subtle differences in steric requirements.     

Solvent Effect on the Ligand Exchange between Bis(diethyldithiocarbamato)copper(II) and Bis(diethyldiselenocarbamato)copper(II)

EPR and spectrophotometric study on the products of ligand‐exchange taking place on mixing bis(diethyldiselenocarbamato)copper(II), [Cu(Et₂dsc)₂], and bis(diethyldithiocarbamato)copper(II), [Cu(Et₂dtc)₂], solutions is reported. EPR spectra monitored at room temperature for one month period reveal a stable equilibrium among the parents (chromophores CuS₄ and CuSe₄) and the obtained mixed‐chelate [Cu(Et₂dtc)(Et₂dsc)] complex (chromophore CuS₂Se₂) in heptane, hexane, benzene, toluene, acetone, DMFA, DMSO and dichloromethane. In CCl₄ and CHCl₃ two new additional EPR spectra appear attributed to the mixed‐chelate complexes with the chromophores CuSSe₃ and CuS₃Se which are not observed with electronic spectroscopy. The intensities of all five EPR spectra decrease with the time. It is assumed that the new mixed‐chelates observed in CCl₄ and CHCl₃ are obtained in a reaction of [Cu(Et₂dtc)(Et₂dsc)] or [Cu(Et₂dtc)₂] with the ester of diselenocarbamic acid which is formed in a parallel reaction of [Cu(dsc)₂]with CCl₄ or CHCl₃.