Halogen-bridged Complexes Research Articles

Synthesis of halogen-bridged complexes [Pt(R 2SO)(μ-X)X] 2 by thermolysis of cis-[Pt(R 2SO)(R′CN)X 2]. X-ray structure of di-μ-chloro-dichlorobis(diethyl sulfoxide) diplatinum(II)

The reactions of K[Pt(R 2SO)X 3] with R′CN in water, substitution of acetonitrile in cis-[Pt(MeCN) 2Cl 2] for sulfoxides and the bridge-cleavage reactions of [Pt(R 2SO)(μ-Cl)Cl] 2 with R′CN lead to isolation of cis-[Pt(R 2SO)(R′CN)X 2] (R=Me, R′=Me, X=Cl, Br; R=Et, Ph, R′=Me, X=Cl; R=Me, R′ =CH 2Ph, CH 2CO 2Et, Ph, X=Cl). The reaction of [Pd(MeCN) 2Cl 2] with Me 2SO in acetone followed by removal of the solvent results in isolation of the solid [Pd(Me 2SO)(μ-Cl)Cl] 2. Ligands R′CN in cis-[Pt(R 2SO)(R′CN)X 2] rapidly abstracted on heating in the solid phase or in solution producing halogen-bridged compounds [Pt(R 2SO)(μ-X)X] 2. The structure of the complex [Pt(Et 2SO)(μ-Cl)Cl] 2 was determined by X-ray analysis. The compound crystallizes in the P2 1/ b space group. The unit cell dimensions are a = 5.925(1), b = 11.175(2), c = 14.195(3) Å, γ = 98.79°, V = 928.8(3) Å 3, Z = 2. A comparison of PtCl bond lengths in the molecule [Pt(Et 2SO)(μ — Cl)Cl] 2 suggests that the trans- influence of diethyl sulfoxide is higher than that of the chloride ion.

Solid-state 13C high-resolution NMR in one-dimensional halogen-bridged nickel complexes and palladium(II)—palladium(IV) mixed-valence complexes

Solid-state high-resolution 13C NMR (CP/MAS) spectra were measured on one-dimensional halogen-bridged complexes [Ni(R,R-chxn) 2X]X 2 (X = Cl, Br; R,R-chxn = 1R,2R-cyclohexanediamine) to elucidate the metal valence state. The spectra observed were compared with those of Pd(II)–Pd(IV) mixed-valence complexes: [Pd(R,R-chxn) 2] [PdX 2(R,R-chxn) 2]Y 4 (X = Cl, Br; Y = ClO 4, Cl) and [Pd(en) 2] [PdX 2(en) 2] (ClO 4) 4 (X = Cl, Br; en = ethylenediamine) together with a monomer 'Pd(II) complex [Pd(R,R-chxn) 2]Cl 2. The one-dimensional Pd complexes showed a clear 1:1 doublet 13C signal for en ligands and also for the α-carbons in chxn ligands indicating the presence of two kinds of Pd valence states: Pd(II) and Pd(IV). On the other hand, a sharp singlet line was observed for the α-carbons in the Ni complexes and the Pd monomer complex. These results mean that all Ni atoms in the chain are equivalent and the paramagnetic Ni(III) state is formed. Small chemical shifts observed in the Ni complexes comparable to those in the diamagnetic Pd complexes imply the presence of strong antiferromagnetic interactions between neighboring Ni(III) sites in the chain.

Magnetization anomalies in one-dimensional halogen-bridged paltinum complex: Field-induced diamagnetic transition and antiferromagnetism

We present dc magnetization measurements on one-dimensional iodine-bridged platinum complex which demonstrates a magnetic-field-induced diamagnetic transition and an antiferromagnetic ordering. This is the first evidence for a field-induced transition in a one-dimensional insulator. The crystals were synthesized from a solution of [Pt(en)2]1-k[Pt(en)2I2]1+k(CIO4)2 (0≤k≤1). Depending on temperature, field intensity and sample quality, a paramagnetism, antiferromagnetism and diamagnetic-paramagnetic transition were observed. The diamagnetic signals as large as 0.5–16.5 % of that for perfect diamagnetism (Meissner effect) were observed over a wide temperature range. Sharp field-induced transition from diamagnetism to paramagnetism occurred around 180 K. The crystallization from a molar imbalance solution leads to disordered platinum configuration (e.g. PtII-I-PtIII-I-PtIII-I-PtIII). The magnetization anomalies may be attributed to such a disorder.

Optical absorption of linear-chain gold complexes under pressure: AuX2 dibenzylsulfide (X2=Cl2,Br2,ClBr).

The effect of pressure on the polarized optical absorption spectra of the quasi-one-dimensional (1D) halogen-bridged mixed-valence gold complexes ${\mathrm{AuCl}}_{2}$(DBS), ${\mathrm{AuBr}}_{2}$(DBS), and AuClBr(DBS) (with DBS denoting dibenzylsulfide) has been studied up to 6 GPa. The visible absorption edges for light polarized parallel to the chain direction, corresponding to intrachain charge-transfer transitions, exhibit exceptionally large initial red shifts ranging from -0.21 to -0.29 eV/GPa, which is interpreted as a characteristic feature of quasi-1D charge-density-wave systems. The pressure dependence of the visible absorption edges for polarization perpendicular to the chain direction supports an interpretation in terms of interchain charge-transfer transitions. The results for Au complexes are compared with those for the related 1D platinum complexes.

Resonance raman spectra of metal II/IV dimer chain complexes of platinum and palladium: Analysis of the component structure to the band assigned to the symmetric XMX chain stretching mode (X = Cl or Br)

Resonance Raman spectra of the linear-chain, mixed-valence, halogen-bridged complexes [Pt(pn) 2] [Pt(pn) 2X 2] (ClO 4) 4, where X = Cl or Br, and [Pd(pn) 2] [Pd(pn) 2Br 2] (ClO 4) 4 have been obtained over the range of excitation wavelengths 457.9 to 647.1 nm. Of particular interest is the symmetric metal—halogen stretch, ν 1, which has several components. The relative intensities of these components change with variation of the wavenumber of excitation within the intervalence electronic absorption. This effect and the origin of the different components are discussed.

Neutral chain bromide- and iodide-bridged platinum(II,IV) complexes of 1,2-diaminoethane and thiocyanate: synthesis, electronic, infrared, Raman, and resonance-Raman studies

The complexes Pt(en)(SCN)2X, en = 1,2-diaminoethane, X = Br or I, have been synthesised and, on the basis of a study of their electronic, i.r., and resonance-Raman spectra, established to be linear-chain, halogen-bridged complexes, [Pt(en)(SCN)2][Pt(en)(SCN)2X2]. The electronic spectra are characterised by broad, intense bands (maxima at ca. 17 800 cm–1 for X = Br and at < 13 000 cm–1 for X = I). The i.r. spectra are near superpositions of those of the constituent complexes, the band shifts on complex formation being greater for the iodide-bridged complex. The resonance-Raman spectra are dominated by long overtone progressions in ν1, the Raman-active, symmetric (X–PtIV–X) stretch, reaching 7ν1 for X = Br or I. Subsidiary progressions v1ν1+νn are observed for X = Br, where νn is identified as ν(Pt–S)eq. The form of the resonance-Raman spectra, ν1 excitation profiles, and ν1 wavenumber dependence on the wavenumber of the exciting line, ν0, are discussed in terms of unresolved components of ν1 and of their relative intensity dependence on temperature and ν0.

A route for the synthesis of novel asymmetric binuclear pentafluorophenyl derivatives of palladium(II)

Binuclear halogen-bridged complexes of the type (C 5F 5) 2Pd(μ-Cl) 2ML 2 (M  Ni, Pd (L 2  dpe), Pt (L  PEt 3)] have been prepared by reaction of cis-Pd(C 6F 5) 2(PhCN) 2 with the corresponding halo complexes, MCl 2L 2, in dichloromethane, IR and NMR structural data are discussed.

Excitation line dependence of the symmetric chain-stretching mode of linear-chain, mixed-valence palladium complexes

The wavenumber, nu 1, of the symmetric chain-stretching mode of linear-chain, halogen-bridged mixed-valence palladium complexes of the type (Pd(LL)2)(Pd(LL)2X2)(ClO4)4, where LL=1,2-diaminoethane (en), 1,2-diaminopropane (pn) or 1,3-diaminopropane (tn) for X=Cl, and LL=en for X=Br, increases as the wavenumber of the excitation line ( nu 0) increases. For all four complexes studied nu 1 consists of several components whose relative intensities change with a change in nu 0. Possible explanations for the dependence of the components of nu 1 on nu 0 are considered.

Vibrational studies of, and model for, halogen-bridged linear-chain mixed-valence complexes

A number of complexes of the type [M II (LL) 2 ] [Pt IV (LL) 2 Cl 2 ] [ClO 4 ] 4 , where M = Ni, Pd or Pt and LL = 1,2-diaminoethane (en) or 1,2-diaminopropane (pn), as well as the monomers [Pt IV (LL) 2 Cl 2 ] Cl 2 and [M II (LL) 2 ] Cl 2 have been studied using Fourier transform infrared (f.t.i.r.) and resonance Raman spectroscopy. Under conditions of low tem perature and moderate resolution ( ca . 0.5 cm -1 ) it has proved possible to observe chlorine isotopic splitting in bands due to both the symmetric and the antisymmetric stretching modes of the linear Pt IV Cl 2 units in the chains. On the basis that the one-dimensional electronic properties of these chains are likely to be related to the in-chain Pt IV -Cl stretching force constants, a simple vibrational model is presented, which is able to reproduce the observed splitting patterns to well within experimental error. A comparative study of the Pt IV -Cl stretching force constants for the series of en complexes shows the trend: trans -[Pt IV (en) 2 Cl 2 ] Cl 2 (monomer) &gt; Pd II - Pt IV &gt; Ni II - Pt IV &gt; Pt II −Pt lV . This trend is in line with that of the M II …Pt IV intervalence band maxima, namely Pd II - Pt IV (25000 cm -1 ) &gt; Ni II - Pt IV (22200 cm -1 ) &gt; Pt II - Pt IV (20800 cm -1 ), indicating an increase in M II … Cl chain interaction (and an expected increase in conductance) along the series.

Übergangsmetall—carbin-komplexe

Abstract Irradiation of hexacarbonyl chromium in dichloromethane at low temperature yields an intensely yellow solution, in which the presence of “Cr(CO) 5 (CH 2 Cl 2 )” is supposed. After addition of carbyne complexes of chromium or tungsten to these solutions the new halogen-bridged dinuclear carbyne complexes (I–V) can be isolated. They are readily cleaved, even by weak donors, to form the corresponding carbyne complex and the pentacarbonyl derivative of the donor.

The application of resonance raman spectroscopy to the study of the vibrational and electronic properties of inorganic species

The application of resonance Raman spectroscopy to the study of the vibrational and electronic properties of molecular inorganic species, metal-metal bonded complexes, oxygen- nitrogen- and dinitrogen bridged complexes, and to linearchain halogen-bridged complexes is described, and shown to yield valuable and, in many cases, unique molecular information.

Halogen-bridged complexes of platinum(II) and their reactions with dimethylformamide

Bridged compounds, [Pt(L)Cl2]2 (L = pyridine, picoline, and lutidine) have been prepared from the reactions between K[Pt(L)Cl3] and perchloric acid. The molecular weight measurements indicate that they are dimers in chloroform solutions. When [Pt(L)Cl2]2 is dissolved in dimethylformamide (DMF), [Pt(L)(DMF)Cl2] is formed and has been isolated. Infrared and nmr studies have shown that DMF is coordinated to platinum through the oxygen atom.

Halogen-bridged complexes of platinum with alkylsulphoxides

Halogen-bridged complexes of platinum with alkylsulphoxides

Metal-halogen and metal-nitrogen stretching modes in the far-infrared spectra of octahedral halogen-bridged complexes MX2(pyridine)2 and related systems. A clarification of confused literature

Metal-halogen and metal-nitrogen stretching modes in the far-infrared spectra of octahedral halogen-bridged complexes MX2(pyridine)2 and related systems. A clarification of confused literature

Disproportionation of a halogen-bridged complex containing platinum and palladium

31 P N.m.r. spectroscopy shows that complexes of the type [PdPtCl4LaLb][Laand Lb are either the same or different tertiary-phosphide ligands (PPr3 or Pbu3)] are formed in chloroform solution when equimolar amounts of [Pd2Cl4(La)2] and [Pt2Cl4(Lb)2] are mixed at room temperature. All three complexes are in dynamic equilibrium, and a kinetic study indicates that the exchange occurs via a tetrameric intermediate involving four metal centres. Attempts to isolate the mixed metal complexes have proved unsuccessful. The first measurement of platinum–platinum coupling constants is reported for the complexes [Pt2Cl4(PBu3)2] and [Pt2I4(Pbu3)2].

Far-infrared and Raman studies of mono complexes of 2,2′-bipyridine and 1,10-phenanthroline

Far-i.r. and low-frequency Raman spectra of the mono complexes M(bipy) X 2 and M(phen) X 2, where X = Cl for M = Ni, Cu, Zn and X = Cl and Br for M = Mn are reported. Metal-isotope-substitution studies of the Ni, Cu and Zn complexes have enabled the MCl, MN, and several of the activated-ligand frequencies to be identified. The MN stretching frequenciesoccur at ca. 240–290 cm −1 in the chloride complexes. The chlorine bridging frequencies of the octahedral halogen-bridged complexes occur at ca. 170–200 cm −1.

Synthesis of some 1,5-cyclooctadieneruthenium(II) complexes

The polymeric, halogen-bridged complex [(diene)RuX 2] n (where diene = 1,5-cyclooctadiene) reacts with acetylacetone, benzoylacetone, salicylaldehyde, 2-mercaptopyridine, 8-hydroxyquinoline and 2-mercaptobenzthiazole in hot dimethylformamide in the presence of sodium carbonate, to give chelate complexes [(diene)ruthenium(chel) 2]. Two geometrical isomers of 1,5-cyclooctadiene bis(benzoylacetonato)ruthenium(II) have been characterised. Diene bis(dimethyldithiocarbamato)ruthenium(II) complexes [diene = 1,5-COD or bicyclo[2.2.1]hepta-2,5-diene] are also described.

Binuclear halogen-bridged complexes of palladium(II) with thiourea: Pd 2Tu 2X4 and their bridge-splitting reactions

I.R. spectra show that the non-electrolyte complexes Pd 2Tu 2 X 4 ( X = Cl, Br) have a binuclear trans-symmetrical halogen-bridged structure and that palladium(II) is S-bonded to thiourea. By means of bridge-splitting reactions with p-toluidine, pyridine and thiourea (L) and with ethylenediamine (en) the complexes give trans-PdL 2 X 2 and cis-Pden X 2 complexes, respectively. The electronic spectra of the complexes Pd 2Tu 2 X 4 show a d− d band at 21·3–21·5 kK for the chloride and at 20·4–20·8 kK for the bromide, in agreement with the position of the two halide ions in the spectrochemical series.

The far-infrared spectra of dihalogenotetra(pyridine)metal(II) complexes and related six-co-ordinate compounds containing terminal metal-halogen bonds

Far-infrared (450-80 cm −1, in some cases to 20 cm −1) and some Raman spectra have been studied for MX 2(pyridine) 4 [ M = Mn; X = I. M = Co; X = Cl or Br. M = Ni; X = Cl, Br, or I], MX 2(pyridine- d 5) 4 [ M = Co or Ni; X = Cl], MX 2(pyrazole) 4 [ M = Ni; X = Cl, Br, or I. M = Mn; X = Cl or Br], and MX 2(hydrazine) 2 [ M = Mn or Co; X = Cl or Br]. Assignments are reported for ν( MX), ν( MN), and some of the deformation modes. The ν( MX) bands are similar in position to those found in octahedral halogen-bridged complexes of these metals, but are of lower intensity relative to ν( MN), and markedly dependent upon M- X bond length. Careful analysis of the spectra is needed to assign ν( MX) and to distinguish terminal from bridged halogen in this type of environment.

Raman (300-10 cm −1) and further far-infrared (100-20 cm −1) spectra of octahedral halogen-bridged transition metal(II) complexes

Raman spectra of halogen-bridged complexes of Mn(II), Fe(II) and Ni(II) halides with pyrazine and/or pyridine have been obtained for the first time, and previously reported far-i.r. measurements have been extended to 20 cm −1. Assignments are given in terms of the polymeric structures of these compounds.