Metal Chain Compounds Research Articles

Heterometallic Second-Row Transition Metal Chain Compounds in Two Charge States: Syntheses, Properties, and Electronic Structures of [Mo-Mo-Ru](6+/7+) Chains.

Reaction of Mo2(dpa)4 (dpa = 2,2'-dipyridylamido) with (1)/2 equiv of [Ru(CO)3Cl2]2 in molten naphthalene at 250 °C provides facile access to the first all-second-row transition metal heterometallic chain compound, MoMoRu(dpa)4Cl2 (1). The one-electron oxidized compound [MoMoRu(dpa)4Cl2](OTf) (2) is synthesized by reaction of 1 with FeCp2(OTf). X-ray crystallography reveals a contraction of the Mo-Ru bond distance from 2.38 Å in 1 to 2.30 Å in 2, and an elongation of the Mo-Mo bond distance from 2.12 Å in 1 to 2.21 Å in 2. The short Mo-Ru bond distances indicate significant electron delocalization along the Mo-Mo-Ru chain, which is quantified by density functional theory (DFT) calculations. Molecular orbital analyses of both compounds based on DFT results reveal full delocalization of the orbitals of σ and π symmetry for both compounds. Additionally, δ orbital delocalization is observed in 2.

Bonding in the Extended Metal Chain Compound La4Cl5C2

Bonding in the Extended Metal Chain Compound La₄Cl₅C₂

A structural study of a three-membered linear metal chain compound at elevated pressure

Single crystal X-ray diffraction studies of the symmetrical molecular wire compound Co3(dpa)4Cl2·(dcm) have been performed up to a pressure of 3.6 GPa using both synchrotron and conventional sources. It is found that the terminal Co-Cl bond distance initially increases by 0.013(4) Å at 0.32 GPa after which it continuously decreases. Extensive theoretical calculations show that population of a thermally excited state containing increased Co-Cl anti-bonding character is a possibility at 0.32 GPa. The relative occupancy of the disordered dcm solvent molecule changes significantly with pressure and this is explained by the analysis of void spaces and Hirshfeld surfaces at different pressures. At 3.2 GPa, fingerprint plots derived from Hirshfeld surfaces indicate that neighbouring metal chain compounds approach each other such that short H···H interactions appear.

Two‐Dimensional Metallic Chain Compounds Y5M2Te2 (M: Fe, Co, Ni) that Are Related to Gd3MnI3. The Hydride Derivative Y5Ni2Te2D0.4.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Valence-Ordering Structures and Magnetic Behavior of Metallic MMX Chain Compounds

Chains change: Novel valence-ordering structures of the ground states of MMX chain compounds, [Pt2(RCS2)4I]∞ (1: R=nBu, 2: R=Et), are determined by low-temperature crystal-structure analyses to be -Pt2+-Pt3+-I−-Pt3+-Pt2+-I−-. Magnetic susceptibility measurements of 1 (see graph) revealed an abrupt drop in magnitude from a 1D antiferromagnetic spin system to a spin-singlet state accompanying a first-order phase-transition around 210 K. This result is in contrast to the spin degree of freedom of 2 that survived down to 2 K.

Valence-Ordering Structures and Magnetic Behavior of Metallic MMX Chain Compounds

Kettenwechsel: Wie aus einer Tieftemperatur-Kristallstrukturanalyse hervorgeht, lassen sich die Valenzordnungsstrukturen der Grundzustände von NMX-Kettenverbindungen [Pt2(RCS2)4I]∞ (1: R=nBu, 2: R=Et) durch die Formel -Pt2+-Pt3+-I−-Pt3+-Pt2+-I−- beschreiben. Messungen ergaben, dass die magnetische Suszeptibilität von 1 bei 210 K begleitet von einem Phasenübergang 1. Ordnung abrupt abfällt (siehe Diagramm). Der Kurvenverlauf entspricht einem Übergang von einem eindimensionalen antiferromagnetischen Spinsystem zu einem Spin-Singulett-Zustand. Für 2 beobachtet man dagegen den Erhalt der Spin-Freiheitsgrade bis 2 K.

Finite-frequency optical absorption in 1D conductors and mott-hubbard insulators

The frequency-dependent conductivity is studied for the one-dimensional Hubbard model, using a selection rule, the Bethe ansatz, and symmetries associated with conservation laws. For densities where the system is metallic the absorption spectrum has two contributions, a Drude peak at omega = 0 separated by a pseudogap from a broad absorption band whose lower edge is characterized by a nonclassical critical exponent. Our findings shed new light on the "far infrared puzzle" and other optical properties of metallic organic chain compounds.

Synthesis, Crystal Structure, EXAFS, and Magnetic Properties of catena-Poly[μ-tris(4-(2-hydroxyethyl)-1,2,4-triazole-N1,N2)copper(II)] Diperchlorate Trihydrate: Relevance with the Structure of the Iron(II) 1,2,4-Triazole Spin Transition Molecular Materials

[Cu(hyetrz)3](ClO4)2·3H2O (hyetrz = 4-(2-hydroxyethyl)-1,2,4-triazole) represents the first structurally characterized metal(II) chain compound containing triple N1,N2-1,2,4-triazole bridges. The structure has been solved at 298 K by single-crystal X-ray analysis. catena-Poly[μ-tris(4-(2-hydroxyethyl)-1,2,4-triazole-N1,N2)copper(II)] diperchlorate trihydrate (C12H27N9Cl2O14Cu) crystallizes in the monoclinic space group P21/n, a = 13.877(3) Å, b = 23.023(5) Å, c = 15.351(2) Å, β = 91.10(2)°, Z = 8 (Cu(II) units). The Cu(II) ions are linked by triple N1,N2-1,2,4-triazole bridges yielding a slightly alternating chain with Cu1−Cu2 = 3.853(2) Å and Cu2−Cu3 = 3.829(2) Å. The EXAFS results are consistent with the crystal structure. At 30 K, the EXAFS signature of the multiple scattering path Cu1−Cu2−Cu3 is clearly observed, confirming that such exceptional long distance EXAFS signals can be used to detect metal alignments in inorganic long chains when crystal structures are not available. The thermal behavior of this multiple scattering signal was compared to those of similar Fe(II) low-spin compounds, and the observed differences have been discussed by comparing their electronic (dynamic Jahn−Teller effect) and vibrational properties. The Cu(II) ions are weakly antiferromagnetically coupled with J = −1.18(2) cm-1 (based on the Hamiltonian, H = −J[∑i Si·Si+1]). The nature and the magnitude of the antiferromagnetic exchange have been discussed on the basis of the structural features.

A new type of poly metallic chain compounds: carboranyl derivatives of thallium (iii) containing a B-Tl-transition metal bond sequence

The interaction of NaM(CO)5 (M=Mn, Re) with (m-H2C2B10H9-9)TlCl2 in THF yields the stable polymetallic chain compounds (m-H2C2B10H9-9)Tl(Cl)M(CO)5. The stability of the compounds obtained is compared to that of the analogous (B-carboranyl)mercury derivatives.

ChemInform Abstract: Stacked Complexes of Iridium and a Novel Form of Charge Compensation.

AbstractMixed‐valence metal chain compounds based on the anion (I) are prepared by inert atmosphere electrochemical oxidation with a variety of alkyl ammonium cation based electrolytes.

ChemInform Abstract: Two Extended Metal Chain Compounds, Y4I5C and Y6I7C2. Synthesis, Structure, Properties, and Bonding.

AbstractThe title compounds (IV) and (V) crystallize in the space group C2/m with Z=2.

Two extended metal chain compounds, yttrium iodide carbides (Y4I5C and Y6I7C2). Synthesis, structure, properties, and bonding

The title phases are obtained in high yield from the reactions of stoichiometric quantities of Y, YI/sub 3/, and graphite at 850-950/degree/C in welded Nb containers. The crystal structures of the two phases determined by standard x-ray diffraction means are related to those published for Er/sub 4/I/sub 5/ and Er/sub 6/I/sub 7/ (C2/m, Z = 2, /alpha/ = 18.479 (6) and 21.557 (8) /angstrom/, b = 3.947 (1) and 3.909 (1) /angstrom/, c = 8.472 (3) and 12.374 (6) /angstrom/, /beta/ = 103.22 (4) and 123.55 (3)/degree/, R/R/sub w/ = 4.6/5.4 and 3.2/3.7% for Y/sub 4/I/sub 5/C and Y/sub 6/I/sub 7/C/sub 2/, respectively). The two compounds contain infinite single and double chains of carbon-centered yttrium octahedra, respectively, condensed by edge-sharing and sheathed by edge-bridging iodine atoms together with square-planar iodine atoms that bridge between chains. Extended Hueckel MO band calculations were carried out for the empty and the carbon-centered compounds in both structures. Metal-based bands near E/sub F/ in the empty chains exhibit characteristic strong interactions with carbon valence orbitals that generate low-lying valence bands. E/sub F/ in both cases falls within a broad, metal-based conduction band. Resistivity and magnetic susceptibility measurements on Y/sub 6/I/sub 7/C/sub 2/ support the predictedmore » metallic character. 26 refs., 11 figs., 3 tabs.« less

ChemInform Abstract: Preparation and Properties of the New One‐Dimensional Conductor, Partially‐Oxidized Calcium Bis(oxalato)platinate.

Abstract A new metal chain compound, Ca 0.756 [Pt(C 2 O 4 ) 2 ]·3H 2 O, was prepared electrochemically and found to have a triclinic lattice and an average Pt-Pt separation of 2.889 ± 0.01 rA . It was also found to have a room-temperature conductivity of 2.4 – 12.1 S/cm and a temperature dependence similar to that of a one-dimensional (1-D) complex such as KCP (Br). The interchain coupling constant was estimated as 0.029 using the Horovitz equation, and it was proved to be the smallest among the compounds in this series (which were shown to have stronger interchain interaction than partially oxidized tetracyanoplatinates). Interchain interaction was also discussed in relation to Braude's classification of the isostructural partially-oxidized bis(oxalato)platinates with divalent cations. The ratio of the three-dimensional ordering temperature to the Peierls transition temperature, T 3D / T P , was found to be a convenient indicator for the magnitude of the interchain interaction in 1-D metal chain conductors.

Preparation and properties of the new one-dimensional conductor, partially-oxidized calcium bis(oxalato)platinate

A new metal chain compound, Ca 0.756[Pt(C 2O 4) 2]·3H 2O, was prepared electrochemically and found to have a triclinic lattice and an average Pt-Pt separation of 2.889 ± 0.01 rA. It was also found to have a room-temperature conductivity of 2.4 – 12.1 S/cm and a temperature dependence similar to that of a one-dimensional (1-D) complex such as KCP (Br). The interchain coupling constant was estimated as 0.029 using the Horovitz equation, and it was proved to be the smallest among the compounds in this series (which were shown to have stronger interchain interaction than partially oxidized tetracyanoplatinates). Interchain interaction was also discussed in relation to Braude's classification of the isostructural partially-oxidized bis(oxalato)platinates with divalent cations. The ratio of the three-dimensional ordering temperature to the Peierls transition temperature, T 3D/ T P, was found to be a convenient indicator for the magnitude of the interchain interaction in 1-D metal chain conductors.

Why are certain substances metallic?

Metallic properties are by no means confined to elemental substances alone. A variety of materials, both inorganic and organic, show metallic properties. Some of these exotic substances exhibit electrical conductivities comparable to those of elemental metals like copper. A large number of systems traverse the transition from the metallic state to the nonmetallic state when there is a change in temperature, pressure or composition. Metal oxides provide a wide range of materials exhibiting metallic behaviour or going through the metal to non-metal (M-NM) transition. Alkali metal-ammonia solutions, with which chemists are all too familiar, probably constitute one of the earliest and most widely studied examples of theM-NM transition. However, a proper recognition of the metallization of ammonia in the context of the variety of solid systems exhibitingM-NM transitions has only been possible recently. Another interesting class of substances is that of expanded metals such as Hg and Cs which become non-metallic when the density is reduced below a critical value. Several organic solids, metal-chain compounds and polymers are not only metallic, but also become superconducting at low temperatures. With such a galaxy of chemical substances exhibiting metallic behaviour, the fundamental, recurring question of vital interest is “what makes a metal?”. In this contribution, we shall examine operational criteria as well as criteria derived from models to answer this question. A related question of equal interest to chemists is “how many atoms are necessary to bring about metallic properties?”.

Evidence for Conduction Electron-Intramolecular Vibration Interaction in a Platinum Chain Salt

Abstract Polarized reflectance measurements on K1.75 Pt(CN)4·1.5H2O, or K(def)CP reveal that there is a deep indentation in the chain-axis reflectance at a substantially lower frequency (1725 cm−1) than the ordinary C [mddot] N stretching frequency (2180 cm-1). The frequency-dependent conductivity, found by Kramers-Kronig analysis of the reflectance, has a deep antiresonance at about the same frequency. This structure is attributed to a phase-phonon mode of the coupled electron-intramolecular vibration system. These data provide the first direct evidence for the importance of the interaction of the conduction electrons with molecular vibrations in a metal chain compound. The dimensionless electron phonon coupling constant is estimated to be Λ ~ 0.28, a result which suggests that this interaction might be important for stabilizing the Peierls distortion in K(def)CP and that it might influence the dc conductivity of the material. In summary, we have found the first direct evidence for the coupling of intramolecular vibrations to the conduction electrons in an inorganic Pt chain salt. This coupling has important consequences for the Peierls transition in K(def)CP as well as for the optical and transport properties.

ChemInform Abstract: SURVEY OF METAL CHAIN COMPOUNDS

Chemischer InformationsdienstVolume 12, Issue 15 Reviews ChemInform Abstract: SURVEY OF METAL CHAIN COMPOUNDS P. DAY, P. DAYSearch for more papers by this author P. DAY, P. DAYSearch for more papers by this author First published: April 14, 1981 https://doi.org/10.1002/chin.198115353AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue15April 14, 1981 RelatedInformation

Optical and elastic properties of linear metal–chain compounds: The 1,2-benzoquinonedioximates (bqd) of nickel, palladium, and platinum, M(bqd)2

Polarized single crystal reflectance spectra of the linear metal–chain complexes Pt(bqd)2, α-Pd(bqd)2, β-Pd(bqd)2, Pd(bqd)2I0.55, Ni(bqd)2, and Ni(bqd)2I0.5 (bqd−=ion of 1,2-benzoquinonedioxime, bqdH) have been recorded at room temperature. Well-defined sharp absorption bands polarized parallel to the metal atom chains are observed in the frequency region from 0.5 to 2.5 eV, and are most reasonably identified as the interband electronic transitions between the ndz2 valence and the (n+1) pz conduction bands in a direct optical excitation process (n=3, 4, 5). The elastic behavior (Young’s modulus and internal friction) examined using a vibrating reed technique in the temperature range 17–300 K reveals, in the case of α-Pd(bqd)2, a peculiar phase transformation occurring along the metal atom chains below 100 K. From powder x-ray diffraction patterns recorded at ambient and at liquid nitrogen temperatures, this phase transition is interpreted as a lattice distortion resulting in the formation of stable chains of dimerized neutral metal complexes.

Evidence for intrinsic electrical conduction in the linear metal-chain semiconductor bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd) 2

The four-electrode dc conductivity of single crystals of the linear metal-chain compound bis(1,2-benzoquinonedioximato)platinum(II), Pt(bqd) 2, measured parallel to the long axis of the crystals, reveals ohmic behavior over the temperature range 77–550°K, and averages to σ = 3.3 × 10 −3 Ω −1 cm −1 at room temperature. Unlike the well-characterized Magnus' Green Salt (MGS), Pt(NH 3) 4PtCl 4 ( σ = 5.5 × 10 −4 Ω −1 cm −1) , the present compound is found to be an intrinsic, small band gap semiconductor. The PtPt distance of 3.180 Å, the shortest yet observed in Pt(II) glyoximates, was determined by powder X-ray diffraction. The small band gap is related to the unusually high conductivity of Pt(bqd) 2, which is most reasonably interpreted in terms of this short PtPt separation. Preliminary results of polarized single crystal reflectance spectra demonstrating the anisotropic behavior of this compound are presented.

Evidence for Impurity Effects in Metal Chain Compounds: The Electron Paramagnetic Resonance of "Extrinsic" Magnus's Green Salt

Electron-paramagnetic-resonance studies of the one-dimensional metal-chain compound Magnus's green salt, ${\mathrm{P}\mathrm{t}(\mathrm{N}{\mathrm{H}}_{3})}_{4}$Pt${\mathrm{Cl}}_{4}$, has revealed the presence of localized hole states having an axial resonance with ${g}_{\ensuremath{\parallel}}=1.939\ifmmode\pm\else\textpm\fi{}0.002$ and ${g}_{\ensuremath{\perp}}=2.504\ifmmode\pm\else\textpm\fi{}0.002$. These states have been identified as bound ${d}_{{z}^{2}}$-like states associated with a ${d}_{{z}^{2}}$-like valence band. From the observed hyperfine pattern we infer that the holes, although localized, have orbits extended over several Pt sites along the chain. We show how the states can be introduced in a series of doping experiments with Magnus's green salt powders.