Osmium Halides Research Articles

J=0 nonmagnetic insulating state in K2OsX6 (X=F,Cl,andBr)

In $4d/5d$ transition-metal systems, many interesting physical properties arise from the interplay of bandwidth, electronic correlations, and spin-orbit interactions. Here, using {\it ab initio} density functional theory, we systematically study the double-perovskite-like system K$_2$Os$X_6$ (X = F, Cl, and Br) with a $5d^4$ electronic configuration. Our main result is that the $J = 0$ nonmagnetic insulating state develops in this system, induced by strong spin-orbital coupling. Specifically, the well-separated Os$X_6$ octahedra lead to the cubic crystal-field limit and result in dramatically decreasing hoppings in nearest neighbor Os-Os sites. In this case, the three degenerate $t_{2g}$ orbitals are reconstructed into two ``effective'' $j_{\rm eff}$ ($j_{\rm eff} = 1/2$ and $j_{\rm eff} = 3/2$ states) states separated by the strong SOC, opening a gap with four electrons occupying the $j_{\rm eff} = 3/2$ orbitals. Furthermore, the hybridization between the Os $5d$ orbitals and the $X$ ($X$ = F, Cl, and Br) $p$ orbitals increases from F to Br, leading the electrons in K$_2$OsF$_6$ to be more localized than in K$_2$OsCl$_6$ and K$_2$OsBr$_6$, resulting in a smaller bandwidth for K$_2$OsF$_6$ than in the Cl- or Br- cases. Our results provide guidance to experimentalists and theorists working on this interesting family of osmium halides.

Electronic and magnetic properties of quasi-one-dimensional osmium halide OsCl4

Using ab initio density functional theory, we study the electronic and magnetic properties of the van der Waals chain material OsCl4. In the nonmagnetic state, a strongly anisotropic band structure was observed, in agreement with its anticipated one-dimensional crystal geometry. Based on Wannier functions, we found that the four electrons of the 5d Os atom form a low-spin S = 1 state, with a large crystal field between the dxz/yz and dxy orbitals, corresponding to a strong Jahn–Teller distortion (Q3< 0). As a consequence, the magnetic properties are mainly contributed by the dxz/yz states. Furthermore, when a Mott gap develops after the introduction of the Hubbard U and Hund coupling J, we found that the staggered spin order is the most likely magnetic state, namely, spins arranged as (↑-↓-↑-↓) with π wavevector along the chain. In addition, the energy differences between various spin states are small, suggesting a weak magnetic exchange coupling along the chain. Our results provide guidance to experimentalists and theorists working on quasi-one-dimensional osmium halides chain materials.

Surface‐Assisted Synthesis and Behavior of Dimetallic Mixed‐Metal Complexes [M2Cl2(μ‐Cl)4(CO)6M′(L)2] (M = Ru, Os; M′ = Fe, Co; L = CH3CH2OH, H2O)

AbstractThe reductive carbonylation of ruthenium and osmium halides in the presence of cobalt and iron surfaces was studied. In these surface‐assisted reactions the metal surface plays an active role in releasing metal ions, which can be used for the in situ synthesis of mixed‐metal compounds. A linear, dimetallic, chlorido‐bridged, trinuclear complex [Ru2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2] was obtained by the interaction between reducing RuCl3 and the cobalt surface. In the reaction the RuCl3 is reduced with carbon monoxide in the presence of a solid cobalt surface in ethanol solution. During the reduction of the RuCl3 the cobalt surface was simultaneously corroded, releasing cobalt cations. In addition to [Ru2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2], the reaction also produced other trinuclear complexes and mononuclear products, such as a bent and linear dimetallic, chlorido‐bridged complex with the aqua ligand [Ru2Cl2(μ‐Cl)4(CO)6Co(H2O)2] and ionic [RuCl3(CO)3]2[Co(H2O)6]. The carbon monoxide reduction of RuI3 produced the ionic complex [RuI3(CO)3]2[M′(H2O)6] (M′ = Fe, Co) in the presence of iron, stainless steel or cobalt. Iodido‐bridged trinuclear mixed‐metal complexes were not observed. The surface‐assisted process proved to be useful with other metal combinations as well. When RuCl3 was replaced with OsCl3, a variety of trinuclear mixed‐metal complexes, such as [Os2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2] and ionic [OsCl3(CO)3]2[M(H2O)6] (M = Fe, Co), were obtained, depending on the metal surface used. Due the lability of the chlorido‐bridged trinuclear complexes, the possible decomposition steps of [M2Cl2(μ‐Cl)4(CO)6M′(CH3CH2OH)2] (M = Ru, Os; M′ = CO, Fe) were studied computationally, using DFT methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Complexes of osmium with tertiary arsines and carbonmonoxide

Osmium halides (Cl and Br) react with monotertiary arsines Ph2RAs (R=Me, Et, Pr and Bu) in alcoholic medium to give paramagnetic octahedral complexes of the type OsX3L3 (X=Cl, Br; L=Ph2RAs) which further react with carbonmonoxide to give dihalo dicarbonyl complexes of osmium(II) of the type OsX2 (CO)2 L2. Similarly, osmium halides react with tertiary arsines in the presence of formaldehyde to give monocarbonyl complexes of osmium(II) of the type OsX2 (CO)L3. Structures have been assigned to all these compounds on the basis of IR and NMR studies.

Cyclopentadienyl-ruthenium and -osmium chemistry. IV. Convenient high-yield synthesis of some cyclopentadienyl ruthenium or osmium tertiary phosphine halide complexes

High-yield one-pot syntheses of RuCl(PR3)2(η-C5H5) (R = Ph or p-MeC6H4) and OsBr(PPh3)2- (η-C5H5) from ruthenium or osmium halides, the tertiary phosphine and cyclopentadiene are described.

Complexes of osmium halides with monodentate and bidentate ligands

Complexes of osmium halides with donor ligands L (L = PPh 3, AsPh 3, SbPh 3, PMePh 2, C 2H 4(AsPh 2) 2, PPr 2 n Ph, CH 2(AsPh 2) 2) have been prepared. The IR and NMR spectra of complexes of the type trans-[OsCl 4L 2], fac-[OsX 3L 3] and trans-[OsX 2L 4] are recorded and discussed. For the trans complexes the halogen sensitive modes occur near those of the related [OsX 4] 2− species. Tentative assignments for ν(OsY) (Y = P, As, Sb) are discussed on the basis of the experimental results. Raman and ESR spectra of selected complexes have been recorded and are discussed. NMR data indicates the presence of monodentate diarsine ligands in trans- (OsCl 4(CH 2(AsPh 2) 2) 2)·C 2H 5OH.

Transition-metal complexes containing phosphorus ligands. Part VI. Convenient synthesis of some tertiary phosphine (and arsine) nitrosyl halide derivatives of ruthenium and osmium

A selection of ruthenium and osmium nitrosyl halide complexes, MX3(NO)(AR3)2[M = Ru, Os; X = Cl, Br; A = P, R = alkyl, aryl, or mixed alkyl aryl; A = As, R = phenyl] have been prepared by a convenient single-stage synthesis involving addition of ruthenium or osmium halides and N-methyl-N-nitrosotoluene-p-sulphonamide or pentyl nitrite to a solution of the appropriate tertiary phosphine or arsine in a boiling alcoholic solvent. Attempts to prepare the tri-iodo-derivatives, Ml3(NO)(AR3)2, by this technique using ruthenium or osmium chlorides in the presence of a large excess of lithium iodide gave the required products, the corresponding chlorodi-iodo-derivatives or a mixture of complexes, depending on the nature of the neutral ligands present. A mechanism for the nitrosyl formation, involving ruthenium(IV) and osmium(IV) monohydrides, MX3H(AR3)2, as intermediates is discussed, and an explanation for the formation of the mixed chlorodi-iodo derivatives is advanced. E.s.r. and i.r. spectroscopic evidence for the formation of a paramagnetic nitrosyl, tentatively formulated RuCl2(NO)(PPh3)2, as a minor product in the synthesis of RuCl3(NO)(PPh3)2 is reported.

Hydride complexes of osmium halides with carbon monoxide, dinitrogen, and tertiary phosphines as co-ligands

The complexes [OsH2Cl2(PR3)3](PR3= PMePh2, PEt2Ph, PEtPh2, or PPhPrn2) have been prepared by the amalgamated-zinc reduction, under dihydrogen, of mer-[OsCl3(PR3)3]. The compounds mer-[OsXY(L)(PR3)3](X = H or D; Y = Cl or Br; L = CO or N2; PR3= PMe2Ph or PEt2Ph) result from mer-[OsY2(L)(PR3)3] by sodium borohydride or lithium aluminium deuteride reduction. The 1H n.m.r. and i.r. spectra of these compounds are recorded and used to assign the configuration of the monohydrido-complexes. The dihydro-complexes react with carbon monoxide, tertiary phosphines and carbon tetrachloride–dichlorine with loss of dihydrogen. With one mole of anhydrous HCl the dihydrido-complexes give the unstable compounds [OsHCl3(PR3)3](PR3= PMePh2 or PEt2Ph) which readily give fac-[OsCl3(PR3)3] and ½H2 when heated. Dinitrogen does not react with [OsH2Cl2(PMePh2)3]. The compound mer-[OsHCl(N2)(PEt2Ph)3] reacts with anhydrous HCl in toluene to give [OsCl2(N2)(PEt2Ph)3] and dihydrogen.

Reactions of complexes of ruthenium and osmium halides with ammonia, amines, and hydrazine

Ammonia and primary amines (am) react with [MX3(PR3)3](M = Ru or Os, X = Cl or Br, and PR3= tertiary phosphine) in ethanol at 20° to form M(II) complexes, mer-[MX2am(PR3)3], and acetaldehyde. Secondary and tertiary amines with [MX3(PMe2Ph)3] also cause reduction, but the product is an alcohol complex [MX2(C2H5OH)(PMe2Ph)3]. The reduction may occur through a hydride complex intermediate because some hydrogen is produced in all the above reactions. The alcohol complexes are probably formed for steric reasons because the least sterically hindered secondary amine, piperidine, forms a piperidine complex.When the alcohol contains a small amount of water di-n-alkylamines (CnH2n+ 1)2NH are dealkylated to form the corresponding primary amine complexes [MX2 am (PR3)3](cf. similar decarbonylation of alcohol and aldehydes). The cleaved alkyl group generally appears as Cn–1H2n and all the lower n-alkanes down to methane, but from dimethylamine higher hydrocarbons are obtained and from diethylamine a little propane.Hydrazine in limited amounts forms mononuclear complexes [MCl2(N2H4)(PMe2Ph)3] or more commonly hydrazine-bridged complexes [M2X4(N2H4)2(PR3)4]. Nitrogen, hydrogen, and hydrazine hydrochloride are also produced. Under more vigorous reaction conditions [Ru(NH3)5N2]2+ is formed.

Osmium carbonyl halides and their derivatives. Part II

The reaction of carbon monoxide with osmium halides has been investigated and, on the basis of infrared evidence, structures have been assigned to Os(CO)4X2 and Os(CO)2X2. The carbonyl halides react with a variety of ligands to give compounds Os(CO)2L2X2. Infrared spectra are reported and discussed.

The chemistry of osmium. Part III. Complexes of tertiary arsines with bivalent and trivalent osmium halides

The chemistry of osmium. Part III. Complexes of tertiary arsines with bivalent and trivalent osmium halides