A Terminal Osmium(IV) Nitride: Ammonia Formation and Ambiphilic Reactivity

Low‐valent osmium nitrides are discussed as intermediates in nitrogen fixation schemes. However, rational synthetic routes that lead to isolable examples are currently unknown. Here, the synthesis of the square‐planar osmium(IV) nitride [OsN(PNP)] (PNP=N(CH₂CH₂P(tBu)₂)₂) is reported upon reversible deprotonation of osmium(VI) hydride [Os(N)H(PNP)]⁺. The Os^IV complex shows ambiphilic nitride reactivity with SiMe₃Br and PMe₃, respectively. Importantly, the hydrogenolysis with H₂ gives ammonia and the polyhydride complex [OsH₄(HPNP)] in 80 % yield. Hence, our results directly demonstrate the role of low‐valent osmium nitrides and of heterolytic H₂ activation for ammonia synthesis with H₂ under basic conditions.     

Deposition of crystalline copper films from tetranuclear copper (II) complexes without application of reducing atmosphere

Crystalline copper films were deposited by aerosol‐assisted chemical vapor deposition (AACVD) in the absence of hydrogen from two newly synthesized complexes [Cu(deae)(TFA)]₄·1.25THF ( 1 ) and [Cu₄(OAc)₆(bdmap)₂(H₂O)₂]·4H₂O ( 2 ) [deae = N, N‐diethylaminoethanolate, TFA = trifloroacetate, OAc = acetate and bdmap = 1,3‐bis(dimethylamino)‐2‐propanolato]. These precursors were prepared in high yield using mixed ligands and crystallized in tetragonal and triclinic crystal systems with space groups 14₁/a and P ? 1. Complexes 1 and 2 thermally decomposed at 290 and 250 °C, respectively, to yield copper films which were characterized by SEM/EDX for their morphology and composition and PXRD for their crystallinity and phase. These films have smooth morphologies with particle sizes within the range of 0.3–0.6 µm and may find applications in fabrication of ultralarge‐scale integrated circuits. Copyright © 2010 John Wiley & Sons, Ltd.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der mer‐Trihalogeno‐tris‐Pyridin‐Osmium(III)Komplexe mer‐[OsX3Py3], X = Cl,Br, I

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the mer ‐Trihalogeno‐tris‐Pyridine‐Osmium(III) Complexes mer‐[OsX₃Py₃], X = Cl, Br, I By reaction of the hexahalogenoosmates(IV) with pyridine and iso‐amylalcohol mer‐trihalogeno‐tris‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of mer‐[OsBr₃Py₃] (monoclinic, space group P2₁/n, a = 9.098(5), b = 12.864(5), c = 15.632(5) Å, β = 90.216(5)°, Z = 4) and mer‐[OsI₃Py₃] (monoclinic, space group P2₁/n, a = 9.0952(17), b = 13.461(4), c = 15.891(10), β = 91.569(5)°, Z = 4). The pyridine rings are twisted propeller‐like against the N₃ meridional plane with mean angles of 49° (Cl), 46° (Br), 44° (I). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry, the IR and Raman spectra are assigned by normal coordinate analysis. Due to the stronger trans influence of pyridine as compared with the halide ligands for N'–Os–X ^· axes significantly different valence force constants are observed in comparison with symmetrically coordinated octahedron axes: f_d(OsCl) = 1.74, f_d(OsCl^·) = 1.49, f_d(OsBr) = 1.43, f_d(OsBr ^· ) = 1.18, f_d(OsI) = 0.99, f_d(OsI ^· ) = 0.96, f_d(OsN) between 1.96 and 2.07 and f_d(OsN') between 2.13 and 2.32 mdyn/Å.     

Pincer and diamine Ru and Os diphosphane complexes as efficient catalysts for the dehydrogenation of alcohols to ketones

The ruthenium and osmium complexes [MCl₂(diphosphane)(L)] (M=Ru, Os; L=bidentate amino ligand) and [MCl(CNN)(dppb)] (CNN=pincer ligand; dppb=1,4‐bis‐ (diphenylphosphino)butane), containing the N–H moiety, have been found to catalyze the acceptorless dehydrogenation of alcohols in tBuOH and in the presence of KOtBu. The compounds trans‐[MCl₂(dppf)(en)] (M=Ru 7 , Os 13 ; dppf=1,1′‐bis(diphenylphosphino)ferrocene; en=ethylenediamine) display very high activity and different substrates, including cyclic and linear alcohols, are efficiently oxidized to ketones by using 0.8–0.04 mol % of catalyst. The effect of the base and the comparison of the catalytic activity of the Ru versus Os complexes are reported. The ruthenium complex 7 generally leads to a faster conversion into ketones with respect to the osmium complex 13 , which displays better activity in the dehydrogenation of 5‐en‐3β‐hydroxy steroids. The synthesis of new Ru and Os complexes [MCl₂(PP)(L)] (PP=dppb, dppf; L=(±)‐trans‐1,2‐diaminocyclohexane, 2‐(aminomethyl)pyridine, and 2‐aminoethanol) of trans and cis configuration is also reported.     

Neue wasserlösliche Osmiumkomplexe des 5,10,15,20‐Tetrakis(4‐sulfonatophenyl)‐porphyrin‐Anions

Metal Complexes with Tetrapyrrole Ligands. LXXVI. New Water‐soluble Osmium Complexes of 5,10,15,20‐Tetrakis(4‐sulfonatophenyl)porphyrin‐Anion The new symmetrical osmium(II) porphyrinates [Os(tpps₄)L₂]^4– ( 1 b – g ) are formed from [OsO₂(tpps₄)]^4– ( 1 a ) by reduction in presence of the ligands L. 1 e – g react with 1‐methylimidazole to yield the unsymmetrical complexes [Os(tpps₄)LL′]^4– ( 1 h – j ). Except for 1 g – h the osmium(II) porphyrinates are not inert in presence of air and are oxidized to the osmium(III) porphyrinates [Os(tpps₄)L₂]^3– ( 2 b – f ) and [Os(tpps₄)LL′]^3– ( 2 i – j ). These anions are deposited as sodium salts.     

Chemistry of osmium in N2P2Br2 coordination sphere: Synthesis,structure and reactivities

A family of three mixed-ligand osmium complexes of type [Os(PPh₃)₂(N-N)Br₂], where N-N=2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (Me₂bpy) and 1,10-phenanthroline (phen), have been synthesized and characterized. The complexes are diamagnetic (low-spin d⁶, S=0) and in dichloromethane solution they show intense MLCT transitions in the visible region. The two bromide ligands have been replaced from the coordination sphere of [Os(PPh₃)₂(phen)Br₂] under mild conditions by a series of anionic ligands L (where L=quinolin-8-olate (q), picolinate (pic), oxalate (Hox) and 1-nitroso-2-naphtholate (nn)) to afford complexes of type [Os(PPh₃)₂(phen)(L)]⁺, which have been isolated and characterized as the perchlorate salt. The structure of the [Os(PPh₃)₂(phen)(pic)]ClO₄ complex has been determined by X-ray crystallography. The PPh₃ ligands occupy trans positions and the picolinate anion is coordinated to osmium as a bidentate N,O-donor forming a five-membered chelate ring. The [Os(PPh₃)₂(phen)(L)]⁺ complexes are diamagnetic and show multiple MLCT transitions in the visible region. The [Os(PPh₃)₂(N-N)Br₂] complexes show an osmium(II)–osmium(III) oxidation (−0.02 to 0.12 V vs. SCE) followed by an osmium(III)–osmium(IV) oxidation (1.31 to 1.43 V vs. SCE). The [Os(PPh₃)₂(phen)(L)]⁺ complexes display the osmium (II)–osmium (III) oxidation (0.26 to 0.84 V vs. SCE) and one reduction of phen (−1.50 to −1.79 V vs. SCE). The osmium (III)–osmium (IV) oxidation has been observed only for the L=q and L=Hox complexes at 1.38 V vs. SCE and 1.42 V vs. SCE respectively. The osmium(III) species, viz. [Os^III(PPh₃)₂(N-N)Br₂]⁺ and [Os^III(PPh₃)₂(phen)(L)]²⁺, have been generated both chemically and electrochemically and characterized in solution by electronic spectroscopy and cyclic voltammetry.     

Osmium Complexes with Tridentate 6‐Pyrazol‐3‐yl 2,2′‐Bipyridine Ligands: Coarse Tuning of Phosphorescence from the Red to the Near‐Infrared Region

We have prepared and characterized a series of osmium complexes [Os₂(CO)₄(fpbpy)₂] ( 1 ), [Os(CO)(fpbpy)₂] ( 2 ), and [Os(fpbpy)₂] ( 3 ) with tridentate 6‐pyrazol‐3‐yl 2,2′‐bipyridine chelating ligands. Upon the transformation of complex 2 into 3 through the elimination of the CO ligand, an extremely large change in the phosphorescence wavelength from 655 to 935 nm was observed. The results are rationalized qualitatively by the strong π‐accepting character of CO, which lowers the energy of the osmium d_π orbital, in combination with the lower degree of π conjugation in 2 owing to the absence of one possible pyridine‐binding site. As a result, the energy gap for both intraligand π–π* charge transfer (ILCT) and metal‐to‐ligand charge transfer (MLCT) is significantly greater in 2 . Firm support for this explanation was also provided by the time‐dependent DFT approach, the results of which led to the conclusion that the S₀→T₁ transition mainly involves MLCT between the osmium center and bipyridine in combination with pyrazolate‐to‐bipyridine ³π–π* ILCT. The relatively weak near‐infrared emission can be rationalized tentatively by the energy‐gap law, according to which the radiationless deactivation may be governed by certain low‐frequency motions with a high density of states. The information provided should allow the successful design of other emissive tridentate metal complexes, the physical properties of which could be significantly different from those of complexes with only a bidentate chromophore.     

MOF‐on‐MOF: Oriented Growth of Multiple Layered Thin Films of Metal–Organic Frameworks

The precise alignment of multiple layers of metal–organic framework (MOF) thin films, or MOF‐on‐MOF films, over macroscopic length scales is presented. The MOF‐on‐MOF films are fabricated by epitaxially matching the interface. The first MOF layer (Cu₂(BPDC)₂, BPDC=biphenyl‐4,4′‐dicarboxylate) is grown on an oriented Cu(OH)₂ film by a “one‐pot” approach. Aligned second (Cu₂(BDC)₂, BDC=benzene 1,4‐dicarboxylate, or Cu₂(BPYDC)₂, BPYDC=2,2′‐bipyridine‐5,5′‐dicarboxylate) MOF layers can be deposited using liquid‐phase epitaxy. The co‐orientation of the MOF films is confirmed by X‐ray diffraction. Importantly, our strategy allows for the synthesis of aligned MOF films, for example, Cu₂(BPYDC)₂, that cannot be grown on a Cu(OH)₂ surface. We show that aligned MOF films furnished with Ag nanoparticles show a unique anisotropic plasmon resonance. Our MOF‐on‐MOF approach expands the chemistry of heteroepitaxially oriented MOF films and provides a new toolbox for multifunctional porous coatings.     

Mediated glucose enzyme electrodes by cross-linking films of osmium redox complexes and glucose oxidase on electrodes

Here, we report on a novel, versatile approach for the preparation of mediated enzyme electrodes, demonstrated using cross-linked films of glucose oxidase and a range of functionalised osmium complexes on graphite electrodes. Response of enzyme electrodes are optimised by evaluation of glucose response as a function of variation in ratios of [Os(2,2′-bipyridine)₂(4-aminomethyl pyridine)Cl]⁺ redox mediator, polyallylamine support and glucose oxidase enzyme cross-linked using a di-epoxide reagent in films on graphite. Lowering of the redox potential required to mediate glucose oxidation is achieved by synthesis of complexes using (4,4′-dimethyl-2,2′-bipyridine) or (4,4′-dimethoxy-2,2′-bipyridine) as a ligand instead of (2,2′-bipyridine). Enzyme electrodes prepared using the complexes based on dimethoxy- or dimethyl-substituted bipyridines provide glucose oxidation current densities of 30 and 70 μA?cm^?2 at 0.2 and 0.35 V applied potential compared to 120 μA?cm^?2 at 0.45 V for the initial enzyme electrode, under pseudo-physiological conditions in 5 mM glucose, with stability of signals proving inadequate for long-term operation. Current output and stability may be improved by selection of alternate anchoring and cross-linking methodology, to provide enzyme electrodes capable for application to long-term glucose biosensors and anodes in enzymatic fuel cells.

Hinweise auf reversibles öffnen und schliessen einer metallmetall-bindung in dem trimethylsilylnitren-sulfido-cluster Os3(CO)9(μ3-S)(μ-3NSiMe3)

The thermal reaction of Os₃(CO)₁₂ with S(NSiMe₃)₂ yields the cluster compound Os₃(CO)₉(μ₃-S(μ₃-NSiMe₃. The structure of the molecule was solved by a single crystal X-ray structure analysis. In the solid state the osmium atoms define an “open” isosceles triangle which is bridged by both a sulphur and a trimethylslylnitrene ligand. The distance between the osmium atoms at the long edge of the triangle (3.498(2) Å compared to 2.774(2) and 2.777(2) Å for the short edges) suggests that these two Os atoms are not in bonding contract. A variable-temperature ¹³C NMR study reveals the structure of the molecule to be dynamic in solution; the spectra are indicative of the existence of two different structures at elevated temperatures. We interprete our findings as reconcilable with the assumption that a reversible closing and opening process of the Os-Os bonds can occur in solution.     

Ligandless C‐C bond formation via Suzuki–Miyaura reaction in micelles or water–ethanol solution using PdPtZn and PdZn nanoparticle thin films

PdPtZn and PdZn nanoparticle (NP) thin films were synthesized by the reduction of [PdCl₂(cod)], [PtCl₂(cod)] (cod = cis,cis‐1,5‐cyclooctadiene) and [Zn(acac)₂] (acac = acetylacetonate) complexes at an oil–water interface. The structure and morphology of the as‐prepared NPs were characterized with X‐ray diffraction, transmission electron microscopy and energy dispersive analysis of X‐rays. Catalytic activity of the prepared NPs was investigated in the Suzuki–Miyaura cross‐coupling reaction in H₂O–EtOH and various micellar media systems such as cetyltrimethylammonium bromide (cationic surfactant), sodium dodecylsulfate (anionic surfactant) and Pluronic P123 (non‐ionic surfactant). PdPtZn and PdZn thin films exhibited higher catalytic activity compared to Pd thin film in the Suzuki–Miyaura coupling reaction due to the appropriate interaction between palladium, platinum and zinc metals. Copyright © 2015 John Wiley & Sons, Ltd.     

Mechanistic Insight into the Facilitation of β‐Lactam Fragmentation through Metal Assistance

The mechanism of OsH₆(PiPr₃)₂‐mediated fragmentation of a 4‐(2 pyridyl)‐2‐azetidinone has been investigated by DFT calculations. The addition of the C4?H bond of the substrate to OsH₂(PiPr₃)₂ allows the active participation of an osmium lone pair in the B‐type β‐lactam fragmentation process. This new mechanism makes the N1?C4/C2?C3 fragmentation of the lactamic core thermally accessible through a stepwise process.     

Mechanism of Elimination Reactions : by W.H. Saunders Jr., and A.F. Cockerill,Wiley, New York,London, 1973,x + 641 pages. ß11.15.

The structure of H₃Os₃(CO)₉CCH₃ has been determined by a combination of nematic-phase PMR and X-ray powder photography; the compound is iso-structural with the analogous H₃Ru₃(CO)₉CCH₃, with an osmium to (bridging) hydride proton distance of 1.82 Å and an OsHOs angle of 103°.     

Kristallstrukturen,Normalkoordinatenanalysen und 15N‐NMRund 77Se‐NMR‐Verschiebungen von trans‐[OsO2(NCO)4]2–, trans‐[OsO2(NCS)4]2– und trans‐[OsO2(SeCN)4]2–

Crystal Structures, Normal Coordinate Analyses, and ¹⁵N NMR and ⁷⁷Se NMR Chemical Shifts of trans ‐[OsO₂(NCO)₄]^2–, trans ‐[OsO₂(NCS)₄]^2–, and trans ‐[OsO₂(SeCN)₄]^2– The crystal structures of trans‐(Ph₃PNPPh₃)₂[OsO₂(NCO)₄] ( 1 ) (orthorhombic, space group Pbca, a = 19.278(3), b = 16.674(4), c = 19.982(2) Å, Z = 4), trans(n‐Bu₄N)₂[OsO₂(NCS)₄] ( 2 ) (triclinic, space group P1, a = 12.728(3), b = 12.953(3), c = 16.255(6) Å, α = 97.39(4), β = 105.62(2), γ = 95.25(3)°, Z = 2) and trans‐(n‐Bu₄N)₂[OsO₂(SeCN)₄] ( 3 ) (tetragonal, space group I4/m, a = 13.406(2), c = 12.871(1) Å, Z = 2) have been determined by single‐crystal X‐ray diffraction analysis, showing the bonding of NCO and NCS via the N atom but the coordination of SeCN via the Se atom to osmium. Based on the molecular parameters of the X‐ray determinations the vibrational spectra have been assigned by normal coordinate analyses. The valence force constants are for 1 f_d(OsO) = 6.43, f_d(OsN) = 3.32, f_d(NC) = 14.50, f_d(CO) = 12.80, for 2 f_d(OsO) = 6.56, f_d(OsN) = 1.75, f_d(NC) = 15.00, f_d(CS) = 5.50, and for 3 f_d(OsO) = 6.75, f_d(OsSe) = 0.99, f_d(SeC) = 3.23, f_d(CN) = 15.95 mdyn/Å. The observed NMR shifts are δ(¹⁵N) = –386.6 ( 1 ), δ(¹⁵N) = –294.7 ( 2 ) and δ(⁷⁷Se) = 108.8 ppm ( 3 ).     

Osmium(IV) thiocarbamide complexes. Synthesis and crystal and molecular structures of [Os(Thio)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>] · 2H<Subscript>2</Subscript>O

Tetrachlorobis(thiocarbamide)osmium(IV) dehydrate, [Os(Thio)₂Cl₄] · 2H₂O, was synthesized by the reaction of K₂[OsO₂(OH)₄] with thiocarbamide in 6 M HCl. The compound was characterized by chemical analysis and IR, UV, and X-ray photoelectron spectroscopies. The structure was determined by X-ray diffraction analysis. The coordination polyhedron of the osmium atom lying in the axis 2 is a distorted cis-octahedron formed by four chlorine atoms and two sulfur atoms of two monodentate thiocarbamide ligands: Os-S 2.3075(18) Å and Os-Cl 2.3625(18) Å (trans to Cl) and 2.4294(19) Å (trans to S). The conditions for the formation of the osmium(IV) thiocarbamide complexes in HCl solutions were determined using spectrophotometry, and the spectral characteristics of [Os(Thio)Cl₅]^? were obtained.     

Chemical transformation of cluster osmium thioselenochloride Os<Subscript>3</Subscript>S<Subscript>7</Subscript>SeCl<Subscript>8</Subscript>

The binuclear osmium complex Os₃S₇SeCl₈ was prepared by the reaction of cluster chalcogen chloride K₆Os₂S₂O₆(CN)₈ with an aqueous KCN solution. In the complex, the distance between the osmium atoms is 2.85 Å, and they are linked by μ-SO ₂ ^2? bridges with the OsSOs angle of 75.9°. The osmium coordination number is 6. In the reaction with CN^? ligands under study, the individual fragments of the structure are retained; however, the trinuclear cluster skeleton of Os₃S₇SeCl₈ is destroyed.     

Chiral and Nonchiral [OsX2(diphosphane)(diamine)] (X: Cl,OCH2CF3) Complexes for Fast Hydrogenation of Carbonyl Compounds

The osmium complexes trans‐[OsCl₂(dppf)(diamine)] (dppf: 1,1′‐bis(diphenylphosphino)ferrocene; diamine: ethylenediamine in 3 , propylenediamine in 4 ) were prepared by the reaction of [OsCl₂(PPh₃)₃] ( 1 ) with the ferrocenyl diphosphane, dppf and the corresponding diamine in dichloromethane. The reaction of derivative 3 with NaOCH₂CF₃ in toluene afforded the alkoxide cis‐[Os(OCH₂CF₃)₂(dppf)(ethylenediamine)] ( 5 ). The novel precursor [Os₂Cl₄(P(m‐tolyl)₃)₅] ( 2 ) allows the synthesis of the chiral complexes trans‐[OsCl₂(diphosphane)(1,2‐diamine)] ( 6 – 9 ; diphosphane: (R)‐[6,6′‐dimethoxy(1,1′‐biphenyl)‐2,2′‐diyl]bis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylMeObiphep) or (R)‐(1,1′‐binaphthalene)‐2,2′‐diylbis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylbinap); diamine=(R,R)‐1,2‐diphenylethylenediamine (dpen) or (R,R)‐1,2‐diaminocyclohexane (dach)), obtained by the treatment of 2 with the diphosphane and the 1,2‐diamine in toluene at reflux temperature. Compounds 3 – 5 in ethanol and in the presence of NaOEt catalyze the reduction of methyl aryl, dialkyl, and diaryl ketones and aldehydes with H₂ at low pressure (5 atm), with substrate/catalyst (S/C) ratios of 10 000–200 000 and achieving turnover frequencies (TOFs) of up to 3.0×10⁵ h^?1 at 70 °C. By employment of the chiral compounds 6 – 9 , different ketones, including alkyl aryl, bulky tert‐butyl, and cyclic ketones, have successfully been hydrogenated with enantioselectivities up to 99 % and with S/C ratios of 5000–100 000 and TOFs of up to 4.1×10⁴ h^?1 at 60 °C.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der Tetrahalogeno‐bis‐Pyridin‐Osmium(III)‐Komplexe cis‐(n‐Bu4N)[OsCl4Py2] und trans‐(n‐Bu4N)[OsX4Py2], X = Cl,Br

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Tetrahalogeno‐bis‐Pyridine‐Osmium(III) Complexes cis ‐( n ‐Bu₄N)[OsCl₄Py₂] and trans ‐( n ‐Bu₄N)[OsX₄Py₂], X = Cl, Br By reaction of (n‐Bu₄N)₂[OsX₆], X = Cl, Br, with pyridine and (n‐Bu₄N)[BH₄] tetrahalogeno‐bis‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of cis‐(n‐Bu₄N)[OsCl₄Py₂] ( 1 ) (triclinic, space group P1, a = 9.4047(9), b = 10.8424(18), c = 17.007(2) Å, α = 71.833(2), β = 81.249(10), γ = 67.209(12)°, Z = 2), trans‐(n‐Bu₄N)[OsCl₄Py₂] ( 2 ) (orthorhombic, space group P2₁2₁2₁, a = 8.7709(12), b = 20.551(4), c = 17.174(4) Å, Z = 4) and trans‐(n‐Bu₄N)[OsBr₄Py₂] ( 3 ) (triclinic, space group P1, a = 9.132(3), b = 12.053(3), c = 15.398(2) Å, α = 95.551(18), β = 94.12(2), γ = 106.529(19)°, Z = 2). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry for the anion of 1 and D_2h point symmetry for the anions of 2 and 3 the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants of 1 are in the Cl–Os–Cl axis f_d(OsCl) = 1.58, in the asymmetrically coordinated N′–Os–Cl ^· axes f_d(OsCl ^· ) = 1.45, f_d(OsN′) = 2.48, of 2 f_d(OsCl) = 1.62, f_d(OsN) = 2.42 and of 3 f_d(OsBr) = 1.39 and f_d(OsN) = 2.34 mdyn/Å.     

On the structure of H2Os3(CO)12

Infrared, far-infrared and Raman data are reported and discussed for H₂Os₃(CO)₁₂. ¹³C NMR studies for H₂Os₃(CO)₁₂ are also reported. These data are consistent with a linear arrangement of the three osmium atoms with terminal hydrides occupying equatorial positions on the end osmium atoms.     

Cobalt titanate–cobalt oxide composite thin films deposited from heterobimetallic precursor

A single molecular heterobimetallic complex, [Co₂Ti(μ₃‐O)(TFA)₆(THF)₃] (1) [TFA = trifluoroacetate, THF = tetrahydrofuran], was synthesized, structurally and spectroscopically characterized and implemented as a single‐source precursor for the preparation of CoTiO₃–CoO composite thin films by aerosol‐assisted chemical vapour deposition (AACVD). The precursor complex was prepared by interaction of Co(OAc)₂.4H₂O [OAc = (CH₃COO^?)] with Ti(iso‐propoxide)₄ in the presence of trifluoroacetic acid in THF, and was analysed by melting point, CHN, FT‐IR, single‐crystal X‐ray diffraction and thermogravimetric analysis. The precursor complex thermally decomposed at 480 °C to give a residual mass corresponding to a CoTiO₃–CoO composite material. Good‐quality crystalline CoTiO₃–CoO composite thin films deposited at 500 °C by AACVD and characterized through powder X‐ray diffraction and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy show that the crystallites have a rose‐flower‐like morphology with an average petal size in the range of 2–6 µm. Copyright © 2012 John Wiley & Sons, Ltd.