Synthesis of tetramethyldisilane-bridged bis(1-indenyl) tetracarbonyl di-iron: A novel thermal rearrangement reaction between the Si-Si and Fe-Fe bonds

The title complex (Me₂SiSiMe₂)(η⁵-l-indenyl)Fe(CO)]₂(μ-CO)₂ (1) was prepared by the reaction of 1,2-bis(1-indenyl)tetramethyl-disilane and Fe(CO)₅ in refluxing heptane. Its thermal rearrangement product [Me₂Si(η⁵-1-indenyl)Fe(CO)₂]₂ (2) was also obtained from the reaction. 1 in refluxing xylene can be readily converted into 2. The crystal structures of the cis isomer 1c and the trans isomer 2t were determined by X-ray diffraction.     

Neodymium Complex Obtained from Reductive-coupling of Carbodiimide: Synthesis and Structure of [(Cp")2Nd(NR)2C-C(NR)2Nd(Cp")2]

A bimetallic oxalamidino complex of neodymium [(Cp")₂Nd(NR)₂C-C(NR')₂Nd(Cp")₂][Cp"=η⁵-C₅H₃-1,3-(SiMe₃)₂, R=C₆H₁₁](2) was obtained via reaction between NdI₂ and carbodiimide[RN=C=NR] (R=C₆H₁₁)(molar ratio 1:1) in tetrahydrofuran(THF) solution, followed by the addition of [KCp"(THF)](1)(molar ratio 1:2) at a low temperature through a reductive-coupling reaction with carbodiimide. The structure of the intermediate product was confirmed by means of elemental analysis, ¹H NMR and ¹³C NMR. Characterization of the product by single crystal X-ray diffraction confirmed the diamidinate type of structure.     

La-NMR-spektroskopie an allyllanthan(III)-komplexen

¹³⁹La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C₄H₈O₂)_3/2 [La(ν³-C₃H₅)₄], [Li(C₄H₈O₂)₂][Cp′_nLa(ν³-C₃]H₅)_4−n] (Cp′ = Cp(ν⁵-C₅H₅); n = 1, 2 and Cp′ = Cp * (ν⁵-C₅Me₅); N = 1) and Li[R_nLa(ν³-C₃H₄)₄−n] (R = N(SiMe₃)₂; n = 1, 2 and R = CCsIMe₃; n = 4), as well as for neutral compounds for formulae La(ν³-C₃H₅)₃L_n (L = (C₄H₈O₂)_1.5, (HMPT)₂, TMED), Cp′_nLa(ν³-C₃H₅)_3−n (Cp′= Cp(ν⁵-Cp₅H₅), Cp *(ν⁵-C₅Me₅); n = 1, 2) and La(ν³-C₃H₂)₂X(THF)₂ X = Cl, Br, I). Typical ranges of the ¹³⁹La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum.

Zusammenfassung

¹³⁹La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung ]- [La)ν³-C₃H₅)₄, [Li(C₄H₈)₂][Cp′_nLa(ν³-C₃H₅)_4−n(Cp′ = Cp(ν⁵-C₅H₅); n = 1, 2 und Cp′ = Cp * (ν⁵-C₅Me₅); N = 1) und Li[R_nLa(ν³-C₃H₅)_4−n (R = B(SiMe₃)₂; n = 1, 2 und R = CCSiMe₃; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν³-C₃H₅)₃L_n (L_n = (C₄H₈O₂)_1.5, (HMPT)₂, TMED), Cp′_n, La(ν³-C₃H₅)_3−n (Cp′ = Cp(ν⁵-C₅H₅), Cp * (ν⁵- Cp₅Me₅); n = 1, 2) und La(ν³-Cp₃H₅)₂X(THF)₂ (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt.     

Reactions of Lewis bases with tetrakisdiphenylamide uranium(IV)

The coordinatively unsaturated uranium(IV) complex U[N(C₆H₅)₂]₄ has been prepared via the stoichiometric reaction of diphenylamine with [(Me₃Si)₂N]₂ H₂. U[N(C₆H₅)₂]₄ coordinates Lewis bases such as Et₂O, THF, pyridine or (EtO)₃PO, based on electronic absorption spectroscopy and ¹H NMR studies. Exchange between U[N(C₆H₅)₂]₄ and U[N(C₆H₅)₂]₄(L), where L is THF or pyridine, is rapid on the NMR time-scale between 307 and 323 K. Measurement of equilibrium constants for L = THF provides ΔH and ΔS values of −60 kJ mol⁻¹ and −1.8 × 10² J K⁻¹ mol⁻¹, respectively. U[N(C₆H₅)₂]₄ coordinates and binds (EtO)₃PO much more tightly (K_eq = & > 10⁴ M⁻¹) than THF or pyridine with the exchange rate between U[N(C₆H₅)₂]₄ and U[N(C₆H₅)₂]₄[OP(OEt)₃] being close to the NMR time-scale.     

Ring-opening metathesis polymerization of norbornene and norbornadiene by tungsten(II) and molybdenum(II) complexes

The reaction of norbornene (NBE) and norbornadiene (NBD) in the presence of seven-coordinate tungsten(II) and molybdenum(II) complexes of the [(CO)₄M(μ-Cl)₃M(SnCl₃)(CO)₃] and [MCl(M′Cl₃)(CO)₃(NCMe)₂] (M=W, Mo; M′=Sn, Ge) types leads to ring-opening metathesis polymerization (ROMP) and to the formation of high molecular weight polymers. The geometric structure of these polymers was determined by means of ¹H- and ¹³C-NMR spectroscopy. The monitoring of the reaction between cyclic olefins and the metal complex by means of ¹H-NMR spectroscopy allowed us to observe the coordination of NBD to metal atoms in the initiation step of the polymerization process. Compounds of the [MCl(SnCl₃)(CO)₃(η⁴-NBD)] type prepared directly from [(CO)₄M(μ-Cl)₃M(SnCl₃)(CO)₃] or [MCl(M′Cl₃)(CO)₃(NCMe)₂] (M=W, Mo) in the presence of an excess of NBD initiate the ROMP reaction immediately. The detection of the first-formed products in the reaction between the metal complex and cyclic olefins provides valuable information concerning the nature of the initiating species.     

Synthesis and characterisation of the methylene-inserted mixed-chalcogenide compounds Fe2(CO)6(μ-SeCH2Te) and Fe2(CO)6(μ-SCH2Te)

The methylene-bridged, mixed-chalogen compounds Fe₂(CO)₆(μ-SeCH₂Te) (1) and Fe₂(CO)₆(μ-SCH₂Te) (3) have been synthesised from the room temperature reaction of diazomethane with Fe₂(CO)₆(μ-SeTe) and Fe₂(CO)₆(μ-STe), respectively. Compounds 1 and 3 have been characterised by IR, ¹H, ¹³C, ⁷⁷Se and ¹²⁵Te NMR spectroscopy. The structure of 1 has been elucidated by X-ray crystallography. The crystalsare monoclinic,space group P2₁/n, A = 6.695(2), B = 13.993(5), C = 14.007(4)Å, β = 103.03(2)°, V = 1278(7) ų, Z = 4, D_c = 2.599 g cm⁻³ and R = 0.030 (R_w = 0.047).     

Synthesis, structure and hydrogenation catalytic activity of [Ru3(μ3,η-ampy)(μ,η:η-PhC=CHPh)(CO)6(PPh3) (Hampy = 2-amino-6-methylpyridine)

The compound [RU₃(μ₃,η²- -ampy)(μ₃η¹:η²-PhC=CHPh)(CO)₆(PPh₃)₂] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU₃(η-H)(μ₃,η²- ampy) (μ,η¹:η²-PhC=CHPh)(CO)₇(PPh₃)] with triphenylphosphine at room temperature. However, the reaction of [RU₃(μ-H)(μ₃, η² -ampy)(CO)₇(PPh₃)₂] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU₃(μ₃,η²-ampy)(μ,η ¹:η² -PhC=CHPh)(μ,-PPh₂)(Ph)(CO)₅(PPh₃)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H₂), although progressive deactivation of the catalytic species is observed. The dihydride [RU₃(μ-H)₂(μ ₃,η²-ampy)(μ,η¹:η²- PhC=CHPh)(CO)₅(PPh₃)₂] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.     

An improved synthetic method and vibrational study of (pentamethylcyclopentadienyl) dicarbonylrhenium dihalides (η-C5Me5)Re(CO)2X2 (X = C1, Br and I)

An improved synthetic method has been found for the preparation of the pentamethylcyclopentadienyl rhenium dicarbonyldihalide complexes. From the reaction of (η⁵-C₅Me₅)Re(CO)₃ with Br₂ or I₂ in THF-H₂O a mixture of cis and trans isomers of (η⁵-C₅Me₅)Re(CO)₂X₂ X = Br and I is formed. On the other hand, the reaction of [(η⁵-C₅Me₅)Re(CO)₃C1][SbC1₆] in water gives the cis-(η⁵-C₅Me₅)Re(CO)₂C1₂ complex. The solid IR spectra of the dicarbonyldihalide complexes are recorded and an assignment of the normal modes in terms of local symmetry is suggested by comparison with those observed in analogous molecules. A normal coordinate analysis performed using a modified general valence force field and considering simplified models, confirms most of the experimental assignments. The set of valence force constants reflects the structure of the isomers under study.     

Substituted cyclopentadienyl ligands—10. Intramolecular steric interactions in [(η-C5H3(SiMe3)2)Mo(CO)2(L)I]

Reaction of C₅H₄(SiMe₃)₂ with Mo(CO)₆ yielded [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₃]₂, which on addition of iodine gave [(η⁵-C₅H₃(SiMe₃)₂Mo(CO)₃I]. Carbonyl displacement by a range of ligands: [L = P(OMe)₃, P(OPrⁱ)₃,P(O-o-tol)₃, PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(m-tol)₃] gave the new complexes [(η⁵-C₅H₃(SiMe₃)₂ MO(CO)₂(L)I]. For all the trans isomer was the dominant, if not exclusive, isomer formed in the reaction. An NOE spectral analysis of [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₂(L)I] L = PMe₂Ph, P(OMe)₃] revealed that the L group resided on the sterically uncongested side of the cyclopentadienyl ligand and that the ligand did not access the congested side of the molecule. Quantification of this phenomenon [L = P(OMe)₃] was achieved by means of the vertex angle of overlap methodology. This methodology revealed a steric preference with the trans isomer (less congestion of CO than I with an SiMe₃ group) being the more stable isomer for L = P(OMe)₃.     

Stabile Bis(η-alkin)MCl2-komplexe; Darstellung und reaktivität

The synthesis and reactivity of {(η⁵-C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂} MCl₂ (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η⁵-C₅H₄SiMe₃) ₂Ti(CSiMe₃)₂ (1) with equimolar amounts of MCl₂ (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂ (1) and [Fe(dipy)₂]Cl₂ (5a) or [Fe(phen)₂]Cl₂ (5b). 1/n[Cu^IHal]_n (6) or 1/n[Ag^IHal]_n (7) (Hal = Cl, Br) react with {(η⁵ -C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂}FeCl₂ (3a), by replacement of the FeCl₂ building block in 3a, to yield the compounds {(η⁵-C₅H₄SiMe₃)₂Ti(C CSiMe₃)₂}Cu^IHal (8) or {(η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂}Ag^IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me₃SiCC-units is η²-coordinated to monomeric Cu^I Hal or Ag^IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η⁵-C₅H₄SiMe₃)₂ Ti(CSiMe₃)₂ (1) with 1/n[Cu^IHal]_n (6) or 1/n [Ag^IHal]_n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, ¹H-NMR, MS). The magnetic moments of compounds 3 were measured.     

Synthesis and application of diphenylbis (3,5-dimethylpyrazol-1-yl)methane to form η-arene complexes of molybdenum

The neutral nitrogen-bidentate ligand, diphenylbis(3,5-dimethylpyrazol-1-yl)methane, Ph₂CPz′₂, can readily be obtained by the reaction of Ph₂CCl₂ with excess HPz′ in a mixed-solvent system of toluene and triethylamine. It reacts with [Mo(CO)₆] in 1,2-dimethoxyethane to give the η²-arene complex, [Mo(Ph₂CPz′₂)(CO)₃] (1). This η²-ligation appears to stabilize the coordination of Ph₂CPz′ ₂ in forming [Mo(Ph₂CPz′₂)(CO)₂(N₂C₆H₄NO₂-p)][BPh₄] (2) and [Mo(Ph₂CPz′₂)(CO)₂(N₂Ph)] [BF₄] (3) from the reaction of 1 with the appropriate diazonium salt but the stabilization seems not strong enough when [Mo{P(OMe)₃} ₃(CO)₃] is formed from the reaction of 1 with P(OMe)₃. The solid-state structures of 1 and 3 have been determined by X-ray crystallography: 1-CH₂Cl₂, monoclinic, P2₁/n, a = 11.814(3), b = 11.7929(12), c = 19.46 0(6) Å, β = 95.605(24)°, V = 2698.2(11) ų, Z = 4, D_calc = 1.530 g/cm³ , R = 0.044, R_w = 0.036 based on 3218 reflections with I > 2σ(I); 2 (3)-1/2 hexane-1/2 CH₃OH-1/2 H₂O-1 CH₂Cl₂, monoclinic, C2/c, a = 41.766(10), b = 20.518(4), c = 16.784(3) Å, β = 101.871(18)°, V = 14076(5) ų, Z = 8, D_calc = 1.457 g/cm³, R = 0.064, R_w = 0.059 based on 5865 reflections with I > 2σ(I). Two independent cations were found in the asymmetric unit of the crystals of 3. The average distance between the Mo and the two η²-ligated carbon atoms is 2.574 Å in 1 and 2.581 and 2.608 Å in 3. The unfavourable disposition of the η²-phenyl group with respect to the metal centre in 3 and the rigidity of the η²-arene ligation excludes the possibility of any appreciable agostic C---H → Mo interaction.     

The lively chemistry of the di-μ-methylene-bis(pentamethylcyclopentadienyl-rhodium) complexes, analogues of surface reactions in heterogeneous catalysis

The chemistry of the di-μ-methylene-bis(pentamethylcyclopentadienyl-rhodium) complexes is reviewed. The complex [{(η⁵-C₅Me₅)RhCl₂}₂] (1a) reacted with MeLi to give, after oxidative work-up, blood-red cis-[{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(Me)₂], 2. This has the two rhodiums in the +4 oxidation state (d⁵), and linked by a metal-metal bond (2.620 Å). Trans-2 was formed on isomerisation of cis-2 in the presence of Lewis acids, or by direct reaction of 1a with Al₂Me₆, followed by dehydrogenation with acetone. The Rh-methyls in [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(Me)₂] were readily replaced under acidic conditions (HX) to give [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(X)₂] (X = Cl, Br or I); these latter complexes reacted with a variety of RMgX to give [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(R)₂] (R = alkyl, Ph, vinyl, etc.). Trans-2 also reacted with HBF₄ in the presence of L to give first [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(Me)(L)]⁺ and then [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(L)₂]²⁺ (L = MeCN, CO, etc.). The {(η⁵-C₅Me₅)Rh(μ-CH₂)}₂ core is rather kinetically inert and also forms a variety of complexes with oxy-ligands, both cis-, e.g. [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(μ-OAc)]⁺ and trans-, such as [(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(H₂O)₂]²⁺. The complexes [{(η⁵-C₅Me₅)Rh(μ-CH₂)}₂(R)L]⁺ (R = Me or aryl) in the presence of CO, or [{(η⁵-C₄Me₅)Rh(μ-CH₂)}₂(R)₂] (R = Me, Ph or CO₂Me) in the presence of mild oxidants, readily yield the C---C---C coupled products RCH=CH₂. The mechanisms of these couplings have been elucidated by detailed labelling studies: they are more complex than expected, but allow direct analogies to be drawn to C---C couplints that occur during Fischer-Tropsch reactions on rhodium surfaces.     

Bis(η-pentamethylcyclopentadienyl)-and(ηcyclopentadienyl) (η-pentamethylcyclopentadienyl)-platinium dications: Pt(IV) metallocenes

Reaction of [Pt₂(η⁵-C₅Me₅)₂(η-Br)₃]³⁺(Br⁻)₃ with C₅R₅H (R = H,Me) in the presence of AgBF₄ gives the first platinocenium dications, [Pt(η⁵-C₅Me₅)(η⁵-C₅R₅)]²⁺(BF₄⁻ )₂. On electrochemical reduction, [pt(η⁵-C₅Me₅)₂]²⁺ yields [Pt(η⁴-C₅Me₅H)(η²-C₅Me₅)]+ BF₄⁻. kw]Cyclopentadienyl; Metallocenes; Platinum; Electrochemistry     

Synthese und reaktivität von dienylmetall-verbindungen : XXVII. Ein einfacher weg zur synthese von cyclopentadienylcobalt(III)-dikationen

CpCo(CO)₂ is oxidised by [Cp₂Fe]BF₄ (Cp = C₅H₅) in the presence of neutral ligands L to give the dications [CpCoL₃]²⁺ (L = SMe₂, S(n-C₄H₉)₂, PMe₃, C₅H₅N, MeCN; Me = CH₃). In [CpCo(SMe₂)₃]²⁺, sulfane ligands are substituted by neutral ligands L, L---L and L---L---L, to give the complexes [CpCoL₃]²⁺ (L = SeMe₂, TeMe₂, PMe₃, P(OMe)₃, AsMe₃, SbMe₃, t-C₄H₉NC, C₅H₅N, MeCN), [Cp-Co(L---L)SMe₂]²⁺ (L---L = R₂P(CH₂)_nPR₂, n = 1, 2, R = C₆H₅; bipyridine, o-phenanthroline, neocuproin) and [CpCo(L---L---L)]²⁺ (L---L---L = RP(CH₂CH₂PR₂)₂, R = C₆H₅). The dications react with iodide resulting in the monocations [CpCoL₂I]⁺ and [CpCo(L---L)I]⁺. Azacobaltocinium cations [CpCo(C₄R₂H₂N)]⁺ (R = H, CH₃) are obtained by reaction of [CpCo(SMe₂)₃]²⁺ with metal pyrrolides.     

P and C NMR investigation of the system tetracarbonyldi-μ-chlorodirhodium(I) — tertiary phosphine

¹³C and ³¹P{¹H} NMR data at low temperature prompted us to characterize cis-[Rh(CO)₂(PR₃)Cl] (3) (3a, PR₃ = PPh₃; 3b, PR₃ = PMe₂Ph), as surprisingly stable products of the reaction between [{Rh(CO)₂(μ-Cl)}₂] (1) and tertiary phosphines in toluene (P : Rh = 1). Every attempt to isolate solid 3a led to the cis- and trans- halide-bridged dimers [{Rh(CO)₂(μ-Cl)}₂] (5a) and 6a which are formed from 3a by slow decarbonylation, a process which is greatly accelerated by the evaporation of the solvent under vacuum.

The analogous reaction of 1 with dimethylphenylphosphine follows a similar pathway; in this case, however, low temperature NMR spectra allowed us to characterize the pentacoordinated dinuclear species [{Rh(CO)₂(μ-Cl)}₂] (2b) as the unstable intermediate of the bridge-splitting process.

The reaction of 3 with a second equivalent of phosphine (P : Rh = 2) leads, at room temperature, to the well known product trans-[Rh(CO)(PR₃)₂Cl] (8) accompanied by evolution of CO; however our data show that when the reaction is performed at 200 K, decarbonylation is prevented and spectroscopic evidence of trigonal bipyramidal pentacoordinate [Rh(CO)₂(PR₃)₂Cl] (7), stable only at low temperature, can be obtained.     

The chemistry of compounds of the type Ru(η---C5Me4Et)(CO)2X (X=Cl, Br or I)

The title compounds react with unidentate ligands, L, containing either phosphorus or arsenic donor atoms to yield the corresponding compounds of the type Ru(η⁵---C₅Me₄Et)(CO)LX; with didentate phosphorus donor ligands the major species formed is the bridged complex {Ru(η⁵---C₅Me₄Et)(CO)X}₂{Ph₂P(CH₂)_nPPh ₂} n = 1, X = Br; n = 2, X = Cl). In contrast, unidentate ligands containing nitrogen donor atoms such as pyridine did not react with Ru(η⁵---C₅Me₄Et)(CO)₂Cl although reaction with 1,10-phenanthroline or diethylenetriamine yielded the ionic products [Ru(η⁵---C₅Me₄Et)(CO)L]⁺Cl⁻ (L = phen or (NH₂CH₂CH₂)₂NH). Reaction of Ru(η⁵---C₅Me₄Et)(CO)₂Br with AgOAc yielded the corresponding acetato complex Ru(η⁵---C₅Me₄Et)(CO)₂0Ac. Ru(η⁵--- C₅Me₄Et)(CO)₂X reacts with AgY (Y = BF₄ or PF₆) in either acetone or dichloromethane to give the useful solvent intermediates [Ru(η⁵---C₅Me₄Et)(CO)₂(solvent)]⁺Y⁻, which readily react with ligands L to yield ionic derivatives of the type [Ru(η⁵---C₅Me₄Et)(CO)₂L]⁺Y⁻ (where L = CO, NCMe, py, C₂H₄ or MeO₂CCCCO₂Me).     

Photochemical reactions of the isostructural 17- and 18-electron complexes (η-C5H5)M(Me)PPh3 (M=Co, Ni)

The photochemical reactions of the title complexes were studied in air-free benzene solution. In both cases photolysis leads to the production of complexes of the formula (η⁵-C₅H₅)M(PPh₃)₂. Both reactions are the result of the initial loss of a methyl radical from the excited state. The primary photoproduct, (η⁵-C₅H₅)MPPh₃ (M=CO, Ni), then scavenges neutral ligands from the solution to yield, in the case of PPh₃, (η⁵-C₅H₅)M(PPh₃)₂. In the absence of uncoordinated ligand in the reaction solution, the cobalt derivative reacts with the starting material to yield (η⁵-C₅H₅)Co(PPh₃)₂, a methyl radical and (η⁵-C₅H₅)Co(solvent)_n.     

Synthesis and crystal structure of a novel mixed valence tri-iron complex salt: [hexakis(thiazole)iron(II)][μ-oxo- bis(trichloroiron(III))]

The title compound, [Fe(tz)₆][Fe₂OCl₆] (1) (tz = thiazole) has been synthesized under argon by the reaction of anhydrous FeCl₃ with thiazole in ethanol. 1 crystallises in the cubic space group (no. 205) with a = 15.001(5) Å, V = 3375(2) ų, Z = 4, R = 0.061 and R_w = 0.073. 1 consists of a face-centered cubic array of [Fe(tz)₆]² cations, with the oxo-bridged [Fe₂OCl₆]²⁻ anion occupying the cell and edge centres.     

新型磷-钒-氧层状化合物[H2en]2[H3O]6[Co(H2O)2(VO)8(OH)4(PO4)8]的水热合成与晶体结构

金属磷酸盐材料在吸附、离子交换、离子传导和催化剂方面有潜在的应用前景[1～5]. 近年来, 通过水热反应合成了一些A-V-P-O化合物. 在这些化合物中, A一般为碱金属或有机阳离子, 如层状结构的[H2N(C4H8)2NH2][(VO)4(OH)4(PO4)2][6] 和[H2N(C2H4)3NH2][(VO)8(HPO4)3(PO4)4*(OH)2]*2H2O[6], 一维链状结构的 [H2NCH2CH2NH3(VO)(PO4)][7], 手性双螺旋结构的 [(CH3)2NH2]K4[(VO)10(H2O)2(OH)4(PO4)7]*H2O[8]以及具有三维骨架结构的化合物 [H3N(CH2)3NH3K(VO)3(PO4)3][9], [H3N(CH2)3NH3]2[V(H2O)2(VO)6(OH)2(HPO4)3(PO4)5]*3H2O[10]和[H3N(CH2)2NH3][(VO)3(H2O)2(PO4)2(HPO4)4][11].     

Mixed-metal cluster chemistry Part 20. Syntheses, crystal structures and electrochemical studies of W2Ir2(μ-L)(CO)8(η-C5H4Me)2 (L=dppe, dppf)

The 60-electron tetrahedral clusters W₂Ir₂(μ-L)(CO)₈(η⁵-C₅H₄Me)₂ [L=dppe (2), dppf (3)] have been prepared from reaction between W₂Ir₂(CO)₁₀(η⁵-C₅H₄Me)₂ (1) and the corresponding diphosphine in 52 and 66% yields, respectively. A structural study of 2 reveals that three edges of a WIr₂ face are spanned by bridging carbonyls, that the iridium-ligated diphosphine coordinates diaxially and that the tungsten-bound methylcyclopentadienyls coordinate axially and apically with respect to the plane of bridging carbonyls. A structural study of 3 reveals that the dppf ligand bridges an Ir---Ir bond which is also spanned by a bridging carbonyl; tungsten-ligated methylcyclopentadienyl ligands and terminal carbonyls result in electronic asymmetry (17e and 19e iridium atoms) in the electron-precise cluster. Both clusters show two reversible one-electron oxidation processes and an irreversible two-electron reduction; the dppf-containing cluster 3 has a further, irreversible, one-electron oxidation process. UV–vis-NIR spectroelectrochemical studies of the 2→2⁺→2²⁺ progression reveal the appearance of a low-energy transition on oxidation to 2⁺ which persists on further oxidation to 2²⁺.