Zur koordination mehrfunktioneller thioether in cyclopentadienyleisen-komplexen

[C₅H₅Fe(CO)₂thf]⁺ reacts with the ligands LL and LLL to give the cations [C₅H₅Fe(CO)₂LL]⁺ (LL = RS(CH₂)_nSR, 1,4-dithiane) and [C₅H₅Fe(CO)₂LLL]⁺ (LLL = 1,3,5-trithiane, tris(methylmercapto)methane) containing monodentate coordinated sulfur ligands. In a similar way, sulfur ligand bridged dinuclear dications [(C₅H₅Fe(CO)₂)₂(μ-LL)]²⁺ and [(C₅H₅Fe(CO)₂(μ-LLL)]²⁺ and tri-nuclear trications [(C₅H₅Fe(CO)₂)₃(μ-LLL)]³⁺ are formed. Irradiation of the mononuclear cations gives the chelate complexes [C₅H₅Fe(CO)(η²-LL)]⁺.     

The preparation and structure of μ-iodobis(h5-cyclopentadienyldicarbonyliron) fluoroborate

The identity and structure of a compound which arises frequently in the generation of (h⁵-C₅H₅)Fe(CO)₂⁺ ion from (h⁵-C₅H₅)Fe(CO)₂I and AgBF₄ have been determined. The substance was shown to be {[h⁵-C₅H₅)Fe(CO)₂]₂I}BF_4s a compound already known from the work of Fischer and Moser. It consists of a BF₄^? anion and a cation formed by two (h⁵-C₅H₅)Fe(CO)₂, groups having the expected shape and dimensions, united by a bridging iodine atom. The FeI bonds have an average lenght of 2.588 » and the FeIFe angle is 110.8(1)°. The FeFe distance of 4.26 » is consistent with the expectation that there should be no metalmetal bond. Presumably the large FeIFe angle results from a compromise between the tendency of I to maximize p character in its bonding orbitals and the necessity of niminizing non-bonded contact between the (h⁵-C₅H₅)Fe(CO)₂ groups. Crystallographic data are: space group, P2/a; unit cell dimensions, a=15.605(2)», b=9.607(2)», c=12.373(2)», β=104.86(1)°, V=1792.9(6)»³; d_ealc=2.10 g/cm³ for Z=4; d_obs=2.08±0.02 g/cm³. Refinement using 1595 independent reflections with F_o²>3σ(F_o² was terminated at residuals of R₁=0.076 and R₂=0.114.     

The [Cp(CO)2Fe] (Fp) group as a donor in donor/acceptor substituted disilanes: synthesis,structure and electronic properties of FpSi2Me4C6H4CHC(CN)2

UV–vis absorption spectroscopy and cyclic voltammetry are used to study electronic interactions in the donor/acceptor substituted disilane FpSi₂Me₄C₆H₄CHC(CN)₂ (Fp=η⁵-C₅H₅Fe(CO)₂) (1). The synthesis of 1 was achieved by a conventional chemical route, the model substances FpSiMe₃ (2), FpSi₂Me₅ (3) and FpSi₂Me₄C₆H₅ (4) were obtained by the electrolysis of Fp₂ in the presence of the appropriate chlorosilane. The structure of 1, determined by X-ray diffraction, exhibits an all-trans-array of the FeSiSiC_aryl fragment, a basic requirement for optimal through-bond interaction. UV–vis and CV data indicate strong intramolecular donor/acceptor interaction in 1.     

Permetalloplumbanes: Preparation of [Pb{Co(CO)3(L)}4] and [Pb{Fe(CO)2(NO)(L)}4].: Complexes containing four transition metal to lead bonds (L = tertiary arsine,phosphine or phosphite).

The sole and unexpected products from the reactions of a variety of lead (II) and lead (IV) compounds with [Co₂(CO)₆(L)₂] complexes (L = tertiary arsine, phosphine, or phosphite) in refluxing benzene solution are the blue, air-stable percobaltoplumbanes [Pb{Co(CO)₃(L)}₄]. These have also been obtained from the reaction of Na[Co(CO)₃(L)] (L  PBu₃ⁿ) with lead (II) acetate which with Na[Fe(CO)₂(NO)(L)] forms the isoelectronic [Pb{Fe(CO)₂(NO)(L)}₄] [L  P(OPh)₃]. The IR spectra of the complexes in the v(CO) and v(NO) regions are consistent with tetrahedral PbCo₄ or PbFe₄ fragments, trigonal bipyramidal coordination about the cobalt or iron atoms and linear PbCoAs, PbCoP, or PbFeP systems. Unlike [Pb{Co(CO)₄}₄], our complexes do not dissociate to [Co(CO)₃(L)]^? or [Fe(CO)₂(NO)(L)]^? ions when dissolved in donor solvents.     

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: XXXII. Insertions- und metathesereaktionen von metallorganischen eisen-selen-komplexen

The compound (μ-Se)[η⁵-C₅H₅)Fe(CO)₂]₂ (1) has labile metalselenium bonds and therefore undergoes insertion and metathesis reactions. Thus, reaction with elemental selenium gives the novel FeSeSeFe chain-type complex (μ,η¹:η¹-Se₂)[(η⁵-C₅H₅)Fe(CO)₂]₂ (2). Both compounds 1 and 2 react with the homodinuclear chromium complex [(η⁵-C₅H₅)Cr(CO)₃]₂ with formation of the heterodinuclear derivatives of composition (η⁵-C₅H₅)₂CrFe(CO)₅. (3; single-crystal X-ray structure: d(CrFe) 290.1(1) pm) and (μ-Se₂)[(η⁵-C₅H₅)₂CrFe(CO)₄] (4). The latter compound exhibits a diselenido bridge ligand in η¹:η²-coordination (single-crystal X-ray structure: d(CrSe) 249.5(2) and 255.5(2) pm, d(FeSe) 238.9(2), d(SeSe) 229.7(1) pm) and can also be obtained by treatment of the chromium complex 3 with elemental selenium.     

Kinetic determination of the metalmetal bond dissociation energy in bis(dicarbonyl η5-cyclopentadienyliron)

The ironiron bond energy in [C₅H₅Fe(CO)₂]₂ (I) has been determined by measuring the rate of disproportionation of the monoacetyl complex (AcC₅H₄)(C₅H₅)Fe₂(CO)₄ (II) to I and [AcC₅H₄Fe(CO)₂]₂ (III). The reaction follows first order kinetics in benzene solution in the temperature range of 60–100°C with activation parameters calculated as: ΔH^≠ = 26.9 ± 2.7 kcal mol^?1 and ▽s^≠ = 2.0 ± 3.2 cal mol^?1 deg^?1.     

Syntheses of σ-cyclobut-1-en-3-onyl complexes by cycloaddition of ketenes to some transition metal alkynyl complexes

Reactions of ketenes (R¹R²CCO) with (η⁵-C₅H₅)Ni(PPh₃)CCR (I) and (η⁵-C₅H₅)Fe(CO)(L)CCR (III, L = CO and PPh₃) give σ-cyclobut-1-en-3-onyl complexes, {(η⁵-C₅H₅)Ni(PPh₃)$\text{CC(R)COC}$}R¹R² (VI) and (η⁵-C₅H₅)Fe(CO)(L)$\text{CC(R)COC}$R¹R² (IX)}, (2 + 2) cycloaddition products, in good yields. The σ-cyclobutenonyl complexes also can be prepared by the reaction of I and III with acyl chlorides in the presence of triethylamine.     

Lineare oligophosphaalkane: XVIII. Addition Ph-funktioneller methylenbisphosphane an die MoMo-Dreifachbindun in (η5-C5H5)2Mo2(CO)4

By means of the addition of the PH-functional methylenebisphosphanes R¹R²-PCH₂PR³H (PCP) to the MoMo triple bond in (η⁵-C₅H₅)₂Mo₂(CO)₄(MoMo) the complexes (η⁵-C₅H₅)₂Mo₂(CO)₄(PCP) containing a five-membered ring system Mo₂P₂C are obtained. Starting with unsymmetrically substituted methylenebisphosphanes R′₂PCH₂PRH only one isomer is formed, while the disecondary derivatives RHPCH₂PHR (as the diastereomeric mixture) gave two isomers of (η⁵-C₅H₅)₂Mo₂(CO)₄(PCP) (A₂ and AB) as indicated by the ³¹P{¹H} and ¹³C{¹H} NMR spectra.X-ray structural analysis of the derivative of the racemate of t-BuHPCH₂PH(t-Bu) space group C2/c, monoclinic, a 18.034(2), b 14.909(1), c 11.106(1) Å, α 90, β 99.788(8), γ 90°) reveals a puckered Mo₂P₂C five-membered ring system (dihedral angle PMoMo′P′ 54.4(2)°) with square-pyramidal coordination geometry at the Mo atoms. Two of the CO ligands (C(6)O(1) and C(6′)O(1′)) are almost coplanar with the molybdenum atoms, while the terminal CO groups (C(7)O(2) and C(7′)O(2′)) are about orthogonal (dihedral angle C(7)MoMo′C(7′) 88.4(3), MoMo′ 3.2109(4), MoP 2.4567(8), PC(8) 1.834(3), PH(P) 1.37(3) Å).     

Electrochemistry of platinum(II) coordination compounds II. Electroreduction of trimetallic dimetalliobis(isocyanide)platinum(II) complexes

Linear trimetallic MPPt^IIL₂M complexes (M = Cr(CO)₃(η-C₅H₅), Mo(CO)₃- (η-C₅H₅), W(CO)3(η-C₅-H₅), Mn(CO)₅, Fe(CO)₃NO, Co(CO)₄; L = t-BuNC, cyclo- C₀H₁₁ NC) are reduced on platinum and gold electrodes in non-aqueous medium. All these complexes undergo irreversible one electron reductions, which result in the rupture of one Ptmetal bond and the liberation of one M^? ion per mole reduced. Coupled ESR spectroscopy and coulometry show that a radical is generated during the reduction of the trimetallic complexes. The several ESR signals obtained for these paramagnetic Pt¹ species exhibit no hyperfine structure.The electrochemical behaviour of MPtL₂M complexes is compared with that of the following linear trimetallic complexes: MHgM and (MAuM)^?.     

Evidence for enhanced reactivity in the photofragmentation of the bridged dinuclear system Me2Si[η5-C5H4Fe(CO)2(η1-CH2C6H5)]2

Experimental evidence that the dinuclear complex Me₂Si[η⁵-C₅H₄Fe(CO)₂-(η¹-CH₂C₆H₅)]₂ shows enhanced reactivity over its mononuclear analogy η⁵-C₅H₅Fe(CO)₂(η¹-CH₂C₆H₅ in photogragmentation to produce bibenzyl and FeFe bonded product is presented. Information from a series of competition and crossover experiments indicate that two factors are involved in the enhancement: (1) the ability to photochemically produce a 16-electron unsaturated benzyl unit in close proximity to a saturated partner, and (2) the inability of the FeFe bonded species 4 to quench free benzyl radicals in solution. Chemical reaction of Me₂Si[η⁵-C₅H₄Fe(CO)₂(η¹-CH₂C₆H₅)]₂ with Me₃NO produces bibenzyl and establishes that loss of CO is the initial step in the fragmentation reaction. In addition, trapping experiments with 9,10-dihydroanthracene show that bibenzyl is formed from free benzyl radical; BBased on these results an overall mechanism is proposed.     

Alkylidenverbrückte diphosphane und dichlalkogenodiphosphorane als liganden in kationischen cyclopentadienyleisencarbonyl-komplexen

Oxidative cleavage of the FeFe bond in [C₅H₅Fe(CO)₂]₂ in the presence of alkylide-bridged diphosphanes LL (LL = (C₆H₅)₂P(CH₂)_n(P(C₆H₅)₂; n = 1–3), (C₆H₅)₂PCH₂As(C₆H₅)₂ and dichalcogenodiphosphoranes (X)LL(X) ((X)LL(X) = (C₆H₅)₂P(X)(CH₂)_n(X)P(C₆H₅)₂; X  O, S, Se; n = 1–3) yields the complexes [C₅H₅Fe(CO)₂L′]BF₄ (L′ = LL, (X)LL(X); X  S, Se) in high yield. the complexes react with Ni(CO)₄ under photochemical conditions to form [C₅H₅Fe(CO)₂(μ-L′)Ni(CO)₃]BF₄ in quantitative yield, and lose a CO group under irradiation (λ_max > 300 nm) to form the chelate compounds [C₅H₅Fe(CO)L′]BF₄, which are isolable for L′  LL (P,As ligand) and (X)LL(X) (X = S, Se). Some substitution reactions with phosphanes are described.     

Preparation and properties of new ferrocenyl heterobimetallic complexes with counterion dependent NLO responses

New ferrocenyl-based bimetallic cationic compounds of the type of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]X (X=PF₆, BF₄) and of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNFeCp(CO)₂]PF₆ have been obtained and characterized. The crystal structure of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]BF₄ has been established by means of X-ray diffractometry. The NLO responses of the compounds have been studied by the hyper-Rayleigh scattering technique and the hyperpolarizability is found to be dependent on the nature of the counterion.     

Synthesis of a transition metal-dithionite complex, (η5-C5H5)(CO)2FeS(O)2S(O)2Fe(CO)2(η5-C5H5)

The reaction of Na[η⁵-C₅H₅Fe(CO)₂] with large excess of SO₂ in THF at ?78°C followed by warming to room temperature affords an iron—dithionite complex, (η⁵-C₅H₅)(CO)₂FeS(O)₂S(O)₂Fe(CO)₂(η⁵-C₅H₅).     

Stereo- and regio-specific CC bond formation via the coupling of electrophilic and nucleophilic organotransition-metal complexes: The x-ray crystal structure of [Ru(CO)2(PPh3)(η2,η3-C8H8R)][PF6]·0.5CH2Cl2 (R = CH2C(Me)CH2)

The coupling of [Ru(CO)₂L(η⁴-cot)] (L = CO or PPh₃, cot = cyclooctatetraene) with [Fe(CO)₃(η⁵-cyclohexadienyl)]⁺ or [Fe{P(OMe)₃}(NO)₂(η³-allyl)]⁺ yields respectively the dimetallic species [Ru(CO)₂L(η²,η³-C₈H₈{Fe(CO)₃(η⁴-C₆H₇)}] (3) and the allyl-substituted derivative [Ru(CO)₂L(η⁵-C₈H₈CH₂C(Me)CH₂)][PF₆] (5) whose X-ray structure is reported; paramagnetic [Co(η-C₅H₅)₂] and [Ru(CO)₃(η⁵-cyclohexadienyl)]⁺ give diamagnetic [Ru(CO)₃(η⁴-C₆H₇C₅H₆(o-C₅H₅)] (8) via CC bond formation and one-electron reduction.     

Measurement of barriers to aryl rotation in Cp(CO)2FeCHC6H5+ and Cp(CO)2FeCH(p-CH3C6H4)+

The first observation of barriers to rotation about the C_arylC_carbene bonds in aryl-substituted metal carbene complexes is reported. Using variable temperature ¹H NMR, barriers of 9.1 and 10.4 kcal/mol have been determined for Cp(CO)₂FeCHC₆H₅⁺ and Cp(CO)₂FeCH(p-CH₃C₆H₄)⁺, respectively. The data clearly indicate a geometry of the complex in which the aryl ring lies coplanar with FeC_carbeneC_ipso plane.     

Antiferromagnetic complexes involving metalmetal bonds IV. Synthesis,molecular structure and magnetic properties of the heterotrinuclear cluster, (C5H5Cr)2(μ2-SCMe3)(μ3-S)2Fe(CO)3, with direct and indirect exchange between CrIII and FeI centers

The photochemical reaction between the antiferromagnetic complex (C₅H₅-CrSCMe₃)₂S (I) (containing a CrCr bond 2.689 Å long) and Fe(CO)₅ results in the elimination of two carbonyl groups and one tert-butyl radical to give (C₅H₅Cr)₂(μ²-SCMe₃)(μ³-S)₂ · Fe(CO)₃ (III). As determined by X-ray diffraction, III contains a CrCr bond of almost the same length as in I (2.707 Å), together with one thiolate and two sulphide bridges. The latter are also linked with the Fe atom of the Fe(CO)₃ moiety (average FeS bond length 2.300 Å). Fe also forms a direct bond, 2.726 Å long, with one of the Cr atoms, whereas its distance from the other Cr atom (3.110 Å) is characteristic for non-bonded interactions. Complex III is antiferromagnetic, the exchange parameter, ?2J, values for CrCr, Cr(1)Fe and Cr(2)…Fe are 380, 2600 and 170 cm^?1, respectively. The magnetic properties of III are discussed in terms of the “exchange channel model”. The contributions from indirect interactions through bridging ligands are shown to be insignificant compared with direct exchange involving metalmetal bonds. The effects of steric factors and of the nature of the M(CO)_n fragments on the chemical transformations of (C₅H₅CrSCMe₃)₂S · M(CO)_n are discussed.     

Transition-metal complexes of two valence tautomers of a bulky phenoxide, 2,6-Bu-t2-4-MeC6H2O− (ArO−); preparation and crystal and molecular structure of a phenoxytitanium(III) and a cyclohexadienonylrhodium(I) complex, [Ti(η-C5H5)2 OAr] and [Rh(ArO-η5)(PPh3)2]

The 2,6-di-t-butyl-4-methylphenoxo ligand (ArO^?) is ambidentate, giving rise to the O-bonded 15-electron d¹ [Ti(η-C₅H₅)₂OAr] and the η⁵ -[C(2)-C(6)]-bonded 18-electron d⁸ complex [Rh(ArO-η⁵)(PPh₃)₂], obtained from [{Ti(η-C₅H₅)₂Cl}₂]-LiO Ar and [Rh{N(SiMe₃)₂}(PPh₃)₂]-ArOH, respectively; the average TiC(η) distance is 2.362(10) Å, TiO 1.892(2) Å, and O:C(of Ar) 1.352(3) Å, and TiOC 142.3(2)°; in the Rh^I complex, C(2)C(6) are coplanar (with CC(av.) 1.38(2) Å). C(1)O 1.28 Å, and Rh to C(2) C(6) bond lengthsare in the range 2.19–2.65 Å.     

Complexes ethyleniques de platine(II), cuivre(I) et fer(0)

The vibrational spectra of CC and MC bonds are studied in a series of complexes L_mM(C₂H₄) (M = Pt^II, Cu^I and Fe⁰). It is shown that the σ—π transfers between L_mM and C₂H₄ are determined by the nature of ligands L and the real charge, but not by the formal charge of the metal. Donor—acceptor properties of L_mM towards C₂H₄ vary in the order Fe > Pt > Cu in this series of complexes.     

Gehinderte Ligandenbewegungen in Übergangsmetallkomplexen : VII. Rotation der olefinliganden L = malein- und furmarsäuredimethylester in komplexen des typs C5H5Mn(CO)2L und C5H5Cr(CO)(NO)L

The restricted rotation of the olefin ligands L = dimethyl maleate and dimethyl fumarate in complexes of the type C₅H₅Mn(CO)₂L and C₅H₅Cr(CO)-(NO)L, respectively, has been investigated on the basis of their temperature-dependent ¹H NMR spectra. The olefinic ligand is arranged preferably in a position where the CC double bond is parallel to the plane of the cyclopentadienyl ring. The possible stereoisomers are discussed using this model. The ¹H NMR spectra of C₅H₅Cr(CO)(NO)(trans-CH₃OOCCHCHCOOCH₃) provide direct evidence that the configuration (R or S) at the metal is stable up to 120°C, and that the restricted motion of the olefin is exclusively rotation around the metal—olefin bond. The activation barriers of the olefin rotation are found to be appreciably lower in the C₅H₅Mn(CO)₂L complexes (ΔG^≠(T_C) 11–12 kcal mol^?1) than in the isoelectric C₅H₅Cr(CO)(NO)L compounds (ΔG^≠(T_C) 15–20 kcal mol^?1).     

Studies of layered uranium (VI) compounds. VI. Ionic conductivities and thermal stabilities of MUO2PO4 · nH2O,where M = H,Li,Na,K,NH4 or 12Ca, and where n is between 0 and 4

We have measured the ionic conductivities of pressed pellets of the layered compounds MUO₂PO₄ · nH₂O, and correlated the results with TGA data. The conductivities (in ohm^?1 m^?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li⁺4H₂O, 10^?4; Li⁺, Na⁺, K⁺, and NH₄⁺3H₂O, 10^?4, 10^?2, 10^?4, and 10^?4; H⁺, Li⁺, and Na⁺1.5H₂O, 10^?2, 10^?4, and 10^?4; Na⁺1H₂O, 10^?5; H⁺, K⁺, and NH₄⁺0.5H₂O, all 10^?5; and H⁺, Li⁺, Na⁺, K⁺, NH⁺₄, and $\text{1}\text{2}\text{Ca}{}^{\mathrm{2+}}\text{}\text{OH}{}_2\text{O}$, 10^?5, 10^?5, 10^?4, 10^?5, 10^?5, and 10^?6. A ring mechanism is proposed to account for the high conductivity found in NaUO₂PO₄ · 3.1H₂O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO₂PO₄(A ? x)H₂O, where x can be between 0 and 0.3.