New bimetallic organopalladium(II) compounds containing a PdCo or PdMo bond trans to a PdC bond

The reaction of a chelated palladium compound with Co(CO)^?₄ and [Mo(CO)₃-η-C₅H₅]^? gives new stable bimetallic PdCo and PdMo complexes in which the metal-metal bond is trans with respect to the Pd-carbon σ-bond.     

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.     

Picosecond photochemistry of Cr(CO)6: Solvation and dynamics of the primary intermediate

Picosecond absorption spectroscopy has been used to examine the primary photoproduct of Cr(CO)₆ in both neat and mixtures of THF and cyclohexane. The primary intermediate observed is shown to be the solvated pentacarbonyl in which one solvent molecule occupies the coordination site created by the photoelimination of CO. The rate of exchange of cyclohexane from (cyclohexane)Cr(CO)₅ by THF to form (THF)Cr(CO)₅ was found to be bimolecular, k = (4 ± 1) × 10⁷ mole^?1 s^?1, with an enthalpy and entropy of activation of 1 ± 1 kcal/mole and ?20 ± 4 eu, respectively.     

Metallcarbonyl-synthesen : V. Die reduktive hochdruckcarbonylierung von (η5-C5H5)NbCl4 als einfache und leistungsfähige synthesemethode für (η5-C5H5) Nb(CO)4. Darstellung der isotopenmarkierten derivate (η5-C5H5) Nb(CO)4 − n(13CO)n und (η5-C5H5) Nb(CO)4 − n(13C18O)n

The reductive high-pressure carbonylation of tetrachloro(η⁵-cyclopentadienyl)niobium using sodium as reduction agent and Cu/Al mixture as halogen acceptor system cleanly yields tetracarbonyl (η⁵-cyclopentadienyl)niobium which can be synthesized by means of this new procedure on a 35 g-scale, with yields ranging between 89 and 94%. Under photolysis conditions, (η⁵-C₅H₅) Nb(CO)₄ is converted into the solvent complex (η⁵-C₅H₅) Nb(CO)₃THF which, in turn, incorporates ¹³Co or ¹³C¹⁸O under mild conditions to give the labelled derivatives (η⁵-C₅H₅) Nb(CO)_{4 ? n}(¹³CO)_n and (η⁵-C₅H₅) Nb(CO)_{4 ? n}(¹³C¹⁸O)_n, respectively.     

Anionic bipyridyl complexes of lanthanides. Structure of [Yb(bipy)3][Li(THF)4]

Reactions of Sm^II, Tb^III, Tm^II, Yb^II, and Lu^III iodides with 2,2′-bipyridyllithium in THF afford [Li(THF)₄][Ln(bipy) _n ] complexes (n=3 or 4) containing trivalent lanthanides. X-ray structural analysis demonstrated that in the crystalline state, the Yb derivative has the ionic structure, [Li(THF)₄]⁺[Yb(bipy)₃]^?. In THF solutions, the reversible ligand exchange between metal atoms occurs to yield neutral compounds [Ln(bipy) _n?1(THF) _x ] and [Li(bipy)(THF) _y ]. A decrease in the temperature shifts the equilibrium to ionic pairs.     

Some observations on the systems Co2(CO)8/sodium amalgam and Hg[Co(CO)4]2/sodium amalgam,and the effect of added LiBr

Co₂(CO)₈ and Hg[Co(CO)₄]₂ react sodium amalgam and/or mercury in ethereal solvents to give a variety of products. On treatment with aqueous M(o-phen)₃Cl₂(M  Fe, Ni), the anions [Co(CO)₄^?, [Co₃(CO)₁₀]^?, {Hg[Co(CO)₄]₃}^? and {Hg[Co(CO)₄]₂Cl}^? could be isolated as their [M(o-phen)₃]²⁺ salts. The effect of LiBr on the reacting systems was also investigated and the anion {Hg[Co(CO)₄]₂Br}^? isolated.     

Solvent effects on the asymmetric Pauson-Khand-type reaction by rhodium

The reaction efficiency and enantioselectivity of an asymmetric Pauson-Khand-type reaction catalyzed by cationic rhodium are heavily dependent on the solvent. Coordinating solvents, such as THF, provide a faster reaction and better stereoselectivity than non-coordinating solvents, such as toluene. These beneficial effects can be attributed to a significant increase in the more reactive catalytic species of [Rh(bisphosphane ligand)^∗(solvent)_n]⁺ (3) than of [Rh(bisphosphine ligand)^∗CO(solvent)]⁺(4) and [Rh(bisphosphine ligand)∗(CO)₂]⁺ (5) in a coordinating solvent.     

Characterization of transient species and products in photochemical reactions of Re(dmb) (CO)3 Et with and without CO2

Transient FT-IR spectra of fac-Re(dmb)(CO)₃(Et) after laser excitation (355 nm) were investigated in THF under Ar and CO₂ atmospheres. The CO stretching bands of Re(dmb^⊙)(CO)₃(THF) grow (2008 and 1897 cm^?1) and those of Re(dmb)(CO)₃(Et) bleach (1987 and 1875 cm^?1) at times <1 μs, consistent with clean cleavage of the Re-Et bond. Under a CO₂ atmosphere, the long-lived radical (τ>100 ms) converts slowly to the formato complex Re(dmb)(CO)₃(OC(O)H) (2020, 1916, 1873 and 1630 cm^?1). When the solvent is slightly wet, the bicarbonato complex, Re(dmb)(CO)₃(OC(O)OH), is also observed after photolysis under CO₂.     

Synthesis and chemical characterization of some InFe heteronuclear carbonyl compounds; crystal structure of [NMe3CH2Ph]3[In{Fe(CO)4}3] and [NEt4]2[In2Br4{η-Fe(CO)4}2]

The reaction in THF of Na₂[Fe(CO)₄·xTHF with InBr₃ in an approximate 3.5:1 molar ratio affords the new [In{Fe(CO)₄}₃]³⁻ trianion, which has been isolated as its trimethylbenzylammonium salt and structurally characterized by single-crystal X-ray diffraction studies. On oxidation with two equivalents of AgBF₄ it stepwise affords the anions [In₂Fe₆(CO)₂₄]^x− with x = 4 and 2, respectively. Its reaction with InBr₃ gives species of the composition [InBr_3−x{Fe(CO)_4x}]^x− (x = 1,2), and the anion with the composition [InBr₂{Fe(CO)₄}]⁻ has been structurally characterized as the dimeric species [InBr₂Br₄{η-Fe(CO)₄}₂]²⁻.     

Reaction du meta-diisopropyl-phenyllithium-chrometricarbonyle avec le monoxyde de carbone

The complex CpV(CO)₃THF has been prepared in THF solution (i) photochemically from CpV(CO)₄, and (ii) from [CpV(H)(CO)₃]^?/[Ph₃C]⁺ at low temperatures. THF is replaced by [CpV(H)(CO)₃]^? to form [{CpV(CO)₃}₂-μ-H]^?, and by various ligands L with C, η²-CC, Sn, N, O, S, Se or Te functionality to yield CpV(CO)₃L and cis-[CpV(CO)₂LL] (LL = bipy, o-phen, tolane). The δ (⁵¹V) values range over ca. 1400 ppm and allow the assignment of distinct coordination modes for ambidentate ligands. The temperature gradient is ca. +1.2 ppm/deg. For [CpV(SnCl₃)(CO)₃]^? (δ ?1340 ppm rel. to VOCl₃), ¹J(⁵¹V-^117,119Sn) is 900 Hz. The isotope effect on introducing ¹²CO for ¹³CO in CpV(CO)₄ is ?0.48(2) ppm; ¹J(⁵¹V-¹³C) 107 Hz.     

Reaction Behavior of Decacarbonyldimetalates(2‐) (M = Cr and Mo) towards the Nitrosyl Carbonyls of Iron and Cobalt

The reaction of the nitrosyl carbonyl complexes [Fe(NO)₂(CO)₂] and [Co(NO)(CO)₃] with the decacarbonyldimetalates [M₂(CO)₁₀]^2– (M = Cr and Mo) in THF as the solvent at room temperature was investigated. Thereby a substitution of one nitrosyl ligand towards carbon monoxide was observed in each case. Both reactions afforded the known metalate complexes [Fe(NO)(CO)₃]^– and [Co(CO)₄]^–, respectively. These species were isolated as their corresponding PPN salts [PPN⁺ = bis(triphenylphosphane)iminium cation] in nearly quantitative yields. The products were unambiguously identified by their IR spectroscopic and elemental analytic data as well as by their characteristic colors and melting points.     

Synthesis of pyridine N-imine complexes of methylcobaloxime and reactions of bis(dimethylglyoximato)methyl(Pyridine N-imine)cobalt with acid anyhydrides and acetylenedicarboxylic acid dimethyl ester

Pyridine N-imine complexes of methylcobaloxime, CH₃Co(Hdmg)₂(R¹— C₅H_nN⁺N^?H) (n = 4; R¹ = H, 2-CH₃, 3-CH₃, 4-CH₃: n = 3; R¹ = 2,6-CH₃), have been synthesized by the reaction of CH₃Co(Hdmg)₂S(CH₃)₂ with a pyridine N-imine which is generated from a pyridine, hydroxylamine-O-sulfonic acid and K₂CO₃. The reactions of CH₃Co(Hdmg)₂(C₅H₅N⁺N^?H) with acid anhydrides form new methylcobaloxime complexes with N-substituted pyridine N-imines, CH₃Co(Hdmg)₂(C₅H₅N⁺N^?R²) R² = COPh, COMe, COEt). With maleic anhydride, (pyridine N-acryloylimine)carboxylic acid is formed. With acetylenedicarboxylic acid dimethyl ester, 1,3-dipolar cycloaddition of the ligand gives pyrazolo[1,5-a]pyridine-2,3-dicarboxylic acid dimethyl ester.     

Reactivity of Cyanide and Thiocyanate Towards the Nitrosyl Carbonyl [Co(CO)3(NO)]

The reaction of equimolar amounts of [Co(CO)₃(NO)] and [PPN]CN, PPN⁺ = (PPh₃)₂N⁺, in THF at room temperature resulted in ligand substitution of a carbonyl towards the cyanido ligand presumably affording the complex salt PPN[Co(CO)₂(NO)(CN)] as a reactive intermediate species which could not be isolated. Applying the synthetic protocol using the nitrosyl carbonyl in excess, the title reaction afforded unexpectedly the novel complex salt PPN[Co₂(μ-CN)(CO)₄(NO)₂] ( 1 ) in high yield. Because of many disorder phenomena in crystals of 1 the corresponding NBu₄⁺ salt of 1 has been prepared and the molecular structure of the dinuclear metal core in NnBu₄[Co₂(μ-CN)(CO)₄(NO)₂] ( 2 ) was determined by X-ray crystal diffraction in a more satisfactory manner. In contrast to the former result, the reaction of [PPN]SCN with [Co(CO)₃(NO)] yielded the mononuclear complex salt PPN[Co(CO)₂(NO)(SCN-κN)] ( 3 ) in good yield whose molecular structure in the solid was even determined and its composition additionally confirmed by spectroscopic means.     

Oxidative cleavage of the FeFe bond in [C5Me5Fe(CO)2]2 using ferrocinium ion: A facile route to the synthetically useful complexes [C5Me5Fe(CO)2(solvent)]+

Complexes of the type {Fp′(solvent)}⁺ PF₆^?, 3a–3d, (Fp′ = (η -C₅Me₅)Fe(CO)₂, solvent = THF, CH₃COCH₃, CH₃CN, or pyridine) are conveniently prepared by the reaction between Fp′₂ and Cp₂Fe⁺ PF₆ (Cp = η⁵-C₅H₅) in the solvent under ambient conditions. The complexes {Fp′L}⁺ PF₆^?, 3e–3g, (L = CO, PPh₃, P(OPh)₃) are readily prepared from {Fp′THF}⁺. Fp′H is formed by treatment of 3a with NaBH₄. Fp′SC(S)NMe₂ can be prepared from 3a or 3e and NaSC(S)NMe₂.     

Kristallstrukturelle,Festkörper‐31P‐CP/MAS‐NMR,TOSS, 31P‐COSY‐NMR und mechanistische Beiträge zur Koordinationschemie des Octacarbonyldicobalts mit den Liganden Bis(diphenylphosphanyl)amin,Bis(diphenylphosphanyl)methan und 1,1,1‐Tris(diphenylphosphanyl)ethan

Chemistry of Polyfunctional Molecules. 133. X‐Ray Crystal Structural, Solid‐state ³¹P CP/MAS NMR, TOSS, ³¹P COSY NMR, and Mechanistic Contributions to the Co‐ordination Chemistry of Octacarbonyldicobalt with the Ligands Bis(diphenylphosphanyl)amine, Bis(diphenylphosphanyl)methane, and 1,1,1‐Tris(diphenylphosphanyl)ethane Co₂(CO)₈ reacts with bis(diphenylphosphanyl)amine, HN(PPh₂)₂ (Hdppa, 1 ), in two steps to afford the known compound [Co(CO)(Hdppa‐κ²P)₂][Co(CO)₄] · 2 THF ( 6 a · 2 THF). The intermediate [Co(CO)₂(Hdppa‐κ²P) · (Hdppa‐κP)][Co(CO)₄] · dioxane · n‐pentane ( 5 · dioxane · n‐pentane) was isolated for the first time and was characterized by X‐ray analysis. The cation 5 ⁺ exhibits a slightly distorted trigonal‐bipyramidal geometry. Detailed ³¹P‐NMR investigations (solid‐state CP/MAS NMR, TOSS, ³¹P‐COSY, ³¹P‐EXSY) showed that the additional tautomer [Co(CO)₂(Hdppa‐κ²P)(Ph₂P–N=P(H)Ph₂‐κP)]⁺ ( 5 ′⁺) is present in solution. The tautomer equilibrium is slow in the NMR time scale. In contrast to the solid state only tetragonal pyramidal species of 5 are found in solution. At –90 °C there is slow exchange between the three diastereomeric species 5 a ⁺– 5 c ⁺. Compound 5 forms [Co(CO) · (Hdppa‐κ²P)₂]BPh₄ · THF ( 6 b · THF) in THF with NaBPh₄ under CO‐Elimination. A X‐ray diffraction investigation shows that the cation 6 ⁺ consists of a slightly distorted trigonal‐bipyramidal co‐ordination polyeder. However, a distorted tetragonal‐pyramidal structure has been found for the cation 7 ⁺ of the related compound [Co(CO)(dppm)₂][Co(CO)₄] · 2 THF ( 7 · 2 THF; dppm = bis(diphenylphosphanyl)methane, Ph₂PCH₂PPh₂). A comparison with the known [8] trigonal‐bipyramidal stereoisomer, ascertained for 7 ⁺ of the solvent‐free 7 , is described. In solutions of 6 a · 2 THF and 7 · 2 THF ¹³C{¹H}‐ and ³¹P{¹H}‐NMR spectra indicate an exchange of all CO and organophosphane molecules between cobalt(I) cation and cobalt(–I) anion. A concerted mechanism for the exchange process is discussed. CO elimination leads to discontinuance of the cyclic mechanism by forming binuclear substitution products such as the isolated Co₂(CO)₂ · (μ‐CO)₂(μ‐dppm)₂ · 0.83 THF ( 8 · 0.83 THF), which was characterized by spectroscopy and X‐ray analysis. For the dissolved [Co(CO)₂CH₃C(CH₂PPh₂)₃][Co(CO)₄] · 0.83 n‐pentane ( 9 a · 0.83 n‐pentane) no CO and triphos exchange processes between the cation and the anion are observed. Metathesis of 9 a · 0.83 n‐pentane with NaBPh₄ yields [Co(CO)₂CH₃C(CH₂PPh₂)₃]BPh₄ ( 9 b ) which has been characterized by single‐crystal X‐ray analysis. The cation shows a small distorted tetragonal‐pyramidal structure.     

Ion-solvent interactions: Conductance behavior of NaAlBu4 and Bu4NAlBu4 in benzene and tetrahydrofuran

Conductance measurements are reported for NaAlBu ₄ and Bu ₄ NAlBu ₄ in benzene and in tetrahydrofuran (THF) from a concentration of approximately 5×10^?3 M to the fused state for each salt. This is the first reported study where a comparison of a salt with a small cation is made with one having a large cation in a noncomplexing solvent (benzene) and a complexing solvent (THF). The similarity in conductance behavior in THF and the differences in benzene are considered in terms of ion-ion and ion-solvent interactions.     

Reactions of nitrosonium ion with anionic carbonyl monomers and clusters. Crystal and molecular structure of FeCo2(μ3-NH)(CO)9

The reactions of several mono- and poly-nuclear carbonyl metallates with nitrosonium ion have been studied. Besides simple substitution of a carbon monoxide with NO⁺ some reactions yielded products containing other nitrogeneous ligands. When [CoRu₃(CO)₁₃]^? reacts with NO⁺, low yields of the new nitrido cluster CoRu₃N(CO)₁₂ are formed. Prior conversion of [CoRu₃(CO)₁₃]^? to the new hydrido cluster [H₂CoRu₃(CO)₁₂]^? under hydrogen, followed by nitrosylation, forms the new imido cluster H₂Ru₃(NH)(CO)₉ in very low yield. The reaction of [FeCO₃(CO)₁₂]^? with NO⁺ also generates an imido cluster, FeCo₂(NH)(CO)₉, in 15% yield. This cluster has been characterized by X-ray crystallography and was found to be similar to the tricobalt alkylidyne clusters. (Triclinic crystal system, P$\text{1}$ space group, Z=2, a 6.787(1), b 8.016(1), c 13.881(2) Å, α 95.50(1), β 100.77(1), γ 107.93(1)°. Modifications of the nitrosylations using NO⁺ were studied. In particular, the addition of triethylamine or N-t-butylbenzaldimine allowed the use of NO⁺ in THF without solvent decomposition. With [CpMo(CO)₃]^? and [CpFe(CO)₂]^? the N-nitrosoiminium species appears to form transient alkylmetals which further react to give the dimers [CpMo(CO)₃]₂ and [CpFe(CO)₂]₂.     

Synthesis,molecular structures and PMR spectra of heteronuclear niobocene derivatives containing a niobium-tin bond

Treatment of niobocene carbonylhydride, Cp₂Nb(CO)H (I), with Ph_nSnCl_4?n and Et₂SnCl₂ in THF in the presence of Et₃N leads to the respective heteronuclear complexes Cp₂Nb(CO)SnR_nCl_3?n (R = Ph, n = 3 ÷ 1 (II–IV), R = Et, n = 2 (V)). Treatment of II with HCl in ether gives Cp₂Nb(CO)SnCl₃ (VI). Complex VI and its analog (MeC₅H₄)₂Nb(CO)SnCl₃ (VIII) were prepared by an alternative synthesis using direct reaction of I or (MeC₅H₄)₂Nb(CO)H with an equimolar quantity of SnCl₄ in THF in the presence of Et₃N. Complex VI is also generated by insertion of SnCl₂ into the NbCl bond in Cp₂Nb(CO)Cl (VII). X-Ray analysis of complexes II and VIII was performed: for II, space group P2₁/n, a = 10.1021(21), b = 17.4633(32), c= 14.2473(29) Å, β = 95.578(16)°, Z = 4; for VIII, space group. P2₁/n, a= 8.9369(15), b = 13.3589(12), c = 13.9292(20) Å, β = 99.490(14)°, Z = 4. The NbSn bond in VIII (2.764(9) Å) is shorter than that in II (2.825(2) Å). In both cases the NbSn bond is significantly shorter than the sum of Nb and Sn covalent radii (1.66 + 1.40 = 3.06 Å). It is probably partly multiple in character owing to an additional interaction of the lone electron pair of the Nb^III ion (d² configuration) with the antibonding Sn orbitals. The PMR spectra of II–VI exhibit two satellites of the singlet of C₅H₅ protons because of HSn¹¹⁷ and HSn¹¹⁹ spin-spin coupling (SSC). The SSC constant correlates with the number of electronegative chlorine atoms on the Sn atom.     

Formation of the Salt‐like Complexes [Co{S2CC(PPh3)2}3][Co(CO)4]3 and [(CO)4Mn{S2CC(PPh3)2}][Mn(CO)5] from the Reaction of the Related Carbonyl Compounds with S2CC(PPh3)2

The betain‐like compound S₂CC(PPh₃)₂ ( 1 ), which is obtained from CS₂ and the double ylide C(PPh₃)₂, reacts with [Co₂(CO)₈] and [Mn₂(CO)₁₀] in THF to afford the salt‐like complexes [Co{S₂CC(PPh₃)₂}₃][Co(CO)₄]₃ ( 2 ) and [(CO)₄Mn{S₂CC(PPh₃)₂}][Mn(CO)₅] ( 3 ), respectively, in good yields. At both d⁶ cations 1 acts as a chelating ligand. Disproportionation reactions from formal Co⁰ into Co^III and Co^?I and from Mn⁰ into Mn^I and Mn^?I occurred with the removal of four or one carbonyl groups, respectively. The crystal structures of 2· 5.5THF and 3· 2THF are reported, which show a shortening of the C–C bond in the ligand upon complex formation. The compounds are further characterized by ³¹P NMR and IR spectroscopy.     

Electrochemical studies on organometallic compounds: VIII. Ligand exchange reaction in carbonyl cobalt complexes

The reaction of Co(CO)₃DMPP^? with Co₂(CO)₆(DMPP)₂ (DMPP = dimethylphenylphosphine) yields CoCO₄^? and Co₂(CO)₅(DMPP)₃. The DMPP ligand of Co(CO)₃DMPP^? can be replaced by CO or triphenylphosphite.