Reaction of Tricarbonyl(η3-allyl)iron(0) Anions with Bromine

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at 23°C to give putative tricarbonyl(η³-allyl)iron(0) anion complexes. Trapping of the reactive intermediates with bromine produced nucleophilic-substituted tricarbonyl(η⁴-1,3-diene)iron(0) complexes.     

Unraveling the photochemistry of Fe(CO)5 in solution: observation of Fe(CO)3 and the conversion between 3Fe(CO)4 and 1Fe(CO)4(Solvent)

The photochemistry of Fe(CO)5 (5) has been studied in heptane, supercritical (sc) Ar, scXe, and scCH4 using time-resolved infrared spectroscopy (TRIR). 3Fe(CO)4 ((3)4) and Fe(CO)3(solvent) (3) are formed as primary photoproducts within the first few picoseconds. Complex 3 is formed via a single-photon process. In heptane, scCH4, and scXe, (3)4 decays to form (1)4 x L (L = heptane, CH4, or Xe) as well as reacting with 5 to form Fe2(CO)9. In heptane, 3 reacts with CO to form (1)4 x L. The conversion of (3)4 to (1)4 x L has been monitored directly for the first time (L = heptane, kobs = 7.8(+/- 0.3) x 10(7) s(-1); scCH4, 5(+/- 1) x 10(6) s(-1); scXe, 2.1(+/- 0.1) x 10(7) s(-1)). In scAr, (3)4 and 3 react with CO to form 5 and (3)4, respectively. We have determined the rate constant (kCO = 1.2 x 10(7) dm3 mol(-1) s(-1)) for the reaction of (3)4 with CO in scAr, and this is very similar to the value obtained previously in the gas phase. Doping the scAr with either Xe or CH4 resulted in (3)4 reacting with Xe or CH4 to form (1)4 x Xe or (1)4 x CH4. The relative yield, [(3)4]:[3] decreases in the order heptane > scXe > scCH4 > scAr, and pressure-dependent measurements in scAr and scCH4 indicate an influence of the solvent density on this ratio.     

Solid State Dynamics of Tricarbonyl(eta-1,5-cyclohexadienylium)iron Tetrafluoroborate and Tricarbonyl(eta-1,5-cycloheptadienylium)iron Tetrafluoroborate

The dynamic behavior of [(C(6)H(7))Fe(CO)(3)]BF(4) (I) and [(C(7)H(9))Fe(CO)(3)]BF(4) (II) in the solid state has been investigated principally by NMR spectroscopy. High-resolution variable-temperature (1)H and (13)C NMR spectra indicate that both complexes have a solid state phase transition above which there is rapid reorientation of the cyclodienylium rings and fast exchange of the carbonyl groups. The transition occurs between 253 and 263 K for I and between 329 and 341 K for II. The presence of the phase transition is confirmed by differential scanning calorimetry (DSC). (57)Fe M?ssbauer spectroscopy supports the notion that complex I is highly mobile at room temperature, while II is relatively static. The activation energy for the cyclodienylium group rotation in the high-temperature phase of I is estimated from (1)H spin-lattice relaxation time measurements to be 17.5 kJ mol(-)(1). Static (13)C NMR measurements of the solid complexes in the high-temperature phase indicate that the (13)C chemical shift anisotropies are only 20-30 ppm. This is significantly less than that expected to result from motion of individual groups and thus suggests that rotation of the whole molecule is involved. A single-crystal X-ray structural determination of complex II, at 295 K, showed that the complex is tetragonal (space group P4(1), a = 10.610(1) ?, c = 21.761(3) ?, V = 2449.7(5) ?(3), rho(calc) = 1.734 g cm(-)(3)), with eight cycloheptadienyl cations and eight tetrafluoroborate anions per unit cell. In addition, powder X-ray diffraction studies of both I and II confirm that at low temperatures both complexes have a tetragonal unit cell, which transforms to a cubic unit cell above the phase transition. The powder patterns, recorded above the phase transition, support the proposal that the complexes are undergoing whole-molecule tumbling in their dynamic regimes.     

Oxidation of Tricarbonyl (η1 η2-but-3-en-1-yl)iron(0)and Tricarbonyl (η3-allyl)iron(0) Anion Complexes with Dioxygen

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at ?78 °C to give putative tricarbonyl(η¹,η²-but-3-en-1-y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η³-allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ-unsaturated acids and allylic alcohols, respectively.     

Reactions of Heterocumulenes with Organometallic Reagents: VII. Reactions of Carbanions Derived from Alkoxy- and Alkylthioethenes with Isocyanates as a Simple Route to N-Substituted 2-Alkoxy- and 2-(Alkylthio)acrylamides

Metalated alkoxy- and alkylthioethenes readily add to isocyanates, and subsequent hydrolysis or alkylation of the adducts gives N-mono- and N,N-disubstituted 2-alkoxy- and 2-(alkylthio)acrylamides in up to 86% yield. The reactions with propyl and phenyl isocyanates do not stop at the stage of addition of one isocyanate molecule, and further addition leads to formation of linear and cyclic polyamide structures.     

Reaction of [Fe2(CO)8(mu-CF2)] with AsMe3 and other Lewis bases: syntheses, crystal structures of [Fe(CO)6(AsMe3)2(mu-CF2)] and [Fe(CO)5(AsMe3)3(mu-CF2)], and theoretical considerations

The difluorcarbene complex [Fe2(CO)8(mu-CF2)] (2) reacts with AsMe3 under CO substitution to give the mu-CF2 containing complexes [Fe2(CO)6(AsMe3)2(mu-CF2)] (4) and [Fe2(CO)5(AsMe3)3(mu-CF2)] (5) which have an [Fe2(CO)9]-like structure as shown by X-ray analyses. In the solid state, 4 forms two isomers, 4a and 4b, in a 3 to 1 ratio, which differ in the position of the mu-CF(2) ligand; 4a has a local C(2) axis and 4b has C1 symmetry. The Fe-Fe distances in 4 and 5 are 2.47 A and are the shortest ones found in [Fe2(CO)9]-like compounds. Efforts were also undertaken to replace one or more CO groups in 2 by other ligands, such as N (bpy, phen, pzy, etc.) or P donors (dppe, dppm). With dppm, only the CF(2) free complex, [Fe2(CO)4(mu-Ph2PCH2PPh2)2(mu-CO)] (6), could be detected and characterized by X-ray analysis. Most of the reactions resulted in the formation of red-brown materials which were insoluble in the usual solvents and which could not be characterized. The use of CH2Cl2 during the attempts to crystallize a product from the reaction of 2 and phen gave [Fe(phen)3]Cl2 (7) in low yields. For 4 and 5, the electronic structures were analyzed using the atoms in molecules (AIM) theory. No electron density was found between the two iron atoms, and the short contacts can be interpreted in terms of a pi-interaction.     

Unexpected Reaction of Fe3(CO)12 with Dialkyldithiophosphate: The Case of P–S Bond Activation

The reaction of Fe₃(CO)₁₂ with O,O′‐dialkyldithiophosphate diethylamine salts (RO)₂P{S}SH · Et₂NH (R = CH₃, CH₂CH₃) resulted in the formation of trinuclear cluster complex {μ‐SP(OR)₂Fe[S₂P(OR)₂)]S‐μ]}Fe₂(CO)₆ [R = CH₃ ( 1 ), CH₂CH₃ ( 2 )]. The two complexes were characterized by elemental analysis, FT‐IR, NMR (¹H, ³¹P and ¹³C) spectroscopy, as well as by X‐ray diffraction analyses. Crystal structures reveal that one P–S bond is cleaved during the reaction, yielding the [2Fe2S] unit together with FePS₃(CO)₂. The other dialkyldithiophosphate coordinated with iron by S, S chelating model. The trinuclear cluster was observed with the P‐Fe and S–Fe bond formed by the P‐S activation. In addition, the electrochemical properties for complex 2 as an illustration was also studied by cyclic voltammetry in MeCN.     

Studies on the Reactivity of [Ge9]4− towards [Fe(cot)(CO)3]: Synthesis and Characterization of [Ge8Fe(CO)3]3− and of the Anionic Organometallic Species [Fe(cot)(CO)3]−

Reaction of cyclooctatetraene (COT) iron(II) tricarbonyl, [Fe(cot)(CO)₃], with one equivalent of K₄Ge₉ in ethylenediamine (en) yielded the cluster anion [Ge₈Fe(CO)₃]^3? which was crystallographically‐characterized as a [K(2,2,2‐crypt)]⁺ salt in [K(2,2,2‐crypt)]₃[Ge₈Fe(CO)₃]. The chemically‐reduced organometallic species [Fe(η³‐C₈H₈)(CO)₃]^? was also isolated as a side‐product from this reaction as [K(2,2,2‐crypt)][Fe(η³‐C₈H₈)(CO)₃]. Both species were further characterized by EPR and IR spectroscopy and electrospray mass spectrometry. The [Ge₈Fe(CO)₃]^3? cluster anion represents an unprecedented functionalized germanium Zintl anion in which the nine‐atom precursor cluster has lost a vertex, which has been replaced by a transition‐metal moiety.