Stabilisation of [WF5]+ and WF5 by Pyridine: Facile Access to [WF5(NC5H5)3]+ and WF5(NC5H5)2

The enhanced reactivity of [WF₅]⁺ over WF₆ has been exploited to access a neutral derivative of elusive WF₅. The reaction of WF₆(NC₅H₅)₂ with [(CH₃)₃Si(NC₅H₅)][O₃SCF₃] in CH₂Cl₂ results in quantitative formation of trigonal-dodecahedral [WF₅(NC₅H₅)₃]⁺, which has been characterised as its [O₃SCF₃]⁻ salt by Raman spectroscopy in the solid state and variable-temperature NMR spectroscopy in solution. The salt is susceptible to slow decomposition in solution at ambient temperature via dissociation of a pyridyl ligand, and the resultant [WF₅(NC₅H₅)₂]⁺ is reduced to WF₅(NC₅H₅)₂ in the presence of excess C₅H₅N, as determined by ¹⁹F NMR spectroscopy. Pentagonal-bipyramidal WF₅(NC₅H₅)₂ was isolated and characterised by X-ray crystallography and Raman spectroscopy in the solid state, representing the first unambiguously characterised WF₅ adduct, as well as the first heptacoordinate adduct of a transition-metal pentafluoride. DFT-B3LYP methods have been used to investigate the reduction of [WF₅(NC₅H₅)₂]⁺ to WF₅(NC₅H₅)₂, supporting a two-electron reduction of W^VI to W^IV by nucleophilic attack and diprotonation of a pyridyl ligand in the presence of free C₅H₅N, followed by comproportionation to W^V.     

Spectrokinetic study of SF5 and SF5O2 radicals and the reaction of SF5O2 with NO

UV spectra of SF₅ and SF₅O₂ radicals in the gas phase at 295 K have been quantified using a pulse radiolysis UV absorption technique. The absorption spectrum of SF₅ was quantified from 220 to 240 nm. The absorption cross section at 220 nm was (5.5 ± 1.7) × 10⁻¹⁹ cm². When SF₅ was produced in the presence of O₂ an equilibrium between SF₅, O₂, and SF₅O₂ was established. The rate constant for the reaction of SF₅ radicals with O₂ was (8 ± 2) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. The decomposition rate constant for SF₅O₂ was (1.0 ± 0.5) × 10⁵ s⁻¹, giving an equilibrium constant of K_eq = [SF₅O₂]/[SF₅][O₂] = (8.0 ± 4.5) × 10⁻¹⁸ cm³ molecule⁻¹. The SF₅ O₂ bond strength is (13.7 ± 2.0) kcal mol⁻¹. The SF₅O₂ spectrum was broad with no fine structure and similar to the UV spectra of alkyl peroxy radicals. The absorption cross section at 230 nm was found to (3.7 ± 0.9) × 10⁻¹⁸ cm². The rate constant of the reaction of SF₅O₂ with NO was measured to (1.1 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ by monitoring the kinetics of NO₂ formation at 400 nm. The rate constant for the reaction of F atoms with SF₄ was measured by two relative methods to be (1.3 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. © 1994 John Wiley & Sons, Inc.     

Solid State Structures of AsCl5 and SbCl5

Arsenic pentachloride has a trigonal bipyramidal structure in the solid state with As‐Cl_eq = 210.6, 211.9 pm, As‐Cl_ax= 220.7 pm, space group Pmmn, a = 706.2 (1); b = 760.3 (2), c = 623.3 (1) pm. Antimony pentachloride exists in two modifications: above −54.1 °C it is also trigonal bipyramidal with Sb‐Cl_eq = 227.0 and Sb‐Cl_ax = 233.3 pm, space group P6₃/mmc, a = 741.4 (1), c = 799.0(2)pm. Below −54.1 °C it changes reversibly into a double chlorine bridged dimer resulting in an edge shared double octahedral structure, space group P2₁/c, a = 952.4 (1), b = 1189.9 (1), c = 1219.7 (1) pm, β = 108, 27 (1): In presence of water the formation of AsCl₅ is hindered, two salts containing the octahedral anion AsCl₆⁻ have been isolated, [(H₅O₂⁺)₅AsCl₆⁻(Cl⁻)₄], space group C2/c, a= 1416.9 (2), b = 1316.6 (3), c = 1215.3 (2) pm, β; = 94.96 (1)°, and [(H₅O₂⁺)(AsCl₆⁻)·AsOCl₃], space group P2₁/n, a = 771.6 (3), b = 904.5 (3), c = 2140.7(2)pm, β = 100.21(1). The AsOCl₃ moiety in this compound appears as a monomer, in contrast to pure AsOCl₃, which is a doubly oxygen bridged dimer in the solid state.     

Photolysis of (η5-C5H5)2V(CH3)2: II . Photo-induced formation of ethane

Photolysis of (η⁵-C₅H₅)₂V(CH₃)₂ results in the formation of methane and ethane. The percentage of ethane detected in the evolved gas can vary from a trace to 70%. The percentage of ethane formed is dependent on the solvent, the concentration of (η⁵-C₅H₅)₂V(CH₃)₂, time and temperature. The results of oxidation and reduction reactions involving (η⁵-C₅H₅)₂V(CH₃)₂ are also presented.     

Synthesis and characteristics of novel pentanuclear complexes [(OC)3Mn(η1,η5-C5H4)Fe(CO)2(η1,η5-C5H4CO2)]2M(η5-C5H5)2 (M=Ti, Zr)

The reaction of Cp₂MCl₂ complexes (M=Ti and Zr) with 2 equiv. of (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄COONa) results in the formation of the pentanuclear complexes (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄CO₂)]₂M(η⁵-C₅H₅)₂, which are characterized by IR and¹H NMR spectroscopy and cyclic voltammetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1055–1058, May, 1997.     

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).     

[Co(g5‐Me5C5)(g3‐tBu2PPCH–CH3)] aus [Co(g5‐Me5C5)(g2‐C2H4)2] und tBu2P–P=P(Me)tBu2

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XVII [1] [Co(g⁵‐Me₅C₅)(g³‐^tBu₂PPCH–CH₃)] from [Co(g⁵‐Me₅C₅)(g²‐C₂H₄)₂] and ^tBu₂P–P=P(Me)^tBu₂ [Co(η⁵‐Me₅C₅)(η³‐^tBu₂PPCH–CH₃)] 1 is formed in the reaction of [Co(η⁵‐Me₅C₅)(η²‐C₂H₄)₂] 2 with ^tBu₂P–P 4 (generated from ^tBu₂P–P=P(Me)^tBu₂ 3 ) by elimination of one C₂H₄ ligand and coupling of the phosphinophosphinidene with the second one. The structure of 1 is proven by ³¹P, ¹³C, ¹H NMR spectra and the X‐ray structure analysis. Within the ligand ^tBu₂P¹P²C¹H–CH₃ in 1 , the angle P1–P2–C1 amounts to 90°. The Co, P1, P2, C1 atoms in 1 look like a „butterfly”︁. The reaction of 2 with a mixture of ^tBu₂P–P=P(Me)^tBu₂ 3 and ^tBu–C?P 5 yields [Co(η⁵‐Me₅C₅){η⁴‐(^tBuCP)₂}] 6 and 1 . While 6 is spontaneously formed, 1 appears only after complete consumption of 5 .     

Synthesis and characterization of complexes η5,η5-(CO)3Mn(C5H4-C5H4)(CO)2Fe-η1,η5-C5H4Mn(CO)3 and μ-(C≡C)[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3]2

The complex η⁵,η⁵-(CO)₃Mn(C₅H₄-C₅H₄)(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ was synthesized by the reaction of η⁵-Cp(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with BuⁿLi (THF, ?78 °C) and then with anhydrous CuCl₂. The complex μ-(C≡C)[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃]₂ was prepared by the reaction of η⁵-IC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with Me₃SnC≡CSnMe₃ (2:1) in the presence of Pd(MeCN)₂Cl₂.     

Strukturdynamische organometall-komplexe: III. Synthese,struktur und bindungsverhältnisse der komplexe (η5-C5H5)Pd(η1-C5H5)PR3

The complexes (η₅-C₅H₅)Pd(η¹-C₅H₅)PR₃ which are prepared from [Cl(PR₃)-Pd]₂(μ-OCOCH₃)₂ and TlC₅H₅ are fluxional in solution. According to the ¹H and ¹³C NMR spectra at various temperatures, two dynamic processes occur. The process with the higher activation energy is a π/σ (η⁵/η¹) exchange of the two different cyclopentadienyl ligands, whereas the second one with the lower activation energy presumably is a metallotropic rearrangement (1,2-shift). The coalescence temperature for the η⁵/η¹ exchange depends on the size of the phosphine. The X-ray structural analysis of (C₅H₅)₂PdPPrⁱ₃ proves that it exists as a “frozen” η⁵ + η¹ structure in the crystal with the palladium approximately in a square-planar coordination. The η⁵-bonded cyclopentadienyl ring shows some unusual bonding patterns which are obviously electronic in nature. EHT-MO calculations for (η⁵-C₅H₅)PdCH₃(PH₃) indicate that in this model system alternating CC distances in the ring and a stronger bond of the metal to one of the five carbon atoms of the C₅H₅ ligand are to be expected. The calculations suggest that in similar complexes possessing a six-electron donor ligand like C₅H₅^? and a metal fragment which is isolobal to PdCH₃(PH₃)⁺, analogous distortions should be observed. Some reactions of the compounds (η⁵-C₅H₅)Pd(η¹-C₅H₅)PR₃ are described.     

Population transfer between the fine-structure levels 5s5p 3 P 1 and 5s5p 3 P 0 of114Cd atoms by collisions with molecular gases

Fine-structure mixing of excited¹¹⁴Cd 5³ P _J atoms induced by collisions with various molecular gases (N₂, H₂, D₂, CO, CH₄, C₂H₆) has been investigated by a combined method of absorption and fluorescence spectroscopy. After pulsed optical excitation of the Cd(5³ P ₁) level, the time dependence of the population densities has been measured simultaneously both for the 5³ P ₁ state and for the collisionally populated 5³ P ₀ state. By analyzing the signal curves at different molecular gas pressures cross sections for collisional transfer between the¹¹⁴Cd 5³ P ₁ and 5³ P ₀ levels as well as the quenching cross sections for the 5³ P levels have been obtained.     

Beiträge zur Chemie des Phosphors. 227. HP4º als Komplexligand: Bildung und Eigenschaften von [(η5-C5H5)2ZrCl(P4H)], [(η5-C5Me5)2ZrCl(P4H)] und [(η5-C5H5)3Zr(P4H)]

Contributions to the Chemistry of Phosphorus. 227. HP₄º as a Complex Ligand: Formation and Properties of [(η⁵-C₅H₅)₂ZrCl(P₄H)], [(η⁵-C₅Me₅)₂ZrCl(P₄H)], and [(η⁵-C₅H₅)₃Zr(P₄H)] The novel complexes [(η⁵-C₅H₅)₂ZrCl(P₄H)] ( 1 ), [(η⁵-C₅Me₅)₂ZrCl(P₄H)] ( 2 ), and [(η⁵-C₅H₅)₃Zr(P₄H)] ( 3 ) have been obtained by reaction of a solution of (Na/K)HP₄ with the zirconocen derivatives [(η⁵-C₅H₅)₂ZrCl₂], [(η⁵-C₅Me₅)₂ZrCl₂], and [(η⁵-C₅H₅)₃(η¹-C₅ H₅)Zr] under suitable conditions. The structure of the compounds 1 – 3 , which are only stable in solution, has been elucidated by means of ³¹P-NMR spectroscopy. It is highly probable that the exo,endo isomer exists in each case. In addition, further isomers of lower relative abundancies have been observed, in which the ligands presumably exhibit a different spatial orientation relatively to each other.     

Improved preparation of h5-C5H5 Fe(CO)2(h1-alkyl) complexes from [h5-C5H5Fe(CO)2(h2-alkene)]+BF4−

Sodium cyanoborohydride has been found to be very effective for the conversion of [(h⁵-C₅H₅)Fe(CO)₂(h²-alkene)]⁺BF₄^? complexes to the corresponding h¹-alkyl derivatives.     

Intermediates in associative phosphine substitution reactions of (η5-C5H5)W(CO)2(NO)

The reaction of (η⁵-C₅H₅)W(CO)₂(NO), 6W, with P(CH₃)₃ proceeds rapidly at 25°C to give (η⁵-C₅H₅)W(CO)(NO)[P(CH₃)₃], 7W. The rate of formation of 7W was found to be 4.48 × 10^?2M^?1 [6W] [P(CH₃)₃] at 25.0°c in THF. In neat P(CH₃)₃ at ?23°C, 6W is converted to (η¹-C₅H₅)W(CO)₂(NO)[P(CH₃)₃]₂, 8W. In dilute solution, 8W decomposes to initially give a 2:1 mixture of 6W and 7W. The mixture is then converted to 7W. The reaction of (η⁵-C₅H₅)Mo(CO)(NO), 6Mo, with P(CH₃)₃ is 6.1 times faster than that of the tungsten analog.     

Reactivity modes of bridged bimetallic [(η5-C5H5)Fe(CO)]2-μ-dppe with electrophiles. Preparation and reactions of bimetallic hydride complexes

The complex [(η⁵-C₅H₅)Fe(CO)]₂-μ-dppe (dppe = ethane-1,2-bisdiphenylphosphide) (I) reacts with electrophiles through a η-CO and forms Lewis acid O-Adducts with alkylating reagents (giving cationic μ₂-alkoxycarbyne compounds) or with alkulaluminum compounds. Treatment of I with acid affords a stable μ₂-hydride salt (IV), [CpFe(CO)]₂(μ₂-dppe)⁺, which serves as an intermediate in the stepwise hydrogenation (reversibly) of I to a bridged bimetallic dihydride, [CpFe(CO)H]₂-μ₂-dppe. This dihydride serves as a hydride donor, regenerating IV, towards Ph₃c⁺ or CpFe(CO)₂(η²-CH₂CH₂)⁺ hydride acceptors. The necessity of the μ₂-dppe as a “mechanical linkage” in facilitating some bimetalic reactions is also established.     

Crystal structures of [Rh(η-C5H5)(C3S5)] and [Rh(η-C5Me5)(C3S5)]2 and properties of their oxidized species

[Rh(η⁵-C₅H₅)(C₃S₅)] and [Rh(η⁵-C₅Me₅)(C₃S₅)]₂ [C₃S₅²⁻=4,5-disulfanyl-1,3-dithiole-2-thionate(2-)] were prepared by reactions of [NMe₄]₂[C₃S₅] with [Rh(η⁵-C₅H₅)Cl₂]₂ and [Rh(η⁵-C₅Me₅)Cl₂]₂, respectively. Their X-ray crystal structural analyses revealed a monomeric form for the former complex and a dimeric geometry containing bridging S-Rh-S bonds for the latter in the solid state. They were reacted with bromine to afford [RhBr(L)(C₃S₅)] (L=η⁵-C₅H₅ and η⁵-C₅Me₅) with the Rh-Br bond and one electron-oxidation on the C₃S₅ ligand. ESR spectra and spin densities for these oxidized species are discussed.     

Collisional depolarization of excited114Cd 5s5p 3 P 1 atoms by collisions with molecular gases

Depolarization of excited¹¹⁴Cd 5s5p ³ P ₁ atoms induced by collisions with various molecular gases (N₂, H₂, D₂, CO, CO₂, CH₄, C₂H₆, C₂H₄) has been investigated using polarized fluorescence spectroscopy. After pulsed optical excitation of the Cd 5³ P ₁ level with appropriately polarized light the temporal behaviour of Zeeman quantum beats has been observed showing the influence of collisional destruction of orientation and alignment. By analyzing the signal curves at different molecular gas pressures the corresponding depolarization cross sections for¹¹⁴Cd atoms in the 5³ P ₁ state have been obtained. With regard to a test of a nuclear spin decoupling model for the collisions the cross sections were compared with previously measured hyperfine structure transfer cross sections of¹¹³Cd 5s5p ³ P ₁ atoms.     

Gas phase reactions of the ion C5H5Fe+: A kinetic study

The kinetics of gas phase reactions of the ion C₅H₅Fe⁺ with oxygen (Me₂CO, Me₂O, MeOH, iso-propanol, H₂O) and nitrogen (NH₃, NH₂Me, NHMe₂, NMe₃) donor ligands have been studied by ion trap mass spectrometry. While in the literature reactions of the ion Fe⁺, with the same ligands, the principal reaction path involves fragmentation in almost all the reactions of the ion C₅H₅Fe⁺, formation of adduct ions is the major reaction path. The reactivity of these two ions is briefly compared in the ion trap conditions. Kinetic data for the ion C₅H₅Fe⁺ indicate that the reactions show a large range of efficiency and a linear correlation is found between the log of the reaction rate constants and the ionization energy of ligands with the same donor atom.     

Neue Oxometallate vom BaCuSm2O6-Typ: BaCoHo2O5, BaCoYb2O5 und vom BaNiLn2O5-Typ: BaCoEr2O5

Inhaltsübersicht. (I) BaCoHo₂O₅, (II) BaCoYb₂O₅ und (III) BaCoEr₂O₅ wurden neu dargestellt und an Einkristallen mit Röntgenbeugungsmethoden die Kristallstruktur bestimmt. (I) und (II) gehören zum BaCuSm₂O₅-Typ mit (I): A = 12,267; b = 5,714; c = 7,064 Å; Z = 4; (II): A = 12,138; b = 5,662; c = 7,004 Å; Z = 4. Beide kristallisieren in der Raumgruppe D¹⁶_2h–Pnma. (III) kristallisiert im BaNiLn₂O₅-Typ, Raumgruppe D²⁵_2h–Immm mit a = 3,734; b = 5,770; c = 11,421 Å; Z = 2. Die Koordination um Co²⁺ wechselt von (I, II) nach (III) von tetragonal pyramidal nach oktaedrisch. New Oxides of the BaCuSm₂O₅-Type: BaCoHo₂O₅, BaCoYb₂O₅, and of the BaNiLn₂O₅ Type: BaCoEr₂O₅ (I) BaCoHo₂O₅, (II) BaCoYb₂O₅, and (III) BaCoEr₂O₅ are new compounds prepared by high temperature reactions. X-ray single crystal work show: (I) and (II) belong to the BaCuSm₂O₅-type (space group D¹⁶_2h-Pnma, Z = 4). (I): A = 12.267; b = 5.714; c = 7.064 Å; (II): A = 12.138; b = 5.662; c = 7,004 Å. (III) crystallizes with BaNiLn₂O₅-structure, space group D²⁵_2h-Immm; Z = 2; a = 3.734; b = 5.770; c = 11.421 Å; within (I) and (II) Co²⁺ has a tetragonal pyramidal coordination by oxygen. The coordination changes in (III) to a compressed octehedral O^2– surrounding.