The structure and formation of niobocene carbonyl heteronuclear derivatives. The molecular structures of Cp2Nb(CO)(μ-CO)Mn(CO)4, Cp2Nb(CO)(μ-H)Ni(CO)3 and [Cp2Nb(CO)(μ-H)]2Mo(CO)4

The heteronuclear Cp₂Nb(CO)(μ-CO)Mn(CO)₄ (I), Cp₂Nb(CO)(μ-H)Ni(CO)₃ (II) and [Cp₂Nb(CO)(μ-H)]₂M(CO)₄ (III, M = Mo;IV, M = W) complexes were prepared by reaction of Cp₂NbBH₄/Et₃N with Mn₂(CO)₁₀ in refluxing toluene, direct reaction of Cp₂NbBH₄ with Ni(CO)₄ in ether, and reaction of Cp₂NbBH₄/Et₃N with M(CO)₅. THF complexes (M = Mo or W) in THF/benzene mixture. An X-ray investigation of compounds I–III was performed. It is established that in I the bonding between Mn(CO)₅ and Cp₂Nb(CO) (with the angle (α) between the ring planes being 44.2(5)°) fragments takes place via a direct NbMn bond (3.176(1) Å) and a highly asymmetric carbonyl bridge (MnC_co 1.837(5) Å, NbC_co 2.781(5) Å). On the other hand, in complex II the sandwich Cp₂Nb(CO)H molecule (angle α = 37.8°) is combined with the Ni(CO)₃ group generally via a hydride bridge (NbH 1.83 Å, NiH 1.68 Å, NbHNi angle 132.7°) whereas the large Nb?Ni distance, 3.218(1) Å, shows the weakening or even absence of the direct NbNi bond. Similarly, in complex III two Cp₂Nb(CO)H molecules (with α angles equal to 41.4 and 43.0°, respectively) are joined to the Mo(CO)₄ group via the hydride bridges (NbH 1.83 and 1.75 Å and MoH 2.04 and 2.06 Å) producing a cis-form. The direct NbMo bonds are probably absent, since the Nb?Mo distances are rather long (3.579 and 3.565 Å). The effect of electronic and steric factors on the structure of heteronuclear niobocene carbonyl derivatives is discussed.     

Functionalization of the cluster [FeCp(μ3–CO)]4

The 33-year-old cluster [FeCp(μ₃-CO)]₄ (1) has been functionalized by reaction with lithium diisopropylamide, followed by CO₂, to give the acid RCO₂H, 2 (R=Fe₄(μ₃–CO)₄Cp₃(C₅H₄–)), recently reported by Rauchfuss. The cluster 2 reacts with (CO)₂Cl₂ to give the new cluster RCOCl (3), which reacts with the disulfide {S(CH₂)₁₁NH₃⁺Cl^–}₂ to give the amido-cluster disulfide [Fe₄(μ₃–CO)₄Cp₃{η⁵′-C₅H₄C(O)NH(CH₂)₁₁S}]₂ (4), with NEt₃ to give the diethylamido cluster [Fe₄Cp₃(η⁵-C₅H₄CONEt₂)(μ₃-CO)₄] (5), and with N-hydroxysuccinimide to give the N-succinimidyl ester cluster 6. © 2000 Académie des sciences / Éditions scientifiques et médicales Elsevier SAScluster functionalization / tetrairon-cylopentadienyl-carbonyl cluster     

Synthesis and crystal structure of the double cluster [Cp3Fe4(CO)4(C5H4)]2(p-C6H4)

[Cp₄Fe₄(CO)₄] (1) reacts with p-BrC₆H₄Li and MeOH in sequence to afford the functionalized cluster [Cp₃Fe₄(CO)₄(C₅H₄-p-C₆H₄Br)] (2), while the reaction of 2 with n-BuLi and MeOH produces [Cp₂Fe₄(CO)₄(C₅H₄Bu)(C₅H₄-p-C₆H₄Br)] (3). The double cluster [Cp₃Fe₄(CO)₄(C₅H₄)]₂(p-C₆H₄) (4) has been prepared by treatment of [Cp₄Fe₄(CO)₄] with p-C₆H₄Li₂ and MeOH in sequence. The electrochemistry of 2 and 4, as well as the crystal structure of 4 have been investigated.     

Acetylenic derivatives of metal carbonyls of the triad Fe,Ru, Os—XI Mass spectra of some binuclear complexes

The mass spectra of the following acetylenic derivatives of iron, ruthenium and osmium carbonyls are reported: the iron compounds Fe₂(CO)₆[C₂(C₆H₅)s₂]₂, Fe₂(CO)₆[C₂(CH₃)₂]₂ and Fe₂(CO)₆[C₂(C₂H₅)₂]₂, the ruthenium compounds Ru₂(CO)₆[C₂(C₆H₅)₂]₂, and Ru₂(CO)₆[C₂(CH₃)₂]₂ and the osmium compounds Os₂(CO)₆[C₂(C₆H₅)₂]₂, Os₂(CO)₆[C₂HC₆H₅]₂ and Os₂(CO)₆[C₂(CH₃)₂]₂. Iron compounds exhibit breakdown schemes where binuclear, mononuclear and hydrocarbon ions are present. On the other hand, ruthenium and osmium compounds fragment in a similar way and give rise to singly and doubly charged binuclear ions. Phenylic derivatives of ruthenium and osmium also give weak triply charged ions. The results are discussed in terms of relative strengths of the metal-metal and metal-carbon bonds.     

Synthesis and cleavage reactions of thiocarbonyl-bridged Cp2Fe2(CO)3CS,and preparation of the carbene complexes CpFe(CO)C(N2C2H6)SnPh3 and [CpFe(CO)2C(OMe)2]PF6

The thiocarbonyl-bridged complex Cp₂Fe₂(CO)₃CS is obtained by the reaction of CpFe(CO)₂^? and (PhO)₂CS in THF. Infrared and NMR spectra show that the compound exists in solution in interconverting cis and trans forms, but that the isomerization occurs more slowly than for the carbonyl analog [CpFe(CO)₂]₂. Most reagents which cleave [CpFe(CO)₂]₂, such as Br₂, HgCl₂, and O₂/HBF₄, do not give simple cleavage reactions with Cp₂Fe₂(CO)₃CS. Reductive cleavage of Cp₂Fe₂(CO)₃CS with Na(Hg) gives the thiocarbonyl anion CpFe(CO)(CS)^?, which reacts with Ph₃SnCl to form CpFe(CO)(CS)SnPh₃. Methylamine reacts with CpFe(CO)(CS)SnPh₃ to give CpFe(CO)(CNMe)SnPh₃, while ethylenediamine gives the carbene complexes CpFe(CO)C(N₂C₂H₆)SnPh₃. The preparation of another new carbene complex, [CpFe(CO)₂C(OMe)₂]PF₆, is also described.     

Reaktionen von Nitrosylkomplexen: VIII. Ein alternativer Weg zu Cp3Co3(μ3-NO)2 sowie Synthese des isoelektronischen Clusters Cp3Co2Fe(μ3-NH)(μ3-NO)

Treatment of CpCo(C₂H₄)₂ with NO in hexane yields Cp₃Co₃(μ₃-NO)₂ together with the dinitrosoethane complex CpCo(NO)₂C₂H₄; the mixture of these known compounds can easily be separated. The reaction of [CpFeNO]₂ with excess CpCo(C₂H₄)₂ in THF gives Cp₃Co₂Fe(μ₃-NH)(μ₃-NO) as the main product, which is an isoelectronic congener of Cp₃Co₃(μ₃-NO)₂. Another isoelectronic species of possible composition Cp₃CoFe₂(μ₃-NH)₂ is found as a by-product.     

Optisch aktive übergangsmetall-komplexe: LXXXV. Darstellung,eigenschaften und konformationsanalyse von optisch aktiven CpCo-Komplexen

The Schiff bases from 2-pyridine-carbaldehyde, 2-acetylpyridine, 2-benzoylpyridine, 2-pyrrole-carbaldehyde, and 2-acetylpyrrole with (?)-1-phenylethylamine and (?)-3-aminomethylpinane were synthesized. The pyridine Schiff bases αγ were used as neutral compounds and the pyrrole Schiff bases δHζH were used as anions δζ in the reaction with CpCo(CO)I₂ and CpCo(CO)(C₃F₇)I. In place of the covalently bonded iodine ligand different monodentate ligands bp were incorporated. Compounds of the type CpCo(αζ)(ap) and [CpCo(αζ)(ap)]X with X = I, PF₆ are formed.All the complexes consist of pairs of diastereomers differing only in the Co configuration. The diastereomers exhibit different ¹H NMR spectra. The Co configuration in all the compounds is labile except the C₃F₇ derivatives. A conformational analysis establishes which of the diastereomers is the thermodynamically more stable one, on the basis of the following arguments and methods: NOE-difference spectroscopy, diastereomer ratios at equilibrium, chemical shifts of the Cp signals, and CD spectra.     

Synthesis and properties of dicyclopentadienyltantalum(III) carbonyl compounds

Reaction of Cp₂Ta(H)L (L = C₃H₆, C₄H₈, C₅H₁₀ and C₅H₈) with CO under mild conditions gives alkyltantalum carbonyl complexes Cp₂Ta(CO)R (R = C₃H₇, C₄H₉, C₅H₁₁ and C₅H₉, respectively). Depending upon the position of the olefin relative to the hydride ligand in the hydride-olefin complex, Cp₂Ta(CO)H is also formed during the carbonylation reaction. Reduction of Cp₂TaCl₂ by potassium or t-BuMgCl under one atmosphere of CO affords the very stable compound Cp₂Ta(CO)Cl in moderate yields. Reaction of Cp₂Ta(CO)Cl with RLi or RMgX does not give the Cp₂Ta(CO)R complex.     

Nanoscale ensembles using building blocks inspired by the [FeFe]-hydrogenase active site

The hydrogenase model [Fe₂(S₂C₃H₆)(CN)₂(CO)₄]²⁻ was employed as a molecular tecton for the construction of supramolecular aggregates. IR spectroscopy indicated that cyanide bridged aggregates are formed when [Fe₂(S₂C₃H₆)(CN)₂(CO)₄]²⁻ was treated with Lewis acids such as Zn(tetraphenylporphyrinate), [Cu(NCMe)(2,2′-bipyridine)]PF₆ and [Cu(NCMe)₄]PF₆. Condensation of [Fe₂(S₂C₃H₆)(CN)₂(CO)₄]²⁻ with the tritopic Lewis acid [Cp¹Rh]²⁺ afforded the novel expanded tetrahedron cage, {[Fe₂(S₂C₃H₆)(CN)₂(CO)₄]₆[Cp¹Rh]₄}⁴⁻. The tetrahedron cage was characterized crystallographically as the PPN salt.     

Syntheses,crystal structures,and electrochemistry of novel Fe2SN and FeSN carbonyl complexes with pendant bases

Reactions of Fe₂(CO)₉ with thioacylhydrazones ArCH=NNHCSPh in THF afford Fe₂(CO)₆(μ-κ²S:κ²N-PhC(S)=NNCHArCHArN(CHAr)N=CSPh) (1, Ar?=?C₆H₅; 3, Ar?=?4-CH₃C₆H₄) and Fe(CO)₃(κ²S:N-PhC(=S)NHNCHArCHArN(CHAr)N=CSPh) (2, Ar?=?C₆H₅; 4, Ar?=?4-CH₃C₆H₄). They have been characterized by elemental analyses, IR, ¹H NMR, and ¹³C NMR and structurally determined by X-ray crystallography. Electrochemical studies reveal that when using HOAc as a proton source, they exhibit high catalytic H₂-production.     

The reaction of diiron nonacarbonyl with cis-bicyclo[6.2.0]deca-2,4,6-triene

The reaction of diiron nonacarbonyl with cis-bicyclo[6.2.0]deca-2,4,6-triene in ether at room temperature produces several products which are separable by chromatography on alumina. Compound (A), C₁₀H₁₂Fe₂(CO)₆, obtained in 23% yield, is shown by PMR and IR spectra to have the FeFe bonded Fe₂(CO)₆ group attached to the triene portion of the starting bicyclotriene. Compound (B), C₁₀H₁₂Fe(CO)₃, obtained both from the initial reaction and by heating (A) in refluxing toluene; is the Fe(CO)₃ adduct of tricyclo[4.4.0.0^2.5]deca-7,9-diene, a molecule which has not been isolated in the free state. Compound (C), also obtained on pyrolysis of (A) in minute yield, has not yet been characterized. Compound (D), C₁₀H₁₂Fe₂(CO)₆, from the original reaction, in small yield, appears to have separate Fe(CO)₃ groups bonded to the olefinic portions of a C₁₀H₁₂ monocycle, but spectral data alone do not allow a complete specification of the structure.     

Reactions of Dicyclopentadienyltitanium(III) compounds with carbon monoxide

Reactions of Cp₂TiR (R = Cl, C₆F₅, C₆H₅, o-CH₃C₆H₄) with CO give two types of products: terminally coordinated adducts, Cp₂Ti(R)CO, and insertion products, Cp₂TiCOR, i.e. acyl compounds. The acyl ligand is η²-coordinated at the titanium atom. The preparations and properties of the compounds are described.     

Synthesis and molecular structure of niobocene trimethylacetate and its π-complex with diphenylacetylene

Niobocene trimethylacetate Cp₂Nb(OOCCMe₃) (I) does not react with usual n-donors (pyridine and triphenylphosphine), but readily adds a π-acceptor molecule of diphenylacetylene (tolane) in benzene to form Cp₂Nb(OOCCMe₃)(π-Ph₂C₂) · 0.5 C₆H₆ (II). The structures of the diamagnetic complexes I and II have been determined by an X-ray diffraction study. These molecules represent wedge-like sandwiches wit dihedral angles between cyclopentadienyl ligands equal to 44.4 and 50.7°, and average NbC distances of 2.39 and 2.44 Å, respectively. The bisector plane of I contains the chelate trimethylacetate group (NbO bond lenghts 2.23 and 2.24 Å) and that of II contains the coordinated tolane molecule and the oxygen atom of the terminal trimethylacetate ligand (NbO 2.16, NbC 2.18 and 2.19, CC 1.29 Å, PhCC angles 141 and 146°). An unusually large splitting of OCO stretching frequencies is observed in the IR spectrum of I (1652?1305 = 347 cm^?1). Structural characteristics of the coordinated CC triple bond in II are similar to those found in Cp(π-Ph₄C₄)Nb(CO)(π-Ph₂C₂) studied earlier. The role played by the Nb^III lone pair in I and II is discussed.     

The crystal and molecular structure of μ(1,2,6-η: 3-5-ηbicyglo[6.10]nona-1,3,5-triene)hexacarbonyldiiron (FEFe), and comment on its temperature-dependent 1H NMR spectrum

The crystal and molecular structure of (C₉H₁₀)Fe₂(CO)₆6 has been determined from a three-dimensional, X-ray crystal-structure analysis. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares. With all atoms located and refined the conventional R factor is 0.034, based on 2651 reflections measured with an automated General Electric XRD-6 diffractometer utilizing Mo-Kα radiation. Crystallographic data are: space group P$\text{1}$ with a = 7.229(4), b = 14.699(4) and c = 7.696(2) Å, α = 87.53(2)°, β = 113.48(3)° and γ = 102.08(2)°, Z = 2 and ?_calcd = 1.80 g/cm₃, ?_obsd = 1.78 g/cm₃. Contrary to previous claims the structure of the molecule is of the asymmetric type already established for (C₈H₁₀)Fe₂(CO)₆ and (C₁₀H₁₂)Fe₂(CO)₆. The almost identical bond parameters amongst the three structures are noted. The lengthening of the FeC(carbonyl) trans to FeC σ bond is attributed to the trans-influence of the σ-carbon atom. The fluxional nature of the molecule is also demonstrated by extending the variable temperature ¹H NMR study down to ?127°.     

Reactions of metal carbonyl derivatives X. The synthesis and reactivity of some dinuclear derivatives of iron containing both bridging carbonyls and bridging phosphido or sulphido groups

The tertiary phosphine π-C₅H₅Fe(CO)₂P(C₆H₅)₂ reacts with a suspension of Fe₂(CO)₉ in benzene to give the dinuclear complex π-C₅H₅Fe₂P(C₆H₅)₂(CO)₆. This compound is also obtained by nucleophilic attack of [π-C₅H₅Fe(CO)₂]⁻ on Fe(CO)₄-[P(C₆H₅)₂Cl] in tetrahydrofuran. Irradiation of a benzene solution of π-C₅H₅Fe₂-P(C₆H₅)₂(CO)₆ with ultraviolet light affords π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅ which contains both a bridging carbonyl and a bridging phosphido group. The unstable bridged sulphido derivatives π-C₅H₅Fe₂SR(CO)₆ (R = CH₃ and C₆H₅) and π-C₅H₅Fe₂(t-C₄H₉S)(CO)₅ are similarly obtained employing π-C₅H₅Fe(CO)₂SR as ligand. The reactions of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅ with tertiary phosphines and phosphites yield three types of products depending on the reaction conditions and the ligand involved. Examples include π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄P(C₆H₅)₃, a mono-substituted derivative of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅, and π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅P(C₂H₅)₃ and π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄[P(OCH)₃)₃]₂, mono- and bis-substituted derivatives of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₆, respectively. The reaction of π-C₅H₅Fe₂P(C₆H₅₂(CO)₅ with (C₆H₅)₂PCH₂P(C₆H₅)₂ in benzene under reflux affords [π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄](C₆H₅)₂PCH₂P(C₆H₅)₂ in which the ditertiary phosphine bridges two iron atoms.     

Crystal and molecular structure of (μ-η2,η3-propargyl)- bis(cyclopentadienyl)tetracarbonyldimolybdenum tetrafluoroborate and (μ-η2,η3-1,1-dimethylpropargyl)- bis(cyclopentadienyl)tetracarbonyldimolybdenum tetrafluoroborate

An X-ray study of [(μ-η²,η³-HCCCH₂)Cp₂Mo₂(CO)₄]⁺(BF₄⁻) (1) and [(μ-η²,η³-HCCCMe₂)Cp₂Mo₂(CO)₄]⁺(BF₄⁻) (2) reveals their structures to be similar to the structure of neutral compounds of the series (μ-η²,η²-RCCR)Cp₂Mo₂(CO)₄, the difference between 1 and 2 being mainly due to the markedly different MoC⁺ bond lengths, which accounts for different stability and fluxional behavior of these compounds in solution.     

Molecular Thorium Trihydrido Clusters Stabilized by Cyclopentadienyl Ligands

Hydrogenolysis of alkyl‐substituted cyclopentadienyl (Cp^R) ligated thorium tribenzyl complexes [(Cp^R)Th(p‐CH₂‐C₆H₄‐Me)₃] ( 1 – 6 ) afforded the first examples of molecular thorium trihydrido complexes [(Cp^R)Th(μ‐H)₃]_n (Cp^R=C₅H₂(^tBu)₃ or C₅H₂(SiMe₃)₃, n=5; C₅Me₄SiMe₃, n=6; C₅Me₅, n=7; C₅Me₄H, n=8; 7 – 10 and 12 ) and [(Cp^#)₁₂Th₁₃H₄₀] (Cp^#=C₅H₄SiMe₃; 13 ). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra‐nuclear octahydrido thorium dibenzylidene complex [(Cp^ttt)Th(μ‐H)₂]₄(μ‐p‐CH‐C₆H₄‐Me)₂ (Cp^ttt=C₅H₂(^tBu)₃) ( 11 ) was also isolated. All of the complexes were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. Hydride positions in [(Cp^Me4)Th(μ‐H)₃]₈ (Cp^Me4=C₅Me₄H) were further precisely confirmed by single‐crystal neutron diffraction. DFT calculations strengthen the experimental assignment of the hydride positions in the complexes 7 to 12 .     

Transfer processes of alkoxyl groups in iron carbonyl complexes

The mass spectra of Fe₂(CO)₆C₄(COOCH₃)₄ and Fe₂(CO)₆C₄(COOC₂H₅)₄ are reported. Transfer processes of alkoxyl groups and hydrogen rearrangements are observed, and confirmed by deuterium labelling and the observation of metastable transitions. Fe₃(CO)₈C₄(COOCH₃)₄ and Fe₃(CO)₈C₄(COOC₂H₅)₄ give similar breakdown patterns. Likely fragmentation schemes are suggested.     

半夹芯16电子碳硼烷化合物Cp*CoS2C2B10H10与含磷化合物的反应性

半夹芯16电子碳硼烷化合物Cp~*CoS_2C_2B_(10)H_(10)分别与二苯基甲基膦、苯基二甲基膦和三甲基膦反应得到碳硼烷衍生物(Cp~*CoS_2C_2B_(10)H_(10))(PPh_2Me)(1)、(Cp~*CoS_2C_2B_(10)H_(10))(PPhMe_2)(2)和(Cp~*CoS_2C_2B_(10)H_(10))(PMe_3)(3)。分别用红外、核磁、元素分析、质谱和单晶X射线衍射等表征方法对1、2和3进行了结构表征。紫外可见吸收光谱结果显示化合物1、2和3在乙腈溶剂中均有2个吸收峰,第一个吸收峰分别位于321、316和321 nm;第二个吸收峰分别位于425、399和407 nm。荧光光谱结果显示化合物1、2和3在乙腈中的最大发射波长位于406 nm左右。     

R—P-verbrückte eien-cluster-hydride

Trinuclear clusters RPFe₃(CO)₉H₂ (R = Ph, p-C₆H₄OCH₃, C₆H₁₁, t-Bu CH₂CH₂CN) are obtained in fair yields by treatment of Fe₃(CO)₁₂ with primary phosphanes, RPH₂. X-ray structure analysis of PhPFe₃(CO)₉H₂ reveals a trigonal pyramidal frame-work for the cluster with an iron triangle at the base and the phosphorus atom at the apex. Two of the three FeFe bonds are bridged by hydrogens.Reaction of C₅H₅(CO)₂MnP(C₆H₅)H₂ with Fe₃(CO)₁₂ gives an improved yield of the known trinuclear heterometallic cluster C₅H₅(CO)₂MnFe₂(CO)₆PC₆H₅.