High nuclearity PtRh carbonyl clusters. Synthesis and X-ray characterization of the [Pt2Rh9(CO)22]3− trianion

The new mixed PtRh cluster trianion [Pt₂Rh₉(CO)₂₂]^3? has been isolated as a minor product of the pyrolysis of [PtRh₅(CO)₁₅]^?, and has been characterized by X-ray diffraction. The metal skeleton, which has ideal D_3h symmetry, consists of three face-to-face condensed octahedra, as previously found in the isoelectronic species [Rh₁₁CO)₂₃]^3?, with the Pt atoms on the three-fold axis, in the positions of maximum MM connectivity.     

The thermochemistry of carbonyl complexes of Cr,Mo and W with pyridine and acetonitrile

Microcalorimetric measurements at elevated temperatures of the heats of thermal decomposition and of iodination of a number of [M(CO)_nL_6-n] complexes (M = Cr, Mo, W; n = 3, 4; L = py, MeCN) have led to values for the standard enthalpies of formation of the following crystalline compounds (values given in kJ mol^?) at 25°C: fac-[Mo(CO)₃py₃](275 ± 12), fac-[Mo(CO)₃(NCCH₃)₃]  (410 ± 12), fac-[W(CO)₃py₃](250 ± 12), fac-[W(CO)₃(NCCH₃)₃](405 ± 12) and cis-[Cr(CO)₄py₂](505 ± 20). From these and other data, including estimated heats of sublimation, the bond enthalpy contributions of the various metalligand bonds in the gaseous metal complexes were evaluated as follows (values in kJ mol^?): D(Crpy) 102, D(Mopy) 146, DWPy) 173, D(Mo7z.sbnd;NCMe) 135 and D(WNCMe) 169. For a given metal the bond enthalpy contribution decreased in the order D(MCO) > D(Mpy) > D(Mz.sbnd;NCMe). This order is related to the σ- and π-bonding character of the ligand.     

Zur verwendung von ferricenium-kationen als selektivem oxidationsmittel in der metallorganischen chemie

The use of ferricenium cations [(C₅H₅)₂FE]X (X = BF₄, PF₆, SbF₆) as one-electron oxidizing agents for organometallic complexes is demonstrated. Sandwich compounds M(C₅H₅)₂ (M = Cr, Co, Ni) and Cr(C₆H₆)₂ are oxidized in nearly quantitative yield to the corresponding cations [M(C₅H₅)₂]BF₄ and [(C₆H₆)₂Cr]BF₄. The metalmetal bond in the dinuclear organometallic complexes [DienylM(CO)_n]₂ (M = Mo (n = 3), Fe (n = 2), Ni (n = 1)) and Co₂(CO)₈ is fissioned by (C₅H₅)₂Fe⁺ in the presence of neutral ligands L to form the corresponding cationic compounds [DienylM(CO)_nL_m]X (M = Mo (n = 2), Fe (n = 2), Ni (n = 0)) and [Co(CO)₃L₂BF₄ (L = VB and VIB donor ligands) in high yields.The practical applications of ferricenium cations are discussed in comparison with other methods for the preparation of cationic organometallic complexes.     

Chemical Bonding in Homoleptic Carbonyl Cations [M{Fe(CO)5}2]+ (M=Cu,Ag, Au)

Syntheses of the copper and gold complexes [Cu{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] containing the homoleptic carbonyl cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Au) are reported. Structural data of the rare, trimetallic Cu₂Fe, Ag₂Fe and Au₂Fe complexes [Cu{Fe(CO)₅}₂][SbF₆], [Ag{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] are also given. The silver and gold cations [M{Fe(CO)₅}₂]⁺ (M=Ag, Au) possess a nearly linear Fe-M-Fe’ moiety but the Fe-Cu-Fe’ in [Cu{Fe(CO)₅}₂][SbF₆] exhibits a significant bending angle of 147° due to the strong interaction with the [SbF₆]⁻ anion. The Fe(CO)₅ ligands adopt a distorted square-pyramidal geometry in the cations [M{Fe(CO)₅}₂]⁺, with the basal CO groups inclined towards M. The geometry optimization with DFT methods of the cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Ag, Au) gives equilibrium structures with linear Fe-M-Fe’ fragments and D₂ symmetry for the copper and silver cations and D_4d symmetry for the gold cation. There is nearly free rotation of the Fe(CO)₅ ligands around the Fe-M-Fe’ axis. The calculated bond dissociation energies for the loss of both Fe(CO)₅ ligands from the cations [M{Fe(CO)₅}₂]⁺ show the order M=Au (D_e=137.2 kcal mol⁻¹)>Cu (D_e=109.0 kcal mol⁻¹)>Ag (D_e=92.4 kcal mol⁻¹). The QTAIM analysis shows bond paths and bond critical points for the M−Fe linkage but not between M and the CO ligands. The EDA-NOCV calculations suggest that the [Fe(CO)₅]→M⁺←[Fe(CO)₅] donation is significantly stronger than the [Fe(CO)₅]←M⁺→[Fe(CO)₅] backdonation. Inspection of the pairwise orbital interactions identifies four contributions for the charge donation of the Fe(CO)₅ ligands into the vacant (n)s and (n)p AOs of M⁺ and five components for the backdonation from the occupied (n-1)d AOs of M⁺ into vacant ligand orbitals.     

Synthesis,structure and bonding situation of [(dcpe)Pt(InCp*)2] and {(dcpe)Pt[GaC(SiMe3)3]2}—two novel examples of platinum complexes of low valent Group 13 metal species

In analogy to the corresponding Cp*Al- and Cp*Ga-compounds two further bis(phosphine)platinum complexes [(dcpe)Pt(InCp*)₂] (1(In)) and {(dcpe)Pt[GaC(SiMe₃)₃]₂} (2(Ga)) containing monovalent Group 13 metal species as ligands are accessible by thermal activation of [(dcpe)Pt(H)(CH₂t-Bu)] (dcpe=bis(dicyclohexylphosphino)ethane) followed by the reaction with 2 equiv. of InCp* (Cp*=pentamethylcyclopentadienyl) or GaC(SiMe₃)₃. The crystal structure analysis reveals a distorted tetrahedral coordination of the platinum center for both compounds. The PtIn distances in 1(In) amount to 2.569(1) and 2.556(1) Å. The PtGa distances in 2(Ga) are exceptionally short and amount to 2.315(1) and 2.318(1) Å. Comparative theoretical investigations have been performed on this type of complexes and allow a deeper insight in the bonding situation. The NBO analysis reveals a significantly larger Pt→Ga π-back-donation for the model compound {(dhpe)Pt[GaC(SiH₃)₃]₂} (2M(Ga)) (0.44 e; dhpe=1,2-diphosphinoethane) in comparison with the related model compound [(dhpe)Pt(GaCp)₂] (1M(Ga)) (0.29 e) bearing a strong π-donating organic ligand at the Ga center. A similar trend is observed for the PtGa bond dissociation energies (D_e=33.0 kcal mol⁻¹ for 2M(Ga), D_e=18.3 kcal mol⁻¹ for 1M(Ga)). For the model compound [(dhpe)Pt(InCp)₂] (1M(In)) a value of D_e=19.1 kcal mol⁻¹ has been calculated.     

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.     

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)]⁺.     

Metal complexes as ligands—VII: The chemistry of the monothiooxalate complexes

A synthesis of potassium monothiooxalate, K₂C₂SO₃, and its reactions with metal ions are reported. The spectroscopic properties of the complexes, M(C₂SO₃)_nⁿ⁻, for M  Ni(II), Cu(II), Zn(II) (n = 2); and M  Cr(III), Co(III), Fe(III) (n = 3) are indicative of (SO) chelated ligands while the Al(III) (n = 3) complex is an (OO) bonded chelate. The copper(II) complex undergoes an irreversible oxidation at 0.43 V. This oxidation is accompanied by reduction of the copper(II) and evolution of CO₂ and SCO.The inert cations which accompany the anionic monothiooxalate complexes are readily replaced by the coordinatively unsaturated (Ph₃P)₂M⁺, M  Ag(I), Cu(I) complex cations. The bridging of the monothiooxalate ligand in the resulting polynuclear complexes is of the type MOOC₂SOM′, M  Al(III), Fe(III), M′  Ag(I), Cu(I); M  Cr(III), M′  Cu(I) and MSOC₂O₂M′, M  Cr(III), Co(III), M′  Cu(I).     

Structure/reactivity relationships for cationic (phosphenium)iron tetracarbonyl complexes

An X-ray crystal structure of [(Et₂N)₂PFe(CO)₄]⁺, reveals shortening of the PFe and CO_eq bonds and lengthening of the FeC_eq bonds, possibly suggesting that the CO lability of cationic (phosphenium)iron tetracarbonyl complexes is due to the strong π-acceptor character of the phosphenium ligand.     

Kinetics of nucleophilic attack on coordinated organic moieties : VI. Mechanism of addition of tri-n-butylphosphine to [(C7H7)M(CO)3]BF4 (M = Cr, Mo, W) and related cations

Phosphonium adduct formation via attack of tri-n-butylphosphine on the cations [(C₇H₇)M(CO)₃]⁺ (M = Cr, Mo, W) obeys the rate law, Rate = k [complex] [PBu₃]. The very similar rate constants for the Cr, Mo and W complexes confirm the similar electrophilicities of the tropylium rings in these cations, and also support the view that there is direct addition to the rings. The related complexes [(C₆H₇)Fe(CO)₃]BF₄ and [(C₆H₆)Mn(CO)₃]BF₄ also form adducts with PBu₃, and the quantitative reactivity order [(C₆H₇)Fe(CO)₃]⁺ > [(C₇H₇)Cr(CO)₃]⁺ » [(C₆H₆)Mn(CO)₃]⁺ (160:60:1) has been established.     

The configuration of transition metal coordination compounds containing the anion of hexahydro-1,3,5-triazine-1,3,5-triol

The configuration of Ni(IV), Fe(IV), Mn(IV) and V(IV) complexes of the type M^I₂[M^IVL₂] where M^I=Li, Na, K, Rb and Cs and the ligand L is the anion C₃H₆N₃O³⁻₃ of hexahydro-1,3,5-triazine-1,3,5-triol has been obtained by studying the infrared spectra of the complexes in the region 4000-50 cm⁻¹. Vibrational assignments for the observed bands of the complex ions have been made assuming the molecular symmetry D_3d. The assignments have been based on the observed isotopic frequency shifts due to the substitutions H/D, ¹⁴N/¹⁵N, ¹²C/¹³C, ⁵⁸Ni/⁶²Ni and ⁵⁴Fe/⁵⁷Fe and on the assignment of the bands in the infrared spectrum of hexahydro-1,3,5-triazine-1,3,5-triol, C₃H₆N₃ (OH)₃.     

Zweikernige η5-pentamethylcyclopentadienyl-rhenium-komplexe mit einer chalkogenbrücke. Die molekülstruktur von [(η5-C5Me5)Re(CO)2]2(μ-Se)

We report the synthesis and characterisation of binuclear η⁵-pentamethylcyclopentadienylrhenium complexes, [(η⁵-C₅Me₅)Re(CO)₂]₂(μ-E) (E = S (2), Se (3), Te (4)), containing a chalcogen bridge in addition to a ReRe bond. According to the X-ray structural analysis, 3 possesses approximately C₂ molecular symmetry; the C₅Me₅ ring ligands occupy trans positions with respect to the central Re₂Se unit [d(ReRe) 3.032(1) Å, ∢ ReSeRe 74.9(1)°]. As expected, the complexes of the now complete series [CpRe(CO)₂]₂(μ-E) (E = O (1), S (2), Se (3), Te (4)) show a high degree of similarity in their corresponding mass, IR, ¹H and ¹³C NMR spectra.     

The structure of an arenemanganese tricarbonyl cation; synthesis and X-ray analysis of dodecahydrotriphenylene(tricarbonyl)manganese(I) tetrafluoroborate

The synthesis, spectroscopic properties, and X-ray structure of dodecahydrotriphenylene(tricarbonyl)manganese(I) tetrafluoroborate, [(η⁶-C₁₈H₂₄)Mn(CO)₃][BF₄] are reported. The cation has approximate C₃ symmetry with the MnCO vectors projected across the unbridged CC bonds of the arene ligand.     

The infrared spectra of ethylenediamine complexes—II. Tris-, bis- and mono(ethylenediamine) complexes of metal(II) halides

The i.r. spectra of the complexes M(en)₃X₂ (M = Mn, Fe, Co, Ni, Cu, Zn), trans-Cu(en)₂X₂, Ni(en)₂X₂ and M(en)X₂ (M = Ni, Cu, Zn; X = Cl, Br, I) have been studied. Assignments are proposed for the tris(ethylenediamine) complexes on the basis of ¹⁵N-, N₂D₄- and C₂D₄-labelling of en and the effects of metal ion substitution in relation to our earlier study of [M(en)₃]SO₄ complexes. Assignments for the bis(ethylenediamine) complexes are based on our observations of halogen-sensitivity and earlier studies on metal isotope labelling and ligand deuteration of the halide complexes and a normal coordinate analysis of the [Cu(en)₂]²⁺ species. The spectra of the halide complexes have been extended below 200 cm⁻¹ for the first time. Finally, the spectra of the mono(ethylenediamine) complexes are discussed in relation to their known or probable structures.     

The far-infrared spectra of pyridine complexes of transition metal(II) isothiocyanates

The infrared spectra (500–140 cm^?1) of the complexes [M(pyridine)_n(NCS)₂] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v/M-pyridine and v/M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine)₂Cl₂] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of vM-pyridine bands require revision. The spectra of the yellow [Fe(py)₄(NCS)₂] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans-[Fe(py)₄(NCS)₂] into cis-[Fe(py)₃(NCS)₃]     

Synthesis and x-ray crystallographic characterization of (μ3-Bi)2Fe3(CO)9: A reformulation of Hieber's Bi2Fe5(CO)20

When [HFe(CO)₄]^? is treated first with NaBiO₃ and then dilute H₂SO₄, a complex mixture of neutral metal carbonyl clusters results, some of which can be extracted into petroleum ether. Upon prolonged standing the extract yields a precipitate which has been characterized by X-ray crystallography as Bi₂Fe₃(CO)₉.The complex Bi₂Fe₃(CO)₉ crystallizes in the centrosymmetric orthorhombic space group Cmcm (D_2h¹⁷; No. 63) with a 10.616(2) Å, b 13.458(3) Å, c 11.347(3) Å, V 1621.1(7) ų and Z = 4. Single-crystal X-ray diffraction data (Mo-K_α, 2θ = 4.5–55.0°) were collected on a Syntex P2₁ four-circle diffractometer and the structure was refined to R_F 5.4% and R_WF 4.5% for all 1039 independent data (R_F 4.5% and R_WF 4.5% for those 851 reflections with |F₀| > 3.0σ(|F₀|)). The molecule lies on a site of crystallographic C_2v symmetry and is disordered. The individual molecules have a trigonal bipyramidal Bi₂Fe₃ core with the bismuth atoms occupying the apical sites (BiFe 2.617(2)–2.643(2) Å, FeFe 2.735(5)–2.757(5) Å). Each iron atom is linked to three terminal carbonyl ligands and the molecule has approximate C_3h symmetry. The nine peripheral oxygen atoms are ordered and define a tricapped trigonal prism. The equatorial iron atoms are disordered with the two Fe₃ triangles mutually displaced by approximately 30°; the disordered ensemble has approximate D_3h symmetry.     

Dynamic Jahn–Teller effect and average structure of dicyclopentadienylcobalt, (C5H5)2Co,studied by gas phase electron diffraction

The molecular structure of (C₅H₅)₂Co has been determined by gas phase electron diffraction. The best agreement between calculated and experimental intensity curves is obtained with a model with eclipsed C₅H₅ rings (symmetry D_5h), but a model with staggered rings (symmetry D_5d) cannot be ruled out. The mean CoC and CC bond distances are 2.119(3) Å and 1.429(2) Å respectively. The average angle between the CH bonds and the C₅ ring is 2.1(0.8)°. The value obtained for the CC vibrational amplitude, l(CC) = 0.055(1) Å, is significantly larger than the amplitude calculated from a molecular force field and the corresponding amplitudes in (C₅H₅)₂Fe and (C₅H₅)₂Ni determined by electron diffraction, and confirms the presence of a dynamic Jahn—Teller effect of the magnitude calculated from ESR data. The average structure is compared with those of the metallocenes of the other first row transition elements.     

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.     

Organometalloidal derivatives of the transition metals: X. Photochemical,thermal, and SO2induced 1,2-phenyl and 1,2-sulphinatophenyl migratons from lead to transition metals in the system [(η5-C5H5)M(CO)nPbPh3] (M = Fe,Cr, Mo,W)

The complexes [(η⁵-C₅H₅)M(CO)_nPbPh₃] (M = Fe, Cr, Mo, W) have been studied with respect to their thermal and photochemical stability and their reactivity with respect to SO₂. The iron complex is the only complex that exhibits the ability to decompose via a 1,2-phenyl migration to the transition metal under thermal conditions, but photochemically the tungsten complex also exhibits this behaviour. All complexes react readily with SO₂ to yield the corresponding sulphinatophenyl complexes, LMSO₂Ph, in high yield.