Slippage of η-allenyl/propargyl to an η structure and tautomerization of η-propargyl to η-allenyl in ligand addition and substitution reactions of platinum(II) complexes

Reactions of [(PPh₃)₂Pt(η³-CH₂CCPh)]OTf with each of PMe₃, CO and Br⁻ result in the addition of these species to the metal and a change in hapticity of the η³-CH₂CCPh to η¹-CH₂CCPh or η¹-C(Ph)=C=CH₂. Thus, PMe₃ affords [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)]⁺, CO gives both [trans-(PPh₃)₂Pt(CO)(η¹-CH₂CCPh)]⁺ and [trans-(PPh₃)₂Pt(CO)(η¹-C(Ph)=C=CH₂)]⁺, and LiBr yields cis-(PPh₃)₂PtBr(η¹-CH₂CCPh), which undergoes isomerization to trans-(PPh₃)₂PtBr(η¹-CH₂CCPh). Substitution reactions of cis- and trans-(PPh₃)₂PtBr(η¹-CH₂CCPh) each lead to tautomerization of η¹-CH₂CCPh to η¹-C(Ph)=C=CH₂, with trans-(PPh₃)₂PtBr(η¹-CH₂CCPh) affording [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)]⁺ at ambient temperature and the slower reacting cis isomer giving [trans-(PPh₃)(PMe₃)₂Pt(η¹-C(Ph)=C=CH₂)]⁺ at 54 °C . All new complexes were characterized by a combination of elemental analysis, FAB mas spectrometry and IR and NMR (¹H, ¹³C{¹H} and ³¹P{¹H}) spectroscopy. The structure of [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)]BPh₄·0.5MeOH was determined by single-crystal X-ray diffraction analysis.     

Hetero-polynuclear complexes containing bridging diphenylphosphino-alkenes and -alkynes. The crystal structure of an Rh2{μ−ν:ν−P(Ph2) (CH2)3C≡CR}Co2 complex

The phosphinoalkenes Ph₂P(CH₂)_nCH=CH₂ (n= 1, 2, 3) and phosphinoalkynes Ph₂P(CH₂)_n C≡CR (R = H, N = 2, 3; R = CH₃, N = 1) have been prepared and reacted with the dirhodium complex (η−C₅H₅)₂Rh₂(μ−CO) (μ−η²−CF₃C₂CF₃). Six new complexes of the type (ν−C₅H₅)₂(Rh₂(CO) (μ−η¹:η¹−CF₃C₂CF₃)L, where L is a P-coordinated phosphinoalkene, or phosphinoalkyne have been isolated and fully characterized; the carbonyl and phosphine ligands are predominantly trans on the Rh---Rh bond, but there is spectroscopic evidence that a small amount of the cis-isomer is formed also. Treatment of the dirhodium-phosphinoalkene complexes with (η−CH₃C₅H₄)Mn(CO)₂thf resulted in coordination of the manganese to the alkene function. The Rh₂---Mn complex [(η−C₅H₅)₂Rh₂(CO) (μ−η¹:η¹−CF₃C₂CF₃) {Ph₂P(CH₂)₃CH=CH₂} (η−CH₃C₅H₄)Mn(CO)₂] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co₂(CO)₈ resulted in the coordination of Co₂(CO)₆ to the alkyne function. The Rh₂---Co₂ complex [(η−C₅H₅)₂Rh₂(CO) (μ−η¹:η¹−CF₃C₂CF₃) {Ph₂PCH₂C≡CCH₃}Co₂(CO)₂], C₃₇H₂₅Co₂F₆O₇PRh₂, was fully characteriz spectroscopically, and the molecular structure of this complex was determined by a single crystal X-ray diffraction study. It is triclinic, space group (C_i¹, No. 2) with a = 18.454(6), B = 11.418(3), C = 10.124(3) Å, = 112.16(2), β = 102.34(3), γ = 91.62(3)°, Z = 2. Conventional R on |F| was 0.052 fo observed (I > 3σ(I)) reflections. The Rh₂ and Co₂ parts of the molecule are distinct, the carbonyl and phosphine are mutually trans on the Rh---Rh bond, and the orientations of the alkynes are parallel for Rh₂ and perpendicular for Co₂. Attempts to induce Rh₂Co₂ cluster formation were unsuccessful.     

Dissolution of [RhCl(PPh3)3] in the ionic liquid, 1-ethyl-3-methyl imidazolium chloroaluminate(III), and its reaction with H2. The stabilization of Rh(I) species in an ionic liquid

The solution of [RhCl(PPh₃)₃] in acidic 1-ethyl-3-methylimidazolium chloroaluminate(III) ionic liquid (AlCl₃ molar fraction, x_AlCl3=0.67) was investigated by ¹H and ³¹P{¹H} NMR. One triphenyl phosphine is lost from the complex and is protonated in the acidic media, and cis-[Rh(PPh₃)₂ClX], (2), where X is probably [AlCl₄]⁻, is formed. On, standing, 2 is converted to trans-[Rh(H)(PPh₃)₂X], (3). The reaction of 2 and H₂ also produces trans-[Rh(H)(PPh₃)₂X], (3). ¹H and ³¹P{¹H} NMR support the suggestion that a weak ligand such as [AlCl₄]⁻, present in solution may interact with the metal centre. When [RhCl(PPh₃)₃] is dissolved in CH₂Cl₂/AlCl₃/HCl for comparison, two exchanging isomers of what is probably [RhH{(μ-Cl)₂AlCl₂}{(μ-Cl)AlCl₃}(PPh₃)₂], (6) and (7), are formed.     

Palladium complexes with PCP ligands.: Preparation and structural studies of two forms of [(PCP)Pd(OH2)]BF4

Abstraction of chloride from the Pd complex {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]PdCl with AgBF₄ in THF gives {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(THF)}⁺BF₄ ⁻. Attemped crystallization of this THF complex produced the aqua complex {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺BF₄ ⁻. Crystal structures of two crystalline forms of this compound are reported. In {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺BF₄ ⁻·THF, one hydrogen of the water is hydrogen bonded to the oxygen of the THF, and the other hydrogen is hydrogen bonded to an F of the BF₄ ⁻ anion. Another crystalline form has no THF, but has both of the hydrogens of water hydrogen bonded to different BF₄ ⁻ anions, such that two different BF₄ ⁻ anions bridge two {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺ cations. A crystal structure is also reported for the palladium chloride complex [η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]PdCl.     

Nitrogen atom transfer and redox chemistry of terpyridyl phosphoraniminato complexes of osmium (IV)

Rapid reactions occur between [Os^VI(tpy)(Cl)₂(N)]X (X = PF₆⁻, Cl⁻, tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh₃, PPh₂Me, PPhMe₂, PMe₃ and PEt₃) in CH₂Cl₂ or CH₃CN to give [Os^IV(tpy)(Cl)₂(NPPh₃)]⁺ and its analogs. The reaction between trans-[Os^VI(tpy)(Cl)₂(N)]⁺ and PPh₃ in CH₃CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh₃ and Os^VI with k(CH₃CN, 25°C) = 1.36 ± 0.08 × 10⁴ M⁻ s⁻¹. The products are best formulated as paramagnetic d⁴ phosphoraniminato complexes of Os^IV based on a room temperature magnetic moment of 1.8 μ_B for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆), contact shifted ¹H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans-[Os^IV(tpy)(Cl)₂( NPPh₃)](PF₆)·CH₃CN (monoclinic, P2₁/n with a = 13.384(5) Å, b = 15.222(7) Å, c = 17.717(6) Å, β = 103.10(3)°, V = 3516(2) ų, Z = 4, R_w = 3.40, R_w = 3.50) and cis-[Os^IV(tpy)(Cl)₂(NPPh₂Me)]-(PF₆)·CH₃CN (monoclinic, P2₁/c, with a = 10.6348(2) Å, b = 15.146(9) ÅA, c = 20.876(6) Å, β = 97.47(1)°, V = 3334(2) ų, Z = 4, R = 4.00, R_w = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) Å), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible Os^V/IV and Os^IV/III couples occur for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) in CH₃CN at +0.92 V (Os^V/IV) and −0.27 V (Os^IV/III) versus SSCE. Chemical or electrochemical reduction of trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) gives isolable trans-Os^III(tpy)(Cl)₂(NPPh₃). One-electron oxidation to Os^V followed by intermolecular disproportionation and PPh₃ group transfer gives [Os^VI(tpy)Cl₂(N)]⁺, [OS^III(tpy)(Cl)₂(CH₃CN)]⁺ and [Ph₃=N=PPh₃]⁺ (PPN⁺). trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) undergoes reaction with a second phosphine under reflux to give PPN⁺ derivatives and Os^II(tpy)(Cl)₂(CH₃CN) in CH₃CN or Os^II(tpy)(Cl)₂(PR₃) in CH₂Cl₂. This demonstrates that the Os^VI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers.     

Cis- and trans-titanium complexes with doubly silyl-bridged dicyclopentadienyl ligands: molecular structure of [(TiCl)2(μ-O){(SiMe2)2(η-C5H3)2}]2(μ-O)2

The reaction of TiCl₄ with Li₂[(SiMe₂)₂(η⁵-C₅H₃)₂] in toluene at room temperature afforded a mixture of cis- and trans-[(TiCl₃)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] in a molar ratio of 1/2 after recrystallization. The complex trans-[(TiCl₃)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] was hydrolyzed immediately by the addition of water to THF solutions to give trans-[(TiCl₂)₂(μ-O){(SiMe₂)₂(η⁵-C₅H₃)₂}] as a solid insoluble in all organic solvents, whereas hydrolysis of cis-[(TiCl₃)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] under different conditions led to the dinuclear μ-oxo complex cis-[(TiCl₂)₂)(μ-O){(SiMe₂)₂(η⁵-C₅H₃)₂}] and two oxo complexes of the same stoichiometry [(TiCl)₂(μ-O){(SiMe₂)₂(η⁵-C₅H₃)₂}]₂(μ-O)₂ as crystalline solids. Alkylation of cis- and trans-[(TiCl₃)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] with MgCIMe led respectively to the partially alkylated cis-[(TiMe₂Cl)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] and the totally alkylated trans-[(TiMe₃)₂{(SiMe₂)₂(η⁵-C₅H₃)₂}] compounds. The crystal and molecular structure of the tetranuclear oxo complex [(TiCl)₂(μ-O){(SiMe₂)₂(η⁵-C₅H₃)₂}]₂(μ-O)₂ was determined by X-ray diffraction.     

Reactions of the haloalcohols HO(CH2)nCl (n = 2, 3) with platinum(II) - alkynyl and -alkyne complexes. X-ray crystal structure of trans-[Pt(Me) {C(OCH2CH2Cl) (CH2Ph)} (PPh3)2] [BF4]

The chloro complexes trans-[Pt(Me)(Cl)(PPh₃)₂], after treatment with AgBF₄, react with 1-alkynes HC---C---R in the presence of NEt₃ to afford the corresponding acetylide derivatives trans-[Pt(Me) (C---C---R) (PPh₃)₂] (R = p-tolyl (1), Ph (2), C(CH₃)₃ (3)). These complexes, with the exception of the t-butylacetylide complex, react with the chloroalcohols HO(CH₂)_nCl (n = 2, 3) in the presence of 1 equiv. of HBF₄ to afford the alkyl(chloroalkoxy)carbene complexes trans-[Pt(Me) {C[O(CH₂)_nCl](CH₂R) } (PPh₃)₂][BF₄] (R = p-tolyl, N = 2 (4), N = 3 (5); R=Ph, N = 2 (6)). A similar reaction of the bis(acetylide) complex trans-[Pt(C---C---Ph)₂(PMe₂Ph)₂] with 2 equiv. HBF₄ and 3-chloro-1-propanol affords trans-[Pt(C---CPh) {C(OCH₂CH₂CH₂Cl)(CH₂Ph) } (PMe₂Ph)₂][BF₄] (7). T alkyl(chloroalkoxy)-carbene complex trans-[Pt(Me) {C(OCH₂CH₂Cl)(CH₂Ph) } (PPh₃)₂][BF₄] (8) is formed by reaction of trans-[Pt(Me)(Cl)(PPh₃)₂], after treatment with AgBF₄ in HOCH₂CH₂Cl, with phenylacetylene in the presence of 1 equiv. of n-BuLi. The reaction of the dimer [Pt(Cl)(μ-Cl)(PMe₂Ph)]₂ with p-tolylacetylene and 3-chloro-1-propanol yields cis-[PtCl₂{C(OCH₂CH₂CH₂Cl)(CH₂C₆H₄-p-Me}(PMe₂Ph)] (9). The X-ray molecular structure of (8) has been determined. It crystallizes in the orthorhombic system, space group Pna2₁, with a = 11.785(2), B = 29.418(4), C = 15.409(3) Å, V = 4889(1) ų and Z = 4. The carbene ligand is perpendicular to the Pt(II) coordination plane; the PtC(carbene) bond distance is 2.01(1) Å and the short C(carbene)-O bond distance of 1.30(1) Å suggests extensive electronic delocalization within the Pt---C(carbene)---O moietry.     

Platinum(II) complexes of chelating and monodentate thiourea monoanions incorporating chiral, fluorescent or chromophoric groups

The reaction of cis-[PtCl₂(PPh₃)₂] with trisubstituted thioureas [R¹R²NC(=S)NHR³] in refluxing methanol with triethylamine base, followed by addition of NaBPh₄ gives the salts [Pt{SC(=NR¹R²)NR³}(PPh₃)₂]BPh₄ in high yield; a range of thiourea substituents, including chiral, fluorescent and chromophoric groups can be incorporated. The azo dye-derived complex [Pt{SC(=N(CH₂CH₂)₂O)NC₆H₄N=NC₆H₄NMe₂}(PPh₃)₂]BPh₄ has been characterised by a single-crystal X-ray diffraction study. The formation of a fluorescein-derivatised platinum–thiourea complex is also described. Reaction of cis-[PtCl₂(PPh₃)₂] with PhNHC(S)NHPh or EtNHC(S)NHEt, triethylamine and NaBPh₄ gives, respectively, [Pt{SC(=NHPh)NPh}(PPh₃)₂]⁺ and the known cation [Pt{SC(=NHEt)NEt}(PPh₃)₂]⁺, isolated as tetraphenylborate salts. Reaction of cis-[PtCl₂(PPh₃)₂] with an excess of Na[MeNHC(S)NCN] in methanol gives the bis(thiourea monoanion) complex trans-[Pt{SC(=N---CN)NHMe}₂(PPh₃)₂], characterised by NMR spectroscopy and an X-ray crystal structure determination. When cis-[PtCl₂(PPh₃)₂] is reacted with 1 equiv. of Na[MeNHC(S)N---CN] in methanol, with added NaBPh₄, a mixture of isomers of the [Pt{SC(=NHCN)NMe}(PPh₃)₂]⁺ cation is obtained.     

Ammonia ruthenium complexes for the access to new hydrido, carbonyl and isocyanide ruthenium-alkynyl derivatives

The potential in preparative chemistry of the precursors trans-[Ru(NH₃)(CC---R¹)(Ph₂PCH₂CH₂PPh₂)₂]PF₆ (3) has been studied. They offer a convenient access, by NH₃ displacement, to new functional alkynyl-ruthenium derivatives. Complexes 3 react with alkynes HCC---R² to give unsymmetrical trans-Ru(---CC---R¹)(---CC---R²)(dppe)₂ compounds 4a-c, and with sodium methoxide in methanol they open the route to a variety of mixed hydride complexes 5a-c, trans-Ru(H)(---CC---R¹)(dppe)₂. In contrast, with carbon monoxide or isocyanides CN---R³ (R³:CH₂Ph, C₆H₁₁, Me₃C) they allow the preparation of cationic derivatives trans-(Ru(CO)(---CC---R¹)(dppe)₂]PF₆ (6a-c) or trans-[Ru(CNR³)(---CC---R¹)(dppe)₂]PF₆ (7a-d).     

Heterobimetallic chloro bridgedcomplexes of (η:η−C10H16)-ruthenium(IV) with palladium(II), platinum(II), rhodium(III), iridium(III), copper(I) and rhodium(I)

Metathesis of [(η³:η³−C₁₀H₁₆)Ru(Cl) (μ−Cl)]₂ (1) with [R₃P) (Cl)M(μ-Cl)]₂ (M = Pd, Pt), [Me₂NCH₂C₆H₄Pd(μ-Cl)]₂ and [(OC)₂Rh(μ-Cl)]₂ affords the heterobimetallic chloro bridged complexes (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂M(PR₃)(Cl) (M = Pd, Pt), (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂PdC₆H₄CH₂NMe₂ and (η³:η³-C₁₀H₁₆) (Cl)Ru(μ-Cl)₂Rh(CO)₂, respectively. Complex 1 reacts with [Cp^*M(Cl) (μ-Cl)]₂ (M = Rh, Ir), [p-cymene Ru(Cl) (μ-Cl]₂ and [(Cy₃P)Cu(μ-Cl)]₂ to give an equilibrium of the heterobimetallic complexes and of educts. The structures of (η³:η³-C₁₀H₁₆)Ru(μ-Cl)₂Pd(PR₃) (Cl) (R = Et, Bu) and of one diastereoisomer of (η³:η³-C₁₀H₁₆)Ru(μ-Cl)₂IrCp^*(Cl) were determined by X-ray diffraction.     

The trans influence of F, Cl, Br and I ligands in a series of square-planar Pd(II) complexes. Relative affinities of halide anions for the metal centre in trans-[(Ph3P)2Pd(Ph)X]

Single crystal X-ray diffraction studies of trans-[(Ph₃P)₂Pd(Ph)X] (X = F (1), Cl (2), Br (3), and I (4) were carried out. The four structures split in two isostructural and isomorphous groups, namely orthorhombic for 1 and 2 (space group Pbca, Z = 8) and triclinic for 3 and 4 (space group P-1, Z = 2). According to the Pd---C bond length, the trans influence of X within these pairs follows the trend Cl>F and 1>Br. However, the trans influence of Cl is slightly stronger than that of Br. Both structural and ¹³C NMR studies revealed that electron-donating effects of (Ph₃P)₂PdX increase along the series X=I− for the Pd centre in [(Ph₃P)₂Pd(Ph)]⁻ were studied by ³¹P NMR in rigorously anhydrous CH₂Cl₂ solutions, and equilibrium constants and ΔG values were obtained for all possible combinations. The sequence F⁻ > Cl⁻ > Br⁻ > I⁻ is characteristic of halide preference for the Pd complexes. Dissolving 1 and PPN Cl in dry CH₂Cl₂ resulted in the release of ‘naked’ F⁻ which fluorinated the solvent smoothly to give a mixture of CH₂ClF and CH₂F₂ in high yield. When chloroform was used instead of CH₂Cl₂, dichlorocarbene was generated slowly, forming the corresponding cyclopropane in the presence of styrene. All observations were rationalized successfully in terms of the filled/filled effect and push/pull interactions.     

Comparison in halide binding ability between the unsaturated clusters [Pd3(μ-dppm)3(CO)] and [PdPtCo(μ-dppm)2(CO)3(CNBu)] (dppm = Ph2PCH2PPh2)

The trinuclear clusters [Pd₃(μ-dppm)₃(CO)]²⁺ and [PtPdCo(μ-dppm)₂(CO)₃(CN^tBu)]⁺ exhibit a large and a small cavity, respectively, formed by the phenyl rings of the bridging diphosphine ligands. Their binding constants (K₁₁) with halide ions (X⁻) were obtained by UV-Vis spectroscopy. The binding ability varies as I⁻ > Br⁻ > Cl⁻, and [Pd₃(μ-dppm)₃(CO)]²⁺ > [ptPdCo(μ-dppm)₂-(CO)₃(CN^tBu)]⁺. The MO diagram for the related cluster [Pd₂Co(μ-dppm)₂(CO)₄]⁺ has been addressed theoretically in order to predict the nature of the lowest energy electronic bands. For this class of compounds, the lowest energy bands are assigned to charge transfers from the Co center to the Pd₂ centers.     

Fluoro-hydrido-oxo and other fluoro-oxo complexes of rhenium (V) containing a triphosphine ligand

The fluoro-hydrido-oxo complex [Re(F)(H)(O)Cyttp]⁺ (3, Cyttp = PhP(CH₂CH₂CH₂PCy₂)₂) was prepared in high yield from [Re(H₂)H₄Cyttp]SbF₆ (1(SbF₆), NaSbF₆ and acetone in toluene at reflux. Reaction chemistry of 3 has been studied and, where appropriate, compared with that of the related dihydrido-oxo complex [ReH₂(O)Cyttp]⁺ (2). Unlike 2, which readily reacts with both CO and SO₂, 3 was found to be inert to these reagents under comparable conditions. However, 3(SbF₆) reacts with NaSbF₆ at elevated temperature to afford the difluoro-oxo complex [ReF₂(O)Cyttp]⁺ (4). 4 undergoes fluoride substitution by Cl⁻ or Br⁻ to yield [Re(X)(F)(O)Cyttp]⁺ (X = Cl (5, Br (6)). 5 can also be obtained by treatment of 6(BPh₄) with LiCl. All of these complexes contain mer-Cyttp, and 3–6 contain trans fluoride and oxide ligands as inferred from spectroscopic data.     

The propensity of alkoxide and aryloxide derivatives of tungsten carbonyls to aggregate in solution. Synthesis and X-ray structures of dinuclear, trinuclear and tetranuclear complexes derived from the MeOW(CO)5 anion

The complex [Et₄N][W(CO)₅OMe] (1) has been prepared from the reaction of the photochemically generated W(CO)₅THF adduct and [Et₄N][OH] in methanol. Complex 1 was shown to undergo rapid CO dissociation in THF to quantitatively provide the dimeric dianion, [W(CO)₄OMe]₂²⁻. The resulting THF insoluble salt [Et₄N]₂[W(CO)₄OMe]₂ (2) has been structurally characterized by X-ray crystallography, with the doubly bridging methoxide ligands being in an anti configuration. Complex 2 was found to subsequently react with excess methoxide ligand in a THF slurry to afford the face-sharing octahedron complex [Et₄N]₃[W₂(CO)₆(OMe)₃] (3) which contains three doubly bridging methoxide groups. In the absence of excess methoxide ligand complex 2 cleanly yields the tetrameric complex [Et₄N]₄[W(CO)₃OMe]₄ (4) which has been structurally characterized as a cubane-like arrangement with triply bridging μ³-methoxide groups and W(CO)₃ units. Although complex 3 was not characterized in the solid state, the closely related glycolate derivative [Et₄N]₃[W₂(CO)₆(OCH₂CH₂OH)₃] (5) was synthesized and its structure determined by X-ray crystallography. The trianions of complex 5 are linked in the crystal lattice by strong intermolecular hydrogen bonds. Crystal data for 2: space group P2₁/n, a = 7.696(2), b = 22.019(4), c = 9.714(2) Å, β = 92.22(3)°, Z = 4, R = 6.43%. Crystal data for 4: space group Fddd, a = 12.433(9), b = 24.01(2), c = 39.29(3) Å, Z = 8, R = 8.13%. Crystal data for 5: space group P2₁2₁2₁, a = 11.43(2), b = 12.91(1), c = 29.85(6) Å, Z = 8, R = 8.29%. Finally, the rate of CO ligand dissociation in the closely related aryloxide derivatives [Et₄N][W(CO)₅OR] (R = C₆H₅ and 3,5-F₂C₆H₃) were measured to be 2.15 × 10⁻² and 1.31 × 10⁻³ s⁻¹, respectively, in THF solution at 5°C. Hence, the value of the rate constant of 2.15 × 10⁻² s⁻¹ establishes a lower limit for the first-order rate constant for CO loss in the W(CO)₅OMe⁻ anion, since the methoxide ligand is a better π-donating group than phenoxide.     

The synthesis of substituted bis[(diarylphosphinomethyl)cyclopentadienyl]zirconocene dichloride complexes for the preparation of heterodimetallic complexes containing early/late transition metal combinations

Fulvenes (1a–e) derived from condensation of cyclopentadiene with acetone or a variety of aldehydes were treated with LiPAr₂ (Ar = phenyl, p-tolyl) to yield the respective substituted (diarylphosphinomethyl)cyclopentadienides (2, 3). Subsequent reaction with ZrCl₄(THF)₂ gave the respective bis[(diarylphosphinomethy])cyclopentadienyl]zirconium dichlorides ( Ar = phenyl (4), p-tolyl (5)). The complex rac-[C₅H₄-CH(CH₃)-PPh₂]₂ZrCl₂ (rac-4b) was characterized by X-ray diffraction. The reaction of complexes 4a and 5a [(Cp-CMe₂-PAr₂)₂ZrCl₂] with PdCl₂(NCPh)₂ or PtCl₂(NCPh)₂ leads to the formation of the trans-(metallocene-chelate-phosphane)metal complexes 6–9 (e.g. trans-Cl₂Pd(Ph₂P-CMe₂-Cp)₂ZrCl₂]. Chloride abstraction from the reaction product of [Cp-CH(CMe₃)PPh₂]₂ZrCl₂ with PdCl₂(NCPh)₂ eventually gave the cationic complex [meso,trans-(Cp-CH(CMe₃)PPh₂)₂(Cl)Zr(μ-Cl)Pd(Cl)]⁺ (10) that was also characterized by X-ray diffraction. It features a dimetallabicyclic framework with two Cp-CHR-PPh₂ ligands and a chloride bridging between the early and the late transition metal center.     

Mixed-metal butterfly acetamidediato clusters derived from a highly reactive ruthenium oxo cluster: synthesis and characterization of [(PPh3)2N][MRu3(CO)12(η-μ3-NC(μ-O)CH3)], (M = Mn or Re)

Analogy with the isolable oxo cluster [Fe₃(CO)₉(μ₃-O)]²⁻, which is structurally interesting and synthetically useful, prompted the present attempt to synthesize its ruthenium analog. Although the high reactivity of [Ru₃(CO)₉(μ₃-O)]²⁻ (I) prevented its isolation, the reaction of this species with [M(CO)₃(NCCH₃)]⁺, where M = Mn or Re, yields [PPN][MRu₃(CO)₁₂(η²-μ₃-NC(μ-O)CH₃]⁻. The high nucleophilicity of the oxo ligand in [Ru₃(CO)₉(μ₃-O)]²⁻ (I) appears to be responsible for the conversion of acetonitrile to an acetamidediato ligand and for the instability of I. The crystal structure of [PPN][MnRu₃(CO)₁₂(η²-μ₃-NC(μ-O)CH₃)]] reveals a hinged butterfly array of metal atoms in which the acetamidediato ligand bridges the two wings with μ₃-N bonding to an Mn and two Ru atoms, and μ-O bonding to an Ru atom.     

Organometallic chemistry of diphosphazanes. Rhodium(I) complexes of RN(PX2)2 (R = C6H5; X = OC6H5, OC6H4Br−p, R = CH3; X = OC6H5)

Reactions of [Rh(COD)Cl]₂ with the ligand RN(PX₂)₂ (1: R = C₆H₅; X = OC₆H₅) give mono- or disubstituted complexes of the type [Rh₂(COD)Cl₂{ν²−C₆H₅N(P(OC₆H₅)₂)₂}] or [RhCl{ν²−C₆H₅ N(P(OC₆H₅)₂)₂ }]₂ depending on the reaction conditions. Reaction of 1 with [Rh(CO)₂Cl]₂ gives the symmetric binuclear complex, [Rh(CO)Cl{μ−C₆H₅N(P(OC₆H₅)₂)₂} ₂, whereas the same reaction with 2 (R = CH₃; X = OC₆H₅) leads to the formation of an asymmetric complex of the type [Rh(CO)(μ−CO)Cl{μ−CH₃N(P(OC₆H₅)₂)₂}₂ containing both terminal and bridging CO groups. Interestingly the reaction of 3 (R = C₆H₅, X = OC₆H₄Br−p with either [Rh(COD)Cl]₂ or [Rh(CO)₂Cl]₂ leads only to the formation of the chlorine bridged binuclear complex, [RhCl{ν²−C₆H₅N(P(OC₆H₄Br−p)₂)₂}]₂. The structural elucidation of the complexes was carried out by elemental analyses, IR and ³¹P NMR spectroscopic data.     

Heats of reaction of HMo(CO)3(C5R5) (R = H, CH3) with diphenyldisulfide and of formation of the clusters [PhSMo(CO)x(C5H5)]2, X = 1,2. Thermodynamic study of molybdenum-sulfur bond strengths

The enthalpies of reaction of HMo(CO)₃C₅R₅ (R = H, CH₃) with diphenyldisulfide producing PhSMo(CO)₃C₅R₅ and PhSH have been measured in toluene and THF solution (R = H, ΔH= −8.5 ± 0.5 kcal mol⁻¹ (tol), −10.8 ± 0.7 kcal mol⁻¹ (THF); R = CH₃, ΔH = −11.3±0.3 kcal mol⁻¹ (tol), −13.2±0.7 kcal mol⁻¹ (THF)). These data are used to estimate the Mo---SPh bond strength to be on the order of 38–41 kcal mol⁻¹ for these complexes. The increased exothermicity of oxidative addition of disulfide in THF versus toluene is attributed to hydrogen bonding between thiophenol produced in the reaction and THF. This was confirmed by measurement of the heat of solution of thiophenol in toluene and THF. Differential scanning calorimetry as well as high temperature calorimetry have been performed on the dimerization and subsequent decarbonylation reactions of PhSMo(CO)₃Cp yielding [PhSMo(CO)₂Cp]₂ and [PhSMo(CO)Cp]₂. The enthalpies of reaction of PhSMo(CO)₃Cp and [PhSMo(CO)₂Cp]₂ with PPh₃, PPh₂Me and P(OMe)₃ have also been measured. The disproportionation reaction: 2[PhSMo(CO)₂Cp]₂ → 2PhSMo(CO)₃Cp + [PhSMP(CO)Cp]₂ is reported and its enthalpy has also been measured. These data allow determination of the enthalpy of formation of the metal-sulfur clusters [PhSMo(CO)_nC₅H₅]₂, N = 1,2.     

Synthesis, solution behaviour and molecular structures of 16-electron closo-2-(Ph3P)-1-N,2-[μ-(η-CH2CH=Ch2)]-1-N-(σ-CH2CH=CH2)-2,1- RhCB10H10, the first η-olefinic monocarbon metallacarborane

The first η²-olefinic monocarbon metallacarbone closo-2-(Ph₃P)-1-N,2-[μ-(η²-CH₂CH=Ch₂)]-1-N-(σ-CH₂CH=CH₂)-2,1- RhCB₁₀H₁₀ has been prepared by the reaction of the dimeric anion {[Ph₃PRhB₁₀H₁₀CNH₂]₂-μ-H}⁻[PPN]⁺ with allyl bromide and characterized by a combination of spectroscopic methods and a single-crystal X-ray diffraction study. The variable temperature ¹H and ¹³C NMR studies revealed the fluxional behavior of the η²-olefinic complex in CD₂Cl₂ solution which is associated with the allyl side-chain exchange process.     

The ReH6[P(C6H5)3]2 ion as a ligand: complexes with M(CO)3 fragments (M = Cr, Mo, W)

The reactions of [(H₅C₆)₃P]₂ReH₆⁻ with (CH₃CN)₃Cr(CO)₃, (diglyme)Mo(CO)₃ or (C₃H₇CN)₃W(CO)₃ led to the formation of [(H₅C₆)₃P]₂ReH₆M(CO)₃⁻ (M = Cr, Mo, W) complexes. These have been characterized by IR and NMR spectroscopies, as well as elemental analyses. A single crystal X-ray diffraction study has also been carried out for the M = Cr complex as a K(18-crown-6)⁺ salt. The complex crystallizes as a THF monosolvate in the monoclinic space group P2₁/n with a = 22.323(6), B = 9.523(2), C = 27.502(5) Å, β = 104.98(2)⁰ and V = 5648 ų for Z = 4. The Re---Cr separation is 2.5745(12) Å, and the two phosphine ligands are oriented unsymmetrically. Although the hydride ligands were not found, the presence of three bridging hydrides and a dodecahedral coordination geometry about rhenium could be inferred. Low temperature ¹H and ³¹P NMR spectroscopic studies did not reveal the low symmetry of the solid state structure.