Monocarbonyl cationic rhodium(I) complexes

Summary The preparations and characterisation of cationic complexes of the type [Rh(CO)(MeCN)(PR₃)₂]ClO₄, [Rh(CO)L(PR₃)₂]ClO₄ (L=py or 2-MeOpy), [Rh(CO)(L-L)(PR₃)₂]ClO₄ (L-L = bipy or phen) and [Rh(CO)(PR₃)₃]ClO₄ with PR₃ = P(p-YC₆H₄)₃ (Y=Cl, F, Me or MeO) are described.     

New cationic and anionic tetracoordinate nickel(I) complexes

Summary The preparation, structural study and chemical behaviour of new cationic, monoanionic and dianionic tetracoordinate nickel(I) complexes of the types: [NiL₄][BPh₄] (L=PPh₃, AsPh₃ or SbPh₃), [PR₄][NiX₂L₂] (X=Cl, Br or I; L=PPh₃, AsPh₃ or SbPh₃ and [PR₄]⁺=PPh₄, Ph₃PCH₂Ph or Ph₃PEt) and [PR₄]₂[NiX₃L] (X=Cl, Br or I; L=PPh₃ and [PR₄]⁺=PPh₄ or PPh₃CH₂Ph) are described.     

Dinuclear Pd(II) and Pt(II) compounds bearing a bridging π-conjugated moiety: synthesis and reactivity toward alkynes and isocyanides

Abstract

Dinuclear Pd(II) halides that contain bridging π-conjugated groups, trans,trans-[(PR₃)₂(X)Pd–Y–Pd(X)(PR₃)₂] (X?=?Br; YH₂ = terpyridine, fluorenone, benzil, benzthiadiazole), were prepared by the oxidative addition of corresponding dihalo π-conjugated reagents to [Pd(styrene)(PR₃)₂]. Similar reactions involving dihalobenzil, dihalobithiophene, or dihaloterthiophene afforded dinuclear Pt(II) halides containing bridging π-conjugated groups. Additionally, when the dihalosilole derivatives {2,5-dibromo-1,1-dimethyl (or diphenyl)-3,4-diphenylsilole} reacted with [Pd(styrene)(PR₃)₂], mono or dinuclear Pd(II) complexes bearing a dimethyl (or diphenyl)-3,4-diphenylsilole group were obtained. π-Conjugation extension reactions of dinuclear bithiophene-bridged Pd(II) halides with HC≡C–R {R?=?SiPh₃, C(O)OMe} in the presence of CuI and HNEt₂ led to the unexpected formation of bis(acetylide) Pd(II) complexes of the form, [Pd(C≡C–R)₂(PR₃)₂] and bithiophene. In contrast, treatment of the dinuclear Pd(II) halides with two equiv of organic isocyanide resulted in isocyanide insertion into the Pd???C bonds to afford π-conjugation-extended dinuclear Pd(II) compounds bearing a π-conjugated moiety.     

Anionic and neutral rhodium(I) complexes containing trichlorostannato ligands

The complexes Et₄N[Rh(SnCl₃)₂(diolefin)(PR₃)] (diolefin = COD or NBD) have been isolated and their reactions studied. Reaction with arylic tertiary phosphines led to SnCl₃⁻ displacement and isolation of neutral pentacoordinated Rh(SnCl₃)(diolefin)(PR₃)₂ complexes. Reaction with carbon monoxide involved diolefin displacement when the diolefin was COD, thus giving Et₄N[Rh(SnCl₃)₂(CO)₂(PR₃)] compounds, but SnCl₃⁻ displacement when it was NBD, thus yielding Rh(SnCl₃)(CO)(NBD)(PR₃) complexes. The complexes [Rh(diolefin)Cl]₂ were found to react with triarylphosphines in the presence of SnCl₂ and with CO bubbling through the solution to give Rh(SnCl₃)(CO)(NBD)(PR₃) when the diolefin was NBD but Rh(Cl)(CO)(PR₃)₂ when the diolefin was COD.     

Palladium(II)-, Platin(II)-, Ruthenium(II)-, Rhodium(III)- und Iridium(III)-Komplexe von Desoxyfructosazin

Metal Complexes of Biologically Important Ligands. CIII. [1] Palladium(II), Platinum(II), Ruthenium(II), Rhodium(III), and Iridium(III) Complexes of Desoxyfructosazine The reactions of the pyrazine derivative desoxyfructosazin(pz) with K₂PtCl₄ and with the chlorobridged [M(PR₃)Cl₂]₂ (M = Pd, Pt), [(η⁵-C₅Me₅)MCl₂]₂ and [(η⁶-p-Cymol)RuCl₂]₂ give the watersoluble complexes cis-Cl₂Pt(pz)₂, (R₃P)(Cl)M(pz)M(Cl)(PR₃) (M = Pd, Pt), (η⁵-C₅Me₅)(Cl)₂M(pz)M(Cl)₂(η⁵-C₅Me₅) (M = Rh, Ir), (η⁶-p-Cymol)(Cl₂)Ru(pz)Ru(Cl)₂(η⁶-p-Cymol).     

Zur Reaktivität von alkylthioverbrückten 44‐CVE‐triangularen Platinclustern: Umsetzungen mit bidentaten Phosphanliganden

On the Reactivity of Alkylthio Bridged 44 CVE Triangular Platinum Clusters: Reactions with Bidentate Phosphine Ligands The 44 cve (cluster valence electrons) triangular platinum clusters [{Pt(PR₃)}₃(μ‐SMe)₃]Cl (PR₃ = PPh₃, 2a ; P(4‐FC₆H₄)₃, 2b ; P(n‐Bu)₃, 2c ) were found to react with PPh₂CH₂PPh₂ (dppm) in a degradation reaction yielding dinuclear platinum(I) complexes [{Pt(PR₃)}₂(μ‐SMe)(μ‐dppm)]Cl (PR₃ = PPh₃, 3a ; P(4‐FC₆H₄)₃, 3b ; P(n‐Bu)₃; 3e ) and the platinum(II) complex [Pt(SMe)₂(dppm)] ( 4 ), whereas the addition of PPh₂CH₂CH₂PPh₂ (dppe) to cluster 2a afforded a mixture of degradation products, among others the complexes [Pt(dppe)₂] and [Pt(dppe)₂]Cl₂. On the other hand, the treatment of cluster 2a with PPh₂CH₂CH₂CH₂PPh₂ (dppp) ended up in the formation of the cationic complex [{Pt(dppp)}₂(μ‐SMe)₂]Cl₂ ( 5 ). Furthermore, the terminal PPh₃ ligands in complex 3a proved to be subject to substitution by the stronger donating monodentate phosphine ligands PMePh₂ and PMe₂Ph yielding the analogous complexes [{Pt(PR₃)}₂(μ‐SMe)(μ‐dppm)]Cl (PR₃ = PMePh₂, 3c ; PMe₂Ph, 3d ). NMR investigations on complexes 3 showed an inverse correlation of Tolmans electronic parameter ν with the coupling constants ¹J(Pt,P) and ¹J(Pt,Pt). All compounds were fully characterized by means of NMR and IR spectroscopy. X‐ray diffraction analyses were performed for the complexes [{Pt{P(4‐FC₆H₄)₃}}₂(μ‐SMe)(μ‐dppm)]Cl ( 3b ), [Pt(SMe)₂(dppm)] ( 4 ), and [{Pt(dppp)}₂(μ‐SMe)₂]Cl₂ ( 5 ).     

Reactions of M2Cl4(PR3)4 (M  Mo and W) with carbon monoxide

The reactions of M₂Cl₄(PR₃)₄ derivatives (M  Mo, W and PR₃  PEt₃, PBu₃ⁿ) with CO at atmospheric pressure in toluene at 70°C to afford M(CO)₃(PR₃)₂Cl₂ and trans-M(CO)₄(PR₃)₂ are reported.     

Infrared Laser Photochemistry of Trichlorosilane

IR multiphoton dissociation of trichlorosilane molecules in scavenger gas (O₂, CO₂, OCS, halomethanes, BCl₃, TiCl₄, etc.) media was studied. Stable, volatile dissociation products were determined. It was shown that the product formation mechanism depends on the partial pressure of SiHCl₃. At a high pressure (400–800 Pa) of SiHCl₃, its photolysis in a mixture with fluorine-, chlorine-, or bromine-containing scavengers led to the formation of products of the SiF_{4 – n} Cl _n and SiBr_{4 – n} Cl _n type, where n = 1–4. An SiHCl₃ conversion into SiCl₄ higher than 70% could be achieved. The formation mechanism was proposed for the photolysis products. At a low SiHCl₃ pressure (<70 Pa), the formation of a stable volatile product was observed only in a mixture with BCl₃, which resulted from the reaction of insertion of SiCl₂ in the B–Cl bond.     

Carbonylcobalt(I) complexes. The crystal and molecular structure of [Co(CO)(dppm)2]ClO4

New anionic carbonylcobalt(I) complexes [X₂Co(CO)₂(PPh₃)](PR₄) (X=Cl, PR₄ = PBzPh₃ (I); X = Br, PR₄ = PEtPh₃ (II)) have been prepared by reduction of the cobalt(II) halides with NaBH₄ in the presence of PPh₃ and the phosphonium salt PR₄X. Cleavage of halide bridges in dimeric or polymeric [XCo(PPh₃)₂]_n and [XCo(PPh₃)]_n gives the neutral dicarbonyl derivatives XCo(CO)₂PPh₃)₂. Treatment of ClCo(CO)₂(PPh₃)₂ with alkylating agents gives the known σ- and η- organocobalt(I) derivatives, and reactions with TIClO₄ in the presence of various amounts of different mono- and bi-dentate phosphines give the cationic tricarbonyl [Co(CO)₃(PPh₃)₂]⁺, dicarbonyl [Co(CO)₂(PMePh₂)₃]⁺ and monocarbonyl [Co(CO)L₄]⁺ complexes (L₄ = 4P(OMe)₃, 2 dppe and 2dppm). The dppm complex crystallizes in the monoclinic space group P2₁/c with a 17.895(6), b 10.751(2), c 24.687(4) Å, β 98.92(1)°, and D_calc 1.35 g cm⁻³ for Z = 4. A final R value of 0.077 ( R_w = 0.061), based on 2656 observed reflections, was obtained. The cobalt atom exhibits a distorted trigonal bipyramidal geometry. The perchlorate anion is severely disordered or freely rotating.     

Elektronenreiche übergangsmetallkomplexe : V. Phosphinsubstituierte wolframdicarbonyle

Chloride-bridged tungsten tricarbonylmetalates [(OC)₃W(Cl)₃W(CO)₃]^3?, obtainable in high yields from tungsten hexacarbonyl and tetraalkylammonium chlorides, with allyl halides give π-allylhalogenotungsten dicarbonyls. With phosphines reductive elimination of allylhalide yields bis- or tris-(phosphine)-tungsten-dicarbonyls L₂W(PR₃)₂(CO)₂, LW(PR₃)P₃(CO)₂ (L = CH₃CN). Substitution reactions of L with various ligands under mild conditions are described. IR and electronic spectra of more than twenty new compouonds are discussed and compared with corresponding compounds of molybdenum.     

Synthesis of platinum-mercury clusters and the molecular structure of Pt4(HgBr)2(μ-CO)4(PPh3)4

New platinum-mercury clusters, Pt₄(HgX)₂(μ-CO)₄(PR₃)₄ (X=Cl, Br, I, CF₃, or CCl₃; R=Ph or Et), were synthesized. The molecular and crystal structure of the Pt₄(HgBr)₂(μ-CO)₄(PPh₃)₄ cluster was established by X-ray structural analysis.     

Quantenchemische Untersuchungen zur Stabilität von Si—F-Spezies

Quantumchemical Investigations on the Stability of Si? F Species Semiempirical MO calculations (EHT, CNDO/2) have been used to examine the stability of Si—F-species (SiF₆^2?, SiF₄ planar and tetrahedral, SiF₃⁺ planar and pyramidal, and SiF₂ (SiF₂²⁺) linear and angled). The calculations showed, that the appearance of planar structures is possible from the energetical point in solid state reactions. In the case of SiF₂ (SiF₂²⁺) it was not possible to find an energetic difference between linear and not linear forms. The neutral form is energetic more stable than SiF₂²⁺. A comparison of investigated species shows, that with growing bonding angle and in this way with decreasing number of fluorine atoms in the molecule the bond lengths are decreased. The EHT-bond energies become more negative in the same way.     

Complexes dinucleaires pontes des metaux d8: VII. Reactions d'addition oxydante d'halogenures d'alkyle et d'acycle aux complexes μ-halogenes du rhodium(i) [RhX(CO)(PR3)]2. Structure cristalline de [RhCl(CO)(PMe2Ph)(Me)(Br)]2

The halogen bridged binuclear complexes of rhodium(I) [RhCl(CO)(PR₃)]₂ undergo oxidative addition with methyl halides to yield the complexes [RhCl(CO)(PR₃)(Me)(X)]₂ (X = Cl, Br). The crystal and molecular structures of [RhCl(CO)(PMe₂Ph)(Me)(Br)]₂ have been determined from a single crystal by use of X-ray crystallographic methods. The space group is Pca2₁ or Pacm with a 19.501(5), b 10.381(4), c 13.641(5) e? Z = 4. Parameters of 30 nonhydrogen atoms in the space group Pca2₁ were refined by the full-matrix least squares technique to a conventional R factor of 0.073. In a binuclear unit, each rhodium atom is in an octahedral environment being bonded to a carbonyl group, a methyl group and a tertiary phosphine ligand and three halogen atoms for which, due to a disorder phenomenon, the diffusion factors have been determined as the average between those of chlorine and bromine atoms. In solution the cis-migration of the methyl groups occurs, leading to the acetyl complexes. In the case of CH₃I, it is shown that an equilibrium is present in solution: [RhCl(CO)(PR₃(Me)(I)]₂ ? [RhCl(COMe)(PR₃)(I)(solvant)]₂] Carbonylation reactions shift this equilibrium to give the complexes [RhCl(CO)(COMe)(PR₃(I)]₂. Such complexes are readily prepared by direct oxidative addition of acyl halides to the compounds [RhCl(CO)(PR₃)]₂.     

Experimental and theoretical studies of the basicity and proton affinity of SiF4 and the structure of SiF4H+

A combined experimental and theoretical approach has been employed to establish the basicity and proton affinity of SiF₄ and the structure of SiF₄H⁺. The kinetics and energetics for the transfer of a proton between SiF₄, N₂, and Xe have been explored experimentally in helium at 0.35±0.02 torr and 297±3 K with a selected-ion flow tube apparatus. The results of equilibrium constant measurements are reported that provide a basicity and proton affinity for SiF₄ at 297±3 K of 111.4±1.0 and 117.7±1.2 kcal mol^?1, respectively. These values are more than 2.5 kcal mol^?1 lower than currently recommended values. The basicity order was determined to be GB(Xe)>GB(SiF₄)>GB(N₂), while the proton-affinity order was shown to be PA(Xe)>PA(N₂)>PA (SiF₄). Ab initio molecular orbital computations at MP4SDTQ(fc)/6-311++G(3df,3pd) using geometries from B3LYP/6-31+G(d,p) indicate a value for PA(SiF₄)=118.7 kcal mol^?1 that is in good agreement with experiment. Also, the most stable structure of SiF₄H⁺ is shown to correspond to a core SiF ₃ ⁺ cation solvated by HF with a binding energy of 43. 9 kcal mol^?1. Support for this structure is found in separate SIFT collision induced dissociation (CID) measurements that indicate exclusive loss of HF.     

Influence of the phosphine ligands in the 1H and 31P NMR behaviour of [(η3-allyl)Py(phophine)Cl] complexes

The ¹H and ³¹P NMR spectra of (η³-allyl)Pt(PR₃)Cl] (PR₃ = PMe₃, PCy₃, P-t-Bu₃, P-n-Bu₃, PPh₃, PPh₂Me, PPhMe₂ and P(p-Tol)₃) complexes in chloroform have been studied. The results suggest that there is bonding interaction between the phosphine and the allyl group via central metal atom.     

Iridium-catalyzed regiospecific allylation of dimethyl malonate in ionic liquids

Allylation of dimethyl malonate with 1-(4-chlorophenyl)prop-2-enyl methyl carbonate in the presence of [Pd(All)Cl]₂, [Rh(COD)Cl]₂, [Ir(COD)Cl]₂ (COD is cycloocta-1,5-diene), and a chiral ferrocenyl-containing phosphite ligand based on (R)-BINOL (BINOL is 2,2′-dihydroxy-1,1′-binaphthyl) in CH₂Cl₂ gave a mixture of linear and branched cross-coupling products, the latter having a moderate optical purity (below 51%). The rhodium-and iridium-catalyzed reactions were very highly regioselective (regiospecific in the case of Ir), giving a branched product. In ionic liquids ([bmim][BF₄] and [bdmim][BF₄]) (bmim is 1-butyl-3-methylimidazolium and bdmim is 1-butyl-2,3-dimethylimidazolium), the Ir-catalyzed reaction regiospecifically afforded a branched product as a racemate. The same result was obtained with [Ir(COD)Cl]₂ as a catalyst; this reaction easily occurred in ionic liquids even without a base. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 519–521, March, 2007.     

Structural study of iron carbonyl derivatives: IV. Synthesis and crystal and molecular structure of syn-[μ-(SCH3)Fe(CO)2P(CH3)3]2

Dimeric palladium(I) complexes of the type [μ-(η³-C₅H₅)-μ-XPd₂(PR₃)₂](X  Br, R  i-Pr, Ph, Cy; X  Cl, I, R  i-Pr) have been prepared by reduction of the complexes [(ν⁵-C₅H₅)(PR₃)PdX] with a variety of reducing agents (Mg,Na/Hg, LiAlH(t-BuO)₃, LiAlH₄, NaBH₄, n-BuMgBr). PMR and IR data and some properties of the new complexes are reported.     

Synthese und reaktivität von dienylmetall-verbindungen : III. Phosphinigsäureimide als liganden in cyclopentadienylnickelkomplexen

Phosphinous imides form ionic complexes of the type [C₅H₅Ni-(R₂PNR′PR₂)]X (R = C₆H₅; R′ = CH₃, C₆H₅; X = BF₄, Cl). NaCN reacts with [C₅H₅Ni(R₂PNCH₃PR₂)]BF₄ to give the neutral complex C₅H₅Ni-(R₂PNCH₃PR₂)CN (R = C₆H₅) in which the phosphinous imide acts as a monodentate ligand.     

Synthesis and X-ray Molecular Structure Analysis of Some Au-Co,Au-Mn,and Hg-Co Bonded Compounds

The reaction of NaCo(CO)_4-x (PR₃) _x (x = 0, 1) with Au(PR₃)Cl was examined in THF. The products were characterized by single crystal X-ray analysis and/or XPS spectroscopy. When the THF solution of NaCo(CO)_4-x (PR₃) _x which was in situ prepared by the reduction of the corresponding cobalt carbonyl dimer with Na amalgam was filtered, the main product was (R₃P)Au-Co(CO)₄ and (R₃P)Au-Co(CO)_4-x (PR₃) _x (x = 1,2); phosphine migration from the Au to the Co site was observed for bulky phosphines during the recrystallization process. When the THF solution of NaCo(CO)_4-x (PR₃) _x was not filtered, the main product had the composition of M[Co(CO)₃(PR₃)]₂. The element M was clearly determined to be Hg by XPS spectroscopy. The reaction of NaMn(CO)₅ with Au(PR₃)Cl, however, afforded R₃PAu-Mn(CO)₅. The bonding parameters such as Au-M and Hg-Co bond-lengths were interpreted in terms of the electronic nature of the R group of the monodentate PR₃ ligand.