Ligand exchange and ligand migration reactions involving dicyclopentadienylniobium(III) carbonyl derivatives

The methylniobocene carbonyl (C₅H₅)₂Nb(CH₃)(CO) shows an unexpected lack of reactivity with respect to ligand migration. Whereas (C₅H₅)₂V(CH₃) has been reported to react with CO to yield the acetyl derivative (C₅H₅)₂V(OC-CH₃)(CO) immediately, we find that the niobocene analogue (C₅H₅)₂Nb(CH₃) reacts with CO only to regenerate (C₅H₅)₂Nb(CH₃)(CO), from which it was obtained by photolysis. This resistance of the methylniobocene carbonyl derivative towards ligand migration is interpreted in terms of the bonding properties of the acetyl intermediate (C₅H₅)₂Nb(OCCH₃).     

Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe. VIII. Zweikernige Cobaltkomplexe mit dem Dianion des Bis(cyclopentadienyl)methans und des Bis(tetramethylcyclopentadienyl)dimethylsilans als Brückenliganden

Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes. VIII. Dinuclear Cobalt Complexes with the Dianion of Bis(cyclopentadienyl)methane and Bis(tetramethylcyclopentadienyl)dimethylsilane as Bridging Ligands The dinuclear cobalt complex [CH₂(C₅H₄)₂][Co(CO)₂]₂ ( 4 ) which is obtained from [Co(CO)₄I] ( 2 ) and Li₂[CH₂(C₅H₄)₂] ( 3 ) in 75% yield reacts with PMe₃, PiPr₃, P₂Me₄, Me₂PCH₂CH₂PMe₂ and (EtO)₂POP(OEt)₂, to the compounds 5–9 substituting one CO ligand per cobalt atom. Oxidative addition of CH₃I to [CH₂(C₅H₄)₂][Co(CO)(PMe₃)]₂ ( 5 ) leads to the formation of the dinuclear cobalt(III) complex [CH₂(C₅H₄)₂][Co(COCH₃)(PMe₃)I]₂ ( 11 ). The reaction of 4 with iodide generates [CH₂(C₅H₄)₂][Co(CO)I₂]₂ ( 12 ) which with PMe₃, P(OMe)₃, P(OiPr)₃, and CNMe reacts under CO substitution to [CH₂(C₅H₄)₂][Co(L)I₂]₂ ( 13–16 ) and with PMe₂H to {[CH₂(C₅H₄)₂][Co(PMe₂H)₃]₂}I₄ ( 17 ). The electrophilic addition reactions of NH₄PF₆ and CH₃I to [CH₂(C₅H₄)₂][Co(PMe₃)₂]₂ ( 20 ) produce the complex salts {[CH₂(C₅H₄)₂][CoR(PMe₃)₂]₂}X₂ ( 21 : R = H; 22 : R = CH₃). From 22a (X = I) and LiCH₃ the dinuclear tetramethyldicobalt compound [CH₂(C₅H₄)₂] · [Co(CH₃)₂(PMe₃)]₂ ( 23 ) is obtained which further reacts, via the intermediate 24 , to the chiral complex {[CH₂(C₅H₄)₂] · [CoCH₃(PMe₃)P(OMe)₃]₂}(PF₆)₂ ( 25 ). The reaction of 20 with C₂(CN)₄ and E- or Z-C₂H₂(CO₂Me)₂ gives the olefin(trimethylphosphine) cobalt(I) derivatives 26 und 27 . The synthesis of the dinuclear compounds 31–38 with [Me₂Si(C₅Me₄)₂]^2? as the bridging unit is also described.     

Carbonyl-organocobalt(I) and -(II) complexes

Passage of CO through solutions of complexes (C₆F₅)₂CoL₂ gives carbonyl derivatives (C₆F₅)₂CoL₂(CO) (L₂ = 2 PEt₃, 2 P-n-Bu₃, 2 PPh₃, Ph₂PCH₂CH₃PPh₂). The properties of these compounds are described.The compounds are also produced by treating solutions of (C₆F₅)₂Co-(dioxane)₂ with CO, but a simultaneous reduction to (C₆F₅)Co(CO)₄ takes place. Treatment of the latter complex with monodentate ligands gives substitution products (C₆F₅)Co(CO)₃L (L = PEt₃, P-n-Bu₃, PPh₃) all of which are monomeric, whereas the addition of Ph₂PCH₂CH₂PPh₂ gives the dimer (C₆F₅)(CO)₂CoLLCo(CO)₂(C₆F₅). The properties of these compounds are discussed.     

Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe,V. Heteronukleare Co/Rh-, Co/Ir-, Rh/Ir- und Ti/Ir-Komplexe mit dem Bis(cyclopentadienyl)methan-Dianion als Brückenliganden

Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V^[1]. – Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand^* The lithium and sodium salts of the [C₅H₅CH₂C₅H₄]^- anion, 1 and 2 , react with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [Ir(CO)₃Cl]n to give predominantly the mononuclear complexes [(C₅H₅-CH₂C₅H₄)M(CO)₂] ( 3, 5, 7 ) together with small amounts of the dinuclear compounds [CH₂(C₅H₄)₂][M(CO)₂]₂ ( 4, 6, 8 ). The ¹H- and ¹³C-NMR spectra of 3, 5 , and 7 prove that the CH₂C₅H₅ substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [C₅H₅TiCl₃] the heteronuclear complexes [CH₂(C₅H₄)₂][M(CO)₂][M′(CO)₂] ( 11–13 ) and [CH₂(C₅H₄)₂]-[Ir(CO)₂][C₅H₅TiCl₂] ( 17 ) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH₂(C₅H₄)₂][M(CO)(μ-CO)M′(CO)] ( 14, 15 ). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH₂(C₅H₄)₂][Rh₂(CO)₂(μ-CO)] ( 16 ).     

Komplexchemie polyfunktioneller liganden : XXXVII. Darstellungsmethoden für hydrido-kobalt(I)-komplexe des 1,1,1-tris(diphenylphosphinomethyl)äthans

[Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] (R  C₆H₅) reacts with NaBH₄, depending on the reaction conditions, to give CoH(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂ · BH₃ and CoH(CO)(R₂PCH₂)₃CCH₃. The hydride CoH(CO)(R₂PCH₂)₃CCH₃ is also formed by the reaction of [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] with LiOH, NaOH and NaNH₂. The reaction with LiOH primarily gives (acetone)₃-LiCo(CO)(R₂PCH₂)₃CCH₃, which is also formed by reduction of [Co(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂]₂ with lithium in THF/acetone solution. In liquid ammonia [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] at 20°C yields Co(CONH₂)(CO)(R₂PCH₂)₃CCH₃. This compound reacts in the same solvent at 60°C to yield the hydride CoH(CO)(R₂PCH₂)₃CCH₃. CH₃I and HClO₄ react with CoH(CO)(R₂PCH₂)₃CCH₃ yielding CoI(R₂PCH₂)₃CCH₃ and the unstable [Co(H)₂(CO)(R₂PCH₂)₃CCH₃]ClO₄, respectively. The deutero complex CoD(CO)(R₂PCH₂)₃CCH₃ was also synthesized. The new compounds were characterized, as much as possible, by their IR, ¹H NMR and ³¹P NMR data.     

Variable hapticity of the cyclooctatetraene ring in sandwich compounds of the first row transition metals

Density functional theory methods (B3LYP and BP86) indicate that the preferred structures for such early transition metal derivatives are (η⁸-C₈H₈)M(η⁴-C₈H₈) (M = Ti, V, Cr) with one octahapto η⁸-C₈H₈ ring and one tetrahapto η⁴-C₈H₈ ring. In such structures only 12 of the 16 carbon atoms of the two C₈H₈ rings are bonded to the metal, leading to 16-, 17-, and 18-electron complexes, respectively, in accord with the experimentally known structures for the Ti and V derivatives. The preferred structures for the Mn and Fe derivatives are (η⁶-C₈H₈)M(η⁴-C₈H₈) (M = Mn, Fe) with one hexahapto and one tetrahapto C₈H₈ ring and thus having 17- and 18-electron configurations, respectively, in accord with experimental data on the iron complex. The lowest energy structure for the cobalt complex is (η⁴-C₈H₈)Co(η^2,2-C₈H₈) with two different types of tetrahapto C₈H₈ rings and a 17-electron metal configuration. The nickel complex (C₈H₈)₂Ni appears to prefer a structure with a 16-electron configuration and two trihapto C₈H₈ rings, similar to the known (η³-C₃H₅)₂Ni rather than a bis(tetrahapto) structure with the favored 18-electron configuration. These theoretical studies indicate that in (C₈H₈)₂M derivatives of the first row transition metals, the number of carbon atoms in the pair of C₈H₈ rings involved in the bonding to the central metal atom gives the metal atoms 16-, 17-, or 18-electron configurations.     

Derivate des borabenzols: XVIII. Vanadium-komplexe Des 1-methyl- und 1-phenylborinat-ions

Six borabenzene derivatives of vanadium are described. Reaction of the alkali metal borinates M(C₅H₅BR) (M = Na, K; R = Me, Ph) with VCl₃ yields the paramagnetic, sandwich complexes V(C₅H₅BR)₂. Reaction with HgCl₂ and [Na{O(CH₂CH₂OCH₃)₂}₂][V(CO)₆] affords the tetracarbonyl compounds V(CO)₄(C₅H₅BR). Upon heating in cycloheptatriene, the latter compounds produce the paramagnetic cycloheptatrienyl complexes V(C₅H₅BR)(C₇H₇) with sandwich structures. An X-ray structural study of V(CO)₄(C₅H₅BMe) shows that the V(CO)₄ fragment in the crystal is rotated by 10.4° relative to an ideal, eclipsed conformation where two CO groups are present in the plane through the B, V and C(4) atoms.     

Photo-induced degradation reactions of some alkyl- and aryl-carbonyl derivatives of manganese,molybdenum and tungsten

Photo-induced degradation of CH₃Mn(CO)₅ in pentane solution results in the formation of Mn₂(CO)₁₀, methane and carbon monoxide. Both CH₃D and CH₄ are formed when CH₃Mn(CO)₅ is photolyzed in C₆D₆. Photolysis of C₆H₅CH₂Mn(CO)₅ in pentane solution produces Mn₂(CO)₁₀, toluene and bibenzyl. Analogous photodegradation of C₆H₅Mn(CO)₅ in pentane solution yields Mn₂(CO)₁₀, benzene and carbon monoxide, but not biphenyl. The thermally unstable complex C₂H₅Mn(CO)₅ was studied by photolyzing it in solution at ?40°C. GC analysis indicates that both ethylene and ethane are formed, and that the mole ratio of these products is dependent on the initial concentration of C₂H₅Mn(CO)₅. These results are consistent with a β-hydrogen elimination mechanism for this reaction. Photolysis of CpMo(CO)₃CH₂C₆H₅ in pentane solution produces [CpMo(CO)₃]₂ and toluene, whereas photolysis of CpW(CO)₃CH₂C₆H₅ affords [CpW(CO)₃]₂, CpW(CO)₂(η³-benzyl), toluene, and a small amount (2%) of bibenzyl. When CpM(CO)₂(η₃-benzyl) (M = Mo, W) complexes are subjected to photolysis under similar conditions, the only identifiable product is toluene. CpW(CO)₃C₆H₅ degrades photochemically in pentane solution to form [CpW(CO)₃)₂ and benzene, together with a small amount (6%) of biphenyl.     

Mass spectra of organometallic compounds—VII; Organonitrogen derivatives of metal carbonyls

The positive-ion mass spectra of the following organonitrogen derivatives of metal carbonyls are discussed: (i) The compounds NC₅H₄CH₂Fe(CO)₂C₅H₅, NC₅H₄CH₂COMo(CO)₂C₅H₅, NC₅H₄CH₂W(CO)₃C₅H₅, NC₅H₄CH₂COMn(CO)₄, C₅H₁₀NCH₂CH₂Fe(CO)₂C₅H₅, (CH₃)₂NCH₂CH₂COFeCOC₅H₅ and (CH₃)₂NCH₂CH₂COMn(CO)₄ obtained from metal carbonyl anions and haloalkylamines, (ii) The isocyanate derivative C₅H₅Mo(CO)₃CH₂NCO; (iii) The arylazomolybdenum derivatives RN₂Mo(CO)₂C₅H₅ (R ? phenyl, p-tolyl, or p-anisyl); (iv) The compound (C₆H₅N)₂COFe₂(CO)₆ obtained from Fe₃(CO)₁₂ and phenyl isocyanate; (v) The N,N,N′,N′-tetramethylethylenediamine complex (CH₃)₂NCH₂CH₂N(CH₃)₂W(CO)₄. Further examples of eliminations of hydrogen, CO, and C₂H₂ fragments were noted. In addition evidence for the following more unusual processes was obtained: (i) Elimination of HCN fragments from the ions [NC₅H₄CH₂MC₅H₅]⁺ to give the ions [(C₅H₅)₂M]⁺ (M ? Fe, Mo and W); (ii) Conversion of C₅H₅Mo(CO)₃CH₂NCO to C₅H₅Mo(CO)₂CH₂NCO within the mass spectrometer; (iii) Elimination of N₂ from [RN₂MoC₅H₅]⁺ to give [RMoC₅H₅]⁺; (iv) Novel eliminations of HNCO, FeNCO, and C₆H₅NC fragments in the mass spectrum of (C₆H₅N)₂COFe₂(CO)₆; (v) Facile dehydrogenation of the N,N,N′,-N′-tetramethylethylenediamine ligand in the complex (CH₃)₂NCH₂CH₂N(CH₃)₂W(CO)₄.     

The cyclometallation of bis(di-p-methylbenzylphosphino)methane

The new diphosphine (4-MeC₆H₄CH₂)₂PCH₂P(4-MeC₆H₄CH₂)₂, L, was reacted with [MnMe(CO)₅] to give the novel cyclometallated compound [Mn{(4-MeC₆H₃CH₂)(4-MeC₆H₄CH₂)PCH₂P(4-MeC₆H₄CH₂)₂}(CO)₃], as the mer isomer, and with the ligand in a terdentate [C,P,P] fashion.     

Reactivity of the Unsaturated Triosmium Cluster [Os3(CO)8{Ph2PCH2P(Ph)C6H4}(μ-H)] with Thiols

The reaction of the unsaturated cluster [(-H)Os₃(CO)₈{Ph₂PCH₂P(Ph)C₆H₄}] 2 with C₂H₅SH, CH₃CH(CH₃)SH and C₆H₅SH are reported. The reaction of 2 with C₂H₅SH yields the new complexes [Os₃(CO)₈(-SC₂H₅)(¹-SC₂H₅){Ph₂PCH₂P(Ph)C₆H₄}(-H)] 9 and [Os₃(CO)₈)(SC₂H₅)(Ph₂PCH₂P)(Ph)C₆H₄}] 8 in 24 and 57% yields respectively and the known compound [(Os₃(CO)₈)(-SC₂H₅)(-dppm)(-H)] 7 in 5% yield. Compound 9, which exists as two isomers in solution, converts into 8 almost quantitatively in solution at 25°C and more rapidly in refluxing hexane. Compound8 reacts with H₂ at 110°C to give 7 in high yield (86%). Treatment of 2 with propane-2-thiol yields [Os₃(CO)₈{-SCH(CH₃)CH₃}{Ph₂PCH₂P(Ph)C₆H₄}] 10 and [(Os₃(CO)₈{-SCH(CH₃)CH₃}{¹-SCH(CH₃)CH₃}{Ph₂PCH₂P(Ph)C₆H₄}(-H)] 11 in 75 and 3% yields respectively while with C₆H₅SH, [(Os₃(CO)₈(-SC₆H₅)(-dppm)(-H)] 6 is obtained as the only product in 75% yield. In both 8 and 10, the thiolato ligand bridges the Os–Os edge which is also bridged by the metallated phenyl group. The new compounds have been characterized by elemental analyses and spectroscopic methods (IR, ¹H and ³¹P NMR). The molecular structures of 7, 8, 9 and 10 are reported as determined by X-ray diffraction studies.     

Chemie polyfunktioneller Moleküle. 103 [1]: Chrom-, Molybdän- und Wolframtetra- sowie -tricarbonyl-Komplexe eines Diphenylphosphin-substituierten Cyclophosphamide

Inhaltsübersicht. (Ph₂PCH₂CH₂)₂N-P(O)N(H)CH₂CH₂CH₂O ( 2 ) bildet mit cis-M(CO)₄(C₇H₈) bzw. fac-M(CO)₃(CH₃CN)₃ (M = Cr, Mo, W; C₇H₈ = Norbornadien) die Chelat-komplexe cis-M(CO)₄(PPh₂CH₂CH₂)₂N-P(O)N(H)CH₂CH₂CH₂O ( 3a–c ) bzw. fac-M(CO)₃(PPh₂CH₂CH₂)₂N–P(O)N(H)CH₂CH₂CH₂O ( 4a–c ). 3a kristallisiert mit einem Mol Methanol aus, während 4a–c jeweils ein halbes Mol THF als Solvat enthalten. Alle Verbindungen wurden, soweit möglich, durch IR-, Raman-, ¹H-NMR-, ³¹P-NMR-, ¹³C-NMR- und Massenspektren charakterisiert. Chemistry of Polyfunctional Molecules. 103. Chromium, Molybdenum, and Tungsten Tetra- and Tricarbonyl Complexes of a Diphenylphosphine-substituted Cyclophosphamide Abstract. (Ph₂PCH₂CH₂)₂N–P(O)N(H)CH₂CH₂CH₂O (2) forms with cis-M(CO)₄(C₇H₈) or fac-M(CO)₃(CH₃CN)₃ (M = Cr, Mo, W; C₇H₈ = norbornadiene) the chelate complexes cis-M(CO)₄(PPh₂CH₂CH₂)₂N–P(O)N(H)CH₂CH₂CH₃O ( 3a–c ) or fac-M(CO)₃(PPh₂CH₂CH₂)₂N–P(O)N(H)CH₂CH₂CH₂O ( 4a–c ). 3a crystallizes with one mole of methanol whereas 4a–c contain 1/2 mole of THP as solvate. All compounds were, as far as possible, characterized by their IR, Raman, ¹H NMR, ³¹P NMR, ¹³C NMR, and mass spectra.     

Iron and molybdenum carbonyls of 5,6,7,8-tetramethylenebicyclo[2.2.2]-oct-2-ene

The reaction of the title ligand with iron carbonyls under various conditions gives (tetrahapto)5,6,7,8-tetramethylenebicyclo[2.2.2]oct-2-ene-exotricarbonyliron (I) and the bis(tetrahapto)endoexo-(II) and diexohexacarbonyl diiron (III) complexes as main products. The monoexo complex reacts with Mo(CO)₃(CH₃CN)₃ giving a (tetrahapto)iron(hexahapto)molybdenum complex (IV).     

Synthesis of bridged and linked ruthenium and osmium carbonyl clusters containing a [Au2(Ph2PCH2CH2PPh2)]2+ unit. The crystal and molecular structures of Ru5C(CO)14Au2(Ph2PCH2CH2PPh2) and {Os4H3(CO)12}2Au2(Ph2PCH2CH2PPh2)

Treatment of Au₂(Ph₂PCH₂CH₂PPh₂)Cl₂ with one equivalent of the [Ru₅C(CO)₁₄]²⁻ dianion in the presence of TlPF₆ gives Ru₅C(CO)₁₄Au₂(Ph₂PCH₂CH₂PPh₂) (1) in good yield and the [{Ru₅C(CO)₁₄}₂Au₂(Ph₂PCH₂CH₂PPh₂)]²⁻ (2) anion in low yield. Complex 2 becomes the major product if 2 equivalents of [Ru₅C(CO)₁₄]²⁻ are used. Reaction of [Au₂(Ph₂PCH₂CH₂PPh₂)Cl₂] with 3 equivalents of [H₃Os₄(CO)₁₂]⁻ anion in the presence of TlPF₆ affords {H₃Os₄(CO)₁₂}₂Au₂(Ph₂PCH₂CH₂PPh₂) (3) in reasonable yield. X-ray diffraction studies of 1 and 3 show that they contain the [Au₂(Ph₂PCH₂CH₂PPh₂)]²⁺ fragment in different coordination modes.     

Transition metal derivatives of arenediazonium ions: XIV. Reactions of arenediazomolybdenum(II) complexes with neutral and anionic Lewis bases

The reactions of arenediazomolybdenum(II) complexes such as [(η-C₅H₅)Mo(N₂C₆H₄CH₃-p)I₂]₂, (η-C₅H₅)Mo(CO species with neutral and anionic monodentate or chelating ligands have been investigated. The new arenediazo complexes isolated from these reactions include neutral species such as (η-C₅H₅)Mo(PPh₃)(N₂C₆H₄CH₃-p)I₂ and (η-C₅H₅)Mo(N₂C₆H₄CH₃-p) cations of the type [η-C₅H₅)Mo(bipy)(N₂C₆H₄CH₃-p)I]⁺ and the anion [(η-C₅H₅)Mo(N₂C₆H₄CH₃-p)I₃]^?. The structures of the new complexes are discussed.     

Reaction patterns of cyclopentadienylcobalt(I) carbonyl and acetylene derivatives

Studies have been made of photochemical and thermal reaction sequences through which bisubstituted acetylenes are transformed in (C₅H₅)Co-carbonyl reaction systems into cyclobutadiene and cyclopentadienone complexes and hexasubstituted benzenes. A primary intermediate observed by its IR spectrum in low-temperature photochemical reactions of (C₅H₅)Co(CO)₂ with diphenyl alkynes RCCR is the mixed mononuclear species (C₅H₅)Co(CO)(RCCR). At room temperature this species is converted by excess alkyne into the cyclopentadienone complex (C₅H₅)Co(R₄C₄CO). We have isolated from these reactions systems an important intermediate the mixed binuclear compound(C₅H₅)₂Co₂(μ-CO)(RCCR). In the presence of excess alkyne this compound is thermally converted either to the cyclobutadiene or to the cyclopentadienone complex of (C₅H₅)Co, depending on the partial pressure of CO in the reaction system. The mixed binuclear compound forms a catalyst for the cyclotrimerization of excess 2-butyne. The fluxional binuclear metallocycle (C₅H₅)₂Co₂[(CH₃)₄C₄], which is formed by sodium amalgam reduction of (C₅H₅)Co(CO)I₂ in the presence of 2-butyne, is a true catalyst for alkyne cyclotrimerization.     

Photoelektronenspektroskopie an Niobiodiden

Photoelectron Spectroscopy on Niobium Iodides The photoelectron spectra (AlKα, HeI) of NbI₅, NbI₄, Nb₃I₈, Nb₆I₁₁, HNb₆I₁₁, Nb₆I₈(CH₃NH₂)₆, Nb₆I₈(C₃H₇NH₂)₆, and Nb are measured and discussed. It is shown that the binding energy of the niobium core levels depends linearly on the oxidation number n (n = I/Nb). The relation BE = 201.8 + 1.07 · n holds for the Nb 3d^5/2 level. Using this relation the hydridic character of the hydrogen in HNb₆I₁₁ becomes plausible and the increased electron concentration of the Nb₆I₈ cluster in the compounds Nb₆I₈(CH₃NH₂)₆ and Nb₆I₈(C₃H₇NH₂)₆ is verified. Energy gaps E_g = 0.40 (0.45) eV are found for Nb₆I₁₁(HNb₆I₁₁) and for the amines the top of the valence band is 0.70 (CH₃NH₂) and 0.68 eV (C₃H₇NH₂), resp. below the Fermi level.     

Reactions of pyridyl side chain functionalized cyclopentadiene with ruthenium carbonyl

Abstract  

Reactions of the pyridyl side-chain-functionalized cyclopentadiene [C₅H₅CR₂(CH₂C₅H₄N)] [R ₂ = Et₂ (1), (CH₂)₄ (2)] with Ru₃(CO)₁₂ in refluxing xylene gave the new intramolecular C–H activated trinuclear product [μ-(C₅H₃N)CH₂C(C₂H₅)₂(C₅H₄)Ru(CO)]₂Ru(CO)₂ (3) and the normal dinuclear metal complex [(C₅H₄N)CH₂C(CH₂)₄(C₅H₄)Ru(CO)]₂(μ-CO)₂ (4). The structures of the trinuclear complex 3 and dinuclear complex 4 were characterized by elemental analysis, IR spectra, ¹H-NMR and X-ray diffraction.     

Mass spectra of some neopentylphosphorus derivatives

The fragmentation patterns and major metastable ions of the mass spectra of the neopentyl-phosphorus derivatives [(CH₃)₃CCH₂]₃P, [(CH₃)₃CCH₂]₂P(O)H, [(CH₃)₃CCH₂]_nPX_3-n (n = 1 and 2; X = H, Cl, C₆H₅ and CH = CH₂), [(CH₃)₃CCH₂]₃PS, [(CH₃)₃CCH₂]_nP(S)R_3-n (n = 1 and 2; R = C₆H₅ and CH = CH₂), [(CH₃)₃ CCH₂]₂PCH₂CH₂P[CH₂C(CH₃)₃]₂, ([CH₃)₃CCH₂]₂PCH₂PCH₂-CH₂P(H)C₆H₅ and [(CH₃)₃CCH₂]₂PCH₂CH₂P(S)(CH₃)₂ are described. Fragmentation of a neopentyl group by elimination of either C₄H₈ or CH₃ is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C₄H₈ from all of the neopentyl groups occurs very readily. The resulting [(CH₃)_nPX]^+._3-n ions are often the most intense ions in the mass spectra.     

Oxidative addition of different electrophiles with rhodium(I) carbonyl complexes of unsymmetrical phosphine–phosphine monoselenide ligands

Dimeric chlorobridge complex [Rh(CO)₂Cl]₂ reacts with two equivalents of a series of unsymmetrical phosphine–phosphine monoselenide ligands, Ph₂P(CH₂)_nP(Se)Ph₂ {n = 1( a ), 2( b ), 3( c ), 4( d )}to form chelate complex [Rh(CO)Cl(P∩Se)] ( 1a ) {P∩Se = η²‐(P,Se) coordinated} and non‐chelate complexes [Rh(CO)₂Cl(P～Se)] ( 1b–d ) {P～Se = η¹‐(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH₃I, C₂H₅I, C₆H₅CH₂Cl and I₂ to produce Rh(III) complexes of the type [Rh(COR)ClX(P∩Se)] {where R = ? C₂H₅ ( 2a ), X = I; R = ? CH₂C₆H₅ ( 3a ), X = Cl}, [Rh(CO)ClI₂(P∩Se)] ( 4a ), [Rh(CO)(COCH₃)ClI(P～Se)] ( 5b–d ), [Rh(CO)(COH₅)ClI‐(P～Se)] ( 6b–d ), [Rh(CO)(COCH₂C₆H₅)Cl₂(P～Se)] ( 7b–d ) and [Rh(CO)ClI₂(P～Se)] ( 8b–d ). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH₃I and C₂H₅I reveals a single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d . The CH₃I reacts with the different complexes at a rate 10–100 times faster than the C₂H₅I. The catalytic activity of complexes 1b–d for carbonylation of methanol is evaluated and a higher turnover number (TON) is obtained compared with that of the well‐known commercial species [Rh(CO)₂I₂]^?. Copyright © 2006 John Wiley & Sons, Ltd.