Structures of propionaldehyde, butyraldehyde, and pivalaldehyde complexes of the chiral rhenium fragment [(η-C5H5)Re(NO)(PPh3)]

The crystal structures of propionaldehyde complex (RS,SR)-(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₃)]⁺ PF₆⁻ (1b⁺ PF₆^s−; monoclinic, P2₁/c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex (RS,SR)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₂CH₃)]⁺ PF₆⁻ (1c⁺PF₆⁻; monoclinic, P2₁/a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η⁵-C₅H₅)Re(NO)(PPh₃)(ClCH₂Cl)]⁺ BF₄⁻ and pivalaldehyde gives [(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHC(CH₃)₃)]⁺BF₄⁻ (81%), the spectroscopic properties of which establish a π C O binding mode.     

Indenyl complexes of ruthenium(II) containing optically active diphosphines. X-ray structures of (S,S)-(η-C9H7)-Ru{Ph2PCH(CH3)CH(CH3)PPh2}Cl and of its η-C5H5 analogue

The optically active indenyl complexes ((η⁵-C₉H₇)Ru(L---L)Cl (where L---L is either (S,S)-1,2-dimethyl-1,2-ethanediylbis(diphenylphosphine) (chiraphos) or (R,R)-1,2-cyclopentanediylbis(diphenylphosphine) (cypenphos)) have been synthesized and spectroscopically characterized and compared with the corresponding cyclopentadienyl complexes. Reaction of the new complexes with 2-e-donors give cationic adducts in which the pentahaptocoordination of the indenyl ligand is maintained. The crystal structures of (S,S)-(η⁵-C₉H₇)Ru{Ph₂PCH(CH₃)CH(CH₃)PPh₂}Cl (1) and (S,S)-η⁵-C₅H₅Ru{Ph₂PCH(CH₃)CH(CH₃)PPh₂}Cl (3) have been determined.     

Interaction of half-sandwich alkylmolybdenum(III) complexes with B(C6F5)3. The X-ray structure of [CpMo(η-C4H6)(μ-Cl)(μ-CH2)(O)MoCp][CH3B(C6F5)3]

The reactions of the half-sandwich molybdenum(III) complexes CpMo(η⁴-C₄H₄R₂)(CH₃)₂, where Cp=η⁵-C₅H₅ and R=H or CH₃, with equimolar amounts of B(C₆F₅)₃ have been investigated in toluene. EPR monitoring shows the formation of an addition product which does not readily react with Lewis bases such as ethylene, pyridine, or PMe₃. The analysis of the EPR properties and the X-ray structure of a decomposition product obtained from dichloromethane, [CpMo(η⁴-C₄H₆)(μ-Cl)(μ-CH₂)(O)MoCp][CH₃B(C₆F₅)₃], indicate that the borane attack has occurred at the methyl position.     

Photochemical reactions of the isostructural 17- and 18-electron complexes (η-C5H5)M(Me)PPh3 (M=Co, Ni)

The photochemical reactions of the title complexes were studied in air-free benzene solution. In both cases photolysis leads to the production of complexes of the formula (η⁵-C₅H₅)M(PPh₃)₂. Both reactions are the result of the initial loss of a methyl radical from the excited state. The primary photoproduct, (η⁵-C₅H₅)MPPh₃ (M=CO, Ni), then scavenges neutral ligands from the solution to yield, in the case of PPh₃, (η⁵-C₅H₅)M(PPh₃)₂. In the absence of uncoordinated ligand in the reaction solution, the cobalt derivative reacts with the starting material to yield (η⁵-C₅H₅)Co(PPh₃)₂, a methyl radical and (η⁵-C₅H₅)Co(solvent)_n.     

Synthesis and X-ray crystal structures of [Ph2PMe2][(η-C5H4Bu)2Li] and [(η-C5H4Bu)2Yb(Cl)CH2P(Me)Ph2]

The interaction of [(η⁵-C₅H₄Bu^t)₂YbCl · LiCl] with one equivalent of Li[(CH₂) (CH₂)PPh₂] in tetrahydrofuran gave [Ph₂PMe₂][(η⁵-C₅H₄Bu^t)₂Li] (1) and [(η⁵-C₅H₄Bu^t)₂Yb(Cl)CH₂P(Me)Ph₂] (2) in 10% and 30% yields, respectively. 1 could also be prepared in 70% yield from the reaction of [Ph₂PMe₂][CF₃SO₃] with two equivalents of (C₅H₄Bu^t)Li. Both compounds have been fully characterized by analytical, spectroscopic and X-ray diffraction methods. The solid state structure of 1 reveals a sandwich structure for the [(η⁵-C₅H₄Bu^t)₂Li]⁻ anion.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

The stereochemistry at silicon of an iron to cyclopentadienyl ligand silyl group migration in (η-C5H5)Fe(CO)2SiR3

The silyl group migration observed upon treating (R)(+)-(η⁵-C₅H₅)Fe(CO)₂-SiMePh(1-Np) with n-BuLi occurs with retention of configuration at silicon. The anion resulting from the migration, (η⁵-C₅H₄SiMePh(1-Np))Fe(CO)₂Li, is alkylated with MeI to give (R)-(−)-(η⁵-C₅H₄SiMePh(1-Np))Fe(CO)₂Me (II). Compound II is independently prepared from (η⁵-C₅H₅)Fe(CO)₂Me. A concerted mechanism for the migration involving frontside nucleophilic attack at silicon is suggested.     

First examples of η- and η --- η-coordination in triphosphorus analogues of ferrocene. Crystal structure of the iron sandwich complex [Fe(η-C5H5) (η-C2R2P3)W (CO)5] (R = Bu)

Syntheses of the novel sandwich compounds [Fe(η⁵-C₅H₅)(η⁵-C₂R₂P₃)] and [Fe(η⁵-C₅H₅)(η⁵-C₂R₂P₃)W(CO)₅], (R = Bu^t), are described. The mode of attachment of the [W(CO)₅] fragment in the latter compound has been determined by NMR and single crystal X-ray diffraction studies.     

Photochemical reactions of alkynyl iron (II) complexes with carbon disulfide. Insertion of CS2 into an iron-C(sp) bond

The novel alkynyldithiocarboxylate complexes [Fe(η⁵-C₅H₅)(S₂CCCR) (dppm-P)] (3a,b) and [Fe(η₅-C₅H₅)(S₂CCCR)(PPh₃)] (4a,b) were obtained through the insertion of CS₂ into the iron-akynyl bond in the complexes [Fe(η₅-C₅H₅)(CCR)(L)(L′] L, L′ = dppm R = Ph (1a), ^tBu(1b); L = (CO), L′ = (PPh₃) R = Ph (2a), ^tBu (2b). Variable-temperature ³¹P{¹H} NMR studies indicate the presence of two different isomers, [Fe(η⁵-C₅H₅)(η³-S,C,S′---S₂CCCR)(L)(L′)] and [Fe(η⁵-C₅H₅(η²-S,S′-S₂CCCR)(L)(L′)], which rapidly interconvert at room temperature. The synthesis of the precursor complex [Fe(η⁵-C₅H₅)(CC^tBu)(CO)(PPh₃)] is also described.     

Substituted cyclopentadienyl ligands—10. Intramolecular steric interactions in [(η-C5H3(SiMe3)2)Mo(CO)2(L)I]

Reaction of C₅H₄(SiMe₃)₂ with Mo(CO)₆ yielded [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₃]₂, which on addition of iodine gave [(η⁵-C₅H₃(SiMe₃)₂Mo(CO)₃I]. Carbonyl displacement by a range of ligands: [L = P(OMe)₃, P(OPrⁱ)₃,P(O-o-tol)₃, PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(m-tol)₃] gave the new complexes [(η⁵-C₅H₃(SiMe₃)₂ MO(CO)₂(L)I]. For all the trans isomer was the dominant, if not exclusive, isomer formed in the reaction. An NOE spectral analysis of [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₂(L)I] L = PMe₂Ph, P(OMe)₃] revealed that the L group resided on the sterically uncongested side of the cyclopentadienyl ligand and that the ligand did not access the congested side of the molecule. Quantification of this phenomenon [L = P(OMe)₃] was achieved by means of the vertex angle of overlap methodology. This methodology revealed a steric preference with the trans isomer (less congestion of CO than I with an SiMe₃ group) being the more stable isomer for L = P(OMe)₃.     

Homochiral cyclopentane-based C1-symmetric P,P ligands C5H8(PPh2)(PR2) from C2-symmetric C5H8(PCl2)2

Treatment of 1,2-trans-C₅H₈(PCl₂)₂ with 1,2-C₂H₄(NHPr-i)₂ gave the C₂-symmetric perhydro-1,6,2,5-diazaphosphocine C₅H₈{P(Cl)N(Pr-i)CH₂}₂-cyclo, which produced dissymmetric C₅H₈(PPh₂){P[N(Pr-i)CH₂]₂-cyclo} on further reaction with PhMgBr. Cleavage of the P---N bonds with gaseous HCl afforded C₅H₈(PPh₂)(PCl₂), which was converted to C₅H₈(PPh₂){P(OPh)₂}₂ by reaction with phenol. All chiral P,P derivatives were obtained as racemates as well as resolved (1R,2R)- and (1S,2S)-enantiomers.     

Mechanism of formation of (η-C5H5)2NbH3 from the reaction of (η-C5H5)2NbCl2 with hydridoaluminate reducing agents

The mechanism of the transformation of (η⁵-C₅H₅)₂NbCl₂ to (η⁵-C₅H₅)₂NbH₃ by hydridoaluminate reducing agents has been investigated. Results suggest disproportionation of a niobium(IV) hydrite, leading to the trihydride product and a niobium(III) hydridoaluminate, (η⁵-C₅H₅)₂NbH₂AlR₂, which in turn is converted to the trihydride on hydrolysis. (η⁵-C₅H₅)₂NbH₂AlH₂ has been isolated; deuterium labelling shows that hydrogens exchange between ring and metal-bridging positions in this molecule.     

Synthesis and crystal structure of the complex [MoW(OEt)(μ-CH2){μ-C(C6H4Me-4)C(Me)O}(η-C7H7)(η-C2B9H10Me)]

The complex [MoW(μ-CC₆H₄Me-4)(CO)₂(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)] reacts with diazomethane in Et₂O containing EtOH to afford the dimetal compound [MoW(OEt)(μ-CH₂){μ-C(C₆H₄Me-4)C(Me)O}(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)]. The structure of this product was established by X-ray diffraction. The Mo---W bond [2.778(4) Å] is bridged by a CH₂ group [μ-C---Mo 2.14(3), μ-C---W 2.02(3) Å] and by a C(C₆H₄Me-4)C(Me)O fragment [Mo---O 2.11(3), W---O 2.18(2), Mo---C(C₆H₄Me-4) 2.41(3), W---C(C₆H₄Me-4) 2.09(3), Mo---C(Me) 2.26(3) Å]. The molybdenum atom is η⁷-coordinated by the C₇H₇ ring and the tungsten atom is η⁵-coordinated by the open pentagonal face of the nido-icosahedral C₂B₉H₁₀Me cage. The tungsten atom also carries a terminally bound OEt group [W---O 1.88(3) Å]. The ¹H and ¹³C-{¹H} NMR data for the dimetal compound are reported and discussed.     

Synthese et etude des complexes [C5H4(CH2)3C5H4]Ti(C5H5)2 presentant un pont entre deux ligands cyclopentadienyles

The complex (di-η⁵-C₅H₄CH₂CH₂CH₂C₅H₄)Ti(η¹-C₅H₅)₂ (I) can be obtained unambiguously starting from the corresponding bridged titanocene dichloride. Attempts to synthesize the isomeric compounds (η⁵-C₅H₅)₂ Ti(di-η¹-C₅H₄-CH₂CH₂CH₂C₅H₄) (I′) by the action of a convenient bridged dianion on (C₅H₅)₂ TiCl₂ afford several compounds, one of them is the complex I. The possibility of interconversion of these complexes by a fluctional process is discussed.     

Darstellung von metallkomplexen des thio- und selenoacetaldehyds sowie die kristallstruktur von C5H5Rh(η-CH3CHSe)P(i-Pr)3

The compounds C₅H₅Co(η²-CH₃CHS)PMe₃ (I) and C₅H₅Co(η²-CH₃CHSe)PMe₃ (II) are prepared from C₅H₅Co(CO)PMe₃, CH₃CHBr₂ and NaSH or NaSeH, respectively. The synthesis of the corresponding rhodium complexes C₅H₅Rh(η²-CH₃CHS)P(i-Pr)₃ (VI) and C₅H₅Rh(η²-CH₃CHSe)P(i-Pr)₃ (VII) has been achieved through hydrogenation of C₅H₅Rh(η²-EC=CH₂)P(i-Pr)₃ (E = S, Se), using RhCl(PPh₃)₃ as a catalyst. The crystal structure of VII has been determined.     

Synthesis and characterization of planarly chiral nonbridged bis(1-R-indenyl) zirconium dichloride complexes and X-ray structure of rac-[(η-C9H6-1-C(CH3)2---o-C6H4---OCH3)2ZrCl2]·THF

Reactions of the lithium salts of 3-substituted indenes 1, 2 with ZrCl₄(THF)₂ gave two series of nonbridged bis(1-substituted)indenyl zirconocene dichloride complexes. Fractional recrystallization from THF–petroleum ether furnished the pure racemic and mesomeric isomers of [(η⁵-C₉H₆-1-C(R¹)(R²)---o-C₆H₄---OCH₃)₂ZrCl₂]·nTHF (R¹=R²=CH₃, n=1, rac-1a and meso-1b; R¹=CH₃, R²=C₂H₅; n=0.5 or 0, rac-2a and meso-2b), respectively. Complex 1a was further characterized by X-ray diffraction to have a C₂ symmetrically racemic structure, where the six-member rings of the indenyl parts are oriented laterally and two o-CH₃O---C₆H₄---C(CH₃)₂--- substituents are oriented to the open side of the metallocene (Ind: bis-lateral, anti; Substituent: bis-central, syn). The four zirconocene complexes are highly symmetrical in solution as characterized by room temperature ¹H-NMR, however ¹H–¹H NOESY of meso-1b shows that some of the NOE interactions arise from the two separated indenyl parts of the same molecule, which can only be well explained by taking into account the torsion isomers in solution.     

Stability of the silicon-ruthenium bond in the presence of a strong nucleophile. Phase sensitive H NMR COSY and crystal structure of Ru(CO)2(NH2CH2C6H5)2(Si(C6H5)(CH3)2)I

The ruthenium(II) complex Ru(CO)₂(NH₂(NH₂CH₂C₆H₅)₂(Si(C₆H₅)(CH₃)₂)I has been prepared by the reaction of Ru(CO)₄(Si(C₆H₅)(CH₃)₂)I with benzylamine. Two-dimensional homonuclear ¹H NMR experiments examine the scalar coupling of the enantiotopic amino and methylene protons of the benzylamine ligand. X-ray analysis of Ru(CO)₂(NH₂CH₂C₆H₅)₂(Si(C₆H₅)(CH₃)₂)I·1/3C₅H₁₂ (triclinic; P ; a = 14.266(4), b = 15.748(5), c = 20.082(6) Å; = 94.38(3), β = 96.30(2), γ = 101.52(2)°) indicates three crystallographically unique complexes form a clathrate with a pentane guest.     

Synthesis and decomposition of neutral palladium(IV) complexes containing fac-PdMe2R groups, including reductive elimination by η-propenylpalladium(IV) complexes to form η-propenylpalladium(II) species

Oxidative addition of ethyl iodide to PdMe₂(2,2′-bipyridyl) in (CD₃)₂CO gives the unstable “PdIMe₂Et(bpy)”, which undergoes reductive elimination to form PdIR(bpy) (R = Me, Et), ethane, and propane. Ethene and palladium metal are also formed, and are attributed to decomposition of PdIEt(bpy) via β-elimination. Similar results are obtained with n-propyl iodide, although a palladium(IV) intermediate was not detected, but CH₂=CHCH₂X (X = Br, I) and PhCH=CHCH₂Br give isolable complexes fac-PdXMe₂(CH₂CH=CHR)(L₂) (R = H, Ph; L₂ = bpy, phen). The propenyl complexes decompose at ambient temperature to form ethane, a trace of PdXMe(L₂), and mixtures of [Pd(η³-C₃H₅)(L₂)]X and [Pd(η³-C₃H₅)(L₂)]-[Pd(η³-C₃H₅)X₂]; for fac-PdBrMe₂(CH₂CH=CH₂)(bpy) the major palladium(II) product is [Pd(η³-C₃H₅)(bpy)]Br.     

Synthesis and crystal structure of the novel trimanganese tetrathiolate incomplete cubane: [Mo(η-C5H5)2(H)CO][Mn3(CO)9(μ-SC6H5)4]

An unexpected trimanganese(I) tetrathiolate-bridged complex, [Mn₃(CO)₉(μ-SC₆H₅)₄]⁻, with an incomplete cubane structure, was obtained by thermal reaction of [Mn₂(CO)₁₀] with [Mo(η⁵-C₅H₅)₂(SC₆H₅)₂]. The structure, established by single-crystal X-ray diffraction studies, shows the cation, [Mo(η⁵-C₅H₅)₂(H)CO]⁺, directed towards the vacant site of the cubane structure. Possible routes by which the anion and the cation could be formed are discussed.     

Reactivity of niobocene dihalogenides toward nitroso derivatives. EPR and IR characterization of the first niobium(IV) complexes containing an ArNO-N,O ligand

The reaction of [Nb(η⁵-C₅H₄R)₂X₂] [1: R = SiMe₃, X = Cl; 2: R = SiMe₃, X = Br; 3: R = H, X = Cl; 4: R =^t, X = Cl] with nitroso derivatives ArNO [a: Ar = Ph; b: Ar = o-CH₃-C₃H₄; c: Ar = p-(CH₃)₂NC₆H₄] yields paramagnetic complexes formulated as [Nb(η⁵-C₅H₄R)(η³-C₅H₄R)X₂(ArNO-N,O) 1a, 1b, 1c, 2a, 3a, 4a and 4c, which have been characterized by ESR and IR spectroscopy.