Palladium(II) allylic complexes by carbene transmetalation and migratory insertion reactions: Synthesis and side reactions

New 1,1-alkoxy, aryl substituted palladium η³-allyls [Pd(μ-Br){η³-C(C₆F₅)(OMe)CHR¹CHR²}]₂ can be synthesized from [W(CO)₅{C(OMe)CHR¹CHR²}] and a palladium perfluoroaryl complex. The allyls are formed by transmetalation of the carbene fragment followed by migratory insertion of C₆F₅ to the putative and highly reactive Pd carbene complex. This reaction pathway predominates in all cases, but insertion of the double bond of the tungsten alkoxyvinylcarbenes into the Pd-C₆F₅ bond leads to secondary products, namely C₆F₅(OMe)CCR¹CH(C₆F₅)R².     

Preparation of iron carbonyl complexes of germanium(II) and tin(II) each with a terminal fluorine atom

The reaction of β-diketiminate substituted germanium(II) and tin(II) fluorides (LGeF (1) and LSnF (2)) (L = CH{(CMe)₂(2,6-iPr₂C₆H₃N)₂}) with diiron nonacarbonyl, Fe₂(CO)₉ at room temperature, leads to the iron carbonyl complexes of germanium(II) LGeFFe(CO)₄ (3) and tin(II) LSnFFe(CO)₄ (4), respectively. Compounds 3 and 4 were characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Furthermore, both complexes (3 and 4) were investigated by X-ray structural analysis which shows that both compounds are monomeric in the solid state containing terminal fluorine atoms.     

Five dinuclear iron carbonyl complexes based on substituted tetramethylcyclopentadienyl ligands: synthesis and crystal structures

Thermal treatment of the substituted tetramethylcyclopentadienes [C₅Me₄HR] [R?=?n-propyl (1), i-propyl (2), cyclopentyl (3), cyclohexyl (4), and 4-NMe₂Ph (5)] with Fe(CO)₅ gave five new substituted tetramethylcyclopentadienyl dinuclear iron carbonyl complexes, [η⁵-C₅Me₄CH₂CH₂CH₃]₂Fe₂(CO)₄ (6), [η⁵-C₅Me₄CH(CH₃)₂]₂Fe₂(CO)₄ (7), [η⁵-C₅Me₄CH(CH₂)₄]₂Fe₂(CO)₄ (8), [η⁵-C₅Me₄CH(CH₂)₅]₂Fe₂(CO)₄ (9), and [(η⁵-C₅Me₄)(4-NMe₂Ph)]₂Fe₂(CO)₄ (10). The new complexes were characterized by elemental analysis, IR, and ¹H NMR spectra. The molecular structures of 6, 8, 9, and 10 were determined by X-ray single crystal diffraction.     

Synthesis and characterization of diiron ethanedithiolate complexes with monosubstituted phosphine ligands

Reactions of (μ-edt)Fe₂(CO)₆ (edt = SCH₂CH₂S) (1) with the monophosphine ligands Ph₂PCH₂Ph, Ph₂PC₆H₁₁, Ph₂PCH₂CH₂CH₃, or P(2-C₄H₃O)₃ in the presence of Me₃NO?2H₂O afforded (μ-edt)Fe₂(CO)₅L [L = Ph₂PCH₂Ph, 2; Ph₂PC₆H₁₁, 3; Ph₂PCH₂CH₂CH₃, 4; P(2-C₄H₃O)₃, 5] in 70–88% yields. Complexes 2–5 were characterized by spectroscopy and single crystal X-ray diffraction analysis. The phosphorus of 2–5 is in an apical position of the distorted octahedral geometry of iron.     

Reactions of isonitriles with [Fe3(CO)12] and [Ru3(CO)12] monitored by electrospray mass spectrometry: structural characterisation of [Fe3(CO)10(CNPh)2] and [Ru4(CO)11(μ3-η-CNPh)2(CNPh)]

The reactions of [Fe₃(CO)₁₂] or [Ru₃(CO)₁₂] with RNC (R=Ph, C₆H₄OMe-p or CH₂SO₂C₆H₄Me-p) have been investigated using electrospray mass spectrometry. Species arising from substitution of up to six ligands were detected for [Fe₃(CO)₁₂], but the higher-substituted compounds were too unstable to be isolated. The crystal structure of [Fe₃(CO)₁₀(CNPh)₂] was determined at 150 and 298 K to show that both isonitrile ligands were trans to each other on the same Fe atom. For [Ru₃(CO)₁₂] substitution of up to three COs was found, together with the formation of higher-nuclearity clusters. [Ru₄(CO)₁₁(CNPh)₃] was structurally characterised and has a spiked-triangular Ru₄ core with two of the CNPh ligands coordinated in an unusual μ₃-η² mode.     

2-(Diphenylphosphino)benzoate-functionalized diiron ethane-1,2-dithiolate complexes with uncoordinated or coordinated phosphine ligand

Abstract

Treatment of the starting complex [Fe₂(CO)₆{μ-SCH₂CH(CH₂OH)S}] (1) with 2-(diphenylphosphino)benzoic acid in the presence of N,N’-dicyclohexylcarbodiimide and 4-dimethylaminopyridine gave the corresponding ester derivative [Fe₂(CO)₆{μ-SCH₂CH(CH₂O₂CC₆H₄PPh₂-2)S}] (2) in 92% yield. Further treatment of complex 2 with one equivalent of Me₃NO · 2?H₂O as the decarbonylating agent yielded diphenylphosphino-substituted complex [Fe₂(CO)₅{μ-SCH₂CH(CH₂O₂CC₆H₄PPh₂-2)S}] (3) in 79% yield. Both complexes were characterized by elemental analysis, spectroscopy, as well as by X-ray crystallography. Additionally, the electrochemical properties of these complexes were studied by cyclic voltammetry.     

New antimony-capped iron(II) and cobalt(III) clathrochelate precursors of the polytopic hybrid cage complexes: Synthesis,X-ray structures and electrochemistry

Direct template macrocyclization of the three dimethylglyoxime molecules on the iron(II) ion and the capping of nonmacrocyclic K₃CoDm₃ tris-dimethylglyoximate with triethylantimony(V) derivatives led to the formation of triethylantimony-capped iron(II) and cobalt(III) clathrochelates. The complexes obtained have been characterized using elemental analysis, MALDI-TOF mass, IR, UV–Vis, ⁵⁷Fe Mössbauer and ¹H and ¹³C NMR spectroscopies, and X-ray crystallography. The influence of the nature of an encapsulated metal ion, the capping groups and the chelate fragments on a clathrochelate framework geometry is discussed. The cyclic voltammograms show oxidation and reduction waves assignable to Fe^2+/3+ and Co^2+/3+ couples of the encapsulated metal ion.     

Synthesis of (η-arene)(η-cyclopentadienyl) iron (II) complexes with heteroatom and carbonyl substituents Part II, Amino substituents

A variety of methods have been used in the synthesis of amino-substituted (η⁶-arene)(η⁵-cyclopentadienyl) iron(II) complexes. Conventional thermal ligand exchange of 2-fluoroaniline with ferrocene in the presence of Devarda’s alloy gave an Ullmann coupling product, 2,2′ diaminobiphenyl complex, whereas omitting metal powder gave the 2-fluorobenzene complex. Double S_NAr substitution of the 1,2-dichlorobenzene complex by dimethylamine is reported. Microwave-assisted S_NAr reactions have led to the development of a one-pot synthesis of N-arylaminoacids. Acetylation of amino-complexes is described and the product anilide complexes used in S_NAr displacements to form aminoanilide analogues. Hexamethyldisilazane was found to be an efficient aminating agent in the presence of alcohols or phenols in DMSO, leading to the synthesis of the (η⁶-1,2-diaminobenzene)(η⁵-Cp) iron(II) complex, the first (ArFeCp)⁺ species reported containing two primary amino groups.     

Rhodium(I) carbonyl complexes of ether‐phosphine ligands and their reactivity

The reactions of dimeric complex [Rh(CO)₂Cl]₂ with hemilabile ether‐phosphine ligands Ph₂P(CH₂) _nOR [n = 1, R = CH₃ (a); n = 2, R = C₂H₅ (b)] yield cis‐[Rh(CO)₂Cl(P ～ O)] (1) [P ～ O = η ¹‐(P) coordinated]. Halide abstraction reactions of 1 with AgClO₄ produce cis‐[Rh(CO)₂(P ∩ O)]ClO₄ (2) [P ∩ O = η ²‐(P,O)chelated]. Oxidative addition reactions of 1 with CH₃I and I₂ give rhodium(III) complexes [Rh(CO)(COCH₃)ClI(P ∩ O)] (3) and [Rh(CO)ClI₂(P ∩ O)] (4) respectively. The complexes have been characterized by elemental analyses, IR, ¹H, ¹³C and ³¹P NMR spectroscopy. The catalytic activity of 1 for carbonylation of methanol is higher than that of the well‐known [Rh(CO)₂I₂]^? species. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis,crystal structures and magnetic properties of two iron (II) tris(pyridyl)phosphine selenides complexes

We reported the synthesis of tris(pyridyl)phosphine selenide (TppSe) and tris(4-methylpyridin-2-yl)phosphine selenide (MeTppSe), which were prepared by a simple and straightforward one-pot method with red phosphorus in a KOH/DMSO suspension, and treatment of resulted phosphines with selenium in hot toluene. These compounds were characterized by mass spectroscopy, ¹H, ¹³C and ³¹P NMR spectroscopies and the structure of MeTppSe was characterised by a single-crystal X-ray diffraction. Furthermore, The reactions of selenides with Fe(ClO₄)₂·6H₂O afforded two new iron(II) mononuclear metal complexes [Fe(TppSe)₂][ClO₄]₂·3DMF (1) and [Fe(MeTppSe)₂][ClO₄]₂·2DMF (2). Detailed structural analyses and magnetic susceptibility measurements confirm no spin transition from low-spin to the high-spin state between 2 and 300 K in two iron(II) complexes.     

Iron(II) and iron(III) complexes containing ethynyl thiophene fragments

The synthesis of the new complexes Cp*(dppe)FeCC2,5-C₄H₂SR (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; dppe = 1,2-bis(diphenylphosphino)ethane; 2a, R = CCH; 2b, R = CCSi(CH₃)₃; 2c, R = CCSi(CH(CH₃)₂)₃; 3a, R = CC2,5-C₄H₂SCCH; 3c, R = CC2,5-C₄H₂SCCSi(CH(CH₃)₂)₃) is described. The ¹³C NMR and FTIR spectroscopic data indicate that the π-back donation from the metal to the carbon rich ligand increases with the size of the organic π-electron systems. The new complexes were also analyzed by CV and the chemical oxidation of 2a and 3c was carried out using 1 equiv of [Cp₂Fe][PF₆]. The corresponding complexes 2a[PF₆] and 3c[PF₆] are thermally stable, but 2a[PF₆] was too reactive to be isolated as a pure compound. The spectroscopic data revealed that the coordination of large organic π-electron systems to the iron nucleus produces only a weak increase of the carbon character of the SOMO for these new organoiron(III) derivatives.     

Ethylene oligomerization by diimine iron(II) complexes/EAO

The catalytic properties of a series of Fe(II) diimine complexes (diimine=N,N′-o-phenylenebis(salicylideneaminato), N,N′-ethylenebis(salicylideneaminato), N,N′-o-phenylenebisbenzal, N,N′-ethylenebisbenzal) in combination with ethylaluminoxane (EAO) for ethylene oligomerization have been investigated. Treatment of the iron(II) complexes with EAO in toluene generates active catalytic systems in situ that oligomerize ethylene to low-carbon olefins. The effects of reaction temperature, ratios of Al/Fe and reaction periods on catalytic activity and product distribution have been studied. The activity of complex FeCl₂(PhCH=o-NC₆H₄N=CHPh) with EAO at 200°C is 1.35×10⁵ g oligomers/mol Fe·h, and the selectivity of C_4–10 olefins is 84.8%.     

Ferrocene bridged and substituted tetramethylcyclopentadienyl (or indenyl) carbonyl complexes of iron, ruthenium, and molybdenum

Reactions of ferrocene bridged and substituted tetramethylcyclopentadiene ligands 1,1′-Fc(C₅Me₄H)₂ (1) (Fc = 1,1′-ferrocenediyl) and (C₅H₅FeC₅H₄)C₅Me₄H (5) with Ru₃(CO)₁₂, Fe(CO)₅, and Mo(CO)₃(CH₃CN)₃ in refluxing xylene gave the corresponding trinuclear and tetranuclear complexes Fc[(C₅Me₄)M(CO)]₂(μ-CO)]₂ [M = Ru (2), Fe (3)], Fc[(C₅Me₄)Mo(CO)₃]₂ (4) and [(C₅H₅ FeC₅H₄)C₅Me₄M(CO)]₂(μ-CO)₂ [M = Ru (6), Fe (7)], [(C₅H₅FeC₅H₄)C₅Me₄Mo(CO)₃]₂ (8). Reactions of (3-indenyl)ferrocene (9) with Ru₃(CO)₁₂ or Fe(CO)₅ in refluxing xylene or heptane, also gave the corresponding tetranuclear metal complexes [(C₅H₅FeC₅H₄)C₉H₆M(CO)]₂(μ-CO)₂ [M = Ru (10), Fe (11)]. The molecular structures of 2 and 3 were determined by X-ray diffraction analysis.     

Equilibrium constants and kinetics of carbon monoxide insertion in alkyl complexes of ruthenium(II)

The equilibrium constants of the reaction of cis, trans-[Ru(CO)₂(PMe₃)₂(CH₃)I] (Mc) with carbon monoxide to give cis, trans[Ru(CO)₂(PMe₃)₂ (COMe)i] (Ac) and trans, trans[Ru(CO)₂(PMe₃)₂(COMe)I] (At) were measured at various temperatures in toluene. The thermodynamic parameters are compared with those obtained for the isoelectronic complexes of iron, and the trend is discussed. The kinetics of the carbonylation reaction of Mc, as well as those of the inverse decarbonylation reaction of At were measured. The kinetics of the carbonylation of the new complex trans, trans-[Ru(CO)₂(PMe₃)₂(CH₃)I] (Mt) were also investigated. All the results afford further support to the previously proposed CO insertion mechanism occurring via methyl migration. The comparison of these kinetic results with those of isoelectronic complexes of iron indicates that ruthenium is more reactive than iron, which is reflected by its greater aptitude to act as catalyst in many processes.     

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.     

A new ruthenium(II) hydride carbonyl complex with pyrimidine ligand

The reaction of [RuHCl(CO)(PPh₃)₃] with pyrimidine gives [RuHCl(CO)(PPh₃)₂(C₄H₄N₂)]. The compound has been studied by IR, UV-Vis and X-ray crystallography. The molecular orbital diagram of the complex has been calculated with density functional theory (DFT). The spin-allowed singlet-singlet electronic transitions of the complex have been calculated with time-dependent DFT method, and the UV-Vis spectrum of the compound has been discussed on this basis. Emission of the compound was studied.     

Spin-state splittings of iron(II) complexes with trispyrazolyl ligands

We report a computational study at the OPBE/TZP level on the chemical bonding and spin ground-states of mono-nuclear iron(II) complexes with trispyrazolylborate and trispyrazolylmethane ligands. We are in particular interested in how substitution patterns on the pyrazolyl-rings influence the spin-state splittings, and how they can be rationalized in terms of electronic and steric effects. One of the main observations of this study is the large similarity of the covalent metal–ligand interactions for both the borate and methane ligands. Furthermore, we find that the spin-state preference of an individual transition-metal (TM) complex does not always concur with that of an ensemble of TM-complexes in the solid-state. Finally, although the presence of methyl groups at the 3-position of the pyrazolyl groups leads to ligand–ligand repulsion, it is actually the loss of metal–ligand bonding interactions that is mainly responsible for shifts in spin-state preferences.     

Structural and spectroscopic characterization of tetranuclear iron complexes containing a bridge

A pair of tetranuclear iron complexes consisting of two Fe₂(Cl₂bdt)(CO)₅ subunits (Cl₂bdt?=?3,6-dicholorobenzene-1,2-dithiolate) bridged by different cyclic 1,5-diaza-3,7-diphosphacyclooctane (P₂N₂) ligands were prepared and structurally characterized. In the solid state, the P₂N₂ ligands adopt a boat conformation, which results in rather short distances between the two Fe₂(Cl₂bdt)(CO)₅ clusters that promotes electronic communication across the diphosphine ligand.     

Thio-azo proligands based on 5,6-derivatives-1,10-phenanthroline and their use for iron(II) complexes: Synthesis,characterization and crystal structures

The preparation and characterization of 5,6-substituted-1,10-phenanthrolines, phdtos = 5,6-bistosyl-1,10-phenanthroline (1) and phdbt = 5,6-dibenzyltiol-1,10-phenanthroline (2) are described. The synthesis of (1) was achieved in good yield via the corresponding dihydroxide and 2 was obtained by cross-coupling reaction of 5,6-dibromo-1,10-phenanthroline and benzylthiol mediated by a palladium catalytic system in refluxing toluene (120 °C). These phenanthroline derivatives were used as ligands to afford [Fe^II(phdtos)₃](PF₆)₂ (5) and [Fe^II(phdbt)₃](PF₆)₂ (6) complexes.     

Synthesis,characterization, and structures of nickel(II) and palladium(II) complexes of aromatic thiohydrazides

Nickel(II) and palladium(II) form neutral 1?:?2 chelates with aromatic thiohydrazides, for example. thiobenzhydrazide, o-hydroxythiobenzhydrazide, furan-2-thiohydrazide, and thiophen-2-thiohydrazide. All the compounds are diamagnetic and have been characterized by elemental analysis and spectroscopic methods. o-Hydroxythiobenzhydrazido complexes of nickel(II) and palladium(II) were crystallized from DMSO and their structures were solved by X-ray diffraction. The complexes are isostructural with planar structures. Metal ion is linked to two identical deprotonated ligands through trans hydrazinic nitrogen and sulfur. Hydrogen of OH is involved in intramolecular hydrogen-bonding.