Isolation of the Metalated Ylides [Ph3P−C−CN]M (M=Li,Na, K): Influence of the Metal Ion on the Structure and Bonding Situation

The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph₃P−C−CN]M ( 1-M ; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium ( 1-Na ) and potassium ( 1-K ) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η²-coordination mode to the two central carbon atoms. The formation of the yldiide was accompanied by structural changes leading to shorter C−C and longer C−N bonds. This could be attributed to the delocalization of the free electron pairs at the carbon atom into the antibonding orbitals of the CN moiety, which was confirmed by IR spectroscopy and computational studies. Detailed density functional theory calculations show that the changes in the structure and the bonding situation were most pronounced in the lithium compounds due to the higher covalency.     

Synthesis,Isolation and Crystal Structures of the Metalated Ylides [Cy3P-C-SO2Tol]M (M = Li,Na, K)

The preparation and isolation of the metalated ylides [Cy₃PCSO₂Tol]M ( ^Cy1-M ) (with M = Li, Na, K) are reported. In contrast to its triphenylphosphonium analogue the synthesis of ^Cy1-M revealed to be less straight forward. Synthetic routes to the phosphonium salt precursor ^Cy1 - H₂ via different methods revealed to be unsuccessful or low-yielding. However, nucleophilic attack of the ylide Cy₃P = CH₂ at toluenesulfonyl fluoride under basic conditions proved to be a high-yielding method directly leading to the ylide ^Cy1-H . Metalation to the yldiides was finally achieved with strong bases such as nBuLi, NaNH₂, or BnK. In the solid state, the lithium compound forms a tetrameric structure consisting of a (C–S–O–Li)₄ macrocycle, which incorporates an additional molecule of lithium iodide. The potassium compound forms a C₄-symmetric structure with a (K₄O₄)₂ octahedral prism as central structural motif. Upon deprotonation the P–C–S linkage undergoes a remarkable contraction typical for metalated ylides.     

Recent development of aminophosphine chalcogenides and boranes as ligands in s-block metal chemistry

The coordination chemistry of the aminophosphine chalcogenide ligands [Ph₂P(O)NHR], [Ph₂P(S)NHR], and [Ph₂P(Se)NHR] (R = 2,6-Me₂C₆H₃,^tBu, CHPh₂, CPh₃) or corresponding borane derivative [Ph₂P(BH₃)NHR] toward group 1 and 2 metals is reviewed. The structural characterization of a huge number of mono- and bis-aminophosphine chalcogenide/borane complexes with group 1 and 2 metals—in most cases lithium, sodium, potassium, magnesium, calcium, strontium, and barium complexes—reveals a poly-metallacyclic motif in each case. The coordination takes place from adjacent chalcogen/borane and nitrogen as donor atom or group of the ligand confirming the direct bond between metal and chalcogen/borane to develop homoleptic and heteroleptic complexes. The heteroleptic group 2 metal complexes were used as pre-catalysts in hydrophosphination and hydroamination reactions. Similarly, aminophosphine chalcogenide alkaline earth metal complexes were used in the catalytic ring-opening polymerization (ROP) study of ?-caprolactone.     

Methyl-perthiooxalate und deren Reaktion mit Ph3P

Methyl-perthiooxalates and their Reaction with Ph₃ O-Methyl-1,1-dithiooxalate reacts with d⁸ transition metal ions with the spontaneous formation of mononuclear perthio/dithiooxalate complexes [(i-dtoMe)M(ptoMe)] (M = Ni, Pd, Pt). The mass spectrometric fragmentation of this complexes is discussed. The spontaneous sulfur insertion can be reversed by reaction with Ph₃P. Following up reactions with different Ph₃P equivalents are investigated for the Ni^II compound. Beside the synthesis of the square planar mixed ligand complex [(Ph₃P)Ni(i-dtoMe)₂] a Ni^I complex was detected by EPR spectroscopy.     

Bridging the Gap between Bisylides and Methandiides: Isolation,Reactivity, and Electronic Structure of an Yldiide

Bisylides and methandiides are two unique families of carbon bases that have found a variety of applications in recent years. Metalated ylides (yldiides) are the link between these types of compounds. Yet, only little is known about their properties, reactivities, and particularly their electronic structure. Here, we report the preparation of the metalated ylide [Ph₃P‐C‐SO₂Tol]^? ( 1 ) with different alkali metal counterions. The compounds have been studied by X‐ray diffraction analysis and NMR spectroscopy and the first structures of a sodium and potassium yldiide are presented. The electronic structure of 1 was explored by DFT calculations confirming its relation with other divalent carbon species. Reactivity studies demonstrate the strong nucleophilicity of the yldiide and its capability to act both as a σ‐ and π‐donor.     

Mechanism of oxidation of triphenylphosphine,triphenylarsine, and triphenylstibine by potassium peroxodisulfate

The kinetics of oxidation of triphenyl derivatives of group V elements Ph₃M (M = P, As, Sb) by potassium peroxodisulfate have been investigated spectrophotometrically in 60% acetonitrile–40% water (v/v) mixture. The reaction follows second-order kinetics, first order in each reactant. Changes in the [H⁺] and ionic strength have negligible effect on the reaction rate. Addition of acrylonitrile fails to inhibit the rate. The results indicate a rate-determining nucleophilic displacement of the Ph₃M molecule on the peroxide linkage. The relative rate order has been found to be Ph₃P > Ph₃Sb > Ph₃As. This can be attributed to two conflicting trends.     

The first synthesis, isolation and X-ray structure of a phosphonium phosphide, (Ph3PMe){[C6H2(CF3)3-2,4,6]2P}

The synthesis of a bulky secondary phosphine, Ar₂PH [Ar=C₆H₂(CF₃)₃-2,4,6], and its use in the first synthesis and isolation of a phosphonium phosphide, (Ph₃PMe)+(Ar₂P)⁻, via the deprotonation of Ar₂PH with a nonstabilised phosphorus ylide, Ph₃P=CH₂, are reported. An X-ray structure of this salt reveals that cations and anions are weakly associated in the solid state through C–HP interactions.     

Phosphine‐NHC Manganese Hydrogenation Catalyst Exhibiting a Non‐Classical Metal‐Ligand Cooperative H2 Activation Mode

Deprotonation of the Mn^I NHC‐phosphine complex fac‐[MnBr(CO)₃(κ²P,C‐Ph₂PCH₂NHC)] ( 2 ) under a H₂ atmosphere readily gives the hydride fac‐[MnH(CO)₃(κ²P,C‐Ph₂PCH₂NHC)] ( 3 ) via the intermediacy of the highly reactive 18‐e NHC‐phosphinomethanide complex fac‐[Mn(CO)₃(κ³P,C,C‐Ph₂PCHNHC)] ( 6 a ). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16‐e mangana‐substituted phosphonium ylide complex fac‐[Mn(CO)₃(κ²P,C‐Ph₂P=CHNHC)] ( 6 b ) as key intermediate able to activate H₂ via a non‐classical mode of metal‐ligand cooperation implying a formal λ⁵‐P–λ³‐P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre‐catalysts for ketone hydrogenation in the Mn^I series reported to date (TON up to 6200).     

Ylide-Functionalization via Metalated Ylides: Synthesis and Structural Properties

The α-metallated ylides [Ph₃P−C−Z]⁻M⁺ (with Z=SO₂Tol or CN and M=Na or K) were used as versatile nucleophiles for the facile access to ylide-substituted compounds. Halogenations, alkylations, carbonylations and functionalization reactions with main group element halides were easily accomplished by simple trapping reactions with the appropriate electrophiles. X-ray crystallographic studies of all compounds – including the first structures of α-fluorinated P-ylides – showed remarkable differences in the ylide backbone depending on the substituents. In the fluorinated compounds, a change from a fully planar to a pyramidalized ylidic carbon centre was observed despite the strongly anion-stabilizing ability of the yldiide substituent. π-Donation from the ylide substituent also resulted in geometric restrictions depending on the steric and electronic properties of the introduced substituents.     

Five-membered cyclopalladated complex containing bidentate phosphine ligands; Synthesis,characterization, and highly efficient Suzuki cross-coupling reactions

A nonsymmetric phosphorus ylide and its palladium(II) complex have been synthesized as potential catalytically active compounds. The reaction of 1 equiv nonsymmetric phosphorus ylide, Ph₂PCH₂PPh₂C(H)C(O)PhBr with [Pd(dppe)Cl₂], followed by treatment with 2 equiv AgOTf led to [(dppe)Pd(Ph₂PCH₂PPh₂C(H)C(O)PhBr)](OSO₂CF₃)₂, which contains a five-membered P,P chelate ring on one side and a five-membered P,C chelate ring on the other side. The palladium complex was synthesized and investigated by fourier transform infrared spectroscopy (FT-IR), UV–visible, multinuclear (¹H, ³¹P and ¹⁹F) nuclear magnetic resonance (NMR), and electrospray ionisation-mass spectroscopic techniques. FT-IR and ³¹P NMR studies revealed that the phosphorus ylide is coordinated to palladium via the terminal phosphorus (P_c) of the ylide and methene group (CH). Suzuki reactions for varying aryl halides using the cyclopalladated complex as an efficient catalyst were performed. Various aryl halides were coupled with arylboronic acids in DMF, under air, in the presence of 0.001?mol% of the homogeneous catalyst to afford the corresponding cross-coupled products in good to excellent yields.     

Extension de la reaction de wittig—II : Condensation “d'ylures enolates” sur les cetones aliphatiques α,β-insaturees

The enolate ylide Ph₃P⁺-C^?=C(Ph)O^?Li⁺, obtained by reaction of HMPT-Li with the benzoylmethylenetriphenylphosphorane Ph₃P=CH-CO-Ph, reacts with aliphatic α,β-unsaturated ketones. The betaïne obtained by Michael-type addition gives a substituted cyclohexenone by intramolecular ketolisation.     

Synthesis,characterization, and catalytic activity of a new series of Ni(II), Cu(II), and Zn(II) complexes of N,N-O,O mixed-bidentate ligands for C–C cross-coupling reactions

Abstract

A new series of air stable transition metal(II) complexes [M(II)(L)(Phen)], [M(II)(L)(Pip)] (M?=?Ni, Cu, and Zn) (H₂L = 2,2′-methylenebis(4-nitrophenol)) (Phen =1,10-phenanthroline) (Pip?=?Piperazine) has been synthesized by incorporating the metal ion with bisphenol and 1,10-phenanthroline/piperazine ligands. The prepared metal complexes were characterized by FT-IR, UV–vis, ¹H NMR, EPR, and mass spectrometry. The metal(II) complexes were potent catalysts for Suzuki–Miyaura and Kumada–Corriu coupling of various aryl halides under optimized conditions.     

{Ph2(Carb)P}MCl3 (M = Pd,Pt; Carb = 2,3-dihydro-1,3-diisopropyl-4,5dimethylimidazol-2-ylidene) – a Novel Cationic Phosphane Ligand [1]

The phosphane ligand [Ph₂(Carb)P]⁺ forms neutral complexes {Ph₂(Carb)P}MCl₃ (Carb = 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene; M = Pd, Pt) through the reaction of it's chloride salt with (PhCN)₂MCl₂; the triarylphosphane type properties of the ligand are revealed by n.m.r. and structural data.     

Tris(mercaptoimidazolyl)hydroborato complexes of cobalt and iron, [TmPh]2M (M=Fe,Co): structural comparisons with their tris(pyrazolyl)hydroborato counterparts

The tris(mercaptophenylimidazolyl)borate iron and cobalt complexes [Tm^Ph]₂M (M=Fe, Co) have been synthesized by reaction of [Tm^Ph]Tl with MI₂. Structural characterization by X-ray diffraction demonstrates that the potentially tridentate [Tm^Ph] ligand binds through only two sulfur donors in these ‘sandwich’ complexes and that the ‘tetrahedral’ metal centers supplement the bonding by interactions with the two B–H groups. Comparison of the structures of [Tm^Ph]₂M (M=Fe, Co) with the related tris(pyrazolyl)borate [Tp^Ph]₂M counterparts indicates that the tris(mercaptoimidazolyl) ligand favors lower primary coordination numbers in divalent metal complexes. The trivalent complexes, {[Tp^Ph]₂Fe}[ClO₄] and {[pzBm^Me]₂Co}I, however, exhibit octahedral coordination, with the ligands binding using their full complement of donor atoms.     

Binuclear and polymeric Hg(II) complexes of an ambidentate phosphorus ylide: Synthesis,crystal structure,antibacterial activity,and theoretical studies

The new α-keto-stabilized phosphorus ylide Ph₃PCHC(O)PhCN ( Y ) was synthesized by addition of triphenylphosphine to 2-bromo-4′-cyanoacetophenone, followed by treatment with NaOH 10%. Reaction of ligand ( Y ) with methanolic solution of mercury(II) halides under mild conditions yielded the binuclear complexes [Y·HgX₂]₂ [X=Cl ( 1 ), Br ( 2 ), I ( 3 )]. The new organic/inorganic composite polymer [Hg(NO₃)₂(Y)]_n ( 4 ) was synthesized by the reaction of mercury(II) nitrate with the phosphorus ylide Y . Compounds synthesized were characterized by Fourier-transform infrared, ¹H, ³¹P, and ¹³C nuclear magnetic resonance spectroscopic methods, which confirmed the coordination of ylide to the metal center through the ylidic carbon atom. Single-crystal X-ray structures of phosphorus ylide Y and polymeric complex 4 were also determined and the crystallographic data of complex 4 showed that the title complex has an infinite one-dimensional structure. Furthermore, the electronic and molecular structures of complexes 1 – 3 were investigated at the BP86/def2-SVP level of theory, indicating an increasing trend for C→M bond lengths: Hg₂I₂ > Hg₂Br₂ > Hg₂Cl₂ in [Y→HgX₂]₂ (X = Cl, Br, I) complexes. In addition, the antibacterial activity of ligand Y and all complexes using the agar disc diffusion method was examined against both selected gram-positive and gram-negative bacteria. Results indicated that the ligand Y and complexes 1 and 4 show good antibacterial effect against gram-positive bacteria tested; besides, the inhibition zones of complexes were significantly larger than those of chloramphenicol as standard.     

When Metathesis Reactions Go Wrong: Novel Structural Consequences

The complex [Yb(Ph₂pz)₃(LiOBu)]₂ ( 1 ) (Ph₂pz = 3,5‐diphenylpyrazolate), fortuitously obtained from reaction of Yb metal with a lithium containing sample of [SnMe₃(Ph₂pz)] at elevated temperatures forms a centrosymmetric butoxy‐ and pyrazolate‐bridged open box structure. Each ytterbium atom is eight coordinate with one chelating Ph₂pz ligand, one μ‐η²:η² bridging pyrazolate, one μ‐η²(Yb):η⁴(Li) Ph₂pz group and two bridging butoxide ligands. Each lithium atom is unsymmetrically chelated by an η²‐Ph₂pz group, η⁴(N,C(pz)C₂(Ph)) bonded by another pyazolate group, and bridged through a butoxide oxygen atom to two ytterbium atoms. The type of η⁴‐pyrazolate coordination is unprecedented and is the first observation of interactions to a metal by the Ph rings of the Ph₂pz ligand. The complex [Li(dme)₃][Eu(Ph₂pz)₃(dme)] ( 2 ) obtained from reaction of Eu metal with the same sample of [SnMe₃(Ph₂pz)] in dme at room temperature is a charged separated species with the first anionic pyrazolatolanthanoidate(II) complex in which europium is eight coordinate with three chelating Ph₂pz ligands and a chelating dme.     

Titanium and zirconium complexes with aminoiminophosphorane ligands

A series of titanium and zirconium complexes based on aminoiminophosphorane ligands [Ph₂P(Nt‐Bu)(NR)]₂MCl₂ ( 4 , M = Ti, R = Ph; 5 , M = Zr, R = Ph; 6 , M = Ti, R = SiMe₃; 7 , M = Zr, R = SiMe₃) have been synthesized by the reaction of the ligands with TiCl₄ and ZrCl₄. The structure of complex 4 has been determined by X‐ray crystallography. The observed very weak interaction between Ti and P suggests partial π‐electron delocalization through both Ti and P. The complexes 4–7 are inactive for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) or i‐Bu₃Al–Ph₃CB(C₆F₅)₄ under atmospheric pressure, and is probably the result of low monomer ethylene concentration and steric congestion around the central metal. Copyright © 2005 John Wiley & Sons, Ltd.     

Elucidating the Reactivity of Vicinal Dicarbenoids: From Lewis Adduct Formation to B−C Bond Activation

The reactivity of the diaminoacetylene Pip‐C≡C‐Pip (Pip=piperidyl=NC₅H₁₀) towards phenyldichloro‐ and triphenylborane is presented. In the case of the less Lewis acidic PhBCl₂, the first example of a double Lewis adduct of a vicinal dicarbenoid is reported. For the more Lewis acidic triphenylborane, coordination to the bifunctional carbene leads to a mild B?C bond activation, resulting in a syn‐1,2‐carboboration. Ensuing cis/trans isomerization yields a novel ethylene‐bridged frustrated Lewis pair (FLP). The compounds were characterized using multinuclear NMR spectroscopy, structural analysis, and mass spectrometry. Reactivity studies of both isomers with the N‐heterocyclic carbene 1,3‐dimethylimidazol‐2‐ylidene (IMe) aided in elucidating the proposed isomerization pathway. DFT calculations were carried out to elucidate the reaction mechanism. The rather low free energy of activation is consistent with the observation that the reaction proceeds smoothly at room temperature.     

[(Ph3PCH2)(Ph3P)PtCl][AlCl4], ein in CH2Cl2-lösung dreifach koordinierter kationischer platin(II)-komplex

The interaction of cis-[(Ph₃PCH₂)(Ph₃P)PtCl₂] with aluminium(III) chloride in CH₂Cl₂ affords the three coordinate cationic platinum(II) complex [(Ph₃PCH₂)(Ph₃P)PtCl][AlCl₄] which is a useful starting material for platinum complexes with four different ligands. With Ph₃As and Me₂S the cationic phosphorus ylide complexes [(Ph₃PCH₂)(Ph₃P)(Ph₃As)PtCl][AlCl₄] and [(Ph₃PCH₂)(Ph₃P)(Me₂S)PtCl][AlCl₄] are formed. 851 V 3     

Photochemical reactions of M(CO)6 (M = Cr,Mo, W) with Ph2P(S)P(S)Ph2

New complexes {M(CO)₄[Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo and W), (1a)–(3a), [(1a), M = Cr; (2a), M = Mo; (3a), M = W] and {M₂(CO)₁₀[-Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo, W), [(1b)–(3b) [(1b), M = Cr; (2b), M = Mo; (3b), M = W]] have been prepared by the photochemical reaction of M(CO)₆ with Ph₂P(S)P(S)Ph₂ and characterized by elemental analyses, f.t.-i.r. and ³¹P-(¹H)-n.m.r. spectroscopy and by FAB-mass spectrometry. The spectra suggest cis-chelate bidentate coordination of the ligand in {M(CO)₄[Ph₂P(S)P(S)Ph₂]} and cis-bridging bidentate coordination of the ligand between two metals in (M = Cr, Mo and W).