Theoretical studies on the pentacoordinate silylenoid PhCH<Subscript>2</Subscript>(NH<Subscript>2</Subscript>)CH<Subscript>3</Subscript>SiLiF

The structures of pentacoordinate silylenoid PhCH₂(NH₂)CH₃SiLiF were studied by density functional theory at the B3LYP/6-31G(d) level. Three equilibrium structures, the three-membered ring (1), the p-complex (2), and the σ-complex (3) structures, were located. Their energies are in the order of 2 > 1 > 3 both in vacuum and in THF. To exploit the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reactions of 1 and PhCH₂(NH₂)CH₃Si into C–F have been investigated, respectively. The results show that the insertion of PhCH₂(NH₂)CH₃Si is more favorable. To probe the influence of amine-coordination to the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reaction of PhCH₃CH₃SiLiF was also investigated. The calculations indicate that the insertion of PhCH₃CH₃SiLiF is more favorable than that of 1. So the N atom plays an important role on the stability of silylenoid PhCH₂(NH₂)CH₃SiLiF.     

Conformational analysis and stereochemical dependences of 31P–1H spin–spin coupling constants of bis(2‐phenethyl)vinylphosphine and related phosphine chalcogenides

Theoretical energy‐based conformational analysis of bis(2‐phenethyl)vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6‐311G** level to study stereochemical behavior of their ³¹P–¹H spin–spin coupling constants measured experimentally and calculated at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major planar s‐cis and minor orthogonal ones, while ³¹P–¹ H spin–spin coupling constants under study are found to demonstrate marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the vinyl group around the P(X)‐C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated phosphines and phosphine chalcogenides. Copyright © 2009 John Wiley & Sons, Ltd.     

The structures and stability of pentacoordinate germylenoid PhCH2(NH2)CH3GeLiF

The structures and stability of pentacoordinate germylenoid PhCH₂(NH₂)CH₃GeLiF were first theoretically studied by density functional theory. Two equilibrium structures, the three-membered ring and the p-complex structures, were located. The three-membered ring structure is more stable both in vacuum and in solvents (ether, THF, and acetone). The Ge–N coordination energies at the B3LYP/6-311+G(d,p) level are 35.8 and 7.9 kJ/mol in the three-membered ring and the p-complex structures, respectively. The insertion reactions with CH₃F indicate that germylenoid PhCH₂(NH₂)CH₃GeLiF is more stable than germylene PhCH₂(NH₂)CH₃Ge. The insertion barrier of PhCH₂(NH₂)CH₃GeLiF with CH₃F is higher than that of PhCH₃CH₃GeLiF, indicating that the amine coordination make PhCH₂(NH₂)CH₃GeLiF more stable.     

Reaction of secondary phosphine selenides with the system Se/MOH (M = Li, Na, K, Rb, Cs): A novel three-component synthesis of diorganodiselenophosphinates

Secondary phosphine selenides, R₂P(Se)H (R = PhCH₂CH₂, PhCH(Me)CH₂, 4-t-BuC₆H₄CH₂CH₂, NaphthylCH₂CH₂, Ph), react with the system Se/MOH (M = Li, Na, K, Rb, Cs) in the system THF/EtOH at ambient temperature unusually fast (20–30 s) to give cleanly and almost quantitatively (in 94–100% yield) earlier unknown diorganodiselenophosphinates of alkali metals.     

Synthesis of new secondary phosphine chalcogenides with bulky substituents from aryl(hetaryl)ethenes,red phosphorus,sulfur, and selenium

Phosphine generated along with hydrogen from red phosphorus and aqueous potassium hydroxide selectively reacts with aryl(hetaryl)ethenes (α-methylstyrene, 2-vinylnaphthalene and 5-vinyl-2-methylpyridine) in superbasic system KOH-DMSO(H₂O) to give secondary phosphines. The latter are practically quantitatively oxidized by elemental sulfur or selenium (20–25°C, toluene, 0.5 h), to afford the hitherto unknown secondary phosphine chalcogenides with bulky arylalkyl pyridine and naphthyl substituents.     

Synthesis of chalcophosphinic acid amides with pyridine rings*

Bis[2-(2-pyridyl)ethyl]phosphine chalcogenides react with secondary amines in the system Et3N–CCl4, forming previously unknown bis[2-(2-pyridyl)ethyl]chalcophosphinic acid amides.     

Side-chain oxidation of some phenyl-substituted alcohols in aqueous solution: Formation and fragmentation of radical-cations

The reactions of the hydroxyl radical (at low pH) and SO₄^−. have been employed to oxidize a number of phenyl-substituted alcohols in aqueous solution; ESR spectroscopy has been employed to study directly the radicals formed by fragmentation of first-formed radical-cations. Examples of deprotonation (to give benzyl radicals), C_α−C_β bond scission (e.g. PhCH₂CH₂OH to PhCH₂ ^.) and longer-range fragmentation (e.g. PhCH₂CH₂CMe₂OH to PhCH₂CH₂ ^.) are described and discussed: evidence is obtained for intramolecular nucleophilic attack as a route for overall electron-transfer from side-chain to aromatic ring. Solvation of the proton and of oxygen-conjugated carbonium ions is thought, at least in part, to account for differences between fragmentations induced in the gaseous and aqueous phases.     

Ligating properties oftert-phosphine/arsine sulphides or selenides,Part IX. Preparation and spectroscopic studies of copper(I)/copper(II) complexes with bis(—phosphine chalcogenides)

Summary The analytical, molar conductance and spectroscopic studies of new complexes of copper(I) and copper(II) with bis(—phosphine chalcogenides), Ph₂P(E)(CH₂)_n-P(E)Ph₂(L-L) are reported. The complexes are of the types: (a) [CuX(L-L)](X, n, E: Cl, 2–4, Br, 2, S; Cl, Br, 1, Se); (b) [Cu₂X₂(L-L)] (X, n, E: Cl, Br, 2, 3, Se) and (c) [CuCl₂(L-L)] (n, E: 2, 3, S). Possible structures have been derived.     

Bis(trimethylsilyl)-hypophosphit und Alkoxycarbonylphosphonigsäure-bis(trimethylsilyl)ester als Schlüsselsubstanzen für die Synthese von Organophosphorverbindungen

Bis(trimethylsilyl)hypophosphite und Alkoxycarbonylphosphonous Acid Bis(trimethylsilyl) esters as Building Blocks in Organophosphorus Chemistry The oxidation of pure bis(trimethylsilyl)hypophosphite ( BTH ) with chalcogenides forming (Me₃SiO)₂P(X)H (X = O, S, Se, Te) is described as well as its reactions with alkylhalides RX (X = Cl, Br, I) and Cl? C(O)OR (R = Me, Et, Bzl). By reaction with oxygen, sulfur, and selenium the alkoxycarbonylphosphonous acid bis(trimethylsilyl)esters form RO? C(O)? P(X)(OSiMe₃)₂ (X = O, S, Se) whereas with Cl? C(O)OR the bis(alkoxycarbonyl)-phosphinic acid trimethylsilylesters are obtained. After partial hydrolysis the resulting instable RO? C(O)? P(O)H(OSiMe₃) gives RO? C(O)? P(O)(OSiMe₃)? CH₂? NH? A? COOR′ (A = CH₂, CH₂CH₂, CHCH₃, CH₂CH₂SH, CHCH(CH₃)₂,…) when allowed to react with hexahydro-s-triazines of the aminoacid esters. Reactions of the alkoxycarbonyl-P-silylesters with NaOR or NaOH result in the corresponding mono-, di-, or trisodium salts. With mineral acids decarboxylation occurs, but H? P(O)(OH)? CH₂? NH? A? COOH can be obtained, too. The structure of the compounds described are discussed by their n.m.r. data.     

Extraction of f-elements from nitric acid solutions with phosphoryl ketones

The extraction ability and selectivity of a series of phosphoryl ketones Ph₂P(O)CH₂C(O)Me, and Ph₂P(O)CRR’CH₂C(O)Me (R = H, Me; R’ = H, Me, n-C₅H₁₁, Ph, 2-thienyl, 2-furyl) towards trivalent lanthanides (La^III, Nd^III, Ho^III, Yb^III) and actinides (U^VI, Th^IV) were studied. The efficiency and selectivity of the new ligands in the extraction of f-elements from nitric acid solutions into chloroform were compared to those of model phosphine oxide Ph₂P(O)Bu and known extractants: tributyl phosphate (BuO)₃P(O), trioctylphosphine oxide (C₈H₁₇)₃P(O), and carbamoylmethyl phosphine oxide Ph₂P(O)CH₂C(O)NBu₂.     

Synthesis and Characterization of New Silicon and Titanium Derivatives of Bis(anilino)phosphine Oxide

The reactions of bis(anilino)phosphine oxide (C ₆ H ₅ NH) ₂ P(O) H with (C ₅ H ₅ )₂TiCl₂ or Me₂SiCl₂ in a 1:1 molar ratio in THF results in the isolation of new phosph(V)azane complexes (C₅H₅)₂Ti[(N C₆H₅)₂P(O)H] (1) or Cl ₂ Si[(N C ₆ H ₅ )₂P(O)H] (2), respectively. In these reactions, HCl or CH₄ elimination occurs and N-Ti or N-Si bonds form directly between a bis(anilino)phosphine oxide ligand and organotitanium or organosilicon compounds. The products(1) and (2) have been fully characterized by elemental analysis as well as ¹ H, ³¹ P, ²⁹ Si NMR, and IR spectroscopy.     

Mechanism of the Nickel-Catalyzed Electrosynthesis of Ketones by Heterocoupling of Acyl and Benzyl Halides

Summary.  The mechanism of the nickel-catalyzed electrosynthesis of ketones by heterocoupling of phenacyl chloride and benzyl bromide has been investigated by fast scan rate cyclic voltammetry with [Ni(bpy)²⁺ ₃](BF₄ ⁻)₂ as the catalytic precursor (bpy = 2,2{−}{ bipyridine}). The key step is an oxidative addition of Ni⁰(bpy) (electrogenerated by reduction of the Ni(II) precursor) to PhCH₂Br whose rate constant is found to be 10 times higher than that of PhCH₂COCl. The complex PhCH₂Ni^IIBr(bpy) formed in the oxidative addition is reduced at the potential of the Ni^II/Ni⁰ reduction by a two-electron process which affords an anionic complex PhCH₂Ni⁰(bpy)⁻ able to react with PhCH₂COCl to generate eventually the homocoupling product PhCH₂COCH₂Ph. The formation of the homocoupling product PhCH₂COCOCH₂Ph is prevented because of the too slow oxidative addition of Ni⁰(bpy) to PhCH₂COCl compared to PhCH₂Br. The formation of the homocoupling product PhCH₂CH₂Ph is also prevented because PhCH₂Ni⁰(bpy)⁻ does not react with PhCH₂Br. This explains why the electrosynthesis of the ketone can be performed selectively in a one-pot procedure, starting from an equal mixture of PhCH₂COCl and PhCH₂Br and a nickel catalyst ligated by the bpy ligand. Received June 27, 2000. Accepted July 11, 2000     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

Syntheses,spectroscopic study and crystal structures of some new <Emphasis Type="Italic">N</Emphasis>-benzoylphosphoric triamides

The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C₆H₅C(O)NHP(O)(X)₂, X=NH–CH(CH₃)₂ (1), NH–CH₂–CH(CH₃)₂ (2), NH–CH₂–CH(OCH₃)₂ (3), N(CH₃)[CH₂CH(OCH₃)₂] (4) and N(CH₃)(C₆H₁₁) (5) that were characterized by ¹H,¹³C,³¹P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular –P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline lattice.     

Reduction of bis[(2-phosphinoethyl)tetramethyl-cyclopentadienyl]zirconium dichlorides: intramolecular C-H activation <Emphasis Type="Italic">vs.</Emphasis> stabilization of the low-valence metal center

Reduction of the R₂P-functionalized zirconocene dichlorides [C₅Me₄(CH₂)₂PR₂] (C₅Me₅)ZrCl₂ (R = Me (1) and Ph (2)) and [C₅Me₄(CH₂)₂PMe₂][C₅Me₄(CH₂)₂PR₂]ZrCl₂ (R = Me (3) and Ph (4)) with amalgamated magnesium was studied. In the reduction of compounds 1 and 2, intramolecular C-H activation highly selectively afforded the fulvene hydride complexes Zr(H)(η⁵−C₅Me₅)[η⁵:η²(C,P)−(CH₂)C₅Me₃CH₂CH₂PR₂] (R = Me (7), Ph (8)); in the case of compound 2, the aryl hydride Zr(H)(η₅:C₅Me₅)[η⁵:η¹(C)−C₅Me₄CH₂CH₂PPh(o−C₆H₄)] (9) was also formed. The reduction of complexes 3 and 4 gave the Zr^II derivatives Zr[η⁵:η¹(P)− C₅Me₄CH₂CH₂PMe₂]₂ (12) and Zr[η⁵:η₁(P)−C₅Me₄CH₂CH₂PMe₂][η⁵:η¹(P)−C₅Me₄CH₂ CH₂PPh₂] (14) stabilized by two phosphine groups. The second product in the reduction of compound 4 was the fulvene hydride complex Zr(H)(η⁵−C₅Me₄CH₂CH₂PPh₂)[η⁵:η²(C,P)−(CH₂)C₅Me₃CH₂CH₂PMe₂] (15). The reaction of compound 7 with an excess of MeI resulted selectively in replacement of the hydride ligand by iodide to give the complex ZrI(η⁵−C₅Me₅)[η⁵:η²(C,P)−(CH₂)C₅Me₃CH₂CH₂PMe₂] (10). In contrast, in the reaction of compound 7 with Me₂Si(H)Cl, the Zr-CH₂ bond underwent cleavage to give the chloride hydride complex Zr(H)Cl(η₅−C₅Me₅)[η⁵:η¹(P)−C₅Me₃(CH₂SiMe₂H)CH₂CH₂PMe₂] (11). In the reaction of complex 12 with CO, a phosphine group was replaced by CO to form the complex Zr(CO)(η5−C₅Me₄CH₂CH₂PMe₂)[η⁵:η¹(P)−C₅Me₄CH₂CH₂PMe₂] (13). The results obtained were compared with analogous reduction reactions of MeO-, MeS-, and Me₂N-functionalized zirconocene dichlorides. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 65–74, January, 2008.     

The Er and Yb Complexes with Silicon-Containing Phosphates and Fluorine-Containing Phosphine Oxide: Synthesis,Spectra, and Films

Three new silicon- and fluorine-containing ligands, namely bis(dimethylamido)(3-triethoxysilylpropylamido)phosphate O=P(NMe₂)₂NHCH₂CH₂CH₂Si(OEt)₃, diphenyl(3-triethoxysilylpropylamido)phosphate O=P(OPh)₂NHCH₂CH₂CH₂Si(OEt)₃, and tris(3,3,3-trifluoropropyl)phosphine oxide O=P(CH₂CH₂CF₃)₃ are synthesized. The erbium and ytterbium complexes with amine, phosphate, and phosphine oxide ligands Ln(NH₂R)₃Cl₃, Ln[O=P(NMe₂)₂NHR]₃Cl₃, Ln[O=P(OPh)₂NHR]₃Cl₃ (R=CH₂CH₂CH₂Si(OEt)₃), Ln[O=P(OPh)₃]₃Cl₃, Ln[O=P(CH₂CH₂CF₃)₃]₃Cl₃ are produced and their electronic absorption spectra and photoluminescence spectra are studied. The silicon-containing compounds form transparent thermostable films on silicate glass or quartz surface.     

A Novel Synthesis of AlCl[(NPh)2P(O)H] and SiCl2[(NPh)2P(O)H]: Two New Phosph(V)azane Derivatives

Reactions of phosph(V)azane derivatives of bis(anilino)phosphine oxide (PhNH)₂P(O)H (1) with AlCl₃ and SiCl₄ produce two new phosph(V)azane complexes, AlCl[(NPh)₂P(O)H] (2) and SiCl₂[(NPh)₂P(O)H] (3). In these reactions, an HCl elimination occurs and M─N bonds (M = Si, Al) form directly between a bis(anilino)phosphine oxide ligand with aluminum and silicon halides. The reactions do not require any base to deprotonate the phosphazane ligand. The final products have been fully characterized by means of elemental analysis and IR, MS, and multinuclear NMR (¹H, ¹³C, ³¹P, ²⁷Al, and ²⁹Si) spectroscopy.     

A novel series of nickel(II)-dppe-arylazoimidazole complexes. Synthesis and spectroscopic characterization

Reaction of [Ni(dppe)Cl₂/Br₂] with AgOTf in CH₂Cl₂ medium following ligand addition leads to [Ni(dppe)(OSO₂CF₃)₂] and then [Ni(dppe)(RaaiR)](OSO₂CF₃)₂ [RaaiR′ = p–R–C₆H₄–N=N–C₃H₂–NN-1–R′,(1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion]. ³¹P{¹H}-NMR confirm that stable bis-chelated square planar Ni(II) azoimine–dppe complex formation with one sharp peaks. The ¹H NMR spectral measurements suggest azoimine link is present with lot of phenyl protons in the aromatic region. Considering all the moities there are a lot of different carbon atoms in the molecule which gives many different peaks in the ¹³C(¹H)-NMR spectrum. In the ¹H-¹H COSY spectrum in the present complexes and contour peaks in the ¹H-¹³C-HMQC spectrum in the present complexes, assign the solution structure and stereoretentive conformation in each complexes.     

Synthesis and characterization of trichlorogermyl dioic acids: crystal structures and complementary hydrogen bonding motifs in 3-(trichlorogermyl) pentanedioic acid and 2-[(trichlorogermyl)methyl]butanedioic acid

A series of trichlorogermyl-substituted dicarboxylic acids of general formula HOOC–R′–COOH where R′=–CH₂CH(GeCl₃)CH₂– 1, –CH(CH₂GeCl₃)CH₂– 2, –CH(GeCl₃)CH₂– 3 and –CH(CH₃)CH(GeCl₃)– 4 were synthesized by the hydrogermylation reaction of unsaturated acids, such as trans-glutaconic (2-pentenedioic acid), itaconic (methylenebutanedioic acid), fumaric (2-butenedioic acid), and citraconic (2-methyl-2-butenedioic acid) acids with HGeCl₃, which was produced in situ by the reaction of GeO₂ with 37% HCl in presence of NaH₂PO₂ · H₂O. All these compounds were characterized by melting point, CHN analysis, FTIR, and multinuclear NMR (¹H; ¹³C; H,H-COSY). X-Ray crystal structures of 1 and 2 were analyzed to show supramolecular structures in which central Ge atom in each of these structures is four-coordinated with a slightly distorted tetrahedral geometry. Structurally, both compounds adopt supramolecular forms via strong intermolecular O–H–O interactions through 8-membered and 22-membered hydrogen bonded rings. Supplementary material to this paper is available in electronic form at Correspondence: Muhammad Mazhar, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan.     

Preparation,characterization and catalytic oxidation properties of bis‐quaternary ammonium peroxotungstates and peroxomolybdates complexes

Several novel kinds of bis‐quaternary ammonium peroxotungstates and peroxomolybdates, such as PhCH₂N(CH₂CH₂)₃NCH₂Ph[W₂O₃(O₂)₄], PhCH₂N(CH₂CH₂)₃NCH₂Ph [Mo₂O₃(O₂)₄], [PhCH₂(CH₃)₂NCH₂]₂[W₂O₃(O₂)₄] and [PhCH₂(CH₃)₂NCH₂]₂[Mo₂O₃(O₂)₄], have been synthesized and characterized by elemental analysis, IR and Raman spectroscopy. Their catalytic properties in mild oxidation of benzyl alcohol and ring‐substituted benzyl alcohols were investigated with aqueous 30% H₂O₂ under halide‐ and organic solvent‐free conditions. Copyright © 2007 John Wiley & Sons, Ltd.