The synthesis of some bidentate bismuth-containing ligands

The synthesis and properties including mass spectra of (o-diphenylphosphinophenyl)diphenylbismuthine, o-C₆H₄(PPh₂)(BiPh₂) and (o-diphenylarsinophenyl)-diphenylbismuthine, o-C₆H₄(AsPh₂)(BiPh₂) are described. The failure of attempts to prepare α, ω-bis(disphenylbismuthino)alkanes is discussed.     

Facile and new convenient route for synthesis of some C2-symmetric bidentate phosphine ligands derived from d-mannitol

The preparation of two novel C₂ symmetric bidentate phosphine ligands derived from cheap and available D-mannitol has been reported. These new ligands accompanied by unprecedented one-pot reaction for the regioselective reductive opening of 1,3:4,6-di-O-benzylidene-D-mannitol have been achieved. All reported compounds are fully characterized by standard analytical methods including the measurement of optical activities.     

Aluminum complexes incorporating bidentate amido phosphine ligands

A series of aluminum complexes supported by o-phenylene-derived amido phosphine ligands, N-(2-diphenylphosphinophenyl)-2,6-dimethylanilide ([Me-NP]-) and N-(2-diphenylphosphinophenyl)-2,6-diisopropylanilide ([iPr-NP]-), have been prepared. The reactions of trialkylaluminum with H[Me-NP] and H[iPr-NP], respectively, in refluxing toluene produced the corresponding dialkyl complexes [Me-NP]AlR(2) and [iPr-NP]AlR(2) (R = Me, Et). Deprotonation of H[Me-NP] with n-BuLi in THF at -35 degrees C followed by addition of AlCl(3) in toluene at -35 degrees C afforded [Me-NP]AlCl(2), which was subsequently reacted with 2 equiv of trimethylsilylmethyllithium in toluene to give [Me-NP]Al(CH(2)SiMe(3))(2). The aluminum complexes were all characterized by (1)H, (13)C, (31)P, and (27)Al NMR spectroscopy. The solid-state structures of monomeric, four-coordinate [Me-NP]AlEt(2) and [iPr-NP]AlMe(2) and five-coordinate [Me-NP]AlCl(2)(THF) were determined by X-ray crystallography. The (1)H NMR studies of [Me-NP]AlEt(2), [Me-NP]Al(CH(2)SiMe(3))(2), and [iPr-NP]AlEt(2) indicate diastereotopic alpha-hydrogen atoms in these molecules. Heteronuclear COSY and NOE experiments suggest that the phosphorus donor in [Me-NP]Al(CH(2)SiMe(3))(2) and [iPr-NP]AlEt(2) is coupled to only one of the diastereotopic alpha-hydrogen atoms that is virtually antiperiplanar with respect to the phosphorus atom.     

Nickel(II) complexes containing bidentate amido phosphine ligands derived from alpha-iminophosphorus ylides: synthesis and structural characterization

The reactions of prop-2-ynyltriphenylphosphonium bromide with a series of primary aromatic or aliphatic amines in refluxing acetonitrile generated the corresponding 2-hydrocarbylaminoprop-1-enyltriphenylphosphonium bromide [RNHC(Me)=CHPPh(3)]+Br- (R = 2,6-C(6)H(3)iPr(2) (1a), 2,6-C(6)H(3)Me(2) (1b), Ph (1c), t-Bu (1d)) as crystalline solids. Deprotonation of 1a-d with NaH in THF at -35 degrees C afforded the alpha-iminophosphorus ylides RN=C(Me)CH=PPh(3) (2a-d) in high yield. Spectroscopic and crystallographic data of 2 suggest a strong intramolecular interaction between the imino nitrogen and the phosphorus atom. In contrast to N-arylated 2a-c, the N-tert-butyl-derived 2d is extremely moisture-sensitive. Hydrolysis of 2d led to elimination of benzene and generated concomitantly the phosphine oxide 3d that contains an ene-amine functionality. The reactions of 2a-c with Ni(COD)(2) in the presence of an excess amount of pyridine in toluene produced the divalent nickel complexes of the type [kappa(2)-RNC(Me)=CHPPh(2)]Ni(Ph)(Py) (4a-c). The solution and solid-state structures of these new compounds are presented.     

Synthesis and characterisation of nonclassical ruthenium hydride complexes containing chelating bidentate and tridentate phosphine ligands

The synthesis and characterisation of nonclassical ruthenium hydride complexes containing bidentate PP and tridentate PCP and PNP pincer-type ligands are described. The mononuclear and dinuclear ruthenium complexes presented have been synthesised in moderate to high yields by the direct hydrogenation route (one-pot synthesis) or in a two-step procedure. In both cases [Ru(cod)(metallyl)(2)] served as a readily available precursor. The influences of the coordination geometry and the ligand framework on the structure, binding, and chemical properties of the M--H(2) fragments were studied by X-ray crystal structure analysis, spectroscopic methods, and reactivity towards N(2), D(2), and deuterated solvents.     

Reduction of the pertechnetate anion with bidentate phosphine ligands

The reduction of ammonium pertechnetate with bis(diphenylphosphino)methane (dppm), and with diphenyl-2-pyridyl phosphine (Ph(2)Ppy), has been investigated. The neutral Tc(II) complex, trans-TcCl(2)(dppm)(2) (1), has been isolated from the reaction of (NH(4))[TcO(4)] with excess dppm in refluxing EtOH/HCl. Chemical oxidation with ferricinium hexafluorophosphate results in formation of the cationic Tc(III) analogue, trans-[TcCl(2)(dppm)(2)](PF(6)) (2). The dppm ligands adopt the chelating bonding mode in both complexes, resulting in strained four member metallocycles. With excess PhPpy, the reduction of (NH(4))[TcO(4)] in refluxing EtOH/HCl yields a complex with one chelating Ph(2)Ppy ligand and one unidentate Ph(2)Ppy ligand, mer-TcCl(3)(Ph(2)Ppy-P,N)(Ph(2)Ppy-P) (3). The cationic Tc(III) complexes, trans-[TcCl(2)(Ph(2)P(O)py-N,O)(2)](PF(6)) (4) and trans-[TcCl(2)(dppmO-P,O)(2)](PF(6)) (5) (Ph(2)P(O)py = diphenyl-2-pyridyl phosphine monoxide and dppmO = bis(diphenylphosphino)methane monoxide), have been isolated as byproducts from the reactions of (NH(4))[TcO(4)] with the corresponding phosphine. The products have been characterized in the solid state and in solution via a combination of single-crystal X-ray crystallography and spectroscopic techniques. The solution state spectroscopic results are consistent with the retention of the bonding modes revealed in the crystal structures.     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: I. Synthesis and characterisation

The rhodium(I) complexes (Ph₃P)₂Rh(LL′), in which LL′ is an unsaturated chelate coordinating via L = S and L′ = N, O, P or S, have been prepared from RhCl(PPh₃)₃ by two routes.Direct substitution of one Ph₃P and Cl^? by the chelate anion gives (Ph₃P)₂Rh[Ph₂PC(S)S] (L = S, L′ = P). Oxidative addition of an NH bond followed by reductive elimination of HCl results in (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S), (Ph₃P)₂Rh[PhNC(S)NMe₂] (L = S, L′ = N), (Ph₃P)₂Rh[Ph₂PC(S)NPh) (L = S, L′ = P) and (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] (L = S, L′ = O).Reaction of the complexes (Ph₃P)₂Rh(LL′) with CO gives (CO)(Ph₃P)Rh(LL′) with CO trans to the chelate donor atom with the lowest trans-influence. Pt(PPh₃)₄ reacts with Me₂NC(S)N(H)C(S)NMe₂ and HN(Ph)C(S)PPh₂, respectively, to give H(Ph₃P)Pt[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S) and H(Ph₃P)Pt[Ph₂PC(S)NPh] (L = S, L′ = P).The coordinating atoms and their configurations have been assigned by IR ³¹P NMR and ¹H NMR. Some trend in IR and ³¹P NMR paramaters are discussed.     

Polyimide-polydimethylsiloxane copolymers containing nitrile groups

A novel series of nitrile-containing polyimide-polydimethylsiloxane copolymers was prepared by polycondensation reaction of 4,4′-oxydiphthalic anhydride with a mixture of an aromatic diamine, namely 2,6-bis(3-aminophenoxy)benzonitrile, and bis(aminopropyl)oligodimethylsiloxane of controlled molecular weight, in different ratios. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidone, N,N-dimethylformamide as well as in less polar solvents such as chloroform, and can be cast from solution into thin flexible films. The inherent viscosity was in the range of 0.43-0.55 dL/g. The polymers showed good thermal stability, the decomposition temperature being above 430 °C. They exhibited a glass transition temperature in the range of 149-219 °C, with reasonable interval between glass transition temperature and decomposition temperature. The surface morphology was investigated by scanning electron microscopy. The water dynamic contact angles were measured by tensiometric method. The free surface energy was evaluated based on Owens and Wendt equation. A composite film based on a polyimide-polydimethylsiloxane copolymer and pyrite ash powder has been prepared and its nanoactuation has been investigated.     

Synthesis and electrochemistry of phenyl-functionalized diiron propanedithiolate complexes with bidentate phosphine ligands

Carbonyl substitution reactions of [μ-(SCH₂)₂CHC₆H₅]Fe₂(CO)₆ with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph₂P)₂N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) and a symmetrically substituted bridging complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄[μ-(PPh₂)₂N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) was investigated.     

Zirconium and hafnium complexes containing bidentate diarylamido-phosphine ligands

The first examples of mononuclear, structurally characterized triarylphosphine complexes of zirconium and hafnium are reported. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPrNP]Li(THF)2 ([iPrNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-diisopropylanilide) or [MeNP]Li(THF)2 ([MeNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-dimethylanilide) in toluene at -35 degrees C produced the corresponding [iPrNP]MCl3(THF) and [MeNP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [MeNP]MCl3(THF) and [iPrNP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPrNP]MCl3(THF) and [MeNP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. The geometry of these six-coordinate complexes is best described as a distorted octahedron in which the chloride ligands in [iPrNP]MCl3(THF) adopt a virtually meridional coordination mode whereas those in [MeNP]2MCl2 are trans to each other.     

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.     

Ruthenium carbene complexes containing bidentate and tridentate PO ligands

Treatment of [Ru(CHR)Cl₂(PCy₃)₂] (Cy = cyclohexyl) with Tl[N(Pr₂ⁱPO)₂] and AgL_OEt (L_OEt⁻ = [CpCo{P(O)(OEt)₂}₃]⁻) afforded the Ru carbene complexes [Ru(CHPh)(PCy₃)Cl{N(Pr₂ⁱPO)₂}] (1) and [L_OEtRu(CHR)(PCy₃)Cl] (2), respectively. Chloride abstraction of complex 2 with TlPF₆ in MeCN afforded [L_OEtRu(CHPh)(PCy₃)(MeCN)][PF₆] (3). Complexes 1 and 2 are capable of catalyzing ring-closing metathesis of diethyl 1,2-diallylmalonate. The crystal structure of complex 2 has been determined.     

Preparation and properties of palladium(II) and rhodium(I) complexes containing bidentate phosphine sulphide and selenide ligands

Summary The synthesis and properties of cationic complexes of general formula [ML₂{CH₂(Ph₂PE)₂}]BF₄, where M = Pd^II and Rh^II, L₂ = ³-MeC₃H₄, {P(O)(OR)₂}₂H (R = Me, Et), COD, (CO)₂, (CO)PPh₃ and E = S, Se are described. The methylene proton of the coordinated phosphine sulphide or selenide ligands react with strong bases as BuLi in n-hexane or NaH in THF, to give neutral complexes of the type [ML₂{CH(Ph₂PE)₂}], where M = Pd^II, Rh^I; L₂ = ³-MeC₃H₄, COD and E = S, Se. The complexes have been characterized by elemental analyses, molar conductivities, i.r., ¹H n.m.r. and ³¹P{¹H} n.m.r. spectroscopy.     

Modification of epoxy-novolac resins with polysiloxane containing nitrile functional groups: synthesis and characterization

Synthesis of the statistical epoxidized polycyanopropylmethylsiloxane-co-polydimethylsiloxanes (PCPMS-co-PDMS) has been demonstrated. The modified polysiloxanes were prepared via a two-step method; (1) the ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) and tetramethylcyclotetrasiloxane (D₄H), (2) hydrosilylation reaction of the polysiloxane prepolymers with allyl cyanide and allyl glycidyl ether. Molar ratios of D₄H and D₄ were varied to produce the modified polysiloxanes with differences in polarity. ¹H-NMR, ²⁹Si-NMR, ¹³C-NMR and FTIR were used to monitor the formation of the modified polysiloxanes and DSC was used to study their thermal behaviors (T_g, −118 to −68 °C). The use of the modified polysiloxanes as an elastomeric component in epoxy-novolac networks was also investigated. TEM and their transition temperatures suggested that the epoxy-novolac networks with high content of PDMS modifiers exhibited microphase separation. The fracture toughness properties of the networks with the polysiloxane modifiers were improved over the controls without polysiloxanes.     

The intriguing substitution behavior of CO with bidentate phosphine ligands induced by a gem-dialkyl effect

The reaction of the complexes [FeCpX(CO)₂] (X = Cl, Br, I) into either [FeCp(CO)(PP)]X or [FeCpX(PP)] (PP = a bidentate diphosphine ligand) is shown to be highly dependent of the phosphine ligand used. Diphosphine ligands that form stable chelates favor formation of the neutral complex, whereas diphosphine ligands that form less stable chelates favor formation of the cationic complex. Thus, with the use of dppdmp (= 1,3-bis(diphenylphosphino)-2,2-dimethylpropane) the [FeCpX(PP)] complexes (X = Cl, Br, I) are selectively formed, induced by a gem-dialkyl effect. Apart from the bidentate phosphine ligand, the halide ion present in the iron complex has a significant influence on the course of the substitution reaction.     

Rhodium(I) complexes bound to silica via bidentate phosphine ligands

Triethoxysilyl substituted diphosphines of the novel type (EtO)₃Si(CH₂)_nP(Ph)CH₂CH₂PPh₂ (n=1, 3) have been prepared and used to immobilize rhodium(I) complexes to silica. The complexes were found to be effective catalysts for hydrogenation of 1,3-cyclooctadiene under mild conditions.

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- (EtO)₃Si(CH₂)_nP(Ph)CH₂CH₂PPh₂ (n=1,3) SiO₂. 1,3- .

     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: II. Reactions with O2 and H2

The rhodium(I) complexes (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂], (Ph₃P)₂Rh[SC(S)NMe₂] and (Ph₃P)₂Rh[PhNC(S)NMe₂] react with O₂ to give 1/1 dioxygen adducts. In solution, trans-(Ph₃P)₂Rh(O₂)[Me₂NC(S)NC(S)NMe₂], cis- and trans-(Ph₃P)₂Rh(O₂)[SC(S)NMe₂] and cis- and trans-(Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂] are observed. For (Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂], there is a solvent effect on the initial cis—trans ratio and the rate of O=PPh₃ formation. In C₆H₆, O=PPh₃ formation from (Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂] is inhibited by additional PPh₃.The reaction of (Ph₃P)₂Rh[Ph₂PC(S)NPh] with O₂ in the presence of additional PPh₃ gives O=PPh₃ and cis-(Ph₃P)₂Rh(O₂)[Ph₂P(O)C(S)NPh] as the only products. The same complex also can be prepared from (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] and O₂.Only (Ph₃P)₂Rh[PhNC(S)NMe₂] reacts with H₂ at room temperature to give (Ph₃P)₂RhH₂[PhNC(S)NMe₂], which is a catalyst for cyclohexene hydrogenation.