Triphenylphosphine Adduct Research Articles

New Phosphonite Ligands with High Steric Demand and Low Basicity: Synthesis, Structural Properties and Cyclometalated Complexes of Pt(II)

Two phosphonite ligands bearing the highly sterically demanding 2,6-bis (2,6-dimethylphenyl)phenyl group (ArXyl2), PArXyl2(OPhNO2)2 and PArXyl2(OPhNO2,Me)2, were prepared from the parent dihalophosphines PArXyl2X2 (X = Cl, Br) and the corresponding phenols, 4-nitrophenol and 4-nitro-2,6-dimethylphenol, respectively. DFT methods were used to examine their structural features and to determine three steric descriptors, namely the Tolman cone angle, the percentage of buried volume, and the percentage of the coordination sphere protected by the ligand. A comparison with the related terphenyl phosphines is also provided. Reactions of PArXyl2(OPhNO2)2 and PArXyl2(OPhNO2,Me)2 with several Pt(II) precursors were investigated, revealing a high tendency of both phosphonites to undergo C-H activation processes and generate five- or six-membered cyclometalated structures. The coordination chemistry of the new ligands was explored with isolation, among others, of three carbonyl complexes, 1-3∙CO, and the triphenylphosphine adduct 3∙PPh3. X-ray diffraction methods permitted the determination of the solid-state structures of the mononuclear methyl carbonyl complex 1∙CO, the dinuclear chloride-bridged complex 2 and the doubly cyclometalated complex 3∙SMe2, including the conformations adopted by the ligands upon coordination. All of the new compounds were characterized by multinuclear NMR spectroscopy in solution.

Reactions of Cyclic Osmacarbyne with Coinage Metal Complexes

The reactions of the five-membered cyclic osmacarbyne complex, i.e., osmapentalyne, with a complete set of coinage metal (Cu, Ag, and Au) complexes have been investigated. Osmapentalyne 1 reacts with CuCl or AuCl(PPh3) via its metal–carbon triple bond, leading to the formation of osmapentalyne-copper(I) chloride adduct 2 or osmapentalyne-gold(I)-triphenylphosphine adduct 3, respectively. Moreover, it can react with AgOTf in the presence of 1,10-phenanthroline to give osmapentalyne-silver(I)-phenanthroline adduct 4. All the compounds have been characterized by X-ray diffraction analysis. The formation of these bimetallic adducts can be regarded as the “alkyne-like” interaction of an osmium–carbon triple bond with the coinage metal center. The interaction is weak and these adducts can readily dissociate to regenerate precursor osmapentalyne 1 in essentially quantitative yield with the assistance of PPh3 or chloride ligands.

A bis-Au(III) [28]hexaphyrin triphenylphosphine adduct

Triphenylphosphine was added regioselectively at the C(3) position of bis-Au(III) complex of [26]hexaphyrin 5 in the presence of trifluoroacetic acid to produce [28]hexaphyrin triphenylphosphine adduct 6 in 62% yield, which has been fully characterized by NMR, UV-vis/NIR absorption, and MS spectroscopies, and X-ray diffraction analysis. The rigid planar structure forces 6 to take Hückel antiaromaticity, which has been supported by its 1H NMR spectrum. Curiously, the detailed structural analysis elucidated that the triphenylphosphine moiety exists as a phosphorane form in the solid state. A plausible mechanism via a double protonated 5 is proposed, which can explain the observed regioselectivity.

Isomorphism in the structural chemistry of two-coordinate adducts of diphenyl(2-formylphenyl)phosphine and triphenylphosphine with gold(I) halides

Single crystal X-ray structure determinations are recorded for diphenyl(2-formylphenyl)phosphine gold(I) halides [Ph2(Ph-CHO)PAuX], X=Cl, Br and I, and for redeterminations of enhanced precision for triphenylphosphine gold(I) halides [Ph3PAuX], X=Cl, Br, I, and SCN0.91Br0.09. These complexes, other than [Ph2(Ph-CHO)PAuCl], together with a diverse array of other structures, crystallize as an isomorphous series in the orthorhombic space group P212121a=9.804(1)–11.906(3), b=11.771(2)–12.996(3) and c=12.871(1)–14.169(3)Å. In these complexes, introduction of the formyl group results in only minor differences between the conformations of the two phosphine ligands and the corresponding Au–P, Au–X, and Au–P–X bond lengths and angles. The crystal packings of [Ph3PAuX] for X=Cl, Br, I and of [Ph2(Ph-CHO)PAuX] for X=Br and I show that, while these structures are isomorphous, different supramolecular synthons may be present, suggesting global packing considerations are all-important rather than specific supramolecular interactions. This is borne out by the different packing found for the centrosymmetric [Ph2(Ph-CHO)PAuCl] structure. Crystallization of the mixed anion structure [Ph3PAuSCN0.91Br0.09] in the above P212121 lattice rather than the P21/c lattice reported for pure [Ph3PAuSCN] suggests that co-crystallization with bromide may impose constraints on packing considerations which favor crystallization in the P212121 lattice.

Synthesis and Characterization of Triphenylphosphine Adducts of Ferrocene-Based Palladacycles and Their Performance in the Suzuki and Sonogashira Reactions with Bromo- and Chloroarenes

A new triphenylphosphine adduct of cyclopalladated ferrocenylpyridazine containing a chloride anion, 2a, has been synthesized from the reaction of the chloride-bridged palladacyclic dimer 1a with triphenylphosphine. The corresponding adducts 3a,b containing iodide anion have been readily prepared through anion exchange reactions of 2a,b with NaI in acetone. These complexes were characterized by elemental analysis, IR and 1H-NMR. Additionally, their crystal structures have been determined by X-ray diffraction and intermolecular C–H···X (Cl, Br, I) bonds were found in the crystals. The use of these palladacycles as catalysts for the Suzuki and Sonogashira reactions was examined. The complexes 2a,b exhibited higher catalytic activity than the corresponding 3a,b in the Suzuki reaction. However, the order of activity of adducts with varying halogen anions is 3a~3b > 2a~2b in the Sonogashira reaction.

Catalysis of the Suzuki–Miyaura coupling reaction in water by heteroannular cyclopalladated ferrocenylimine complexes

Catalytic studies on the air- and moisture-stable triphenylphosphine (PPh3) adducts of heteroannular cyclopalladated ferrocenylimines [PdCl{C5H4FeC5H4CHRN=CHC4H3X}(Ph3P)] (R = H, CH3; X = S, O) indicate that they are all effective catalysts for the Suzuki–Miyaura coupling reaction of activated aryl bromides with phenylboronic acid in water under air atmosphere. Typically, using 1 mol‰ of catalyst in the presence of 1.2 equivalents of K3PO4 as base in water at 100 °C provided the corresponding biaryls in good to excellent yields. Meanwhile, the structure of [PdCl{C5H4FeC5H4CH(CH3)N=CHC4H3S}(PPh3)] has been established by the single-crystal X-ray diffraction technique. According to the crystal structure, the palladium atom is bound to the unsubstituted Cp ring, showing the four-coordinate structure typical of palladium complexes.

Synthesis and characterization of some metal(II) complexes of isomeric unsymmetrical Schiff bases and their adducts with triphenylphosphine

We report the isolation of two unsymmetrical isomeric Schiff bases obtained from condensation of 2,4-pentanedione/1-phenyl-1,3-butanedione and 2-hydroxy-4-methoxyacetophenone/2-hydroxy-4-methoxybenzophenone with ethylenediamine and their VO(IV), Co(II), Ni(II), and Cu(II) complexes. Further reaction of each complex with triphenylphosphine resulted in formation of 1 : 1 adducts, with water occupying the sixth position in some, except copper and cobalt formed 1 : 2 adducts with [ML1]. The purities of the ligands and complexes were established by microanalyses and the complexes were characterized by magnetic susceptibility, conductance, infrared and electronic spectral measurements. The involvement of the azomethine N and phenolic O in bonding resulted in an N2O2 chromophore around the central metal atom. Infrared and electronic spectral data are consistent with square-planar/tetrahedral geometry for Ni(II), Co(II), and Cu(II) complexes and a five-coordinate, square-pyramidal geometry for the VO(IV) complexes. Evidence for triphenylphosphine adducts is adduced from microanalyses, spectral changes, and magnetic susceptibility measurements.

Ferrocenylimidazoline Palladacycles: Efficient Phosphine‐Free Catalysts for Suzuki—Miyaura Cross‐Coupling Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An Efficient Catalyst for the Synthesis of ortho‐Substituted Biaryls by the Suzuki Cross‐Coupling: Triphenylphosphine Adduct of Cyclopalladated Ferrocenylimine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Ferrocenylimidazoline palladacycles: efficient phosphine-free catalysts for Suzuki–Miyaura cross-coupling reaction

A series of new ferrocenylimidazoline ligands 5 with different substituents in the imidazoline ring and their corresponding cyclopalladated complexes 6 were synthesized. Chloride-bridged palladacycle dimers 6, which are thermally stable and insensitive to air and moisture, have been evaluated as effective phosphine-free catalysts for the Suzuki reaction of aryl bromides with arylboronic acid. The catalyst 6b presents the highest efficiency in the coupling processes for less reactive 2-bromothiophene. Moreover, the reactions can be carried out at room temperature under aerobic conditions to give the corresponding biaryls in high yields. Additionally, the triphenylphosphine adduct of cyclopalladated ferrocenylimidazoline 7a was structurally characterized by single-crystal X-ray diffraction.

Ferrocenylimidazoline palladacycles: Syntheses, crystal structures and applications as catalysts for Suzuki cross coupling reaction in water

The air and moisture stable triphenylphosphine (PPh 3) adducts of cyclopalladated ferrocenylimidazoline complexes 2a and 2b have been synthesized and structurally characterized by single crystal X-ray diffraction. The catalytic studies on 2a and 2b indicate that they are effective catalysts for the Suzuki reaction of activated aryl chlorides with phenylboronic acid in neat water under air atmosphere.

An efficient catalyst for the synthesis of ortho-substituted biaryls by the Suzuki cross-coupling: Triphenylphosphine adduct of cyclopalladated ferrocenylimine

The air and moisture stable triphenylphosphine adduct of cyclopalladated ferrocenylimine 2 has been successfully used in palladium-catalyzed Suzuki cross-coupling for the synthesis of ortho-substituted biaryls in air. In the presence of 0.05 mol% of 2 as catalyst and 3 equivalent of CsF as base in dioxane at 100 °C, ortho-substituted biaryls were synthesized with moderate to high yields in the reactions of 2-methoxy-1-naphthylboronic acid with aryl halides, and 14 new ortho-substituted biaryls were obtained and characterized.

A multinuclear solid-state magnetic resonance study of silver nitrate triphenylphosphine

Variable-temperature solid-state31P,15N, and2H NMR spectroscopy, X-ray diffraction, and differential scanning calorimetry studies of the 1:1 adduct of silver nitrate and triphenylphosphine (AgNO3·PPh3) reveal a solid–solid phase transition at 300 K. The principal components of the phosphorus and nitrogen chemical shift tensors for both phases are determined from NMR spectra of MAS and stationary samples. In addition, the indirect spin-spin coupling between phosphorus and the naturally occurring isotopes of silver (107Ag and109Ag) are resolved. Experimental2H NMR line shapes for silver nitrate perdeuterated triphenylphosphine are those characteristic of rigid phenyl groups at temperatures above and below the phase-transition temperature. Powder and single-crystal X-ray diffraction data for AgNO3·PPh3obtained at 193, 295, and 313 K are reported; data obtained at 193 and 295 K are almost identical, but are significantly different from those obtained at 313 K and from an earlier single-crystal X-ray diffraction investigation performed at 298 K. All X-ray studies found that AgNO3·PPh3crystallizes in the monoclinic form, space group P21/c.Key words: 1:1 silver nitrate triphenylphosphine adduct, solid-state NMR, X-ray diffraction, phase transition.

Synthesis and structural characterisation of linear Au(I) N-heterocyclic carbene complexes: New analogues of the Au(I) phosphine drug Auranofin

The synthesis and characterisation of a series of neutral Au(I) N-heterocyclic carbene complexes [(NHC)AuX] (X = Cl and 2′,3′,4′,6′-tetra- O-acetyl-β- d-glucopyranosyl-1-thiolato) are reported. The chloro complexes were synthesised either by reaction of the appropriate 1,3-dialkylimidazol-2-ylidene with [(Me 2S)AuCl] or by transmetallation between the appropriate Ag(I)–NHC complex and [(Me 2S)AuCl]. The 2′,3′,4′,6′-tetra- O-acetyl-β- d-glucopyranosyl-1-thiolato complexes were prepared from the appropriate [(NHC)Au(I)Cl] complex and 2′,3′,4′,6′-tetra- O-acetyl-1-thio-β- d-glucopyranose under basic conditions. A cationic Au(I)–NHC triphenylphosphine adduct was also prepared. Structural studies (X-ray diffraction) of a number of the complexes show that in each case the gold atom is (quasi-) linearly two-coordinate, having C–Au–Cl, C–Au–S or C–Au–P coordination. In one case, a new phase of [(Cy 2Im)AuCl], the molecules pack pair-wise with a close Au⋯Au interaction (3.1566(6) Å). Preliminary studies show this complex is luminescent in the solid state.

Triphenylphosphine adducts of silver di-iso-propyl dithiophosphate

AbstractThe molecular structure of dimeric {[S2P(OiPr)2](PPh3)}2· 2 CHCl3is built up about a centrosymmetric eight-membered ring that adopts a chair conformation as a result of bidentate bridging dithiophos phate ligands. The silver atom is in a trigonal planar geometry. Relatively close transannular Ag…S interactions are noted which, if considered significant, leads to a tridentate dithiophosphate ligand and a distorted tetrahedral geometry for silver. The presence of two PPh3molecules in the coordination sphere of silver in monomeric Ag[S2P(OiPr)2](PPh3)2· 3 CHCl3as well as a bidentate di thiophosphate ligand gives rise to a tetrahedral geometry. Adducts with lower or greater numbers of PPh3ligands could not be obtained pointing to the inherent stability of the characterised structures.

Triphenyl phosphine adducts of platinum(IV) and palladium(II) dithiocarbamates complexes: a spectral and in vitro study

Triphenyl phosphine adducts of dithiocarbamate complexes of platinum(IV) and palladium(II) of the type [Pt(L) 2PPh 3Cl 2] and [Pd(L) 2PPh 3] [L: morpholine dithiocarbamate (L 1), aniline dithiocarbamate (L 2) and N-(methyl, cyclohexyl) dithiocarbamate (L 3)] were prepared and characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. Thermal studies of the complexes were carried out. In vitro antitumor activity has been screened towards human adenocarcinoma cell lines and showed significant inhibition even at very low concentration.

Cobalt tris(mercaptoimidazolyl)borate complexes: synthetic studies and the structure of the first cobaltaboratrane.

The paramagnetic complexes (TmtBu)CoX (X = Cl, Br, I) have been readily prepared and structurally characterized and provide a convenient entry into cobalt(II) tris(mercaptoimidazolyl)borate chemistry. A number of derivatives, including mononuclear triphenylphosphine adducts [(TmtBu)Co(PPh3)]X and dinuclear compounds [Co2(TmtBu)2X]Y, have been prepared in order to ascertain whether cobalt is a reliable surrogate for zinc in biological systems, particularly in sulfur-rich coordination environments. The structure of the first cobaltaboratrane is also reported.

Crystal structures and vibrational and solution and solid-state (CPMAS) NMR spectroscopic studies in triphenyl phosphine, arsine, and stibine silver(I) bromate systems, (R3E)xAgBrO3 (E = P, As, Sb; x = 1-4).

Adducts of triphenyl phosphine, triphenyl arsine, and triphenyl stibine with silver(I) bromate have been synthesized and characterized both in solution ((1)H and ESI MS spectroscopy) and in the solid state (IR, single-crystal X-ray structure analysis). The triphenyl phosphine complexes have been also investigated by (31)P[(1)H] solution and (31)P cross-polarization magic-angle-spinning (CPMAS) NMR spectroscopy. The topology of the structures in the solid state was found to depend on the nature of EPh(3) and on the stoichiometric ratio AgBrO(3)/EPh(3). In AgBrO(3)/PPh(3) (1:1)(4) (1) and AgBrO(3)/PPh(3) (1:2) (2), the bromate is in the unfamiliar and hitherto structurally uncharacterized role of coordinating ligand, the complex having a mononuclear form in 2 and a less familiar tetrameric form in 1. In AgBrO(3)/AsPh(3) (1:4).CH(3)OH (7) and AgBrO(3)/SbPh(3) (1:4).C(2)H(5)OH (11), the cations are the familiar homoleptic [Ag(EPh(3))(4)](+) array with the bromate role simply that of counterion. The AgBrO(3)/AsPh(3) (1:2)(2).0.7"H(2)O" derivative (6) is binuclear L(2)Ag(mu-BrO(3))(2)AgL(2) with a four-membered ring core (L = AsPh(3)).

Ligand dependent structural changes in the acid–base chemistry of electron deficient benzoheterocycle triosmium clusters

The reactions of the electron deficient benzoheterocycle clusters Os 3(CO) 9(μ 3-η 2-LH)(μ-H) (L=phenanthridine, 2; 5,6-benzoquinoline, 3; quinoxaline, 4; 2-methyl benzimidazole, 5; 2-methyl benzotriazole, 6; 2-methyl benzothiazole, 7; benzothiazole, 8; 2-methyl benzoxazole, 9; benzoxazole, 10) with n-butylamine and with the protic acids HBF 4 and CF 3CO 2H are reported. Complexes 2 and 3 behave very similarly to the analogous quinoline complex (L=quinoline, 1) forming adducts with n-butylamine with similar spectral properties to 1 and undergoing simple protonation at the metal core with both HBF 4 and CF 3CO 2H. Complexes 4– 10 on the other hand form an additional amine adduct with different spectral characteristics than 1– 3 and in the case of 5 this is the only detectable product. In addition, these compounds also form adducts with acetonitrile while 1– 3 do not. Compounds 4– 9 also exhibit much more complex behavior in the presence of CF 3CO 2H than 1– 3, giving trifluoroacetate adducts subsequent to initial protonation. Although 4, 5 and 10 behave differently than 1 with n-butylamine and protic acids they form exactly the same triphenyl phosphine adduct as 1 and 3 based on multinuclear NMR data. The solid-state structure for the amine adduct of 2 is reported and suggested structures for the other amine and acid adducts, based on NMR data, are presented. The reasons for the differences in the behavior of the three distinct groups of benzoheterocycles ( 1– 3, 4 and 5– 10) are discussed.

Silica-supported imine palladacycles—recyclable catalysts for the Suzuki reaction?

Silica-supported, imine-based palladacyclic catalysts have been synthesised and the crystal structure of complex 9, the triphenylphosphine adduct of the pre-supported precursor complex 8, has been determined. The solid-supported catalysts show considerably lower activity in the Suzuki reaction than their homogeneous counterparts. Poor recyclability of the silica-immobilised catalysts and the presence of active catalysts in solution indicate that imine-based palladacyclic catalysts are unstable with respect to liberation of zero-valent palladium species. Whilst the solid-supported complexes are not useful as catalysts, they do function as excellent mechanistic probes. Studies on model complexes give further information on the processes that cause the liberation of zero-valent species not only from the solid-supported catalysts, but also from homogeneous systems. In all cases it appears that a reductive-elimination event occurs to generate the active catalyst.