Polymeric (diphenylphosphinato)tetrahydro-furanlithium

In the title compound, [Li(C12H10O2P)(C4H8O)]n, the O atoms of adjacent and bridging diphenylphosphinate ligands and that from a tetrahydrofuran (thf) molecule are arranged in a tetrahedral manner around the Li atoms, resulting in a one-dimensional array (parallel to the a axis) of alternate eight-membered and rectangular planar four-membered rings [the two Li-O distances are 1.962 (6) and 1.991 (6) Å, and the Li-O-Li and O-Li-O angles are 88.3 (2) and 91.7 (2)°, respectively]. The Li-O distances for the O atoms of the phosphinate ligand are 1.992 (6) (for the -O atom) and 1.897 (6) Å, and the distance from Li to the O atom of the thf ligand is 2.028 (6) Å

Cyclooctene epoxidation with H \u3c inf\u3e 2 O \u3c inf\u3e 2 and single crystal X-ray determined crystal structures of new molybdenum and tungsten catalysts bearing the hydrophilic ligand hydroxymethyldiphenylphosphine oxide

The dioxo molybdenum and tungsten complexes MoO2Cl2(OPPh2CH2OH)2 and WO2Cl2(OPPh2CH2OH)2 have been synthesized and characterized by FT-IR, 1H and 31P NMR. Their structures, as determined by single crystal X-ray diffraction analysis, reveal distorted octahedral geometries with cis terminal oxygen atoms, trans Cl ligands and that the hydroxymethyldiphenylphosphine oxide ligands coordinate through the oxygen atom bonded to the P atom. Both of the compounds are studied as catalysts for the epoxidation of cis-cyclooctene in the presence of hydrogen peroxide as a source of oxygen. Both complexes showed good activity and very high selectivity for the formation of cyclooctene oxide. © 2007 Elsevier B.V. All rights reserved

New binucleating ligand with two [P,S] chelation pockets on a single phenyl ring: Syntheses and X-ray structures of 1,4-bis(diphenylphosphino)-2,5-difluoro-3,6-bis(methylthio)benzene and of bimetallic complex (CO) \u3c inf\u3e 3 Fe(μ-[(PPh \u3c inf\u3e 2 )(SMe)C \u3c inf\u3e 6 F \u3c inf\u3e 2 (SMe)(PPh \u3c inf\u3e 2 )])Fe(CO) \u3c inf\u3e 3

Double deprotonations of 1,4-dibromo-2,5-difluorobenzene with LDA (2 equiv., T \u3c -90 °C) generate a reasonably stable organodilithium intermediate. Quenching this reaction mixture with chlorophosphines ClPR2 produce p-bis(phosphino)benzenes R2P-C6Br2F2-PR2 (R = Ph, 4a; R = iPr, 4b). Facile lithium-bromine exchange occurs upon exposure of 4a to BuLi (2 equiv., -80 °C), leading to the generation of another organodilithium intermediate. Addition of MeS-SMe (2 equiv.) to such reaction mixtures gives 1,4-bis(diphenylphosphino)-2,5-difluoro-3,6-bis(methylthio)benzene (2). Compound 2 is the first example of a neutral binucleating ligand featuring the [P,S] chelating sites on the opposite sides of a single phenyl ring. Compound 4b does not undergo the analogous transformation when subjected to the same conditions (2BuLi/2MeS-SMe). Addition of 2 to Fe(CO)5/2(Me3NO · 2H2O) reaction mixtures led to the isolation of the bimetallic complex {(CO)3Fe[P,S]-C6F2-[P,S]Fe(CO)3} (3), ([P,S] represents the chelating pockets formed by adjacent -PPh2 and -SMe groups). All of the new compounds were characterized by spectroscopic and analytical techniques (multinuclear NMR, mass-spectrometry, and/or elemental analysis). In addition, compounds 2 and 3 were characterized via single crystal X-ray diffraction methods. © 2006 Elsevier B.V. All rights reserved

New synthetic route to polyphosphine ligands bearing 1,2,4,5-tetrakis(phosphino)benzene framework: Structural characterizations of 1,4-(PPh \u3c inf\u3e 2 ) \u3c inf\u3e 2 -2,5-(PR) \u3c inf\u3e 2 ) \u3c inf\u3e 2 -C \u3c inf\u3e 6 F \u3c inf\u3e 2 (R = Ph, \u3c sup\u3e i \u3c/sup\u3e Pr, Et)

Reactions of 1,4-dibromo-2,5-difluorobenzene with two equivalents of lithium diisopropylamide at low temperature (T \u3c -90 °C) followed by a quench with a slight excess of ClPPh 2 afford 1,4-dibromo-2,5-bis(diphenylphosphino)-3,6-difluorobenzene (1) in good yields. Reacting 1 with two equivalents of BuLi followed by a quench with a slight excess of ClPR 2 yield novel 1,2,4,5-tetrakis(phosphino)-3,6-difluorobenzenes 1,4-(PPh2) 2-2,5-(PR2)2-C6F2 (R = Ph (2a); R = iPr (2b); R = Et (2c)) in moderate yields. Compounds 1 and 2a-c were characterized by multinuclear NMR spectroscopy and elemental analyses. In addition, molecular structures of 2a-c have been determined by single crystal X-ray crystallography. Phosphorus atoms of PPh2/PR2substituents in 2a-c are displaced from the plane of the central phenyl ring due to steric interactions with neighboring groups. © 2004 Elsevier B.V. All rights reserved

Syntheses of symmetric and unsymmetric 2,6-bis(phosphino)phenols

Compounds bearing the structural motif of 2,6-bis(phosphino)phenol have been synthesized via two general methods. Double lithium-halogen exchange occurred in low-temperature reactions of O-protected (by methyl- or tetrahydropyranyl groups) 2,6-dibromo-4-methylphenol derivatives with BuLi (2 equivalents); quenching the reaction mixtures with chlorophosphines ClPR 2 (R = Ph, iPr) and corresponding O-deprotection yielded symmetrically substituted 2,6-bis(phosphino)phenols. Sequential incorporation of -PR2 functionalities was accomplished via single lithium-halogen exchange (1 eq. of BuLi) of tetrahydropyranyl-protected 2,6-dibromo-4- methylphenol followed by ClPR2 quenches, thus enabling the syntheses of unsymmetric 2,6-bis(phosphino)phenols. Such compounds were also obtained via sequential ortholithiations of tetrahydropyranyl-protected 4-tert-but ylphenol, followed by ClPR2 quenches. All of the new compounds have been characterized by spectrometric methods (1H and 31P NMR, and mass spectrometry). In addition, two of the compounds, 1-(diphenylphosphino) -3-(diphenylphosphoryl)-2-methoxy-5-methylbenzene (3a-ox) and 1,3-bis(diphenylphosphino)-2-methoxy-5-methylbenzene (6a) have also been characterized via single crystal X-ray diffraction experiments

Synthesis and structural characterizations of para-bis(dialkyl/ diarylphosphino)phenylenes built around tetrahalogenated benzene cores

Double deprotonation of 1,2-dibromo-4,5-difluorobenzene and 1-bromo-2-chloro-4,5-difluorobenzene by lithium diisopropylamide (LDA) in ethereal solutions is facile at very low temperatures (T \u3c -90 °C). The organo-dilithium intermediates thus generated react readily with chlorophosphines ClPR2 (R = Ph and/or iPr), producing 1,2-dibromo-3,6-bis(diphenylphosphino)-4,5-difluorobenzene (1a), 1,2-dibromo-3,6-bis(diisopropylphosphino)-4,5-difluorobenzene (1b) and 1-bromo-2-chloro-3,6-bis(diphenylphosphino)-4,5-difluorobenzene (1c). Corresponding P-oxides 2a-c are obtained by oxidation of 1a-c with H 2O2. Analogous reactions of 1,2-dibromo-4,5- difluorobenzene and 1-bromo-2-chloro-4,5-difluorobenzene with only 1 equiv. of LDA do not result in selective monodeprotonations, as 1a and 1c are formed preferentially after ClPPh2 quench. All of the isolated new compounds were fully characterized by multinuclear NMR spectroscopy, elemental analysis and/or mass-spectrometry. In addition, 1a, 1c, 2a, and 2b were characterized by single crystal X-ray diffraction methods. © 2005 Elsevier B.V. All rights reserved

Synthesis and characterisation of new molybdenum - oxo complexes containing diphenylphosphinylacetic acid and 2-(tert-butylsulphoxide)phenyldiphenylphosphine oxide as bidentate ligands

Reaction of the ligands diphenylphosphinylacetic acid Ph2P(O)CH2COOH (1) and 2-(tert-butylthio)phenyldiphenylphosphine oxide Ph2P(O)C6H4tBuS (2) with MoO2Cl2 , resulted in two complexes MoO2Cl2Ph2P(O)CH2COOH (3) and MoO2Cl2Ph2P(O)C6H4tBuS(O) (4). Complexes 3 and 4 were isolated and analysed by 1H NMR, 31P NMR and X-ray crystallography. Complex 3 crystallised with a molecule of the free ligand in a 1:1 ratio (3·1) and complex 4 crystallised with molecules of the solvent CH2Cl2 within the unit cell in a 2:1 ratio (4·0.5CH2Cl2). Tetrameric arrangements comprised of hydrogen bonds were observed in complexes 1 and 3. Complex 4 exhibited a seven-membered ring structure owing to the oxidation of the sulphide in 2 to sulphoxide and coordination of this ligand via the oxygen atoms to the molybdenum atom. © 2010 Elsevier B.V. All rights reserved

Synthesis, structures and ligating properties of 2,6-bis(phosphino)thiophenol derivatives

New t-butyl-aryl thioethers where the aryl group is 2,6-bis(phosphino)phenyl have been synthesized. The syntheses were completed via sequential ortho-lithiations of t-butylphenylsulfide, followed by chlorophosphine (ClPR2) quenches; symmetric (2,6-bis(diphenylphosphino)phenyl, (4a)) and unsymmetric (2-diisopropylphosphino-6-diphenylphosphino)phenyl, (4b) aryl groups were obtained. Treatment of 4a with Li or Na naphthalenide yielded 2,6-bis(diphenylphosphino)thiophenol 5. Reactions of 4a or 5 with NiCl2 · 6H2O yielded nickel bis(phosphinothiophenolate) 6. Compounds 4a,b, 5 and 6 were characterized by 1H and 31P NMR, and by mass-spectrometry. In addition, 4a, 5 and 6 were characterized by single crystal X-ray diffraction methods. © 2007 Elsevier B.V. All rights reserved

1,4-Bis(phosphine)-2,5-difluoro-3,6-dihydroxybenzenes and their P-oxides: Syntheses, structures, ligating and electronic properties

Reactions of 1,4-difluoro-2,5-dimethoxybenzene with LDA (1:2) at low temperatures generated organodilithio intermediates; quenching the reaction mixtures with chlorophosphines ClPR2 produced 1,4-bis(phosphino)-2,5-difluoro-3,6-dimethoxybenzenes 1a (R = Ph) and 1b (R = iPr). Demethylation of 1a-b was accomplished by BBr3, yielding bis(phosphino)hydroquinones 2a-b. Treating 2a-b with excess hydrogen peroxide produced bis(phosphinyl)hydroquinones 3a-b. The binucleating properties of 2a were established by the formation of a bimetallic nickel complex upon reaction with Ph2Ni(PMe3)2. Electrochemical activity of hydroquinones 2a-b and 3a-b was examined by cyclic voltammetry. In addition, compounds 2a, 3a and 3b were obtained in crystalline form and characterized by single-crystal X-ray diffraction. The influence of the fluorine substituents on the composition of the frontier orbitals of 2a and 3a was examined by computational methods. © 2008 Elsevier B.V. All rights reserved