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

[(4R,5R)-(2,2-Dimethyl-1,3-dioxolane-4,5-di­yl)bis­(diphenyl­methano­lato)-κ2 O:O′]bis(N-methyl­methanamin­ato)titanium(IV)

In the title four-coordinate complex, [Ti(C2H6N)2(C31H28O4)], two symmetry-independent mol­ecules are present in the asymmetric unit. The TiIV atom displays a distorted tetra­hedral geometry, with Ti—O bond lengths ranging from 1.805 (3) to 1.830 (3) Å and O—Ti—O ligand bite angles of 100.16 (12) and 101.36 (12)°. The short Ti—N bond distances, ranging from 1.877 (4) to 1.905 (4) Å, indicate strong bonding between the TiIV atom and the dimethyl­amide ligands

Polymeric (di­phenyl­phosphinato) tetra­hydro­furanlithium

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

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

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

Discovering Chatter and Incompleteness in the Datagram Congestion Control Protocol

difference between this version and that published in LNCS concerns section 3.5 of the paper. After email discussions with Dr Kohler, one of the editors of DCCP, we agree that we overlooked the reference to initialising GAR to ISS when the variable was first defined in the declarations at the top of section 8.5 (Pseudocode) of DCCP version 11. Hence, DCCP is not incomplete in this way. Thus we have deleted the last paragraph of section 3.5 in this version. We fully agree with Dr Kohler that it would be clearer to insert this initialisation in Step 3 of the pseudocode (LISTEN state) after the “Choose S.ISS ” line. Further, we believe that this only needs to apply to the SERVER, as the first value of GAR at the CLIENT will be the ACK number of the received Response packet, which is not necessarily equal to ISS, as the first request could have been lost and another one sent and responded to with a higher sequence number. Hence we believe that the global initialisation of GAR in the declarations can be safely removed, once GAR is initialised in Step 3. The copyright of this text belongs to Springer-Verlag. The text is re-published in this web page according to the permission stated i

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

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