- Reactions of RSe-EMe3 (E = Si, Ge, Sn, Pb) with XeF2 - RSe-F equivalents in the fluoroselenenylation of acetylenes
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Selenides of the type R1Se-EMe3 (E = Si, Ge, Sn, Pb) react with xenon difluoride by cleavage of the Se-E bond to yield the R1Se-F intermediate and the fluorides Me3E-F, whereas the Se-C bond in PhSe-tBu (E = C) is stable against XeF2. The presence of R1Se-F intermediates is confirmed by addition to acetylenes (4-octyne, 3-hexyne). Thus, the fluoroselenenylation of acetylenes gives fluoro(organylseleno)olefins in preparative yields. In the cases of E = Si, Ge, Sn, and Pb, aryl and n-alkyl groups are suitable as the substituent R1. The X-ray crystal structural analysis of (E)-3-(p- carboxyphenylseleno)-4-fluorohex-3-ene - the first example of an uncharged fluoroselenoolefin synthesized from p-EtO2C-C6H4-Se-SnMe3, XeF2, and 3- hexyne followed by an ester hydrolysis - shows that the addition of the selenenylfluoride intermediate to the acetylene proceeds via a trans- addition, as is known for the R2Se2-XeF2 reagents.
- Poleschner, Helmut,Heydenreich, Matthias,Schilde, Uwe
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p. 1307 - 1313
(2007/10/03)
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- Phosphoranimine phosphines and arsines as heterodifunctional coordinating ligands. Synthesis and characterization of new palladium(II) metallacycles RN=PPh2(CH2)nEPh2PdCl2 (R = SiMe3, GeMe3, H; n = 1, 2; E = P, As) and the crystal and molecular structure of HN=PPh2CH2PPh ...
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Full title: Phosphoranimine phosphines and arsines as heterodifunctional coordinating ligands. Synthesis and characterization of new palladium(II) metallacycles RN=PPh2(CH2)nEPh2PdCl2 (R = SiMe3, GeMe3, H; n = 1, 2; E = P, As) and the crystal and molecular structure of HN=PPh2CH2PPh2PdCl2, the first structural example of a phosphoranimine phosphine complex. Reaction of the N-(trimethylsilyl)- or N-(trimethylgermyl)phosphoranimine phosphines Me3ENPPh2CH2PPh2 (E = Si, Ge) or the N-(trimethylsilyl)phosphoranimine arsine Me3SiNPPh2CH2CH2AsPh2 with PdCl2(PhCN)2 gave metallacyclic PdII derivatives Me3ENPPh2(CH2)nQPh 2PdCl2 (Q = P, n = 1, E = Si or Ge; Q = As, n = 2, E = Si). Water reacts with Me3SiNPPh2CH2PPh2PdCl2 to form the parent imine complex HNPPh2CH2PPh2PdCl2 (12), the structure of which has been determined. (Crystal data for 12 (as a 1:1 adduct with CH2Cl2): monoclinic P21/n (No. 14), a = 8.953 (3) ?, b = 21.151 (4) ?, c = 14.773 (2) ?, β = 93.98 (2)°, Z = 4, final R(F) = 0.034, Rw(F) = 0.037.) The imine ligand adopts an "envelope" five-membered chelate ring configuration bonded at N and P. The Pd-N (2.021 (6) ?) and N=P (1.599 (6) ?) bond lengths are in accord with expectations for Pd-N single and P=N double bonds. The nitrogen atom is pyramidal. 12 is also formed by reaction of Me3SiNPPh2CH2PPh2 with K2PdCl4 in the presence of water. Activated fluoroaromatics (e.g. pentafluorobenzonitrile) replace Me3Si or Me3Ge groups on the ligand framework by elimination of Me3SiF and attachment of the fluoroaromatic exclusively at the para position. Full spectral characterization of all complexes is given. The Me3Ge phosphoranimine phosphine shows conformational behavior similar to that of the Me3Si analogue reported earlier. All conformers in the mixture however give a metal complex with only one conformation. We also describe a more efficient synthesis of Me3GeN3, which was developed in the course of the study.
- Katti,Batchelor,Einstein,Cavell
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p. 808 - 814
(2008/10/08)
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