Reaction of (C6F5)2HGeGeH(C6F5)2 with triethylbismuth: molecular structure of [(C6F5)2Ge]4Bi2

The reaction of (C₆F₅)₂HGeGeH(C₆F₅)₂ with triethylbismuth affords a new polynuclear germylbismuth derivative, [(C₆F₅Ge]₄Bi₂ (1). The metal framework of molecule1 has the form of a gable roof built by two central Bi atoms and four peripheral Ge atoms with covalent Bi-Bi bonds [3.045(3) Å], Bi-Ge [2.724(5)-2.755(4) Å] and Ge-Ge [2.444(6), 2.465(6) Å].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 921–924, May, 1994.     

Aqueous suspension polymerization of isobutene initiated by 1,2-C6F4[B(C6F5)2]2

Lewis acidic, chelating diborane 1 forms stable oxonium acids 2 in the presence of excess MeOH or water. Diborane 1 is shown to be an effective co-initiator for the suspension polymerization of isobutene in aqueous media at sufficiently low temperatures. Poly(isobutene) or butyl rubber is obtained at moderate to high conversion and with Mw < 200 K and PDI approximately 2 under these conditions.     

Preparation and characterization of [Hg[P(C6F5)2]2], [Hg[(mu-P(C6F5)2)W(CO)5]2], and [Hg[(mu-P(CF3)2)W(CO)5]2] and the X-ray crystal structure of [Hg[(mu-P(C6F5)2)W(CO)5]2].2DMF

The thermally unstable compound [Hg[P(C(6)F(5))(2)](2)] was obtained from the reaction of mercury cyanide and bis(pentafluorophenyl)phosphane in DMF solution and characterized by multinuclear NMR spectroscopy. The thermally stable trinuclear compounds [Hg[(mu-P(CF(3))(2))W(CO)(5)](2)] and [Hg[(mu-P(C(6)F(5))(2))W(CO)(5)](2)] are isolated and completely characterized. The higher order NMR spectra exhibiting multinuclear satellite systems have been sufficiently analyzed. [Hg[(mu-P(CF(3))(2))W(CO)(5)](2)].2DMF crystallizes in the monoclinic space group C2/c with a = 2366.2(3) pm, b = 1046.9(1) pm, c = 104.0(1) pm, and beta = 104.01(1) degrees. Structural, NMR spectroscopic, and vibrational data prove a weak coordination of the two DMF molecules. Structural, vibrational, and NMR spectroscopic evidence is given for a successive weakening of the pi back-bonding effect of the W-P bond in the order [W(CO)(5)PH(R(f))(2)], [Hg[(mu-P(R(f))(2))W(CO)(5)](2)], and [W[P(R(f))(2)](CO)(5)](-) with R(f) = C(6)F(5) and CF(3). The pi back-bonding effect of the W-C bonds increases vice versa.     

Two New Modifications of [P(C6H5)4]2[Cu2I4]

Single crystals of two new modifications of [P(C₆H₅)₄]₂[Cu₂I₄] were obtained by reaction of granulated copper with iodine and [P(C₆H₅)₄]I in dry acetone under nitrogen atmosphere. They crystallise monoclinically, space group P2₁/n (No. 14), a = 11.550(6), b = 7.236(2), c = 27.232(13) Å, β = 98.13(3)°, V = 2253(2) ų, and Z = 2 ([P(C₆H₅)₄]₂[Cu₂I₄]-C), and space group Cc (No. 9), a = 17.133(5), b = 15.941(5), c = 18.762 (6) Å, β = 114.02(1)°, V = 4681(3) ų, and Z = 4 ([P(C₆H₅)₄]₂[Cu₂I₄]-D), respectively. In these compounds the [CuI₂]^? anions form dimers di-μ-iodo-diiodocuprate(I), which are either planar ( C ) or folded ( D ).     

Coordination compounds with the general formula trans-[M(18-crown-6)(C5HO2F6)2] as structural-thermochemical analogs. The complexes trans-[Pb(18-crown-6)(C5HO2F6)2] and trans-[Ba(18-crown-6)(C5HO2F6)2]

The molecular geometries of the complexes trans-[M(18-crown-6)(C₅HO₂F₆)₂] (where M = Ca, Sr, Ba (I), Zn, Cd, Sn, Pb (II), Fe, Co, Eu, and Yb) were modeled by the molecular mechanics method with fixed R(M-O) distances. The shielding degrees of the central metal atom in these complexes were calculated and the number and types of possible intermolecular contacts between their molecules in the structure were determined. The intermolecular interactions involve identical fragments (atoms) of the ligands: the CF₃ groups of the hexafluoroacetylacetonate ligands and the methylene fragments of the crown ether. Previously unknown complex II and complex I were synthesized according to an original procedure. The structure and thermochemical properties (including sublimation by the Knudsen method) of complex II were studied. As in complex I, the metal cation in complex II is in the cavity of the macrocycle of the crown ether; the hexafluoroacetylacetonate ligands are trans relative to that cation. The presumed similarity of complexes I and II in thermochemical characteristics was confirmed experimentally. Both the complexes melt in close temperature intervals and sublime at the same temperature (～10^?2 mm Hg) without decomposition. The enthalpies of sublimation of complexes I and II, as well as the entropy contributions to their volatilities, are equal to within the experimental error.     

Insertion reactions of [M(SR)3(PMe2Ph)2] with CS2 (M = Ru, Os; R = C6F4H-4, C6F5). X-ray structures of [Ru(S2CSC6F4H-4)2(PMe2Ph)2], trans-thiolates [M(SR)2(S2CSR)(PMe2Ph)2] (M = Ru; R = C6F5 and M = Os; R = C6F4H-4), and trans-thiolate-phosphine [Os(SC6F5)2(S2CSC6F5)(PMe2Ph)2

Reactions of [M(SR)(3)(PMe(2)Ph)(2)] (M = Ru, Os; R = C(6)F(4)H-4, C(6)F(5)) with CS(2) in acetone afford [Ru(S(2)CSR)(2)(PMe(2)Ph)(2)] (R = C(6)F(4)H-4, 1; C(6)F(5), 3) and trans-thiolates [Ru(SR)(2)(S(2)CSR)(PMe(2)Ph)(2)] (R = C(6)F(4)H-4, 2; C(6)F(5), 4) or the isomers trans-thiolates [Os(SR)(2)(S(2)CSR)(PMe(2)Ph)(2)] (R = C(6)F(4)H-4, 5; C(6)F(5), 7) and trans-thiolate-phosphine [Os(SR)(2)(S(2)CSR)(PMe(2)Ph)(2)] (R = C(6)F(4)H-4, 6; C(6)F(5), 8) through processes involving CS(2) insertion into M-SR bonds. The ruthenium(III) complexes [Ru(SR)(3)(PMe(2)Ph)(2)] react with CS(2) to give the diamagnetic thiolate-thioxanthato ruthenium(II) and the paramagnetic ruthenium(III) complexes while osmium(III) complexes [Os(SR)(3)(PMe(2)Ph)(2)] react to give the paramagnetic thiolate-thioxanthato osmium(III) isomers. The single-crystal X-ray diffraction studies of 1, 4, 5, and 8 show distorted octahedral structures. (31)P [(1)H] and (19)F NMR studies show that the solution structures of 1 and 3 are consistent with the solid-state structure of 1.     

Schwingungs-Resonanz-Raman-Spektren von [n-(C4H9)4N]2[OsBr6] bei 77 K

Vibrational Resonance Raman Spectra of [n-(C₄H₉)₄N]₂[OsBr₆] at 77 K A rotating Raman cell in the 180° scattering geometry is described. It permits the measurement of Raman spectra of deeply coloured solids and liquids at the temperature of liquid nitrogen. Meaningful polarization measurements on solid samples are obtained by the use of optically isotropic pellets of tetraalkylammonium complex salts. In the solid state [n-(C₄H₉)₄N]₂[OsBr₆] displays a rigorous resonance Raman effect. Especially the excitation at 454.4 and 457.9 nm coincides with an intense electric dipole allowed charge-transfer transition of the anion, so that as far as nine overtones of the totally symmetric stretching vibration A_1g and many combination tones of this vibration with the other ra-active fundamentals are to be observed. The determination of the spectroscopic constants ω₁ and x₁₁ demonstrates, that the deviations from the harmonic oscillator are within the limit of error.     

Vaporization of Molecular Strontium and Barium β-Diketonates [Sr(15C5)(C5O2F6H)2] and [Ba(18C6)(C5O2F6H)2]. Structure-Thermochemical Approach

Vaporization of the barium molecular complex [Ba(18C6)(C₅O₂F₆H)₂] and the newly prepared strontium complex [Sr(15C5)(C₅O₂F₆H)₂] was studied using a semiempirical structure-thermochemical approach. The studies of intermolecular steric shielding of individual atoms and analysis of the possible intermolecular contacts in these complexes made it possible to identify the atoms and atom groups with significant contributions to the vaporization enthalpy. The hypothetical vaporization enthalpies were calculated by summing the contributions of groups. The melting and sublimation enthalpies were determined experimentally.     

B(C6F5)3-catalyzed synthesis of benzylic azides

B(C₆F₅)₃ was found to catalyze the reaction between trimethylsilyl azide and benzylic acetates. Secondary and tertiary benzylic acetates were competent substrates in this reaction providing the azide products in moderate to high yields. Mechanistic experiments are consistent with the possible formation of a Lewis acid-base pair between the B(C₆F₅)₃ and trimethylsilyl azide.     

Reactivity of the bis(pentafluorophenyl)boranes ClB(C6F5)2 and [HB(C6F5)2]n towards late transition metal reagents

The reactivities of the highly electrophilic boranes ClB(C(6)F(5))(2) (1) and [HB(C(6)F(5))(2)](n) (2) towards a range of organometallic reagents featuring metals from Groups 7-10 have been investigated. Salt elimination chemistry is observed 1 between and the nucleophilic anions eta(5)-C(5)R(5))Fe(CO)(2)](-)(R = H or Me) and [Mn(CO)(5)](-), leading to the generation of the novel boryl complexes (eta(5)-C(5)R(5))Fe(CO)(2)B(C(6)F(5))(2)[R = H (3) or Me (4)] and (OC)(5)MnB(C(6)F(5))(2) (5). Such systems are designed to probe the extent to which the strongly sigma-donor boryl ligand can also act as a pi-acceptor; a variety of spectroscopic, structural and computational probes imply that even with such strongly electron withdrawing boryl substituents, the pi component of the metal-boron linkage is a relatively minor one. Similar reactivity is observed towards the hydridomanganese anion [(eta(5)-C(5)H(4)Me)Mn(CO)(2)H](-), generating a thermally labile product identified spectroscopically as (eta(5)-C(5)H(4)Me)Mn(CO)(2)(H)B(C(6)F(5))(2) (6). Boranes 1 and 2 display different patterns of reactivity towards low-valent platinum and rhodium complexes than those demonstrated previously for less electrophilic reagents. Thus, reaction of 1 with (Ph(3)P)(2)Pt(H(2)C=CH(2)) ultimately generates EtB(C(6)F(5))(2) (10) as the major boron-containing product, together with cis-(Ph(3)P)(2)PtCl(2) and trans-(Ph(3)P)(2)Pt(C(6)F(5))Cl (9). The cationic platinum hydride [(Ph(3)P)(3)PtH](+) is identified as an intermediate in the reaction pathway. Reaction of with [(Ph(3)P)(2)Rh(mu-Cl)](2), in toluene on the other hand, appears to proceed via ligand abstraction with both Ph(3)P.HB(C(6)F(5))(2) (11) and the arene rhodium(I) cation [(Ph(3)P)(2)Rh(eta(6)-C(6)H(5)Me)](+) (14) ultimately being formed.