Susie M. Miller

Relative Lewis Basicities of Six Al(ORF)4− Superweak Anions and the Structures of LiAl{OCH(CF3)2}4 and [1-Et-3-Me-1,3-C3H3N2][Li{Al{OCH(CF3)2}4}2]

The relative Lewis basicities of six Al(ORF)4− ions, Al{OC(CH3)(CF3)2}4−, Al{OC(CF3)3}4−, Al{OCPh(CF3)2}4−, Al{OC{4-C6H4(tBu)}(CF3)2}4−, Al{OC(Cy)(CF3)2}4−, and Al{OCPh2(CF3)}4−, have been determined by measuring their relative coordinating abilities towards Li+ in dichloromethane. The relative Li+ Lewis basicities of the Al(ORF)4− ions are linearly related to the aqueous pKa values of the corresponding parent HORF fluoroalcohols. The Lewis basicity of Al{OCH(CF3)2}4− could not be measured because two of these anions can coordinate to one Li+ cation. The structures of LiAl{OCH(CF3)2}4 and [1-Et-3-Me-1,3-C3H3N2][Li{Al{OCH(CF3)2}4}2] were determined.

The Role of the Second Coordination Sphere of [Ni(PCy2NBz2)2](BF4)2 in Reversible Carbon Monoxide Binding

The complex [Ni(PCy2NBz2)2](BF4)2, 1, reacts rapidly and reversibly with carbon monoxide (1 atm) at 25 degrees C to form [Ni(CO)(PCy2NBz2)2](BF4)2, 2, which has been characterized by spectroscopic data and by an X-ray diffraction study. In contrast, analogous Ni(II) carbonyl adducts were not observed in studies of several other related nickel(II) diphosphine complexes. The unusual reactivity of 1 is attributed to a complex interplay of electronic and structural factors, with an important contribution being the ability of two positioned amines in the second coordination sphere to act in concert to stabilize the CO adduct. The proposed interaction is supported by X-ray diffraction data for 2 which shows that all of the chelate rings of the cyclic ligands are in boat conformations, placing two pendant amines close (3.30 and 3.38 A) to the carbonyl carbon. Similar close C-N interactions are observed in the crystal structure of the more sterically demanding isocyanide adduct, [Ni(CNCy)(PCy2NBz2)2]2(BF4)2, 4. The data suggest a weak electrostatic interaction between the lone pairs of the nitrogen atoms and the positively charged carbon atom of the carbonyl or isocyanide ligand, and illustrate a novel (non-hydrogen bonding) second coordination sphere effect in controlling reactivity.

Synthesis and structures of poly(perfluoroethyl)[60]fullerenes: 1,7,16,36,46,49-C60(C2F5)6 and 1,6,11,18,24,27,32,35-C60(C2F5)8

The high-temperature reaction of C60 and C2F5I produced poly(perfluoroethyl)fullerenes with unprecedented addition patterns.

Coordination of the new weakly coordinating anions Al(OCH(CF3)2)4−, Al(OC(CH3)(CF3)2)4−, and Al(OC(Ph)(CF3)2)4− to the monovalent metal ions Li+ and Tl+

Abstract The structures of Li+ or Tl+ salts of three new fluoroalkoxide-containing aluminate anions were determined by X-ray crystallography. For LiAl(OC(Ph)(CF3)2)4, monoclinic, C2/c, a=42.297(6), b=10.641(1), c=19.132(2) A, β=114.808(9)°, Z=8, T=−100°C, R=0.052; for TlAl(OC(CH3)(CF3)2)4, monoclinic, P21/c, a=12.650(3), b=9.970(2), c=21.237(4) A, β=94.00(3)°, Z=4, T=−100°C, R=0.073; for TlAl(OCH(CF3)2)4, monoclinic, P21/n, a=14.261(1), b=9.8024(9), c=16.911(2) A, β=93.467(8), Z=4, T=−130°C, R=0.053. The monatomic, monovalent cations interact with their respective anions by means of M–O and M–F bonds. The Tl+ cations in TlAl(OCH(CF3)2)4 and TlAl(OC(CH3)(CF3)2)4 interact with three different aluminate anions. The Li+ cation in LiAl(OC(Ph)(CF3)2)4 interacts with only one aluminate anion, forming a rare trigonal–prismatic LiO2F4 coordination unit.

X-ray structure and DFT study of C1-C60(CF3)12. A high-energy, kinetically-stable isomer prepared at 500 °C

The title compound, prepared from C60 and CF3I at 500 °C, exhibits an unusual fullerene(X)12 addition pattern that is 40 kJ mol−1 less stable than the previously reported C60(CF3)12 isomer.

Synthesis and characterization of the anionic fluorocarboranes 6,7,8,9,10-CB9H5F5 −, 6,7,8,9-CB9H5F4-10-OH−, and 6,7,8,9-CB9H5F4-10-NHCOCH3 −

The reactions of salts of the 6,7,8,9-CB 9 H 6 F 4  − and CB 9 H 10  − anions with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA) in acetonitrile in the presence or absence of trifluoroacetic acid were studied. The addition of trifluoroacetic acid to the reaction mixture significantly changed the concentration ratio of the two pentafluoro isomers produced in the reactions, [6,7,8,9,10-CB 9 H 5 F 5  − ]/[2,6,7,8,9-CB 9 H 5 F 5  − ]. The ratio increased from 0.6 to >23 when the solvent was changed from neat acetonitrile to a 20% solution of trifluoroacetic acid in acetonitrile while simultaneously raising the temperature from 25°C to 60°C. The synthesis and 11 B and 19 F NMR spectroscopic characterization of the 6,7,8,9,10-CB 9 H 5 F 5  − anion are reported here for the first time. Chromatographic separation of the reaction mixtures led to the isolation of salts of two additional new anions, 6,7,8,9-CB 9 H 5 F 4 -10-NHCOCH 3  − and 6,7,8,9-CB 9 H 5 F 4 -10-OH − . The structure of [PPh 4 ][6,7,8,9-CB 9 H 5 F 4 -10-NHCOCH 3 ] was determined by X-ray crystallography: monoclinic, space group P 2 1 / n , a =7.5169(3), b =23.2793(10), c =16.6170(7) A, Z =4, T =−113°C, least-squares refinement on F 2 , R 1 ( I >2 σ ( I ))=0.0805, wR 2 (all data)=0.1922.

New or improved syntheses of the polyfluoroalcohols HOC(cyclo-C6H11)2(CF3), HO(cyclo-C6H11)(CF3)2, and HOC(Ar)(CF3)2 (Ar = 4-C6H4(t-Bu), 2,4,6-C6H2(CF3)3, 4-Si(i-Pr)3-2,6-C6H2(CF3)2, 3,5-C6H3(CH3)2), and 2-C6H4(C(OH)(CF3)2)

Abstract Five new polyfluoroalcohols, HOC(cyclo-C6H11)2(CF3), HO(cyclo-C6H11)(CF3)2, HOC(2,4,6-C6H2(CF3)3)(CF3)2, HOC(4-Si(i-Pr)3-2,6-C6H2(CF3)2)(CF3)2, and HOC(3,5-C6H3(CH3)2)(CF3)2, have been synthesized, and new procedures with improved yields for two known polyfluoroalcohols (HOC(cyclo-C6H11)(CF3)2, HOC(4-C6H4(t-Bu))(CF3)2) have been developed. Variable temperature 19 F NMR spectra and the X-ray structure of one of the new polyfluoroalcohols, HOC(2,4,6-C6H2(CF3)3)(CF3)2, are also reported. In hydrocarbon solution, the OH hydrogen atom of this compound interacts with one of the fluorine atoms of one of the o-CF3 groups in a manner identical to that previously reported by us for HOC(4-Si(i-Pr)3-2,6-C6H2(CF3)2)(CF3)2. In the solid-state, however, the OH hydrogen atom in HOC(2,4,6-C6H2(CF3)3)(CF3)2 appears to interact with one fluorine atom from each of the two geminal CF3 groups.

Improved synthesis and crystal structure of tetrakis(acetonitrile)(η4-1,5-cyclooctadiene)ruthenium(II) bis[tetrafluoroborate(1−)]

Abstract An improved, one-step synthesis of [RuII(1,5-COD)(CH3CN)4]2+ as the BF4− salt has been accomplished in 51% yield, an approximately 75% higher yield than the three-step literature synthesis of the corresponding PF6− salt. The improved synthesis consists of (i) grinding the insoluble [RuCl2(1,5-COD)]x precursor to increase the reaction rate and yield, (ii) treating the resultant [RuCl2(1,5-COD)]x with 2Ag+BF4− in refluxing acetonitrile with excess 1,5-COD present to inhibit 1,5-COD loss in the product and, most importantly, (iii) following the reaction directly by 1H-NMR spectrometry which revealed that the substitution reaction of the Ru(II), d6 precursor is, as expected, quite slow and requires ca. 120 h. The [Ru(1,5-COD)(CH3CN)4][BF4]2 product was characterized by 1H, 13C, and 19F-NMR, elemental analysis, and single-crystal X-ray crystallography. Problems in commercial Ru and F analyses are also addressed since this issue has been inadequately treated in the existing literature.

1,6,11,16,18,26,36,44,48,58-Decakis(trifluoromethyl)-1,6,11,16,18,26,36,44,48,58-decahydro­(C60–Ih)[5,6]fullerene benzene hemisolvate

# 2006 International Union of Crystallography All rights reserved The title compound, C70F30 0.5C6H6, which crystallizes with one half-molecule of benzene in the asymmetric unit, is one of four isomers of C60(CF3)10. The benzene molecule is disposed about a center of inversion. The fullerene molecule has an idealized C60–Ih core, with the ten CF3 groups arranged in an asymmetric para-para-para-meta-para-meta-para-meta-para (pmpmpmp) ribbon of edge-sharing C6(CF3)2 hexagons. There are no cage Csp–Csp bonds. There are intramolecular F F contacts between pairs of neighboring CF3 groups, ranging from 2.565 (1) to 2.727 (1) Å.

Six-co-ordinated vanadium-(IV) and -(V) complexesof benzimidazole and pyridyl containing ligands

A new series of vanadium-(IV) and -(V) complexes with ligands containing functionalities including hydroxyethyl, carboxylate, amine, pyridyl and benzimidazole have been prepared. The crystal structures of three complexes have been determined. All the vanadium atoms are six-co-ordinate even though previous complexes of the diethanolamine type have contained five-co-ordinate vanadium. The V–N (amine) bonds of the benzimidazole complexes are significantly longer than those of pyridyl complexes. An empirical relationship between pK a value of the protonated ligand and the V–N (amine) bond length (trans to an oxo group) of the corresponding vanadium-(IV), -(V) and -(IV/V) complexes was observed. Spectroscopic studies (NMR, ESR and UV/VIS) showed that the complexes remain intact in aqueous solution. In general, the hydroxyethyl substituted vanadium complexes are less stable than corresponding acetate substituted ones and the benzimidazole complexes are less stable than corresponding pyridyl complexes. The combined knowledge concerning the properties of all these complexes provides an excellent platform to design new vanadium complexes pertinent to biological applications.