Synthesis and properties of the tetrakis(trifluoromethyl)borate anion, [b(CF3)4]-: structure determination of Cs[B(CF3)4] by single-crystal X-ray diffraction

Salts of the tetrakis(trifluoromethyl)borate anion, M[B(CF3)4], M=Li, K, Cs, Ag, have been prepared by two different routes for the first time. The colorless compounds are thermally stable up to 425 C (Cs salt) and soluble in anhydrous HF, water, and most organic solvents. Single crystals of Cs[B(CF3)4] were grown from diethyl ether by diffusion of CH2Cl2 vapor into the solution. The molecular structure was obtained by single-crystal X-ray diffraction. Crystal data: rhombohedral space group R3m (no. 160); a =7.883(1), c=13.847(4) A: V=748.2 A3; Z=3; T=150K; R1=0.0118, wR2=0.0290. The internal bond parameters of the [B(CF3)4] ion were compared to those of the C(CF3)4 molecule. Due to a disorder of the anions in the cesium salt, it is not possible to distinguish between T and Td symmetry by X-ray diffraction experiments alone. However, a comprehensive IR and Raman study demonstrated that in the potassium and cesium salt as well as in aqueous solution, the anion exhibits T symmetry with all CF3 groups rotated off the staggered position required for Td symmetry. The vibrational study is supported by DFT calculations, which provide, in addition to the equilibrium structure and vibrational wavenumbers, estimates of IR and Raman band intensities. The anion is resistant against strong oxidizing (e.g., F2) as well as reducing agents (e.g., Na) and is not affected by nucleophiles like C2H5O or electrophiles such as H3O+. It is very weakly coordinating, as demonstrated by the low-equilibrium CO pressure over the [Ag(CO)x][B(CF3)4] (x=1, 2) co-adducts and the formation of [Ag(CO)x][B(CF3)4] (x=3,4) at higher CO pressure. The 11B, 13C, and 19F NMR data as well as the structural parameters of the anion are compared with those for other borates containing F, CN, and CF3 ligands.

Bis(trifluoroacetyl) peroxide, CF(3)C(O)OOC(O)CF(3)

Pure, highly explosive CF(3)C(O)OOC(O)CF(3) is prepared for the first time by low-temperature reaction between CF(3)C(O)Cl and Na(2)O(2). At room temperature CF(3)C(O)OOC(O)CF(3) is stable for days in the liquid or gaseous state. The melting point is -37.5 degrees C, and the boiling point is extrapolated to 44 degrees C from the vapor pressure curve log p = -1875/T + 8.92 (p/mbar, T/K). Above room temperature the first-order unimolecular decay into C(2)F(6) + CO(2) occurs with an activation energy of 129 kJ mol(-1). CF(3)C(O)OOC(O)CF(3) is a clean source for CF(3) radicals as demonstrated by matrix-isolation experiments. The pure compound is characterized by NMR, vibrational, and UV spectroscopy. The geometric structure is determined by gas electron diffraction and quantum chemical calculations (HF, B3PW91, B3LYP, and MP2 with 6-31G basis sets). The molecule possesses syn-syn conformation (both C=O bonds synperiplanar to the O-O bond) with O-O = 1.426(10) A and dihedral angle phi(C-O-O-C) = 86.5(32) degrees. The density functional calculations reproduce the experimental structure very well.

Structures and conformations of trifluoromethyl fluoroformate and perfluorodimethyl carbonate

The conformational properties and geometric structures of trifluoromethyl fluoroformate, CF(3)OC(O)F (1), and perfluorodimethyl carbonate, (CF(3)O)(2)CO (2), have been studied by matrix IR spectroscopy, gas electron diffraction (GED), and quantum chemical calculations (MP2 and B3LYP with 6-311G basis sets). In both compounds the synperiplanar orientation of the O-CF(3) groups relative to the C=O double bond is preferred. If heated Ar/1 and Ar/2 mixtures are deposited as a matrix at 14 K, new bands appear in the matrix IR spectra which are assigned to the anti form of 1 and to the syn/anti form of 2. At room temperature the contribution of the anti rotamer of 1 is 4% (DeltaH degrees = H degrees (anti) - H degrees (syn) = 1.97(5) kcal/mol), and the contribution of the syn/anti conformer of 2 is estimated to be less than 1%. These high-energy conformers are not observed in the GED experiment. The quantum chemical calculations reproduce the structural and conformational properties of both compounds satisfactorily.

Gas-phase structures of acetyl peroxynitrate and trifluoroacetyl peroxynitrate

The molecular structures and conformational properties of acetyl peroxynitrate (PAN, CH3C(O)OONO2) and trifluoroacetyl peroxynitrate (FPAN, CF3C(O)OONO2) were investigated in the gas phase by electron diffraction (GED), microwave spectroscopy (MW), and quantum chemical methods (HF/3-21G, HF/6-31G*, MP2/6-31G*, B3PW91/6-31G*, and B3PW91/6-311+G*). All experimental and theoretical methods show the syn conformer (C=O bond of acetyl group syn to O-O bond) to be strongly predominant relative to the anti conformer. The O-NO2 bonds are extremely long, 1.492(7) A in PAN and 1.526(10) A in FPAN, which correlates with their low bond energy and the easy formation of CX3C(O)OO* and *NO2 radicals in the atmosphere. The O-O bonds (1.418(12) A in PAN and 1.408(8) A in FPAN) are shorter than that in hydrogen peroxide (1.464 A). In both compounds the C-O-O-N dihedral angle is close to 85 degrees.

Superelectrophilic tetrakis(carbonyl)palladium(II)- and -platinum(II) undecafluorodiantimonate(V), [Pd(CO)4][Sb(2)F(11)]2 and [Pt(CO)4][Sb(2)F(11)]2: syntheses, physical and spectroscopic properties, their crystal, molecular, and extended structures, and density functional calculations: an experimental, computational, and comparative study

The salts [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, are prepared by reductive carbonylation of Pd[Pd(SO(3)F)(6)], Pt(SO(3)F)(4) or PtF(6) in liquid SbF(5), or HF-SbF(5). The resulting moisture-sensitive, colorless solids are thermally stable up to 140 degrees C (M = Pd) or 200 degrees C (M = Pt). Their thermal decompositions are studied by differential scanning calorimetry (DSC). Single crystals of both salts are suitable for an X-ray diffraction study at 180 K. Both isostructural salts crystallize in the monoclinic space group P2(1)/c (No. 14). The unit cell volume of [Pt(CO)(4)][Sb(2)F(11)](2) is smaller than that of [Pd(CO)(4)][Sb(2)F(11)](2) by about 0.4%. The cations [M(CO)(4)](2+), M = Pd, Pt, are square planar with only very slight angular and out-of-plane deviations from D(4)(h)() symmetry. The interatomic distances and bond angles for both cations are essentially identical. The [Sb(2)F(11)](-) anions in [M(CO)(4)][Sb(2)F(11)](2,) M = Pd, Pt, are not symmetry-related, and both pairs differ in their Sb-F-Sb bridge angles and their dihedral angles. There are in each salt four to five secondary interionic C- -F contacts per CO group. Of these, two contacts per CO group are significantly shorter than the sum of the van der Waals radii by 0.58 - 0.37 A. In addition, structural, and spectroscopic details of recently synthesized [Rh(CO)(4)][Al(2)Cl(7)] are reported. The cations [Rh(CO)(4)](+) and [M(CO)(4)](2+), M = Pd, Pt, are characterized by IR and Raman spectroscopy. Of the 16 vibrational modes (13 observable, 3 inactive) 10 (Pd, Pt) or 9 (Rh), respectively, are found experimentally. The vibrational assignments are supported by DFT calculations, which provide in addition to band positions also intensities of IR bands and Raman signals as well as internal force constants for the cations. (13)C NMR measurements complete the characterization of the square planar metal carbonyl cations. The extensive characterization of [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, reported here, allows a comparison to linear and octahedral [M(CO)(n)()][Sb(2)F(11)](2) salts [M = Hg (n = 2); Fe, Ru, Os (n = 6)] and their derivatives, which permit a deeper understanding of M-CO bonding in the solid state for superelectrophilic cations with [Sb(2)F(11)](-) or [SbF(6)](-) as anions.

IR and UV spectra of the matrix-isolated peroxy radicals CF3OO, trans-FC(O)OO, and cis-FC(O)OO

The peroxy radicals CF3OO and FC(O)OO are prepared in high yields by vacuum flash pyrolysis of ROONO2 or ROOOR (R=CF3, FC(O)), highly diluted in inert gases, and subsequent isolation in inert-gas matrices by quenching the product mixtures at low temperatures. The IR spectrum of FC(O)OO was observed for the first time and eight fundamentals as well as several combinations were measured and assigned for both cis and trans rotamers of FC(O)OO. Discrepancies in an earlier assignment of the fundamentals of CF3OO have been eliminated and its IR spectrum is reported fully. The matrix UV spectra of both peroxy radicals (X2A"--> 2(2)A" transition) are in agreement with the gas-phase spectra; however, there are differences in the absorption cross-sections, for which possible reasons are discussed. The X2A"--> 1(2)A' transitions in the near IR region are too weak to be detected with our instrumentation.

Vibrational Spectra of cis and trans Oxalyl Fluoride and Their Site-Selective IR-Induced Rotamerization in an Argon Matrix

A cis/trans equilibrium mixture of matrix-isolated oxalyl fluoride was irradiated with a narrowband tunable IR source in the 2nu (CO) spectral region (3680-3710 cm(-1)). Rotamerization of cis into trans and vice versa was achieved (even site selective) by selective IR pumping. The experiments strongly aided a detailed IR analysis of both rotamers. For a complete vibrational analysis, low-temperature Raman measurements were also performed. With the exception of the torsional vibration of cis oxalyl fluoride, all the fundamentals of both rotamers have been observed. Copyright 2000 Academic Press.

The synthesis and the molecular structure of hexakis(carbonyl)hexafluoroantimonato(V)tungsten(II) undecafluorodiantimonate(V), [W(CO)6(FSbF5)][Sb2F11]

The reaction of tungsten hexacarbonyl, W(CO)6, with antimony(V) fluoride, SbF5, in the conjugate Brønsted-Lewis superacid HF-SbF5 at 40 degrees C produces quantitatively the salt [W(CO)6(FSbF5)][Sb2F11] as the main product. The observed 2e- oxidation without any loss of CO is unprecedented. The cation [W(CO)6(FSbF5)]+ is seven coordinated with a distorted C2v capped trigonal prismatic structure. [W(CO)6(FSbF5)][Sb2F11] crystallizes in the monoclinic space group P21 (No. 4). a = 8.2051(12) A, b = 16.511(3) A, c = 8.1432(2) A, beta = 111.5967(6) degrees, V = 1025.8(2) A3, Z = 2. Number of reflections measured = 9112, unique 4410. Residuals on F, I > 3 sigma (I): R (Rw) = 0.023 (0.023). In the [W(CO)6(FSbF5)]+ cation the FSbF5 group is very tightly coordinated to tungsten with the bridging fluorine nearly equidistant from W and Sb. The details of the molecular structure are compared to those to polymeric [[Mo(CO)4]2(cis-mu-F2SbF4)3]x[Sb2F11]x reported by us very recently.

Syntheses, molecular structures, and vibrational spectra of chloropentacarbonylrhodium(III) and -iridium(III) undecafluorodiantimonate(V), [Rh(CO)5Cl][Sb2F11]2 and [Ir(CO)5Cl][Sb2F11]2: an experimental and density functional study

The reactions of either bis(mu-chloro)tetracarbonyldirhodium(I), [Rh(CO)2(mu-Cl)]2, or chlorotricarbonyliridium(I), [Ir(CO)3Cl]n, in the conjugate Brønsted-Lewis superacid HF-SbF5 and in a CO atmosphere, produce [Rh(CO)5Cl][Sb2F11]2 or [Ir(CO)5Cl][Sb2F11]2, respectively. In these oxidative carbonylation reactions, antimony(V) fluoride functions as an oxidizing agent. The reduced product is identified as 6SbF3.5SbF5. [Rh(CO)5Cl][Sb2F11]2 is obtained in the form of single crystals. Crystal data: monoclinic, space group P2(1) (No. 4); a = 9.721(1), b = 12.602(1), c = 10.538(1) A; beta = 106.51(1) degrees; V = 1237.7(2) A3; Z = 2; T = 300 K; R1 [I > 3 sigma (I)] = 0.0367, wR2 = 0.0739. Single crystals of [Ir(CO)5Cl][Sb2F11]2 are produced in small amounts from a solution of mer-Ir(CO)3(SO3F)3 in magic acid, HSO3F-SbF5. The possible source of chlorine will be discussed. Crystal data for [Ir-(CO)5Cl][Sb2F11]2: monoclinic, space group P2(1) (No. 4); a = 9.686(2), b = 12.585(2), c = 10.499(2) A; beta = 106.59(2) degrees; V = 1226.5(4) A3; Z = 2; T = 294 K; R1[I > 3 sigma (I)] = 0.032, Rw = 0.031. The bond lengths and bond angles are nearly identical in the two isostructural salts; however, the cell volume of [Ir(CO)5Cl][Sb2F11]2 is slightly smaller than that of [Rh(CO)5Cl][Sb2F11]2. The cations (point group C4v) feature unusually long M-C bonds (M = Rh, Ir) and correspondingly short CO bonds, as well as high CO stretching wavenumbers and high CO stretching force constants. The [Sb2F11]- anions are not symmetry related, and their dihedral and bridge angles differ slightly in both salts. There are significant interionic contacts in [Ir(CO)5Cl][Sb2F11]2 exclusively of the C-F type (about 2 for each C atom of the five carbonyl groups) resulting in extended structures. The vibrational spectra for both [M(CO)5Cl]2+ cations (M = Rh, Ir) are assigned with the help of density functional calculations, which also provide intensities for IR and Raman bands. While [Rh(CO)5Cl]2+ is the first cationic carbonyl derivative of Rh(III), the vibrational and structural parameters for [Ir(CO)5Cl]2+ are compared to data for [Ir(CO)6]3+ and mer-Ir(CO)3(SO3F)3.

Reaction of CF3 radicals with CO and O2. Isolation of bis(trifluoromethyl)peroxydicarbonate, CF3OC(O)OOC(O)OCF3, and identification of bis(trifluoromethyl)trioxydicarbonate, CF3OC(O)OOOC(O)OCF3

The synthesis of CF3OC(O)OOCF3, CF3OC(O)OOC(O)OCF3, and CF3OC(O)OOOC(O)OCF3 is accomplished by the photolysis of a mixture of (CF3CO)2O, CO, and O2. Pure CF3OC(O)OOCF3 and CF3OC(O)OOC(O)OCF3 are isolated after thermal decomposition of CF3OC(O)OOOC(O)OCF3 and repeated trap-to-trap condensation. Additional spectroscopic data of known CF3OC(O)OOCF3 are obtained by recording NMR, IR, Raman, and UV spectra: At room temperature CF3OC(O)OOC(O)OCF3 is stable for days in the liquid or gaseous state. The melting point is -38 degrees C, and the boiling point is extrapolated to 73 degrees C from the vapor pressure curve log p = 8.657-1958/T (p/mbar, T/K). The new compound is characterized by molecular mass determination and by NMR, vibrational, and UV spectroscopy. The new trioxide CF3OC(O)OOOC(O)OCF3 cannot be separated from CF3-OC(O)OOC(O)OCF3 by distillation due to their similar boiling points. CF3OC(O)OOOC(O)OCF3 decomposes at room temperature within hours into a mixture of CF3OC(O)OOC(O)OCF3, CF3OC(O)OOCF3, CO2, and O2. Its characterization is discussed along with a possible mechanism for formation and decomposition reactions.

The Tetrakis(carbonyl)dioxoosmium(VI) Cation: trans-

The first carbonyl compound of a transition metal in the oxidation state +6 was obtained by reductive carbonylation of OsO(4) in SbF(5). Through the use of extensive IR, NMR, and UV/Vis spectroscopic studies as well as density functional calculations it was determined that the trans-[OsO(2)(CO)(4)](2+) cation adopts the octahedral structure shown in the picture with trans oxygen atoms.

High-Resolution Infrared Fourier-Transform Spectroscopy and Rotational Constants of the nu4 Band of BrNO2

For the first time, high-resolution infrared gas-phase absorption spectra of the BrNO2 molecule were recorded using a Fourier-transform spectrometer. In this paper, the nu4 bands of the 79BrNO2 and 81BrNO2 isotopomers around 1670 cm-1 are investigated. Although the spectra are highly congested, rotational and centrifugal distortion constants for the ground and v4 = 1 states of 79BrNO2 and 81BrNO2 were determined. The results show that BrNO2 is a planar molecule of C2nu symmetry and confirm predictions from a recent ab initio study. Copyright 1998 Academic Press.

Study of the v3 = 1 State of 80SeF6 by Fourier Transform Spectroscopy

The Fourier transform infrared spectrum of monoisotopic 80SeF6 has been recorded in the 760-792 cm-1 region with an effective resolution of ca. 2.3 x 10(-3) cm-1. The 80SeF6 sample was prepared by burning monoisotopic 80Se powder (99.2%) in an excess of fluorine. The analysis of infrared transitions of the nu3 band enabled the determination of parameters of the Hamiltonian developed up to the third order and the fourth order. The standard deviation obtained is equal to 4 x 10(-4) cm-1 for the third-order development and 3.2 x 10(-4) cm-1 for the fourth-order development. In the two analyses, 2900 lines were assigned and fitted. Copyright 1997 Academic Press. Copyright 1997Academic Press

Synthesis and spectroscopic characterization of bis(trifluorophosphinyl)-gold(I) undecafluorodiantimonate(V) [Au(PF3)2][Sb2F11]

The synthesis of [Au(PF3)2][Sb2F11], the first example of a linear, thermally stable metal bis(trifluorophosphine) complex is achieved by CO substitution of [Au(CO)2][Sb2F11] by PF3. The [Au(PF3)2]+ cation can also be generated by reductive phosphorylation by an excess of PF3 in fluorosulfuric acid. Spectroscopic characterization involves 19F and 31P NMR in HSO3F and SO2 solution including spectral simulation by the WIN-DAISY method and FT-IR and Raman spectra. Spectroscopic evidence suggests that the metal–ligand bond involves predominantly σ-bonding with drastically reduced π-back-donation. Key words: gold(I) complex, linear; gold(I) PF3 complex; 31P NMR; 19F NMR; vibrational spectra.

Similarities and differences in couples' grief reactions following a miscarriage: results from a longitudinal study

Recent studies have documented grief and depressive reactions in women after a miscarriage. However, the men's reactions to their partner's experience have been neglected. In a controlled follow-up study, 56 couples were studied shortly after the miscarriage, and 6 (N = 47) and 12 months later (N = 45). The participants completed standardized questionnaires for depression, physical complaints, anxiety, and grief. Contrary to commonly held beliefs, men do grieve, but less intensely and enduringly than their partners. The manner in which they experience their grief is similar to that of the women, except that the men cry less and feel less need to talk about it. Unlike the women they do not react with an increased depressive reaction (compared to age- and sex-matched community control groups). Giving up their personal expectations, hopes for, and fantasies about the unborn child is a major source of grieving for both. Some men feel burdened by their wives' grief or depressive reactions. Conflicting reactions may affect the couples' interactions and promote depressive reactions in the women.

Syntheses and Vibrational and (13)C MAS-NMR Spectra of Bis(carbonyl)mercury(II) Undecafluorodiantimonate(V) ([Hg(CO)(2)][Sb(2)F(11)](2)) and of Bis(carbonyl)dimercury(I) Undecafluorodiantimonate ([Hg(2)(CO)(2)][Sb(2)F(11)](2)) and the Molecular Structure of [Hg(CO)(2)][Sb(2)F(11)](2)

The synthesis of bis(carbonyl)mercury(II) undecafluorodiantimonate(V), [Hg(CO)(2)][Sb(2)F(11)](2), and that of the corresponding mercury(I) salt [Hg(2)(CO)(2)][Sb(2)F(11)](2) are accomplished by the solvolyses of Hg(SO(3)F)(2) or of Hg(2)F(2), treated with fluorosulfuric acid, HSO(3)F, in liquid antimony(V) fluoride at 80 or 60 degrees C, respectively, in an atmosphere of CO (500-800 mbar). The resulting white solids are the first examples of metal carbonyl derivatives formed by a post-transition element. Both salts are characterized by FT-IR, FT-Raman, and (13)C-MAS-NMR spectroscopy. For [Hg(CO)(2)][Sb(2)F(11)], unprecedentedly high CO stretching frequencies (nu(av) = 2279.5 cm(-)(1)) and stretching force constant (f(r) = 21.0 +/- 0.1) x 10(2) Nm(-)(1)) are obtained. Equally unprecedented is the (1)J((13)C-(199)Hg) value of 5219 +/- 5 Hz observed in the (13)C MAS-NMR spectrum of the (13)C labeled isotopomers at delta = 168.8 +/- 0.1 ppm. The corresponding values (nu(av) = 2247 cm(-)(1), f(r) = (20.4 +/- 0.1) x 10(2) Nm(-)(1), (1)J((13)C-(199)Hg) = 3350 +/- 50 Hz and (2)J((13)C-(199)Hg) 850 +/- 50 Hz) are found for [Hg(2)(CO)(2)][Sb(2)F(11)](2), which has lower thermal stability (decomposition point in a sealed tube is 140 degrees C vs 160 degrees C for the Hg(II) compound) and a decomposition pressure of 8 Torr at 20 degrees C. The mercury(I) salt is sensitive toward oxidation to [Hg(CO)(2)][Sb(2)F(11)](2) during synthesis. Both linear cations (point group D(infinity)(h)()) are excellent examples of nonclassical (sigma-only) metal-CO bonding. Crystal data for [Hg(CO)(2)][Sb(2)F(11)](2): monoclinic, space group P2(1)/n; Z = 2; a = 7.607(2) Å; b = 14.001(3) Å; c = 9.730(2) Å; beta = 111.05(2) degrees; V = 967.1 Å(3); T = 195 K; R(F) = 0.035 for 1983 data (I(o) >/= 2.5sigma(I(o))) and 143 variables. The Hg atom lies on a crystallographic inversion center. The Hg-C-O angle is 177.7(7) degrees. The length of the mercury-carbon bond is 2.083(10) Å and of the C-O bond 1.104(12) Å respectively. The structure is stabilized in the solid state by a number of significant secondary interionic Hg- - -F and C- - -F contacts.