Phospha-s-triazines. I. Syntheses and properties of mono(diarylphospha)-s-triazines

A series of monophospha-s-triazines, namely l-diphenylphospha-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine, 1-diphenylphospha-3,5-bis[C₃F₇-[OCF(CF₃)CF₂]_xOCF(CF₃)]-2,4,6-triazine (x = 1 and 2), and the penta-fluorophenyl-substituted analogues were prepared, in yields of 50-75%, from the respective imidoylamidines and trichlorophosphoranes. The physical properties of the corresponding phenyl and pentafluorophenyl monophospha-s-triazines did not differ significantly; the perfluoroalkyl-substituted materials were low melting solids whereas the perfluoroalkyl-ether-containing compositions were liquids. Preliminary degradative studies showed these compounds to be thermally and oxidatively stable. The l-diphenylphospha-3,5-bis[C₃F₇OCF(CF₃)CF₂OCF(CF₃)]-2,4,6-triazine was found to be an effective anti-corrosion additive for perfluoroalkylether type fluids.     

Syntheses and degradations of fluorinated heterocyclics

Tris (perluoro-n-heptyl)-s-triazine, the perfluoroether substituted-s-triazine [C₃F₇OCF(CF₃)CF₂OCF(CF₃]₃C₃N₃, 1,4-bis[(5-perfluoro-n-heptyl)-1, 2,4-oxadiazolyl]benzene, its perfluoroalky ether substituted analogue, and 3,5-bis(perfluoro-n-heptyl)-1,2,4-oxadiazole were synthesized and characterized. Each of these compounds was subjected to thermal and oxidative degradation at 235 and 325°C and to hydrolytic degradation at 235°C. Two benzene derivatives decomposed completely during heating in nitrogen or air at 325°C, tris(perfluoro-n-heptyl)-s-triazine was quantitatively hydrolyzed at 235°C. The perfluoroalkyl ether substituted triazine and 3,5-bis(perfluoro-n-heptyl)-1,2,4- oxadiazole were found to be stable under all conditions employed as evidenced by practically quantitative recovery of the test samples.     

Bulky Polyfluorinated Terphenyldiphenylboranes: Water Tolerant Lewis Acids

Protocols for the synthesis of the bulky polyfluorinated triarylboranes 2,6-(C₆F₅)₂C₆F₃B(C₆F₅)₂ ( 1 ), 2,6-(C₆F₅)₂C₆F₃B[3,5-(CF₃)₂C₆H₃] ( 2 ), 2,4,6-(C₆F₅)₃C₆H₂B(C₆F₅)₂ ( 3 ), 2,4,6-(C₆F₅)₃C₆H₂B[3,5-(CF₃)₂C₆H₃] ( 4 ) were developed. All boranes are water tolerant and according to the Gutmann-Beckett method, 1 – 3 display Lewis acidities larger than that of the prominent B(C₆F₅)₃.     

Fluorocarbon derivatives of nitrogen. Part 14. Studies on some (CF3)2 no-substituted fluoroaromatics; thermal rearrangement of 4-[bis(trifluoromethyl)amino-oxy]tetrafluoropyridine

The sodium salt (CF₃)₂ NO⁻Na⁺ (I) [from (CF₃)₂NOH + NaH in Et₂O], is an alternative bis(trifluoromethyl)amino-oxylating agent to the adduct (CF₃)₂NOH.CsF (III). With pentafluoropyridine it affords 4-X.C₅F₄N (II) + 2,4-X₂.C₅F₃N (IV), [X = (CF₃)₂NO]. It has been used to obtain a number of new bis(trifluoromethyl)amino-oxy-compounds; $\text{i.e.}$ the following conversions have been effected: perfluoro-(4-isopropylpyridine)→ 2-X.C₅F₃N.CF(CF₃)₂-4 (V) + 2,6-X₂.C₅F₂N.CF(CF₃)₂-4 (VI); 3-chlorotetrafluoropyridine → 4-X.C₅F₃N.Cl-3 (VII) and 2-X.C₅F₃N.Cl-5 (VIII) (not separated) + 2,4-X₂.C₅F₂N.Cl-5 (IX), 3,5-dichlorotrifluoropyridine → 2- (XI) and 4-X.C₅F₂N.Cl₂-3,5 (X) (not separated) + 2,4-X₂.C₅FN.Cl₂-3,5 (XII); and perfluorotoluene → 4-X.C₆F₄.CF₃-1 (XIII). Hexafluorobenzene resisted attack by (CF₃)₂NONa under the conditions used with these aromatic substrates ($\text{ca}$ 20 °C). Static pyrolysis (125 °C) of 4-[bis(trifluoromethyl)amino-oxy]tetrafluoropyridine (II) gave a mixture of 6-bis(trifluoromethyl)amino]tetrafluoro-4-azacyclohexa-2, 4-dienone (XV) and 4-[bis(trifluoromethyl)amino]tetrafluoro-4-azacyclohexa-2,5-dienone (XVI). The ¹³C chemical shifts, assigned by analysis of ¹⁹F-coupled and ¹⁹F broad-band decoupled ¹³C n.m.r. spectra, are in accord with a +M effect similar to that of fluorine for a (CF₃)₂NO- substituent in the 2- and 4- positions of a polyfluoropyridine and a slightly smaller -I effect; the steric effect of (CF₃)₂NO on the shifts is less than that of chlorine. In contrast, a ring carbon carrying a (CF₃)₂CF- substituent is markedly shielded compared with one carrying fluorine, presumably by a steric effect.     

C6F5XeF, a versatile starting material in xenon-carbon chemistry

The molecules Ar_FXeF (Ar_F=C₆F₅, 2,4,6-C₆H₂F₃) with a more polar Xe-F bond than XeF₂ are versatile starting materials for substitution reactions. Fluorine-aryl substitutions with Cd(Ar_F)₂, C₆F₅SiMe₃/[F]⁻, and C₆F₅SiF₃ formed symmetric and/or asymmetric diarylxenon compounds. Applying C₆F₅BF₂, with a higher F⁻-affinity than the corresponding aryltrifluorosilane, in contrast gave the salt [RXe] [Ar_FBF₃]. Using the alkenyl and alkyl compounds CF₂=CFSiMe₃/[F]⁻, CF₃SiMe₃/[F]⁻, and Cd(CF₃)₂ in reactions with C₆F₅XeF, the perfluoroalkenyl or -alkyl transfer reagents were consumed without observing C₆F₅XeCF=CF₂ or C₆F₅XeCF₃ but the formation of Xe(C₆F₅)₂ (dismutation product) and in the latter case C₆F₅CF₃ (coupling product), gave hints of the desired intermediates.     

Addition-elimination reactions between phenyllithium and some perfluorovinylether compounds

Reactions between C₆H₅Li and C₃F₇OCFCF₂ (I) yield phenyl substituted perfluorovinylethers. Stoichiometry and reaction temperature dictate the degree of substitution. With each replacement of F^θ by C₆H₅^θ the subsequent substitutions require more forcing conditions. The F^θ is substituted easier than the C₃F₇O^θ during the addition-elimination reactions.     

Selective deoxygenation of gibberellic acid with fluoroarylborane catalysts

Reductive late-stage functionalization of gibberellic acid is reported using three fluoroarylborane Lewis acids; (B(C₆F₅)₃, B(3,5-C₆H₃(CF₃)₂), and B(2,4,6-C₆H₂F₃)₃) in combination with a tertiary silane and a borane (HBCat) reductant. In each case, C–O bond activation occurs, and different products are obtained depending on the reductant and catalyst employed.     

Heavy Carbene Analogues: Donor‐Free Bismuthenium and Stibenium Ions

Kinetically stabilized congeners of carbenes, R₂C, possessing six valence electrons (four bonding electrons and two non‐bonding electrons) have been restricted to Group 14 elements, R₂E (E=Si, Ge, Sn, Pb; R=alkyl or aryl) whereas isoelectronic Group 15 cations, divalent species of type [R₂E]⁺ (E=P, As, Sb, Bi; R=alkyl or aryl), were unknown. Herein, we report the first two examples, namely the bismuthenium ion [(2,6‐Mes₂C₆H₃)₂Bi][BAr^F₄] ( 1 ; Mes=2,4,6‐Me₃C₆H₂, Ar^F=3,5‐(CF₃)₂C₆H₃) and the stibenium ion [(2,6‐Mes₂C₆H₃)₂Sb][B(C₆F₅)₄] ( 2 ), which were obtained by using a combination of bulky meta‐terphenyl substituents and weakly coordinating anions.     

Halogen Complexes of Anionic N-Heterocyclic Carbenes

The lithium complexes [(WCA-NHC)Li(toluene)] of anionic N-heterocyclic carbenes with a weakly coordinating anionic borate moiety (WCA-NHC) reacted with iodine, bromine, or CCl₄ to afford the zwitterionic 2-halogenoimidazolium borates (WCA-NHC)X (X=I, Br, Cl; WCA=B(C₆F₅)₃, B{3,5-C₆H₃(CF₃)₂}₃; NHC=IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, or NHC=IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene). The iodine derivative (WCA-IDipp)I (WCA=B(C₆F₅)₃) formed several complexes of the type (WCA-IDipp)I ⋅ L (L=C₆H₅Cl, C₆H₅Me, CH₃CN, THF, ONMe₃), revealing its ability to act as an efficient halogen bond donor, which was also exploited for the preparation of hypervalent bis(carbene)iodine(I) complexes of the type [(WCA-IDipp)I(NHC)] and [PPh₄][(WCA-IDipp)I(WCA-NHC)] (NHC=IDipp, IMes). The corresponding bromine complex [PPh₄][(WCA-IDipp)₂Br] was isolated as a rare example of a hypervalent (10-Br-2) system. DFT calculations reveal that London dispersion contributes significantly to the stability of the bis(carbene)halogen(I) complexes, and the bonding was further analyzed by quantum theory of atoms in molecules (QTAIM) analysis.     

Mass spectra of perfluoroalkyl and perfluoroalkylether nitriles and acyl halides

Electron impact fragmentation patterns were obtained for perfluoroalkylether nitriles, C,F,O[CF(CF₃)CFIO]ICF(CF₃)CN (x = 1 and 2), perfluoroalkylether acyl halides, CSF,OCF(CF,)-CF₂OCF(CF₃)COX (X = F and Cl), n-perfluorooctanonitrile and n-perfiuorooctanoyl chloride. The perfluoroalkyl and perfluoroalkylether nitriles afforded ions characteristic of the nitrile function. The major fragment from the acyl chlorides was the [COClJ]+ ion; the presence of chlorine was evidenced also by rearrangement ions of the general form [R_fCl] t. The perfluoroalkylether compounds appeared to undergo a typical fragmentation governed by the cleavage of the carbon-oxygen bond.     

Phospha-S-triazines. IX. Chloro-substituted monophospha-S-triazines and derivatives

1-Dichlorophospha-3,5-bis(perfluoro-n-heptyl)-2,4,6- triazine and one of its perfluoroalkylether analogues were synthesized by interaction of phosphorus pentachloride with the respective imidoylamidines; subsequent replacement of the chloro- by azido groups proceeded readily. 1-Chloro(phenyl)- phospha-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine was prepared by a parallel process using tetrachlorophenylphosphorane instead of phosphorus pentachloride; phenoxy and stearyloxy derivatives were formed without difficulty. All the compounds, with the exception of 1-stearyloxy(phenyl)phospha-3,5-bis(perfluoro- n-heptyl)-2,4,6-triazine, exhibited the characteristic mass spectral fragmentation patterns associated with the monophospha- s-triazine ring system.     

Synthesis,Structure, and Lanthanide Derivatives of an Unusual Hexameric Alcohol: [2,4,6-(CF3)3C6H2CH2OH]6

Hitherto unknown 2,4,6-tris(trifluoromethyl)benzyl alcohol ( 3 ) was synthesized in 41 % yield by treatment of freshly prepared R_FLi ( 2 ) with paraformaldehyde (R_F = 2,4,6-tris(trifluoromethyl)phenyl). According to an X-ray diffraction study the crystal structure of 3 consists of S₆ symmetric cyclic hexamers [2,4,6-(CF₃)₃C₆H₂CH₂OH]₆. Deprotonation of 3 with NaN(SiMe₃)₂ in toluene afforded the unsolvated sodium alkoxide derivative R_FCH₂ONa ( 4 ). Homoleptic lanthanide alkoxides of the type Ln(OCH₂R_F)₃ (Ln = Nd ( 5 ), Sm ( 6 ), Yb ( 7 )) were made by treatment of Ln(C₅H₅)₃ with three equivalents of 3 . Similar reactions in a 1:1 molar ratio afforded the bis(cyclopentadienyl)lanthanide alkoxide derivatives (C₅H₅)₂Ln(OCH₂R_F) (Ln = Nd ( 8 ), Sm ( 9 ), Yb ( 10 )).     

Molybdenum(VI) Bis(imido) Complexes: From Frustrated Lewis Pairs to Weakly Coordinating Cations

Molybdenum(VI) bis(imido) complexes [Mo(NtBu)₂(L^R)₂] (R=H 1 a ; R=CF₃ 1 b ) combined with B(C₆F₅)₃ ( 1 a /B(C₆F₅)₃, 1 b /B(C₆F₅)₃) exhibit a frustrated Lewis pair (FLP) character that can heterolytically split H−H, Si−H and O−H bonds. Cleavage of H₂ and Et₃SiH affords ion pairs [Mo(NtBu)(NHtBu)(L^R)₂][HB(C₆F₅)₃] (R=H 2 a ; R=CF₃ 2 b ) composed of a Mo(VI) amido imido cation and a hydridoborate anion, while reaction with H₂O leads to [Mo(NtBu)(NHtBu)(L^R)₂][(HO)B(C₆F₅)₃] (R=H 3 a ; R=CF₃ 3 b ). Ion pairs 2 a and 2 b are catalysts for the hydrosilylation of aldehydes with triethylsilane, with 2 b being more active than 2 a . Mechanistic elucidation revealed insertion of the aldehyde into the B−H bond of [HB(C₆F₅)₃]⁻. We were able to isolate and fully characterize, including by single-crystal X-ray diffraction analysis, the inserted products Mo(NtBu)(NHtBu)(L^R)₂][{PhCH₂O}B(C₆F₅)₃] (R=H 4 a ; R=CF₃ 4 b ). Catalysis occurs at [HB(C₆F₅)₃]⁻ while [Mo(NtBu)(NHtBu)(L^R)₂]⁺ (R=H or CF₃) act as the cationic counterions. However, the striking difference in reactivity gives ample evidence that molybdenum cations behave as weakly coordinating cations (WCC).     

Preparation of ferrocenes with high fluorous-phase affinities

The reaction of 1,1′-bis(pentafluorophenyl)ferrocene with fluorous alkoxides having the general formula NaOCH₂(CF₂)_nCF₃ (n = 0, 2, 5, 7, and 8) afforded a series of ferrocenes of general formula {η⁵-4-[CF₃(CF₂)_nCH₂O]C₆F₄C₅H₄}₂Fe (1). The reaction of 1,1′-bis(4-tetrafluoropyridyl)ferrocene with the same fluorous alkoxides afforded a series of ferrocenes of general formula (η⁵-4-{2,6-[CF₃(CF₂)_nCH₂O]₂C₅F₂N}C₅H₄)₂Fe (2). Perfluoro(methylcyclohexane)/toluene partition coefficients increase with the number (2 or 4) and length (n) of the fluorous substituent. Complexes 1a and 2a (both n = 0) were structurally characterized.     

D–π–A Triarylboron Compounds with Tunable Push–Pull Character Achieved by Modification of Both the Donor and Acceptor Moieties

The push–pull character of a series of donor–bithienyl–acceptor compounds has been tuned by adopting triphenylamine or 1,1,7,7‐tetramethyljulolidine as a donor and B(2,6‐Me₂‐4‐RC₆H₂)₂ (R=Me, C₆F₅ or 3,5‐(CF₃)₂C₆H₃) or B[2,4,6‐(CF₃)₃C₆H₂]₂ as an acceptor. Ir‐catalyzed C?H borylation was utilized in the derivatization of the boryl acceptors and the tetramethyljulolidine donor. The donor and acceptor strengths were evaluated by electrochemical and photophysical measurements. In solution, the compound with the strongest acceptor, B[2,4,6‐(CF₃)₃C₆H₂]₂ ((FMes)₂B), has strongly quenched emission, while all other compounds show efficient green to red (Φ_F=0.80–1.00) or near‐IR (NIR; Φ_F=0.27–0.48) emission, depending on solvent. Notably, this study presents the first examples of efficient NIR emission from three‐coordinate boron compounds. Efficient solid‐state red emission was observed for some derivatives, and interesting aggregation‐induced emission of the (FMes)₂B‐containing compound was studied. Moreover, each compound showed a strong and clearly visible response to fluoride addition, with either a large emission‐color change or turn‐on fluorescence.     

Perfluororganozink-verbindungen: darstellung und eigenschaften von (Rf)2Zn-komplexen (Rf = CF3, C2F5, C3F7, C6F5) [1]

A new method for the preparation of bis(perfluoroorgano) zinc compounds is described: CF₃I and C₆F₅I react with dialkylzinc in the presence of a Lewis base quantitatively to give (CF₃)₂Zn and (C₆F₅)₂Zn complexes, while the analogous reactions with C₂F₅I and iC₃F₇I do not yield the pure compounds. ¹H, ¹⁹F n.m.r, i.r. and Raman spectra are presented.     

Synthesis,Characterization, and Application of Two Al(ORF)3 Lewis Superacids

We report herein the synthesis and full characterization of the donor‐free Lewis superacids Al(OR^F)₃ with OR^F=OC(CF₃)₃ ( 1 ) and OC(C₅F₁₀)C₆F₅ ( 2 ), the stabilization of 1 as adducts with the very weak Lewis bases PhF, 1,2‐F₂C₆H₄, and SO₂, as well as the internal C? F activation pathway of 1 leading to Al₂(F)(OR^F)₅ ( 4 ) and trimeric [FAl(OR^F)₂]₃ ( 5 , OR^F=OC(CF₃)₃). Insights have been gained from NMR studies, single‐crystal structure determinations, and DFT calculations. The usefulness of these Lewis acids for halide abstractions has been demonstrated by reactions with trityl chloride (NMR; crystal structures). The trityl salts allow the introduction of new, heteroleptic weakly coordinating [Cl‐Al(OR^F)₃]^? anions, for example, by hydride or alkyl abstraction reactions.     

Isolation and Structural X‐ray Investigation of Perfluoroalkyl Derivatives of Six Cage Isomers of C84

Perfluoroalkylation of a higher fullerene mixture with CF₃I or C₂F₅I, followed by HPLC separation of CF₃ and C₂F₅ derivatives, resulted in the isolation of several C₈₄(R^F)_n (n=12, 16) compounds. Single‐crystal X‐ray crystallography with the use of synchrotron radiation allowed structure elucidation of eight C₈₄(R^F)_n compounds containing six different C₈₄ cages (the number of the C₈₄ isomer is given in parentheses): C₈₄ (23)(C₂F₅)₁₂ ( I ), C₈₄ (22)(CF₃)₁₆ ( II ), C₈₄ (22)(C₂F₅)₁₂ ( III ), C₈₄ (11)(C₂F₅)₁₂ ( IV ), C₈₄ (16)(C₂F₅)₁₂ ( V ), C₈₄ (4)(CF₃)₁₂ ( VI with toluene and VII with hexane as solvate molecules), and C₈₄ (18)(C₂F₅)₁₂ ( VIII ). Whereas some connectivity patterns of C₈₄ isomers (22, 23, 11) had previously been unambiguously confirmed by different methods, derivatives of C₈₄ isomers numbers 4, 16, and 18 have been investigated crystallographically for the first time, thus providing direct proof of the connectivity patterns of rare C₈₄ isomers. General aspects of the addition of R^F groups to C₈₄ cages are discussed in terms of the preferred positions in the pentagons under the formation of chains, pairs, and isolated R^F groups.     

Positional disorder manifested as compositional in a pseudo‐C2‐symmetrical Pd complex

The title compound {2‐[3,5‐bis(trifluoromethyl)‐1H‐pyrazol‐1‐ylmethyl]‐6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐ylmethyl)pyridine}methylpalladium(II) tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate, [Pd(C₁₈H₁₈F₆N₅)][B(C₈H₃F₆)₄], crystallizes as discrete cations and anions. The cation possesses a pseudo‐twofold axis about which positional disorder of the tridentate ligand is exhibited. The four substituents on the two pyrazole rings exhibit CH₃/CF₃ disorder, while all other atoms are ordered. Thus, this disorder can be conveniently described `locally' as compositional, while `globally' for the entire tridentate ligand it is positional. The anion also exhibits typical rotational positional disorder in three of the CF₃ groups. All disordered CF₃ groups were modeled with idealized C_3v geometry.     

The synthesis, structure and ethene polymerization activity of octahedral heteroligated (salicylaldiminato)(β-enaminoketonato)titanium complexes: The X-ray crystal structure of {3-Bu-2-(O)C6H3CHN(Ph)}{(Ph)NC(Me)C(H)C(Me)O}TiCl2

Treatment of the mono(salicylaldiminato)titanium complexes {3-Bu^t-2-(O)C₆H₃CHN(Ar)}TiCl₃(THF) (Ar = C₆H₅, 2,4,6-Me₃C₆H₂ or C₆F₅) with the potassium β-enaminoketonates (C₆H₅)NC(CH₃)C(H)C(R)OK (R = CH₃, CF₃) yielded the first examples of heteroligated (salicylaldiminato) (β-enaminoketonato)titanium dichloride complexes. The complex {3-Bu^t-2-(O)C₆H₃CHN(C₆H₅)}{(C₆H₅)NC(CH₃)C(H)C(CH₃)O}TiCl₂ was structurally characterized by X-ray diffraction and has an orientation with trans-O,O,cis-Cl,Cl, cis-N,N distorted octahedral geometry. These complexes polymerize ethene when activated with MAO; the highest productivity, 5650 kg PE (mol metal)⁻¹ h⁻¹ atm⁻¹, was afforded by {3-Bu^t-2-(O)C₆H₃CHN(C₆F₅)}{(C₆H₅)NC(CH₃)C(H)C(CF₃)O}TiCl₂ at 60 °C.