Fluorous phase-transfer activation of catalysts: application of a new rate-enhancement strategy to alkene metathesis

Reactions of the bis(pyridine) complex (H2IMes)(Py)2(Cl)2Ru(=CHPh) and fluorous phosphines P(CH2CH2R(fn))3 (n = a, 6; b, 8; c, 10; R(fn) = (CF2)(n-1)CF3) give (H2IMes)(P(CH2CH2R(fn))3)(Cl)2Ru(=CHPh) (2a-c, 64-73%), which are analogs of Grubbs' second generation catalyst and effective alkene metathesis catalysts under organic monophasic and fluorous/organic biphasic conditions. The latter give rate accelerations, which are believed to arise from phase transfer of the dissociated fluorous phosphine.     

"Heavy fluorous" cyclopentadienes and cyclopentadienyl complexes with three to five ponytails: facile syntheses from polybromocyclopentadienyl complexes, phase properties, and electronic effects

The reactions between [(eta5-C5H(5-x)Br(x))M(CO)3] (M = Re, Mn; x = 1, 3, 4, 5) and [IZn[(CH2)(n)R(f8)]] (n = 2, 3; R(f8) = (CF2)7CF3) in the presence of [Cl2PdL2] catalysts give the title complexes [[eta5-C5H(5-x)[(CH2)(n)R(f8)]x]M(CO)3]. In the case of x = 5, the major product is actually [[eta5-C5H[(CH2)(n)R(f8)]4]M(CO)3], in which one of the bromides has been substituted by hydride. Minor amounts of multiple hydride substitution products are formed, all of them readily separable on fluorous silica gel. Irradiation of the manganese complexes in CF3C6H5/MeOH/ether gives uncoordinated cyclopentadienes, which can be deprotonated and reattached to other metals. Partition coefficients have been measured (CF3C6F11/toluene): complexes with three or more ponytails are highly fluorophilic, with values of > 99.8: < 0.2. The IR [symbol: see text]CO bands have been used to probe the inductive effects of the ponytails at the metal centers.     

1H,1H,2H,2H-perfluoroalkyl-functionalization of Ni(II), Pd(II), and Pt(II) mono- and diphosphine complexes: minimizing the electronic consequences for the metal center

A series of fluorous derivatives of group 10 complexes MCl(2)(dppe) and [M(dppe)(2)](BF(4))(2) (M = Ni, Pd or Pt; dppe = 1,2-bis(diphenylphosphino)ethane) and cis-PtCl(2)(PPh(3))(2) was synthesized. The influence of para-(1H,1H,2H,2H-perfluoroalkyl)dimethylsilyl-functionalization of the phosphine phenyl groups of these complexes, as studied by NMR spectroscopy, cyclovoltammetry (CV), XPS analyses, as well as DFT calculations, points to a weak steric and no significant inductive electronic effect. The steric effect is most pronounced for M = Ni and leads in the case of NiCl(2)(1c) (3c) and [Ni(1c)(2)](BF(4))(2) (7c) (1c = [CH(2)P[C(6)H(4)(SiMe(2)CH(2)CH(2)C(6)F(13))-4](2)](2)) to a tetrahedral distortion from the expected square planar geometry. The solubility behavior of NiCl(2)[CH(2)P[C(6)H(4)(SiMe(3-b)(CH(2)CH(2)C(x)F(2x+1)b)-4](2)](2) (3: b = 1-3; x = 6, 8) in THF, toluene, and c-C(6)F(11)CF(3) was found to follow the same trends as those observed for the free fluorous ligands 1. A similar correlation between the partition coefficient (P) of complexes 3 and free 1 was observed in fluorous biphasic solvent systems, with a maximum value obtained for 3f (b = 3, x = 6, P = 23 in favor of the fluorous phase).     

Syntheses and reactivities of disubstituted and trisubstituted fluorous pyridines with high fluorous phase affinities: solid state,liquid crystal,and ionic liquid-phase properties

Reactions of 2,6-dibromo-, 3,5-dibromo-, and 2,4,6-tribromopyridine with IZnCH(2)CH(2)R(f8) (R(f8) = (CF(2))(7)CF(3)) in THF at 65 degrees C in the presence of trans-Cl(2)Pd(PPh(3))(2) (5 mol %) gave the fluorous pyridines 2,6- and 3,5-NC(5)H(3)(CH(2)CH(2)R(f8))(2) (1 and 2; 85%, 31%) and 2,4,6-NC(5)H(2)(CH(2)CH(2)R(f8))(3) (3, 61%). Reaction of 2,6-pyridinedicarboxaldehyde with [Ph(3)PCH(2)CH(2)R(f8)](+)I(-)/K(2)CO(3) (p-dioxane/H(2)O, 95 degrees C) gave 2,6-NC(5)H(3)(CH[double bond]CHCH(2)R(f8))(2) (95%; 70:30 ZZ/ZE), which was treated with H(2) (1 atm, 12 h) and 10% Pd/C to yield 2,6-NC(5)H(3)(CH(2)CH(2)CH(2)R(f8))(2) (5, 95%), a higher homologue of 1. Longer reaction times afforded piperidine cis-2,6-HNC(5)H(8)(CH(2)CH(2)CH(2)R(f8))(2) (6, 98%). The stereochemistry was established by NMR analysis of the N-benzylpiperidine. Pyridines 1-3 and 5 are low-melting white solids with CF(3)C(6)F(11)/toluene partition coefficients (24 degrees C) of 93.8:6.2, 93.9:6.1, >99.7:<0.3, and 90.4:9.6, respectively (6, 93.6:6.4). Reaction of 1 and CF(3)SO(3)H gave a pyridinium salt, and Cl(2)Pd(NCCH(3))(2) (0.5 equiv) yielded trans-Cl(2)Pd(1)(2). The crystal structure of the former, which also exhibited liquid crystalline and ionic liquid phases, was determined.     

Convenient syntheses of fluorous aryl iodides and hypervalent iodine compounds: ArI(L)n reagents that are recoverable by simple liquid/liquid biphase workups,and applications in oxidations of hydroquinones

Iodinations of the ortho, meta, and para fluorous arenes (R(f8)CH(2)CH(2)CH(2))(2)C(6)H(4) (R(f8)=(CF(2))(7)CF(3)) with I(2)/H(5)IO(6) in AcOH/H(2)SO(4)/H(2)O give 3,4-(R(f8)CH(2)CH(2)CH(2))(2)C(6)H(3)I (5) and the analogous 2,4- (6) and 2,5- (7) isomers, respectively. Spectroscopic yields are >90 %, but 5 and 7 must be separated by chromatography from by-products (yields isolated: 70 %, 97 %, 61 %). Reaction of 1,3,5-(R(f8)CH(2)CH(2)CH(2))(3)C(6)H(3) with PhI(OAc)(2)/I(2) gives 2,4,6-(R(f8)CH(2)CH(2)CH(2))(3)C(6)H(2)I (8) on multigram scales in 97 % yield. The CF(3)C(6)F(11)/toluene partition coefficients of 5-8 (24 degrees C: 69.5:30.5 (5), 74.7:25.3 (6), 73.9:26.1 (7), 98.0:2.0 (8)) are lower than those of the precursors, but CF(3)C(6)F(11)/MeOH gives higher values (97.0:3.0 (5), 98.6:1.4 (6), 98.0:2.0 (7), >99.3:<0.3 (8)). Reactions of 5-8 with excess NaBO(3) in AcOH yield the corresponding ArI(OAc)(2) species 9-12 (9, 85 % as a 90:10 9/5 mixture; 10, 97 %; 11, 95 %; 12, 93 % as a 95:5 12/8 mixture). These rapidly oxidize 1,4-hydroquinones in MeOH. Subsequent additions of CF(3)C(6)F(11) give liquid biphase systems. Solvent removal from the CF(3)C(6)F(11) phases gives 5-8 in >99-98 % yields, and solvent removal from the MeOH phases gives the quinone products, normally in >99-95 % yields. The recovered compounds 5-8 are easily reoxidized to 9-12 and used again.     

Syntheses, derivatives, solubility, and interfacial properties of 2-methyl-2-polyfluoroalkenyloxymethyl-1,3-propanediols: potential building blocks for syntheses of amphiphatic macromolecules

2-Hydroxymethyl-2-methyl-1,3-propanediol (A) was reacted with (Me(3)Si)(2)NH and toluenesulfonyl chloride (TsCl) to give mainly CH(3)C(CH(2)OSiMe(3))(3) (1), and CH(3)C(CH(2)OTs)(3) (2), respectively. With allyl bromide, the products were CH(3)C(CH(2)OCH(2)CH[double bond]CH(2))(2)(CH(2)OH) (3) and CH(3)C(CH(2)OCH(2)CH[double bond]CH(2))(CH(2)OH)(2) x H(2)O (4). The reactions of 4 with perfluoroalkyl iodides (R(f)I) were catalyzed by Cu(I)Cl to form 2-methyl-2-polyfluoroalkenyloxymethyl-1,3-propanediols: (R(f)CH=CHCH(2)OCH(2))C(Me)(CH(2)OH)(2) [R(f) = C(4)F(9) (5), C(8)F(17) (6), and (CF(2)CF(2))(4)OCF(CF(3))(2) (7)]. Reduction of 5 and 6 with hydrogen gave two new 2-methyl-2-polyfluoroalkyloxymethyl-1,3-propanediols, 8 and 9. The sodium salt of 9 was reacted with allyl bromide or acetyl chloride to form (C(8)F(17)CH(2)CH(2)CH(2)OCH(2))C(Me)(CH(2)OX)(CH(2)OH)(2) [where X = CH(2)CH=CH(2) (10) or C(O)CH(3) (12)] and (C(8)F(17)CH(2)CH(2)CH(2)OCH(2))C(Me)(CH(2)OX)(2) [where X = CH(2)CH[double bond]CH(2) (11) or C(O)CH(3) (13)]. Reaction of tolenesulfonyl chloride with 7 gave the monotosylate, 14, as the sole product. With 4-trifluoromethylbenzyl bromide, the sodium salt of 4 gave (4-CF(3)C(6)H(4)CH(2)OCH(2))C(Me)(CH(2)CH[double bond]CH(2))(CH(2)OH) x H(2)O (15). The compounds were characterized by NMR ((1)H, (13)C, (19)F, (29)Si), GC-MS, and high-resolution MS or elemental analyses. UV evidence was obtained for partitioning of 9, 12, 14, and 15 between perfluorodecalin and n-octanol. The test compounds acted as surfactants by facilitating the solubility of phenol and Si(CH[double bond]CH(2))(4) in perfluorodecalin. The single-crystal X-ray structure of 8 was also obtained. It crystallized in the monoclinic space group P2(1)/c, and unit cell dimensions were a = 24.966(2) A (alpha = 90), b = 6.1371(6) A (beta = 100.730(2)), and c = 10.5669(10) A (gamma = 90).     

Thermodynamics, kinetics, and mechanism of (silox)3M(olefin) to (silox)3M(alkylidene) rearrangements (silox = tBu3SiO; M = Nb, Ta)

Olefin complexes (silox)(3)M(ole) (silox = (t)Bu(3)SiO; M = Nb (1-ole), Ta (2-ole); ole = C(2)H(4), C(2)H(3)Me, C(2)H(3)Et, C(2)H(3)C(6)H(4)-p-X (X = OMe, H, CF(3)), C(2)H(3)(t)Bu, (c)C(5)H(8), (c)C(6)H(10), (c)C(7)H(10) (norbornene)) rearrange to alkylidene isomers (silox)(3)M(alk) (M = Nb (1=alk), Ta (2=alk); alk = CHMe, CHEt, CH(n)Pr, CHCH(2)C(6)H(4)-p-X (X = OMe, H, CF(3) (Ta only)), CHCH(2)(t)Bu, (c)C(5)H(8), (c)C(6)H(10), (c)C(7)H(10) (norbornylidene)). Kinetics and labeling experiments suggest that the rearrangement proceeds via a delta-abstraction on a silox CH bond by the beta-olefin carbon to give (silox)(2)RM(kappa(2)-O,C-OSi(t)Bu(2)CMe(2)CH(2)) (M = Nb (4-R), Ta (6-R); R = Me, Et, (n)Pr, (n)Bu, CH(2)CH(2)C(6)H(4)-p-X (X = OMe, H, CF(3) (Ta only)), CH(2)CH(2)(t)Bu, (c)C(5)H(9), (c)C(6)H(11), (c)C(7)H(11) (norbornyl)). A subsequent alpha-abstraction by the cylometalated "arm" of the intermediate on an alpha-CH bond of R generates the alkylidene 1=alk or 2=alk. Equilibrations of 1-ole with ole' to give 1-ole' and ole, and relevant calculations on 1-ole and 2-ole, permit interpretation of all relative ground and transition state energies for the complexes of either metal.     

C-H activation and C=C double bond formation reactions in iridium ortho-methyl arylphosphane complexes

The Vaska-type iridium(I) complex [IrCl(CO){PPh(2)(2-MeC(6)H(4))}(2)] (1), characterized by an X-ray diffraction study, was obtained from iridium(III) chloride hydrate and PPh(2)(2,6-MeRC(6)H(3)) with R=H in DMF, whereas for R=Me, activation of two ortho-methyl groups resulted in the biscyclometalated iridium(III) compound [IrCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)] (2). Conversely, for R=Me the iridium(I) compound [IrCl(CO){PPh(2)(2,6-Me(2)C(6)H(3))}(2)] (3) can be obtained by treatment of [IrCl(COE)(2)](2) (COE=cyclooctene) with carbon monoxide and the phosphane in acetonitrile. Compound 3 in CH(2)Cl(2) undergoes intramolecular C-H oxidative addition, affording the cyclometalated hydride iridium(III) species [IrHCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}] (4). Treatment of 2 with Na[BAr(f) (4)] (Ar(f)=3,5-C(6)H(3)(CF(3))(2)) gives the fluxional cationic 16-electron complex [Ir(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)][BAr(f) (4)] (5), which reversibly reacts with dihydrogen to afford the delta-agostic complex [IrH(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}][BAr(f)(4)] (6), through cleavage of an Ir-C bond. This species can also be formed by treatment of 4 with Na[BAr(f)(4)] or of 2 with Na[BAr(f)(4)] through C-H oxidative addition of one ortho-methyl group, via a transient 14-electron iridium(I) complex. Heating of the coordinatively unsaturated biscyclometalated species 5 in toluene gives the trans-dihydride iridium(III) complex [IrH(2)(CO){PPh(2)(2,6-MeC(6)H(3)CH=CHC(6)H(3)Me-2,6)PPh(2)}][BAr(f) (4)] (7), containing a trans-stilbene-type terdentate ligand, as result of a dehydrogenative carbon-carbon double bond coupling reaction, possibly through an iridium carbene species.     

Phosphite copper(I) trifluoroacetates [((RO)3P)mCuO2CCF3] (m = 1, 2, 3): synthesis, solid state structures and their potential use as CVD precursors

Metal-organics [((RO)(3)P)(m)CuO(2)CCF(3)] (R = CH(3): 11a, m = 1; 11b, m = 2; 11c, m = 3. R = CH(2)CH(3): 12a, m = 1; 12b, m = 2; 12c, m = 3. R = CH(2)CF(3): 13a, m = 1; 13b, m = 2; 13c, m = 3) are either accessible by the reaction of [((RO)(3)P)(m)CuCl] (R = CH(3): 5a, m = 1; 5b, m = 2; 5c, m = 3. R = CH(2)CH(3): 6a, m = 1; 6b, m = 2; 6c, m = 3) with [KO(2)CCF(3)] (7), or treatment of [Cu(2)O] (8) with HO(2)CCF(3) (9) and P(OR)(3) (2, R = CH(3); 3, R = CH(2)CH(3); 4, R = CH(2)CF(3)). (31)P{(1)H} NMR spectra [((CH(3)O)(3)P)(m)CuO(2)CCF(3)] (m = 1, 1.5, 2, 2.5, 3, 3.5, and 4) have been studied at 25 and -80 °C showing phosphite ligand exchange in solution. The molecular structures of 11a and 13a-13c in the solid state are reported. Complexes 11a and 13a are tetramers featuring μ-η(2)(1κO:2κO')- and μ(3)-η(2)(1κO:2κO':3κO')-(11a) or μ(3)-η(2)(1κO:2κO':3κO')-bonded O(2)CCF(3) ligands (13a) with the Cu(I) ions being part of CuPO(2) and CuPO(3) units (11a), while in 13a solely a CuPO(3) moiety is present. Skeletal isomerism of 11a vs. 13a is discussed. Compound 13b is dimeric ({CuP(2)O(2)}(2)) with pseudo-tetrahedral Cu environments and μ-η(2)(1κO:2κO')O(2)CCF(3) functionalities. In monomeric 13c the O(2)CCF(3) ligand is η(1)(κO)-bonded to a tetra-coordinated Cu(i) ion. The thermal solid state properties of 11, 12 and 13 were studied by Thermo Gravimetry (TG). These complexes decompose by phosphite elimination, decarboxylation and dealkylation. Hot-wall Chemical Vapour Deposition (CVD) experiments were carried out at 380 °C using 11c as precursor for the deposition of copper onto pieces of TiN-coated oxidized silicon substrates. Copper layers of high purity were obtained with grain sizes between 200-1200 nm.     

Parallel synthesis and study of fluorous biphasic partition coefficients of 1H,1H,2H,2H-perfluoroalkylsilyl derivatives of triphenylphosphine: a statistical approach

A library of fluorous, (1H,1H,2H,2H-perfluoroalkyl)silyl-substituted derivatives of triphenylphosphine, Ph(3-a)P[C(6)H(5-y)[SiMe(3-b)(CH(2)CH(2)C(x)F(2x+1))(b)](y)-pos](a) [a = 1-3; b = 1-3; x = 4, 6, 8, or 10; pos = 3, 4 (y = 1) or 3,5 (y = 2)], was prepared using parallel synthetic techniques. Upon variation of these four parameters, a total of 108 different fluorous phosphines can be synthesized. Using factorial design, 37 phosphines were selected and their partition coefficients in the typical fluorous biphasic solvent system PFMCH/toluene (PFMCH = perfluoromethylcyclohexane) determined. By fitting of the partition coefficient data to linear functions of the parameters a, b, and x, the partition coefficients of the remaining 71 fluorous phosphines, which were not prepared, could be predicted. Using this approach, some unexpected trends in the dependence of the partition coefficient on variations of the four parameters became clear, resulting in a better understanding of the optimum fluorous substitution pattern for obtaining the highest partition coefficient (P). In this way, the partition coefficient was increased by 2 orders of magnitude, i.e., from the initial value P = 7.8 for 1(3, 2, 6, C4) to P > 238 for 1(2, 3, 6, C3C5). Para- and 3,5-substituted phosphines showed irregular behavior in the sense that elongation or increase of the number of perfluoroalkyl tails did not necessarily lead to higher partition coefficients. Particularly high values were found for phosphines containing a total of 72 fluorinated carbon atoms on the meta position(s) of the aryl rings. Linear relationships were found between the predicted log P of 1(a, b, x, C4) and the experimentally determined log P values of fluorous diphosphines [CH(2)P[C(6)H(4)(SiMe(3-b)(CH(2)CH(2)C(6)F(13))(b))-4](2)](2) and monophosphines Ph(3-a)P(C(6)H(4)(CH(2)CH(2)C(6)F(13))-4)(a). One of the most fluorophilic phosphines, i.e., 1(3, 1, 8, C3C5), was applied and efficiently recycled in rhodium-catalyzed, fluorous hydrosilylation of 1-hexene by HSiMe(2)Ph using PFMCH as the fluorous phase and the substrates as the organic phase. It was demonstrated that a higher partition coefficient of the ligand in PFMCH/toluene at 0 degrees C indeed resulted in less leaching of both the catalyst and the free ligand during phase separation.     

Reactions of halofluorocarbons with group 6 complexes M(C(5)H(5))(2)L (M = Mo, W; L = C(2)H(4), CO). Fluoroalkylation at molybdenum and tungsten, and at cyclopentadienyl or ethylene ligands.

The molybdenum(II) and tungsten(II) complexes [MCp(2)L] (Cp = eta(5)-cyclopentadienyl; L = C(2)H(4), CO) react with perfluoroalkyl iodides to give a variety of products. The Mo(II) complex [MoCp(2)(C(2)H(4))] reacts with perfluoro-n-butyl iodide or perfluorobenzyl iodide with loss of ethylene to give the first examples of fluoroalkyl complexes of Mo(IV), MoCp(2)(CF(2)CF(2)CF(2)CF(3))I (8) and MoCp(2)(CF(2)C(6)F(5))I (9), one of which (8) has been crystallographically characterized. In contrast, the CO analogue [MoCp(2)(CO)] reacts with perfluorobenzyl iodide without loss of CO to give the crystallographically characterized salt, [MoCp(2)(CF(2)C(6)F(5))(CO)](+)I(-) (10), and the W(II) ethylene precursor [WCp(2)(C(2)H(4))] reacts with perfluorobenzyl iodide without loss of ethylene to afford the salt [WCp(2)(CF(2)C(6)F(5))(C(2)H(4))](+)I(-) (11). These observations demonstrate that the metal-carbon bond is formed first. In further contrast the tungsten precursor [WCp(2)(C(2)H(4))] reacts with perfluoro-n-butyl iodide, perfluoro-iso-propyl iodide, and pentafluorophenyl iodide to give fluoroalkyl- and fluorophenyl-substituted cyclopentadienyl complexes WCp(eta(5)-C(5)H(4)R(F))(H)I (12, R(F) = CF(2)CF(2)CF(2)CF(3); 15, R(F) = CF(CF(3))(2); 16, R(F) = C(6)F(5)); the Mo analogue MoCp(eta(5)-C(5)H(4)R(F))(H)I (14, R(F) = CF(CF(3))(2)) is obtained in similar fashion. The tungsten(IV) hydrido compounds react with iodoform to afford the corresponding diiodides WCp(eta(5)-C(5)H(4)R(F))I(2) (13, R(F) = CF(2)CF(2)CF(2)CF(3); 18, R(F) = CF(CF(3))(2); 19, R(F) = C(6)F(5)), two of which (13 and 19) have been crystallographically characterized. The carbonyl precursors [MCp(2)(CO)] each react with perfluoro-iso-propyl iodide without loss of CO, to afford the exo-fluoroalkylated cyclopentadiene M(II) complexes MCp(eta(4)-C(5)H(5)R(F))(CO)I (21, M = Mo; 22, M = W); the exo-stereochemistry for the fluoroalkyl group is confirmed by an X-ray structural study of 22. The ethylene analogues [MCp(2)(C(2)H(4))] react with perfluoro-tert-butyl iodide to yield the products MCp(2)[(CH(2)CH(2)C(CF(3))(3)]I (25, M = Mo; 26, M = W) resulting from fluoroalkylation at the ethylene ligand. Attempts to provide positive evidence for fluoroalkyl radicals as intermediates in reactions of primary and benzylic substrates were unsuccessful, but trapping experiments with CH(3)OD (to give R(F)D, not R(F)H) indicate that fluoroalkyl anions are the intermediates responsible for ring and ethylene fluoroalkylation in the reactions of secondary and tertiary fluoroalkyl substrates.     

Light, medium, and heavy fluorous triarylphosphines exhibit comparable reactivities to triphenylphosphine in typical reactions of triarylphosphines

[reaction: see text] The relative reactivities of triphenylphosphine (PPh(3)) and three fluorous triarylphosphines [(p-R(F)(CH(2))(2)C(6)H(4))(n)PPh(3)(-)(n), where n = 1-3] have been compared in internal competition experiments. Product ratios were determined by (31)P NMR spectroscopy. The four phosphines have about the same reactivities in oxidation, alkylation, and Staudinger reactions and give comparable yields in a preparative Mitsunobu reaction. Previously observed rate and yield differences in Staudinger reactions of the fluorous phosphines are attributed to solubility effects, not reactivity differences. A light fluorous phosphine [(p-C(8)F(17)(CH(2))(2)C(6)H(4))PPh(2)] outperforms a commercially available resin-bound phosphine in a competitive benzylation experiment by a factor of about 4.     

Reaction of organylxenonium(II) salts, [RXe][Y], with organyl iodides, R'I, in anhydrous HF: scope and limitation of a new synthetic approach to iodonium salts, [RR'I][Y

Perfluoroalkynylxenonium salts, [RXe][BF(4)] (R = CF(3)C≡C, (CF(3))(2)CFC≡C), reacted with organyl iodides, R'I (R' = 3-FC(6)H(4), C(6)F(5), CF(2)═CF, CF(3)CH(2); no reaction with R' = CF(3)CF(2)CF(2)) in anhydrous HF to yield the corresponding asymmetric polyfluorinated iodonium salts, [RR'I][Y]. The action of the arylxenonium salt, [C(6)F(5)Xe][BF(4)], and the cycloalkenylxenonium salt, [cyclo-1,4-C(6)F(7)Xe][AsF(6)], on 4-FC(6)H(4)I gave [C(6)F(5)(4-FC(6)H(4))I][BF(4)] and [cyclo-1,4-C(6)F(7)(4-FC(6)H(4))I][AsF(6)], respectively, besides the symmetric iodonium salt, [(4-FC(6)H(4))(2)I][Y]. But the aryl-, as well as the cycloalkenylxenonium salt, did not react with C(6)F(5)I, CF(2)═CFI, and CF(3)CH(2)I.     

2-[1-(2,6-Dibenzhydryl-4-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridylcobalt(II) dichlorides: synthesis, characterization and ethylene polymerization behavior

A series of unsymmetrical 2,6-bis(imino)pyridylcobalt(II) complexes, {2-[2,6-(CH(C(6)H(5))(2))(2)-4-Me-C(6)H(2)N==C(CH(3))]-6-(2,6-R(1)(2)-4-R(2)-C(6)H(2)N==CCH(3))-C(5)H(3)NCoCl(2)} where R(1) = Me, Et or (i)Pr, R(2) = H or Me, together with the new symmetrical complex 2,6-[2,6-(CH(C(6)H(5))(2))(2)-4-Me-C(6)H(2)N==C(CH(3))](2)-C(5)H(3)NCoCl(2), were synthesized. All of the compounds were fully characterized by (1)H NMR and IR spectroscopy, as well as by elemental analysis. The molecular structures of Co1 (R(1) = Me, R(2) = H) and Co5 (R(1) = Et, R(2) = Me) were further confirmed by single crystal X-ray diffraction, which indicated that the cobalt centres were penta-coordinate with a pseudo square-pyramidal geometry. Upon treatment with MAO or MMAO, these cobalt pre-catalysts exhibited higher activities than any previously reported cobalt pre-catalysts, with values as high as 4.64 × 10(6) g PE mol(-1)(Co) h(-1) for ethylene polymerization at atmospheric pressure. The polyethylenes obtained were of high molecular weight and narrow molecular weight distribution.     

Synthesis and structures of some new types of lithium beta-diketiminates

The tetracyclic dilithio-Si,Si'-oxo-bridged bis(N,N'-methylsilyl-beta-diketiminates) 2 and 3, having an outer LiNCCCNLiNCCCN macrocycle, were prepared from [Li{CH(SiMe(3))SiMe(OMe)(2)}](infinity) and 2 PhCN. They differ in that the substituent at the beta-C atom of each diketiminato ligand is either SiMe(3) (2) or H (3). Each of and has (i) a central Si-O-Si unit, (ii) an Si(Me) fragment N,N'-intramolecularly bridging each beta-diketiminate, and (iii) an Li(thf)(2) moiety N,N'-intermolecularly bridging the two beta-diketiminates (thf = tetrahydrofuran). Treatment of [Li{CH(SiMe(3))(SiMe(2)OMe)}](8) with 2Me(2)C(CN)(2) yielded the amorphous [Li{Si(Me)(2)((NCR)(2)CH)}](n) [R = C(Me)(2)CN] (4). From [Li{N(SiMe(3))C(Bu(t))C(H)SiMe(3)}](2) (A) and 1,3- or 1,4-C(6)H(4)(CN)(2), with no apparent synergy between the two CN groups, the product was the appropriate (mu-C(6)H(4))-bis(lithium beta-diketiminate) 6 or 7. Reaction of [Li{N(SiMe(3))C(Ph)=C(H)SiMe(3)}(tmeda)] and 1,3-C(6)H(4)(CN)(2) afforded 1,3-C(6)H(4)(X)X' (X =CC(Ph)N(SiMe3)Li(tmeda)N(SiMe3)CH; X' = CN(SiMe3)Li(tmeda)NC(Ph)=C(H)SiMe3)(9). Interaction of A and 2[1,2-C(6)H(4)(CN)(2)] gave the bis(lithio-isoindoline) derivative [C6H4C(=NH)N{Li(OEt2)}C=C(SiMe3)C(Bu(t))=N(SiMe3)]2 (5). The X-ray structures of 2, 3, 5 and 9 are presented, and reaction pathways for each reaction are suggested.     

Oxidations of secondary alcohols to ketones using easily recyclable bis(trifluoroacetate) adducts of fluorous alkyl iodides, CF3(CF2)(n-1)I(OCOCF3)2

Reactions of commercial fluorous alkyl iodides RfnI (1-Rfn; Rfn = CF3(CF2)(n-1); n = 7, 8, 10, 12) with 80% H2O2 and trifluoroacetic anhydride give RfnI(OCOCF3)2 (2-Rfn; 97-89%). These efficiently oxidize aliphatic and benzylic secondary alcohols to the corresponding ketones (92-57%) in the presence of aqueous KBr and absence of organic or fluorous solvents. Bromide ion activates the reagents and/or generates a relay oxidant such as a functional equivalent of Br+. Oxidations are much more rapid (<30 min, 2-R(f8); <70 min, 2-R(f10)) than with other iodine(III) compounds under similar conditions. The coproducts 1-Rfn can be recovered by adding 3-5 volumes of methanol to the reaction mixtures. Fluorous/methanolic liquid/liquid (1-R(f8)) or solid/liquid (1-R(f10)) biphase systems result. The recovered 1-Rfn can be reoxidized to 2-Rfn and reused. Three cycles are conducted with 1-phenyl-1-propanol and 2-R(f10). The propiophenone yields range from 92% to 83% per cycle, and after the final cycle 59-57% of the original charge of the fluorous iodide species is recovered.     

Synthesis and platinum coordination chemistry of the perfluoroalkyl acceptor pincer ligand, 1,3-(CH(2)P(CF(3))(2))(2)C(6)H(4)

The synthesis of perfluoroalkyl-substituted "pincer"-type PCP ligands, 1,3-C6H4(CH2P(Rf)2)2 (Rf = CF3, C2F5), and platinum coordination studies (Rf = CF3) are reported. 1,3-C6H4(CH2P(CF3)2)2 (CF3PCPH) reacts at ambient temperatures with (cod)Pt(Me)Cl (cod = 1,5-cyclooctadiene) and (cod)PtMe2 to afford unmetalated PCPH-bridged products [(CF3PCPH)Pt(Me)Cl]x and cis-[(CF3PCPH)PtMe2]2, respectively. cis-[(CF3PCPH)PtMe2]2 is soluble and has been spectroscopically and crystallographically characterized. Thermolysis of these compounds results in the loss of methane and the formation of metalated complexes (CF3PCP)PtCl and (CF3PCP)PtMe. Treatment of (CF3PCP)PtCl with MeMgBr provides an alternative route to (CF3PCP)PtMe. The carbonyl cation (CF3PCP)Pt(CO)+SbF6- (nu(CO) = 2143 cm(-1)) was readily prepared by chloride abstraction with AgSbF6 under 1 atm CO. nu(CO) data indicates that RfPCP ligands are electronically analogous to trans acceptor phosphine complexes such as trans-((C2F5)2PMe)2Pt(Me)(CO)+ (nu(CO) = 2149 cm-1).     

Dehydration reaction of hydroxyl substituted alkenes and alkynes on the Ru(2)S(2) complex

A variety of inter- and intramolecular dehydration was found in the reactions of [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)(mu-S(2))](CF(3)SO(3))(4) (1) with hydroxyl substituted alkenes and alkynes. Treatment of 1 with allyl alcohol gave a C(3)S(2) five-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)CH(2)CH(OCH(2)CH=CH(2))S]](CF(3)SO(3))(4) (2), via C-S bond formation after C-H bond activation and intermolecular dehydration. On the other hand, intramolecular dehydration was observed in the reaction of 1 with 3-buten-1-ol giving a C(4)S(2) six-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2) [mu-SCH(2)CH=CHCH(2)S]](CF(3)SO(3))(4) (3). Complex 1 reacts with 2-propyn-1-ol or 2-butyn-1-ol to give homocoupling products, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCR=CHCH(OCH(2)C triple bond CR)S]](CF(3)SO(3))(4) (4: R = H, 5: R = CH(3)), via intermolecular dehydration. In the reaction with 2-propyn-1-ol, the intermediate complex having a hydroxyl group, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OH)S]](CF(3)SO(3))(4) (6), was isolated, which further reacted with 2-propyn-1-ol and 2-butyn-1-ol to give 4 and a cross-coupling product, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OCH(2)C triple bond CCH(3))S]](CF(3)SO(3))(4) (7), respectively. The reaction of 1 with diols, (HO)CHRC triple bond CCHR(OH), gave furyl complexes, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SSC=CROCR=CH]](CF(3)SO(3))(3) (8: R = H, 9: R = CH(3)) via intramolecular elimination of a H(2)O molecule and a H(+). Even though (HO)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OH) does not have any propargylic C-H bond, it also reacts with 1 to give [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)C(=CH(2))C(=C=C(CH(3))(2))]S](CF(3)SO(3))(4) (10). In addition, the reaction of 1 with (CH(3)O)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OCH(3)) gives [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(2)][mu-S=C(C(CH(3))(2)OCH(3))C=CC(CH(3))CH(2)S][Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)]](CF(3)SO(3))(4) (11), in which one molecule of CH(3)OH is eliminated, and the S-S bond is cleaved.     

Novel fluorous amphiphilic heteroleptic Ru-based complexes for a dye-sensitized solar cell: the first fluorous bis-ponytailed amphiphilic Ru complexes

A new series of amphiphilic heteroleptic ruthenium(II) sensitizers with a fluorous bis-ponytailed bipyridine ancillary ligand, [Ru(H(2)dcbpy)(4,4'-bis(R(f)CH(2)OCH(2))-2,2'-bpy)(NCS)(2)] [where R(f) = HCF(2)CF(2) (CT4), C(3)F(7) (CT7), and HCF(2)CF(2)CF(2)CF(2) (CT8)], have been synthesized and fully characterized by UV/vis, visible emission, NMR, fast atom bombardment mass spectrometry, and cyclic voltammetric studies. Dye-sensitized solar cells (DSCs) based on these dyes exhibit efficiencies comparable with that of the standard cell based on N719. The conversion efficiency of a CT7- or CT8-based DSC is ~9% higher than that of Z907 with a nonfluorous bis-ponytailed bipyridine ancillary ligand. The fluorous chains were found to increase the dye density on TiO(2) and to help to suppress the dye desorption.     

Fluorous biphasic catalysis: synthesis and characterization of copper(I) and copper(II) fluoroponytailed 1,4,7-Rf-TACN and 2,2'-Rf-bipyridine complexes--their catalytic activity in the oxidation of hydrocarbons,olefins, and alcohols,including mechanistic implications

In this contribution on fluorous biphasic catalysis (FBC), we present the synthesis and characterization of new copper complexes, and define their role, as precatalysts, in the FBC oxidation of hydrocarbons, olefins, and alcohols. Thus the previously reported, but poorly characterized, fluoroponytailed ligand, 2,2'-R(f)-bipyridine (R(f)=-(CH(2))(3)C(8)F(17)) 2, as well as the new Cu(II) fluoroponytailed carboxylate synthon complex [Cu(C(8)F(17)(CH(2))(2)CO(2))(2)] 3, will be addressed. Moreover, the reaction of previously described ligands, 1,4,7-R(f)-TACN 1, or 2,2'-R(f)-bipyridine 2 with 3 afforded new perfluoroheptane-soluble Cu(II) complexes, [Cu(C(8)F(17)(CH(2))(2)CO(2))(2)(R(f)-tacn)] 4 and [Cu(C(8)F(17)(CH(2))(2)CO(2))(2)(R(f)-bpy)] 5, respectively. The reaction of 1 with [Cu(CH(3)CN)(4)]PF(6) or [CuCl] provided new Cu(I) complexes, which could be isolated and fully characterized as [Cu(R(f)-tacn)X']X, in which X=PF(6) (6) or X'=Cl (7) (soluble in perfluoroheptane). The Cu(II) and Cu(I) complexes, 4-7, were characterized by elemental analysis, mass spectrometry, and IR, diffuse reflectance UV/Vis, and EPR spectroscopies; complex 7 was also characterized by (1)H and (19)F[(1)H] NMR spectroscopy. Complexes 4 and 5, as well as 6 and 7 generated in situ, were evaluated as precatalysts for hydrocarbon and olefin functionalization. The oxidation reactions of these substrates in the presence of the necessary oxidants, tert-butyl hydroperoxide (TBHP) and oxygen gas, proceeded under FBC conditions for 5, 7, and Cu(I) salts with 2. However, the complexes with ligand 2 could not be recycled, owing to significant ligand dissociation. The Cu(II) complex 4, with the ligand 1, provide the oxidation of 4-nitrobenzyl alcohol to 4-nitrobenzaldehyde under single-phase FBC conditions at 90 degrees C with TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy) and O(2); the precatalyst 4, can be utilized for an additional four catalytic cycles without loss of activity. Plausible mechanisms concerning these FBC oxidation reactions will be discussed.