Dicarbonyl Hexafluorophosphate

Olefins do not react with cyclopentadienyliron dicarbonyl halides by themselves. However, the preparation of cations [CftHsFe (CO) 2olefin]+, where olefin = ethylene, propylene, 1- 

A 275-mg. (1-mmole) sample of C5H6Fe(CO)2Br is dissolved in 20 ml. of dry cyclohexene. After addition of 800 mg. (3 mmoles) of AlBr3, the red reaction mixture is stirred at room temperature for 4 hours. A red viscous oil is formed quite rapidly, and after 4 hours the solution is almost colorless. The colorless cyclohexene layer is decanted and the residue dried under high vacuum. About 20 ml. of ice-cold water is added while cooling with ice, and the orange solution is filtered into an excess of a concentrated solution of ammonium hexafluorophosphate. The precipitate is collected and dried under high vacuum. For further purification, the yellow salt is dissolved in 10 ml. of acetone, and, after filtration, ether is added drop-wise until no more precipitate separates. After a second crystallization, the product is obtained in about 40% yield, based on C8H5Fe(CO)2Br. Anal. Calcd. C, 38.64 H, 3.74 F, 28.21 Fe, 13.8 P, 7.67. Found C, 38.55 H, 3.75 F, 28.6 Fe, 13.8 P, 7.43. 

The complex salt crystallizes in yellow platelets, is fairly stable in air, darkens at 129°C., is soluble in acetone, and is insoluble in water and ether. 

If cyclopentadienyliron dicarbonyl halides are allowed to react with themselves in the presence of Lewis acids, cations are formed in which the new substituent is the cyclopentadienyliron dicarbonyl halide itself, for example, [CjH6Fe(CO)i-X-(CO)2-FeC8H8]+ (X = Cl, Br, I). All three cations can be prepared best by treatment of the corresponding halides with boron trifluoride diethyl etherate all are isolated as tetrafluoro-borates.18 The bromine complex can also be obtained by a more complicated procedure by the reaction between C8H8Fe-(CO)2Br and AlBr3 in liquid sulfur dioxide 16 the iodine cation can be isolated from a melt of cyclopentadienyliron dicarbonyl iodide and aluminum chloride.17 In the latter two cases the hexafluorophosphate salts can be obtained. These binuclear cations are of special interest, because they are cleaved by electron donors,16-17 e.g., aniline, pyridine, benzonitrile, acetonitrile, acrylonitrile, with the formation of the corresponding [C8H8Fe(CO)2L]+ cations and the parent halide. Equations for preparation of the tetrafluoroborate are  

75-mmole) sample of C8HsFe(CO)2Cl is placed in a small Schlenk tube (see page 10) of about 50-ml. volume. A 7-ml. sample of freshly distilled BF3-0(C2H8)2 is added, and the solution is heated to 40-50°C. for 1 hours. During that time the color changes from light red to deep purple. The reaction mixture is then frozen in liquid nitrogen, and 10 ml. of a saturated solution of sodium tetrafluoroborate is added. The 

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A carbon-iron bond is also formed by the reaction of the cyclopropenium salt 185 with dicarbonyl(i/5-cyclopentadienyl)(trimethylsilyl)iron [92], (Scheme 69) In the reaction with benzocyclobutenylidene- 5-cyclopentadienyliron(II) hexafluorophosphate 186, CpFe(CO)2R (R=cyelo-C3H5, CH2-cyclo-C3H5) is converted to the allene and butadiene complexes, 187 and 188, respectively [93]. (Scheme 70)... 

Experimental Procedure 2.1.3. Preparation of an Iron Carbene Complex by a-Abstraction of Hydride Dicarbonyl(T 5-cyclopentadienyl)(phenylthiocarbene) iron hexafluorophosphate [179]... 

The retrosynthetic analysis of the 2-oxygenated carbazole alkaloids, 2-methoxy-3-methylcarbazole (37), O-methylmukonal (glycosinine) (38), 2-hydroxy-3-methylcar-bazole (52), and mukonal (53) based on the molybdenum-mediated approach led to the molybdenum-complexed cation (663) and 3-methoxy-4-methylaniline (655) as precursors (Scheme 5.51). The cationic molybdenum complex, dicarbonyl (ri -cyclohexadiene)(r -cyclopentadienyl)molybdenum hexafluorophosphate (663), required for the electrophilic substitution, was easily prepared quantitatively through known literature procedures (586,587). 

We reported the first total synthesis of l,T-bis(2-hydroxy-3-methylcarbazole) (213) using our molybdenum-mediated construction of the carbazole framework (560). The required monomer, 2-hydroxy-3-methylcarbazole (52), was obtained in three steps, and 22% overall yield, starting from dicarbonyl(ri -cyclohexa-l,3-diene)(ri -cyclopentadienyl)molybdenum hexafluorophosphate (663) and 3-meth-oxy-4-methylaniline (655) (560) (see Scheme 5.52). Finally, oxidative coupling of the monomer 52 using p-chloranil afforded l,T-bis(2-hydroxy-3-methylcarbazole) (213) in 38% yield (560) (Scheme 5.167). 

FeF602PCuHi3, Iron(l +), ( -cyclopenta-dienyl)dicarbonyl(tetrahydrofuran)-hexafluorophosphate(l-), 26 232 FeMoNO,P2C45H3 Molybdate(l -), hy-drido-nonacarbonyliron-li-nitrido-bis(triphenylphosphorus)-(1+), 26 338... 

Scheme 10 Preparation of dicarbonyl(triphenyl phosphite)(cycloheptadienyl)iron hexafluorophosphate...

Cyclopentadienyl)dicarbonyl(phenylthio)carbenium]iron hexafluorophosphate 103... 

DICARBONYL(iis-CYCLOPENTADIENYL)(THIO-CARBONYL)IRON(l +) HEXAFLUOROPHOSPHATE(l -) AND DICARBONYL(iis-CYCLOPENTADIENYL)-[(METHYLTHIO)THIOCARBONYL]IRON... 

PBFj02WC25H2,i, Tungsten, dicarbonyl(ti -cyclopentadienyl)[tetrafluoroborato-(1 - )](triphenylphosphine)-, 26 98 PBrFftN.,RuC 4H2i, Ruthenium(ll), tris(ace-tonitrile)bromo(ti -1,5-cyclooctadiene)-, hexafluorophosphate( I -), 26 72 PCiHv, Phosphine, trimethyl-, 26 7 tungsten complex, 27 304 C,H , Phosphine, (2,2-dimethylpropyli-dyne)-, 27 249, 251... 

PF6Fe07C,iH ), Iron(l + ), (ri -cyclopenta-dienyl)dicarbonyl(tetrahydrofuran)-, hexafluorophosphate(l -), 26 232 PFftFeaOsCiiiHij, Iron(l + ), p-acetyl-C 0-bis[dicarbonyl(T]-cyclopentadienyl)-, hexafluorophosphate(l -), 26 235 PF7M0O2C5JH4, Molybdenum(II), dicar-bonylbis[ 1,2-ethanediylbis(diphenyl-phosphine)]fluoro-, hexafluorophos-phate(l -), 26 84 PFe04Ci2H, Iron, tetracarbonyl-... 

A twofold excess of alkene was added to a solution of dicarbonyl(j -cyclopentadienyl)phenylcarbeneiron hexafluorophosphate in CHjClj at — 78 °C. After 1 - 2 h of stirring at this temperature the solution was slowly warmed to 25 C. Pentane was added to precipitate iron-containing salts and, after filtration and solvent removal, the phenylcyclopropane was isolated by bulb-to-bulb distillation (oils) or recrystallization (solids). A number of alkenes were reacted according to this procedure. The results are compiled in the table above. 

Tris(acetonitrile)dicarbonyl(i -l,2,3-triphenylcyclopropenyl)molybdenum(I) Hexafluorophosphate (15, X = PFj) Typical Procedure ... 

Dicarbonyl-/i5-cyclopentadienylnitrosylmanganese(l + ) hexafluoro-phosphate(l —) is usually prepared1 by the reaction of tricarbonyl-fi5-cyclopentadienylmanganese with sodium nitrite and hydrochloric acid in refluxing ethanol. The cationic nitrosyl is isolated by the addition of ammonium hexafluorophosphate to the reaction mixture. This procedure yields up to 50 % of the product in a total reaction time of several hours. A more efficient preparation is the direct reaction of [Mn(C5H5)(CO)3] with [NO][PF6] in acetonitrile, which allows the isolation of the cationic complex in quantitative yield in less than one hour. 

FeFg02PC, H 3, Iron(l+), (ri -cyclopenta-dienyl)dicarbonyl(tetrahydrofuran)-, hexafluorophosphate(l—), 26 232 FeF 2N6P2C5oH52, Iron(II), [3,11-dibenzyl-14,20-dimethyl-2,12-diphenyl-... 

OjFjFeSjCgHj, Iron(l-t-), dicaibonyl(Ti -cyclopentadienylXthiocarbonyl)-, tii-fluoromethanesulfonate, 28 186 OsFgFeMoP2C34H2g, Iron(l +X p-acetyl-2icC -lKO-tetracarbonyl-lK C,2K C-bis( 12 (tl "cyclopentadienyl)l(tri-phenylphosphine-1 KP)molybdenum-, hexafluorophosphate(l—), 26 241 OjFgFejPCioHij, Iron(I+), ti-acetyl-C 0-bis(dicarbonyl(Ti-cyclopentadienyl)-, hexafluorophosphate(l—), 26 235 OjHReCj, Rhenium, pentacarbonyl-hydrido-, 26 77... 

Cationic olefin complexes of dicarbonyl(T) -cyclopentadienyl) iron have been of wide interest in syntheses for a number of years. These complexes, generally isolated as their tetrafluoroborate or hexafluorophosphate salts, have been prepared by the reaction of Fe(-n -C5H5)(CO)2Br with simple olefins in the presence... 

The direct conversion of carbyne complexes TpW( = CR)(CO)2 (R = Ph, C6H4Me-4) to cationic c/ -dicarbonyl -phosphinocarbene (metallaphosphacyclo-propene) complexes can be achieved by the addition of chlorodiorganophosphines in the presence of sodium tetraphenylborate or thallium hexafluorophosphate (Scheme 51)/ In the absence of these sodium salts, nucleophile (Cl )-induced carbonyl-carbene coupling affords neutral -phosphinoketene complexes. 

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