Tricarbonyl tetrafluoroborate

Figure 7. Structure and infrared spectrum, carbonyl region, of w-l-methyl-5-ethyl-pentadienyiiron tricarbonyl tetrafluoroborate.

C. 7 ricar6oni/Z[( 1,2,3,4,5-jj)-l-and 2-methoxy-2,4 -cydohexadien-l-yl]-irTriphenylmethyl tetrafluoroborate [Methylium, triphenyl-, tetrafluoroborate] (34 g., 0.103 mole) (Note 20) is dissolved in a minimum volume of dichloromethane and 18 g. (0.072 mole) of tricarbonyl (1- and 2-methoxy-l,3-cyclohexadiene)iron dissolved in a like volume of dichloromethane is added. The resulting dark solution is left for 20-30 minutes and then added with stirring to three times its volume of ether (Note 21). The precipitate is collected and washed with ether to 5ueld 21-22 g. (87-91%) of product as yellow solid (Note 19). 

Treatment with HBF4 in CHCI3 liberates the thiol and returns the derivatizing agent, [(T7- C6H7)Fe(CO)3] BF4 [tricarbonyl[l,2,3,4,5-77]-2,4-cyclohexadien-l-yl-iron(]+) tetrafluoroborate] as a precipitate. ... 

The iron-mediated construction of the carbazole framework proceeds via consecutive C-C and C-N bond formation as key steps [70,71]. The C-C bond formation is achieved by electrophilic substitution of the arylamine with a tricarbonyliron-coordinated cyclohexadienyl cation. The parent iron complex salt for electrophilic substitutions, tricarbonyl[/j -cyclohexadienylium] iron tetrafluoroborate 6a, is readily available by azadiene-catalyzed complexation and subsequent hydride abstraction (Scheme 9). 

BF4MoOPCwH](), Molybdenum(l +), car-bonyl-(-n5-cyclopentadienyl)-(diphenylacetylene)-(triphenylphosphine)-tetrafluoroborate(l -), 26 104 BF4MoO2PC25H20, Molybdenum, dicarbonyl-(T) -cyclopentadienyl)-[tetrafluoroborato(l -)] (triphenylphosphine)-, 26 98 BF4MoOjCbH5, Molybdenum, tricarbonyl-(ry -cyclopentadienyl) [tetrafluorobor-ato (1-)]-, 26 96... 

BF404WC,]Hm, Tungsten(l +), (acetone)-tricarbonyl(r 5-cyclopentadienyl)-tetrai1uoroborate(l -), 26 105 BF40,ReC5, Rhenium, pentacarbonyl-[tetrafluoroborato(l —)]-, 26 108 BF405ReC7H4, Rhenium(l+), pentacar-bonyl-(-r)2-ethene)-tetrafluoroborate( 1 —), 26 110 BO PtC Fl, Platinum(II), (3-methoxy-3-oxo-KO-propyl-KC )bis(triethyl-phosphine)-... 

The relative reactivities of indole, 2- and N-methylindole, pyrrole, thiophene, and furan have been determined in alkylation by a benzenonium ion coordinated to iron tricarbonyl (73CC540). The effects of methyl substituents in pyrrole were determined in alkylation by 4-(7V,7V-dimethyl-amino)benzaldehyde [76JCS(P2)696]. In neither of these methods, nor in the alkylation of indole by aziridinium tetrafluoroborate [67AG(E)178], nor in self-alkylation of a X5-phosphorinyl tetrafluoroborate [73AG (E)753], is a catalyst required. 

Cyclopentadienyl tricarbonyl tungsten anion arylated by benzene-diazonium tetrafluoroborate gave t7-C5H5W(C6H5)(CO)3 in a yield as low as 3%- The main product was identified as 7t-C5H5W(CO)2N=NC6H5,... 

Dienes are generally much less reactive when coordinated to transition metals than when in an uncoordinated state. An important discovery was thus made by Fischer and Fischer (86) in 1960 when they found that cyclo-hexadiene-iron tricarbonyl (XV) (formed from 1,3-cyclohexadiene and iron pentacarbonyl) undergoes hydride ion abstraction by triphenylmethyl tetrafluoroborate to form 7r-cyclohexadienyl-iron tricarbonyl tetra-fluoroborate (XVI) ... 

Although Able et al. (2, 8) had originally set out to prepare 7r-cyclo-heptatrienyl complexes of metals, the cycloheptatriene complexes they actually obtained served as key intermediates in forming the former complexes. In 1958 Dauben and Honnen (61) reported that cycloheptatriene-molybdenum tricarbonyl reacted with triphenylmethyl tetrafluoroborate in methylene chloride solution with abstraction of hydride ion from the molybdenum complex. The reaction products, obtained in nearly quantitative yields, were triphenylmethane and the 7r-cycloheptatrienyl complex [(7r-C7H7)Mo(CO)3]+BF4 . 

Another important development in cyclooctatetraene-metal chemistry has concerned the protonation of C8H8-metal derivatives 59, 221). The complex (C8H8)Fe(CO)3 is readily protonated in strong acids to yield salts of the type [(C8H9)Fe(CO)3] X , where X = Cl, CIO4, or BF4. The proton NMR spectrum indicates the complex contains the bicyclo-[5.1.0]-octadienyl-iron tricarbonyl cation (XXXIX), and this formulation is supported by the observation that when the tetrafluoroborate salt of... 

Rhenium(l +), pentacarbonyl(T) -ethene)-, tetrafluoroborate(I —), 26 110 Rhenium. (2,2 bipyridine)tricarbonyl-fluoro-, 26 82... 

WBF404C, Hii, Tungsten(l + ), (acetone)-tricarbonyl(T -cyclopentadienyl)-, tetrafluoroborate(l -), 26 105 WBiF N OjCiiH, Tung ten(II),tetraki -(acetonitrile)dinitrosyl-,cu-, bi (tetra-fluoroborate(l -)], 26 133 WC H42, Tungsten(VI), tris(2,2-dimethyl-propys)(2.2-demethylpropylidyne)-, 26 47... 

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