Di tetrafluoroborate

BF4Fl5lr2P4C54Hj2, lridium(l +), pentahydri-dobi 1,3-propanediylbis(diphenylphos-phine)]di-, tetrafluoroborate(l -),... 

HiBFJriCwHv, Iridium(l +), [1,4-buta-nedi-bis(diphenylphosphine)]di-, tetra-fluoroborate( I -), 27 26 Hpropanediylbis(diphenyl-phosphine)]di-, tetrafluoroborate (I-), 27 22... 

F4BH,Ir2P4CsJls2, Iridium(l+), pentahydri-dobis[ 1,3-propanediylbis(diphenyl-phosphine)]di-, tetrafluoroborate(I -),... 

Poly[(4,4 -trimethylene-bis- 1-methyl piperidine)-iV-(2,3-butene)di-tetrafluoroborate] SEC, HEMA 2898... 

Fluoride ion attacks the sulfur atom in 2,3-diphenylthiirene 1,1-dioxide to give ck-1,2-diphenylethylenesulfonyl fluoride (23%) and diphenylacetylene (35%). Bromide or iodide ion does not react (80JOC2604). Treatment of S-alkylthiirenium salts with chloride ion gives products of carbon attack, but the possibility of sulfur attack followed by addition of the sulfenyl chloride so produced to the alkyne has not been excluded (79MI50600). In fact the methanesulfenyl chloride formed from l-methyl-2,3-di- -butylthiirenium tetrafluoroborate has been trapped by reaction with 2-butyne. A sulfurane intermediate may be indicated by NMR experiments in liquid sulfur dioxide. 

Thiiranium salts, l-methyI-2-methylene-1-oxide, 7, 134 Thiiranium salts, I-phenyl-collisional activation spectra, 7, 135 Thiiranium tetrafluoroborate, 2,3-di-t-butyl-l-methyl-inversion barriers, 7, 134 Thiiranium ylides formation, 7, 174, 175 Thiiran-2-ones... 

Deprotonation of l-methyl-3-ferrocenylimidazolium tetrafluoroborate or iodide (98JOM(552)45) by lithium di-Mo-propylamide and subsequent reaction with W(C0)5-THF gives the carbene complex 107 and bis-carbene 108, even when excess W(CO)j THF is applied (99JOM(572)177). Numerous ferrocenyl benzimidazoles are known (97RCR613, 99JOM(580)26). 

H- and 3//-Azepines are generally unstable in aqueous acid solution and the few examples of simple azepinium salts, namely perchlorates,77 bromides,105 picrates35201 and a solitary iodide,105 have been prepared under nonaqueous conditions. The fractional crystallization of oxalate salts has been used for the separation of mixtures of 4- and 6-substituted 3f/-azepines,66 and 3,6-di-tm-butyl- and 2,5-di-tert-butyl-3//-azepine, on treatment with tetrafluoroboric acid in acetonitrile, are converted quantitatively into their crystalline tetrafluoroboratc salts.70... 

The thiazepinone 6 reacts with trimethyloxonium tetrafluoroborate in diuhloromethane, followed by aqueous sodium hydrogen carbonate, to give 2,7-di- c-y7-butyl-5-methoxy-l,4-thiazepine (7) in 65 % yield. No further details were reported.48... 

The agents used for oxidative aromatization of various thiopyrans were air-dioxygen (81KFZ38 83KGS1689 91KGS181), trityl tetrafluoroborate (81CC1143 85CL1119), 3,4-di-(/-butyl)-l,2-benzoquinone (DTBQ)... 

On the basis of these redox potentials it seems likely that direct electron release to the benzenediazonium ion takes place only with iodide. This corresponds well with experience in organic synthesis iodo-de-diazoniations are possible without catalysts, light, or other special procedures (Sec. 10.6). For bromo- and chloro-de-di-azoniations, catalysis by cuprous salts (Sandmeyer reaction, Sec. 10.5) is necessary. For fluorination the Balz-Schiemann reaction of arenediazonium tetrafluoroborates in the solid state (thermolysis) or in special solvents must be chosen (see Sec. 10.4). With astatide (211At-), the heaviest of the halide ions, Meyer et al. (1979) found higher yields for astato-de-diazoniation than for iodo-de-diazoniation, a result consistent with the position of At in the Periodic System. It has to be emphasized, however, that in investigations based on measuring yields of final products (Ar-Hal), the possibility that part of the yield may be due to heterolytic dediazoniation is very difficult to quantify. 

Penton and Zollinger (1979, 1981 b) reported that this could indeed be the case. The coupling reactions of 3-methylaniline and A,7V-dimethylaniline with 4-methoxy-benzenediazonium tetrafluoroborate in dry acetonitrile showed a number of unusual characteristics, in particular an increase in the kinetic deuterium isotope effect with temperature. C-coupling occurs predominantly (>86% for 3-methylaniline), but on addition of tert-butylammonium chloride the rate became much faster, and triazenes were predominantly formed (with loss of a methyl group in the case of A V-di-methylaniline). Therefore, the initial attack of the diazonium ion is probably at the amine N-atom, and aminoazo formation occurs via rearrangement. 

Bis[Ar,Ar -di(2-pyridyl)- and -di(2-pyridyl-methyl)-imidazol-2-ylidene]aurate(i) tetrafluoroborates have been prepared from the analogous silver complexes on reaction with (tht)AuCl and their structures determined. The configuration of the cations with sterically well-protected two-coordinate gold centers shows no anomalies. However, fascinating structures are found for the adducts with silver tetrafluoroborate obtained as acetonitrile... 

In the aldohexopyranose series, treatment of methyl 2,3-anhydro-4,6-di-O-methyl-a-D-allopyranoside (34), or of the corresponding 4,6-diacetate (39), with hydrogen tetrafluoroborate in hydrogen fluoride at 70° afforded121 the corresponding derivatives of 2-deoxy-2-fluoro-D-al-tropyranosyl fluoride (35 and 40) and 3-deoxy-3-fluoro-D-glucopyrano-syl fluoride (36 and 41). Compounds 35 and 36 were hydrolyzed, and... 

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