Iridium -, tetrafluoroborate borate

After extensive experimentation, a simple solution for avoiding catalyst deactivation was discovered, when testing an Ir-PHOX catalyst with tetrakis[3,5-bis (trifluoromethyl)phenyl]borate (BArp ) as counterion [5]. Iridium complexes with this bulky, apolar, and extremely weakly coordinating anion [18] did not suffer from deactivation, and full conversion could be routinely obtained with catalyst loadings as low as 0.02 mol% [19]. In addition, the BArp salts proved to be much less sensitive to moisture than the corresponding hexafluorophosphates. Tetrakis (pentafluorophenyl)borate and tetrakis(perfluoro-tert-butoxy)aluminate were equally effective with very high turnover frequency, whereas catalysts with hexafluorophosphate and tetrafluoroborate gave only low conversion while reactions with triflate were completely ineffective (Fig. 1). 

OjBFtFeCijHij, Iron(l +), dicarbonyl(i) -cyclopentadienyl) (tt -2-methyl-l-propene)-, tetrafluoroborate(l —), 28 210 02BF4lrP2C3gH]g, Iridium(l +), diaqua-dihydridobis(triphenylphosphine)-, tetra-fluoroborate(l—), 26 124, 28 58 02BF4lrP2C42H44, Iridium(l +), bis(acetone)dihydTidobis(tri-phenylphosphine)-, tetrafluoro-borate(l -), 26 123, 28 57 O2BF4M0PC25H20, Molybdenum,... 

BClFglrOPgCggHgg, Iridium(IIlX caibonyl-cbloromethyl[tetnlluorobonto-(1 —)]bis(triplienylpliosplime)-, 26 118 BFg, Borate(l -X tetnfluoro-, molybdenum and tungsten complexes, 26 96-105 BFgFeOjC,, H,3, Iron(l +X dicarbonyl(if -cyclopentadienyl) ( f -2-methyl-l-propene)-, tetrafluoroborate(l -),... 

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