Salts of novel chelatoborate anions: [RFBX(ox)]−(RF = CF3, C2F5; X = F, OMe; ox = oxalato) and [RFB(OMe)(cat)]−(RF = CF3, C2F5; cat = catecholato)

•New chelatoborates are easily accessible from readily available starting materials.•Two different synthetic strategies have been developed.•Oxalato and catecholatoborates reveal a great potential for numerous applications.•Three anions have been characterized by X-ray diffraction in their [Ph4P]+ salts.

Tetraethylammonium and tetraphenylphosphonium salts of the oxalatoborate anions [CF3B(OCH3)(ox)]− (1a), [C2F5B(OCH3)(ox)]− (1b), [CF3BF(ox)]− (1c), and [C2F5BF(ox)]− (1d) have been obtained from easily accessible K[RFB(OCH3)3] and K[RFBF3] (RF = CF3, C2F5), respectively. In addition, the related catecholatoborate anions [CF3B(OCH3)(cat)]− (2a) and [C2F5B(OCH3)(cat)]− (2b) have been synthesized starting from K[RFB(OCH3)3] and catechol. Anions 2a and 2b have been isolated as [Ph4P]+ salts. Two different synthetic strategies have been applied: (i) Reaction of the potassium borate with neat oxalic acid or catechol and (ii) reaction of both components in an ethereal solvent. Salts of all six anions have been obtained via these two different routes except for the [CF3BF(ox)]− anion (1c) that was obtained from a reaction in diglyme, only. The new anions have been characterized by multinuclear NMR spectroscopy and by mass spectrometry ((−)-MALDI or (−)-ESI). Furthermore, the tetraphenylphosphonium salts of the chelatoperfluoroalkylborate anions 1a, 1d, and 2a have been characterized by single-crystal X-ray diffraction.

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