Tropylium tetrafluoroborate is an organic compound with the formula [C₇H₇]⁺[BF₄]⁻. Containing the tropylium cation and the non-coordinating tetrafluoroborate counteranion, tropylium tetrafluoroborate is a rare example of a readily isolable carbocation. It is a white solid.^[1]

Tropylium tetrafluoroborate

Names
Preferred IUPAC name Cycloheptatrienylium tetrafluoroboranuide
Other names Cycloheptatrienyl tetrafluoroborate
Identifiers
CAS Number	27081-10-3 Y
3D model (JSmol)	Interactive image
ChemSpider	134784
ECHA InfoCard	100.043.816
EC Number	248-214-5
PubChem CID	152926
UNII	DFS83J4CRL Y
InChI InChI=1S/C7H7.BF4/c1-2-4-6-7-5-3-1;2-1(3,4)5/h1-7H;/q+1;-1 Key: SQVQHTIKOZVGLR-UHFFFAOYSA-N
SMILES F[B-](F)(F)F.c1[cH+]ccccc1
Properties
Chemical formula	[C7H7]+[BF4]−
Molar mass	177.94 g·mol−1
Appearance	white solid
Melting point	200 °C (392 °F; 473 K) decomposition
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Related compounds
Other anions	Tetrafluoroborate
Other cations	Tropylium
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

This compound may be prepared by the reaction of cycloheptatriene with phosphorus pentachloride, followed by tetrafluoroboric acid.^[1][2]